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Du, Jianyi. "Combustion CFD simulation." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0018/NQ56437.pdf.
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Björk, Johan. "Compressor CFD simulation method development : A CFD study." Thesis, Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-69880.
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This master thesis project consisted of three parts that all were performed through CFD simulations with the purpose to develop Scania's methods in the subject of CFD. All parts included simulations on Scania's SC92T70 centrifugal compressor. Part one consisted of performing a mesh study for the purpose of reliability, to investigate the convergence of different parameters by refining the boundary layer. The method used is an inflation option called First layer thickness. Five different meshes were generated where the Richardson extrapolation method was used to examine the parameters between the mesh renements. From the result from the examined parameters, an approximate relative error could be calculated to be less than 0.52 %, and a numerical uncertainty of less than 0.35 %, between Mesh3 and Mesh4. In addition to that, Mesh3 had a simulation time of one hour less than for Mesh4. These results motivated the use of mesh3 to be refined enough for further work in this thesis project. This mesh ended at 37, 915, 257 number of elements. The second part consisted of performing steady state CFD simulations, to examine different parameters in order to find indications of the phenomena surge. Here, experimental data was used as reliance to perform CFD simulations on the compressor. Design points from experimental data was used, that ranged from low mass flow rates where surge arises, to high mass flow rates where another phenomena called choke occur. Except for the design points taken from experimental data, a few extra design points where included at low mass flow rates (in the region of surge). The goal was that the analysis of the different parameters would generate fluctuations on the result for the design points in surge region. Four different rotational speeds on the compressor were examined, 56k, 69k, 87k and 110k revolutions per minute. A total of 140 different parameters were examined, where 10 of these indicated on surge. All of these parameters that indicated on surge where found in regions of vicinity to the compressor wheel, which are the regions subjected to the phenomena.The parameters indicating on surge where mass flow, pressure coefficient, static pressure and temperature. Indications where found at the wheel inlet, ported shroud, and wheel outlet interfaces. The indications were only found for the two lower rotational speeds of the compressor wheel. To capture the behaviour on higher rotational speeds, more design points in the region of surge are needed, or transient simulations. Part three of the thesis project consisted of investigating the methodology of performing a Conjugate Heat Transfer model (CHT) with the CFD code CFX. This part has not been performed by Scania before, so a big part of the problem was to investigate if it actually was achievable. The goal was to use this model to calculate the heat transfer between fluid and solid parts, as well as between the solid parts and the ambient. One question Scania wanted to answer was if the CHT model could generate aerodynamic performance that corresponds to Scania's traditional adiabatic model, as well as to experimental data of the compressor. In this part, both solid and fluid domains were included in the geometryto calculate heat transport, in contrast to the traditional adiabatic model that only uses the fluid domains. Because of that, a big part of the work consisted of defining all interfaces connecting together surfaces between all domains. This is needed to model heat transport between the domains. In the set up part in CFX, the CHT model differed a lot from the traditional adiabatic model in that way that the outer walls was not set up as adiabatic anymore. In the CHT model, instead heat transfer is allowed between the outer walls of the fluids and the solids. From the result simulations, one could see that the CHT model was able to compute the heat transfer between fluids and solids. It also managed to export thermal data such as heat flux and wall heat transfer coefficient to be used for mechanical analysis, which is an important part in Scania's work. From the analysis of aerodynamic performance, a conclusion was drawn that the CHT model was able to compute efficiency and pressure ratio that followed the behaviour ofthe traditional adiabatic model as well as experimental data. However, for lowermass flows, the CHT model started to underpredict which could be explained by the geometrical differences between the CHT and adiabatic model. By analysis of temperature, one could see quantitative differences compared to the traditional adiabatic model. For other parameters (static and total pressure), there were no experimental data to be used for comparison. Because of that, an important part in future work of this CHT method development is to perform more experimental test for CFD data to be compared against. Another important part to compare the models is to have an identical geometry. Without an identical geometry, deviations in result will occur that depends on geometry.
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Vusirikala, Shanti. "CFD simulation of contact planarization." Diss., Rolla, Mo. : University of Missouri-Rolla, 2007. http://scholarsmine.umr.edu/thesis/pdf/Vusirikala_09007dcc80446043.pdf.
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Thesis (M.S.)--University of Missouri--Rolla, 2007.Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed March 25, 2008) Includes bibliographical references (p. 77-79).
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Denton, G. S. "CFD simulation of highly transient flows." Thesis, University College London (University of London), 2009. http://discovery.ucl.ac.uk/18693/.
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This thesis describes the fundamental extension and extensive testing of a robust CFD model for predicting outflow following the failure of pressurised hydrocarbon pipelines. The main thrust of the study involves the extension of the basic outflow model to account for complex pipeline systems, improvements of the theoretical basis and numerical stability. The basic model, based on the numerical solution of conservation equations using the method of characteristics, incorporates a suitable equation of state to deal with pipelines containing pressurised multi-component hydrocarbon mixtures. It utilises the homogeneous equilibrium flow (HEM) assumption, where the constituent phases in a two-phase mixture are assumed to be at thermal and mechanical equilibrium. The first part of the study focuses on the development of an outflow model to simulate the failure of multi-segment pipelines incorporating valves and fittings passing through terrains of different inclinations. In the absence of real data, the numerical accuracy of the model is assessed based on the calculation of a mass conservation index. The results of a case study involving the comparison of the simulated outflow data based on the failure of a multi-segment pipeline as opposed to an equivalent single segment pipeline containing gas, liquid or two-phase inventories are used to highlight the impact of pipeline complexity on the simulated data. The development and extensive testing of two models, namely the Hybrid Model and the Modified Homogeneous Equilibrium Model (MHEM) each addressing a principal limitation of the HEM are presented next. The Hybrid Model deals with the failure of the HEM in predicting post-depressurisation outflow for inclined pipelines containing two-phase mixtures or liquids through its coupling with a hydraulic flow model. The MHEM on the other hand addresses the failure of the HEM to accurately predict the discharge rates of flashing/ two-phase fluids discharging through an orifice. Finally, the dilemma of the appropriate choice of the size and duration of the numerical discritisation steps expressed in terms of the Courant, Friedrichs and Lewy (CFL) criterion on the stability and computational workload of the pipeline failure model is investigated for different classes of hydrocarbon inventories. These include gas, liquid (flashing and incompressible) and two-phase mixtures.
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Shi, Yijian. "Off-design waverider flowfield CFD simulation /." free to MU campus, to others for purchase, 1996. http://wwwlib.umi.com/cr/mo/fullcit?p9717164.
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Kleemann, Andreas Peter. "CFD simulation of advanced diesel engines." Thesis, Imperial College London, 2001. http://hdl.handle.net/10044/1/62159.
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This study uses CFD methodology to simulate an advanced Diesel engine operated at higher than conventional peak cylinder pressures. The existing mathematical models for Diesel combustion, pollutant formation and wall heat transfer are improved and validated for this operating range. The fluid flow is described via the gas-phase Favre-averaged transport equations, governing the conservation of mass, chemical species, momentum and energy, based on the Eulerian continuum framework. These equations are closed by means of the k — e turbulence model. The liquid phase uses the Lagrangian approach, in which parcels, representing a class of droplets, are described by differential equations for the conservation of mass, momentum and energy. The numerical solution of the gas phase is obtained by the finite volume method applied to unstructured meshes with moving boundaries. Diesel ignition is modeled via a reduced kinetics mechanism, coupled with a characteristic timescale combustion model. Additionally, NOx and soot emissions are simulated. For the elevated cylinder temperatures and pressures, the behaviour of the thermophysical properties of the gases and liquids involved is critically examined. A near-wall treatment is applied accounting for the large gradients of thermophysical properties in the vicinity of the wall. Furthermore an alternative combined combustion and emissions modelling approach, RIF, based on the laminar flamelet concept is tested. The methodology is validated by reference to experimental data from a research engine, a constant volume pressure chamber and a high-pressure DI Diesel engine at various operating conditions. The modified near-wall treatment gives better agreement with the heat transfer measurements. The methodology predicts Diesel combustion evolution reasonably well for the elevated pressures. Best agreement was achieved using the LATCT combustion model combined with a NOx and soot model. The predictions of emissions show encouraging trends especially regarding the soot/NOx tradeoff, but require tuning of model coefficients.
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Cedell, Petter. "Forest Simulation with Industrial CFD Codes." Thesis, KTH, Strömningsfysik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-259700.
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Much of the planned installation of wind turbines in Sweden will be located in the northern region, characterized by a lower population density so that problems related to sound pollution and visual acceptance are of lower concern. This area is generally distinguished by complex topography and the presence of forest, that significantly affects the wind characteristics, complicating their modelling and simulation. There are concerns about how good an industrial code can simulate a forest, a question of paramount importance in the planning of new onshore farms. As a first step, a sensitivity analysis was initially carried out to investigate the impact on the ow of different boundary conditions and cell discretization inside the forest for a 2D domain with a homogeneous forest. Subsequently, a comparative analysis between the industrial code WindSim and Large Eddy Simulation (LES) data from Segalini. et al. (2016) was performed with the same domain. Lastly, simulations for a real Swedish forest, Ryningsnäs, was conducted to compare a roughness map approach versus modelling the forest as a momentum sink and a turbulence source. All simulations were conducted for neutral stability conditions with the same domain size and refinement. The main conclusions from each part can be summarized as follows. (i) The results from the sensitivity analysis showed that discretization of cells in the vertical direction inside the forest displayed a correlation between an increasing number of cells and a decreased streamwise wind speed above the canopy. (ii) The validation with the LES data displayed good agreement in terms of both horizontal mean wind speed and turbulence intensity. (iii) In terms of horizontal wind speed for Ryningsnäs, forest modelling was prevailing for all wind directions, where the most accurate simulation was found by employing a constant forest force resistive constant (C2) equal to 0.05. All forest models overestimated the turbulence intensity, whereas the roughness map approaches underestimated it. Based solely on the simulations for Ryningsnäas, a correlation between lower streamwise wind speed and higher turbulence intensity can be deduced.
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Somarathne, Shini. "Dynamic thermal modelling using CFD." Thesis, Brunel University, 2003. http://bura.brunel.ac.uk/handle/2438/5523.
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Buildings expend vast quantities of energy, which has a detrimental impact on the environment. Buildings systems are often oversized to cope with possible extreme environmental conditions. Building simulation provides an opportunity to improve building thermal design, but the available tools are typically used in combination in order to overcome their individual deficiencies. Two such tools, often used in tandem are computational fluid dynamics (CFD) and dynamic thermal modelling (DTM). DTM provides a coarse analysis, by considering external and internal thermal conditions over a building (including its fabric) over time. CFD is usually used to provide steady state analysis. Boundary conditions typically in the form of surface temperatures are manually input from DTM into CFD. CFD can model buildings dynamically, but is not commonly used, since solving for hugely different time constants of solid and air pose significant limitations, due to data generated and time consumed. A technique is developed in this study to tackle these limitations. There are two main strands to the research. DTM techniques had to be incorporated into CFD, starting from first principles of modelling heat transfer through solid materials. These were developed into employing the use of functions such as the 'freeze flow' function (FEF) and the 'boundary freeze' function (BFF) in combination with a time-varying grid schedule to model solids and air simultaneously. The FFF pauses the solution of all governing equations of fluid flow, except temperature. The BFF can be applied to solid boundaries to lock their temperatures whilst all other equations are solved. After extensive research the established DTM-CFD Procedure eventually used the FEF and BFF with transient periods and steady state updates, respectively. The second strand of research involved the application of the DTM-CFD Procedure to a typical office space over a period of 24-hours. Through inter-model comparisons with a fully transient simulation, the DTM-CFD Procedure proved to be capable of providing dynamic thermal simulations 16.4% more efficiently than a typical CFD code and more accurately than a typical DTM code. Additional research is recommended for the further improvement of the DTM-CFD Procedure.
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Chasos, Charalambos Antoniou. "CFD simulation of direct injection gasoline sprays." Thesis, Imperial College London, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.440540.
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Tkaczyk, Piotr. "CFD simulation of annular flows through bends." Thesis, University of Nottingham, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.556100.
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There is particular interest in the oil industry, in gas/liquid distribution in pipe line systems. The presence of bends has a significant effect on gas/liquid flows. Bends are often necessary to fit the equipment into limited spaces e.g. in plants or on oil rig platforms. As part of designing industrial systems, it is therefore important to be able to understand how liquid and gas move around bends. The aim of this research is to develop a method for predicting gas/liquid annular flows. A 3D CFD-based method is therefore developed to solve for annular flows in pipes and is applied to a range of pipe bends. In the presented study, the two-phases are gas and liquid. Multiphase fields can be handled as a continuum gas field, continuum liquid filed and as liquid droplets of varied diameters. The liquid travels along the walls as a film and in the gas core in the form of droplets. The presented approach accounts for the dynamics of the droplets flow in the gas core and their interaction between them. The liquid film is solved explicitly by means of a modified Volume of Fluid (VOF) method. The droplets are traced using a Lagrangian technique. The film to droplets (entrainment) and droplets to film (splashing, spread, bounce and stick) interactions are taken into account using sub- models to complement the VOF model. In free surface flows, a high velocity gradient at the gas/liquid interface results in high turbulence generation. In order to improve the momentum transfer between the phases at the interface, a correction to VOF is also implemented based on the work of Egorov [1]. A detailed comparison between the model and experimental data for vertical, Wolf et al. [2], and horizontal annular flows, Butterworth and Pulling [3], show reasonable agreement. The model is then applied to annular flow in bends, Maddock et al. [4], Anderson and Hills [5], Sakamoto et al. [6]. The comparison between the model and experimental data found in the literature show a good agreement. The model is also successfully applied to medium size (127mm) pipe configurations run at Nottingham University as part of a parent project. The model is finally applied to large pipe diameters encountered in industrial oil/gas applications to investigate scale issues and the model potential in industry.
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Raza, Shan. "Automotive shredded residue : Smelting Cyclone CFD simulation." Thesis, City University London, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.520944.
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Wang, Feng. "Whole aero-engine meshing and CFD simulation." Thesis, Imperial College London, 2013. http://hdl.handle.net/10044/1/27235.
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Aero-engine components are strongly coupled with each other and traditional design tools are not always able to predict the complex phenomenon caused by component interactions. Whole engine simulations could allow designers to capture this phenomenon, increase the design confidence and reduce design cycles. The aim of this thesis is to reduce the turnover time in the pre-processing of whole engine simulations and conduct CFD simulations of the whole engine gas path. This thesis has developed a set of meshing methods for turbomachinery applications. These methods include multi-block structured meshing, 2D/3D Delaunay triangulation, Q-morph, hybrid meshing and hex meshing. These meshing methods are integrated with the in-house geometry database to reduce the required man-hours in the pre-processing of whole engine simulations. This has reduced the required man-hours from days and weeks to a few hours. The whole engine simulation benefits from the development of the developed preprocessing tool, so that the whole engine gas path can be simulated. A compressible reacting gas model is used throughout the domain to ensure the consistency of gas thermodynamic properties. The turnover time of the preprocessing of a whole engine simulation can be reduced to roughly 8 man hours (one working day), which makes the whole engine simulation a feasible tool in the design process.
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Murki, Sai Rohith, and Yaswanth Puttagunta. "CFD Simulation of an Activated Carbon Filter." Thesis, Blekinge Tekniska Högskola, Institutionen för maskinteknik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-13839.
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In various industries, specialized filters with activated carbon are used for adsorbing mercury from air-flows. MRT has eight such Activated CarbonFilters (ACFs) in one of their devices. The main purpose of research is tostudy the flow in the ACF filter and suggest a mathematical model for the complete system through which an improved design can be found.Simulation of a single ACF illustrates how the current system’s air flow does not cover the whole filter leaving part of the carbon bed unused forthe adsorption. This is validated by experimental data. A theoretical studybased on a mathematical model is made and the improved air flow pattern of a re-designed ACF is presented. An additional improvement is that byswitching inlet and outlet the usable time of the filters is prolonged.
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Habr, Klaus. "Gekoppelte Simulation hydraulischer Gesamtsysteme unter Einbeziehung von CFD." Phd thesis, [S.l.] : [s.n.], 2002. http://elib.tu-darmstadt.de/diss/000221.
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Zietara, Rafal. "Simulation of industrial flotation tanks : a CFD approach." Thesis, University of Manchester, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.498783.
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Froth flotation is a separation process widely used to concentrate valuable minerals. It is based on differences in the surface properties of the valuable minerals and the waste (known as gangue). Separation takes place primarily in the underlying pulp phase but minerals are further cleaned in the froth phase. Although there has been a considerable amount of research on froth flotation, the process is still poorly understood. The interaction of many parameters (e.g. the particle size of the ore), operational conditions and chemical interactions, influence the process performance and make it difficult to investigate. The effect of changing operating variables on concentrate grade and mineral recovery has been previously linked with performance changes only by experimental measurements. This thesis attempts to build a mathematical description of the influence of operational conditions on gas, liquid and solid ow behaviour in a flotation tank. Detailed models of pulp and froth were built and implemented in a custom written three dimensional, finite volume framework. The pulp phase model consists turbulent gas-liquid interactions, solid dispersion and selective gas-solid attachment. The froth model includes froth motion, liquid drainage and solid particle dispersion in Plateau borders of froth. Both models were validated separately on a series of test data samples. Finally models were linked in one framework with a pulp-froth interface common for both domains. It was found that pulp phase significantly influences froth phase. The non-uniform distributions of parameters on the pulp-froth interface resulting from computation of pulp phase may change significantly distribution profiles in froth This can possibly affect yield and purity of final product.
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Götz, Sören [Verfasser]. "Gekoppelte CFD/DEM-Simulation blasenbildender Wirbelschichten / Sören Götz." Aachen : Shaker, 2006. http://d-nb.info/1170529135/34.
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Sukdeo, Preeyanand. "CFD simulation of nuclear graphite oxidation / P. Sukdeo." Thesis, North-West University, 2010. http://hdl.handle.net/10394/4231.
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This study investigates the development of a strategy to simulate nuclear graphite oxidation with
Computational Fluid Dynamics (CFD) to determine an estimate of graphite lost.
The task was achieved by comparing the results of the CFD approach with a number of different
experiments. For molecular diffusion, simulated results were compared to analytical solutions.
Mass flow rates under conditions of natural convection were sourced from the 2002 NACOK
experiment. Experimental data from the KAIST facility were sourced for the basic oxidation of
graphite in a controlled environment. Tests included the reactions of carbon with oxygen and
with carbon dioxide.
Finally, the tests at NACOK from 2004 and 2005 were chosen for comparison for the simulation
of oxidation. The 2005 test considered two reacting pebble bed regions at different
temperatures. The 2004 test included multiple detailed structural graphite.
Comparison of results indicated that the phenomenon of diffusion can be correctly simulated.
The general trends of the mass flow rates under conditions of natural convection were obtained.
Surface reaction rates were defined with user functions in Fluent. Good comparisons of the
simulated and the KAIST experimental results were obtained.
For the 2005 NACOK comparison, the pebble bed regions were simulated with a porous
medium approach. Results showed that correct trends and areas of oxidation were estimated.
The 2004 tests were with a combination of a porous medium and surface reaction approaches.
More detailed oxidation experimental data would possibly improve the accuracy of the results.
This research has shown that the CFD approach developed in the present study can identify
areas of maximum oxidation although the accuracy needs to be improved. Both the porous and
detailed surface reaction approaches produced consistent results. The limitations of the
approach were discussed. These included transient phenomena which were estimated with
steady state simulations, and the effects of change in geometry were not considered.Thesis (M.Ing. (Nuclear Engineering))--North-West University, Potchefstroom Campus, 2010.
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Ziegenhein, Thomas, Dirk Lucas, Roland Rzehak, and Eckhard Krepper. "Closure relations for CFD simulation of bubble columns." Helmholtz-Zentrum Dresden-Rossendorf, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:d120-qucosa-144231.
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This paper describes the modelling of bubbly flow in a bubble column considering non-drag forces, polydispersity and bubble induced turbulence using the Eulerian two-fluid approach. The set of used closure models describing the momentum exchange between the phases was chosen on basis of broad experiences in modelling bubbly flows at the Helmholtz-Zentrum Dresden-Rossendorf. Polydispersity is modeled using the inhomogeneous multiple size group (iMUSIG) model, which was developed by ANSYS/CFX and Helmholtz-Zentrum Dresden-Rossendorf. Through the importance of a comprehensive turbulence modeling for coalescence and break-up models, bubble induced turbulence models are investigated. A baseline has been used which was chosen on the basis of our previous work without any adjustments. Several variants taken from the literature are shown for comparison. Transient CFD simulations are compared with the experimental measurements and Large Eddy Simulations of Akbar et al. (2012).
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Le, Roux Frederick Nicolaas. "The CFD simulation of an axial flow fan." Thesis, Stellenbosch : University of Stellenbosch, 2010. http://hdl.handle.net/10019.1/4344.
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Thesis (MScEng (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2010.ENGLISH ABSTRACT: The purpose of this project is to investigate the method and accuracy of simulating axial ow fans with three-dimensional axisymmetric CFD models. Two models are evaluated and compared with experimental fan data. Veri cation data is obtained from a prototype fan tested in a facility conforming to the BS 848 standards. The ow eld over the blade surfaces is investigated further with a visualization experiment comprising of a stroboscope and wool tufts. Good correlation is found at medium to high ow rates and recommendations are made for simulation at lower ow rates as well as test guidelines at the fan test facility. The results and knowledge gained will be used to amend currently used actuator disc theory for axial ow fan simulation.
AFRIKAANSE OPSOMMING: Die doel van hierdie projek is om die metode en akkuraatheid om aksiaalvloeiwaaiers met drie-dimensionele BVM modelle te simuleer, te ondersoek. Twee modelle word geëvalueer en met eksperimentele waaiertoetse vergelyk. Veri- kasie data is verkry vanaf 'n prototipe waaier wat in 'n fasiliteit getoets is en wat aan die BS 848 standaarde voldoen. Die vloeiveld oor die lemoppervlaktes word ondersoek met 'n visualisering eksperiment wat uit 'n stroboskoop en wolletjies bestaan. Goeie korrelasie word gevind vir medium tot hoë massavloeie en aanbevelings word gemaak vir die simulasie by laer massavloeie met riglyne vir toetswerk in die toets-fasiliteit. Die resultate en kennis opgedoen sal gebruik word in die verbetering van huidige aksieskyfteorie vir numeriese aksiaalvloeiwaaier simulasies.
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Riaz, Z. "CFD simulation of an unmanned underwater vehicle manoeuvring." Thesis, University College London (University of London), 2015. http://discovery.ucl.ac.uk/1460228/.
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Bandari, Shiva Ram. "Investigation on Flow Control Valve by CFD Simulation." Thesis, Blekinge Tekniska Högskola, Institutionen för maskinteknik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-13905.
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In a water distribution system, Flow Control Valve is used to control the flow rate in the pipeline connections. In this thesis, a fixed flow control valve is investigated to reduce the flow rate and set to deliver the pre-set flow of 5-6 LPM (litre per minute). Which helps to distribute the water for a maximum period and maintains the usage only for the drinking purpose. A geometry of FCV with a ball check valve is implemented, where the ball check helps to stop the back flow of the fluid from the valve. Detailed inspection of dynamic changes in pressure and flow velocity in the valve are conducted through simulation. The study of fluid properties describes the expected design and specifies the flow structure in the valve. The results of this project demonstrate a good performance of the design-build and influence the requirements. The obtained values in the simulation, analytical and experimental results are compatible, which concludes the survey of FCV is equipped to custom.
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Alghamdi, Jamal Khaled. "CFD Simulation Methodology for Ground-Coupled Ventilation System." Thesis, Virginia Tech, 2008. http://hdl.handle.net/10919/35736.
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In the past two decades, a growing interest in alternative energy resources as a
replacement to the non-renewable resources used now days. These alternatives include
geothermal energy which can be used to generate power and reduce the demands on
energy used to heat and cool buildings. Ground-coupled ventilation system is one of the
many applications of the geothermal energy that have a lot of attention in the early 80â s
and 90â s but all designs of the system where based on single case situations. On the other
hand, computational fluid dynamics tools are used to simulate heat and fluid flow in any
real life situation. They start to develop rapidly with the fast development of computers
and processors. These tools provide a great opportunity to simulate and predict the
outcome of most problems with minimum loss and better way to develop new designs.
By using these CFD tools in GCV systems designing procedure, energy can be conserved
and designs going to be improved.
The main objective of this study is to find and develop a CFD modeling strategy
for GCV systems. To accomplish this objective, a case study must be selected, a proper
CFD tool chosen, modeling and meshing method determined, and finally running
simulations and analyzing results. All factors that affect the performance of GCV should
be taken under consideration in that process such as soil, backfill, and pipes thermal
properties. Multiple methods of simulation were proposed and compared to determine the
best modeling approach.Master of Science
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Lautenberger, Christopher W. "CFD simulation of soot formation and flame radiation." Link to electronic thesis, 2002. http://www.wpi.edu/Pubs/ETD/Available/etd-0115102-002543.
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Thesis (M.S.)--Worcester Polytechnic Institute.Keywords: soot formation; FDS; flame radiation; soot oxidation; field modeling; diffusion flames; soot. Includes bibliographical references (p. 14-15).
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Guo, Zhenyi. "CFD Simulation of Annular Flow Boiling in Microchannels." Thesis, The University of Sydney, 2015. http://hdl.handle.net/2123/14428.
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Flow boiling in microchannels has received enormous interest over the past few decades because of its importance in the thermal management of micro-structured devices. Few of previously published studies focus specifically on microchannel annular flow boiling which is very important due to its prevalence in this system. This thesis provides understanding of the heat and mass transfer in microchannel annular flow boiling via the use of a computational fluid dynamics (CFD) approach. The commercial software ANSYS Fluent was chosen to perform the CFD simulations. A modified height function (HF) method was implemented into the default CSF model to improve the performance of surface tension modelling. Simulation of an inviscid parallel flow demonstrated successful prediction of the onset of Kelvin-Helmholtz (K-H) instability in close accord with the analytical criterion. Studies of imposed numerical perturbations in laminar annular air-water flow showed that viscosity does not affect the stability of interfacial waves but has large impacts on the growth rates. A phase change model was formulated using a kinetic-based model to calculate the interphase mass flux. An established numerical smoothing procedure was used to improve numerical stability. A detailed study of a laminar annular flow boiling was performed using water at 160 kPa in a 0.5 mm diameter channel with constant fluid mass flux G = 60 kg m−2 s−1 and inlet vapour quality x = 0.1. Interfacial waves were observed and flow recirculation and a localised increase of heat transfer coefficient occurred at the interfacial wave troughs, where the liquid film was very thin. A parametric analysis showed that boiling heat transfer coefficient increases with increasing mass flux, system pressure, vapour quality and heat flux but decreases with increasing tube diameter.
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Ottosson, Oscar. "CFD Simulation of Urea Evaporation in STAR-CCM+." Thesis, Linköpings universitet, Mekanisk värmeteori och strömningslära, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-160484.
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Diesel engines produce large amounts of nitrogen oxides (NOX) while running. Nitrogen oxides are highly toxic and also contribute towards the formation of tropospheric ozone. Increasingly stringent legislation regarding the amount of nitrogen oxides that are allowed to be emitted from diesel-powered vehicles has forced manufacturers of diesel-engines to develop after-treatment systems that reduce the amount of nitrogen oxides in the exhaust. One of the main components in such a system is selective catalytic reduction (SCR), where nitrogen oxides are reduced to diatomic nitrogen and water with the help of ammonia. A vital part of this process is the spraying of a urea-water-solution (UWS), which is needed in order to produce the reducing agent ammonia. UWS spraying introduces the risk of solid deposits (such as biuret, ammelide and ammeline) forming in the after-treatment system, should the flow conditions be unfavourable. Risk factors include high temperatures, but also low dynamics and high thickness of the resulting liquid film that forms as the UWS spray hits the surfaces of the after-treatment system. It is thus essential that manufacturers of SCR after-treatment systems have correct data on how much UWS that should be sprayed into the exhaust for any given flow condition. Experimental tests are thoroughly used to assess this but are very expensive and are thus limited to prototype testing during product development. When assessing a wider range of concepts and geometries early on in the product development stage, simulation tools such as computational fluid dynamics (CFD) are used instead. One of the most computationally heavy processes to simulate within a SCR after-treatment system is the UWS spray and its interaction with surfaces inside the after-treatment system, where correct prediction of the formation of solid deposits are of great importance. Most CFD models used for this purpose hold a relatively good level of accuracy and are utilized throughout the whole industry where SCR aftertreatment is applied. Despite this, these models are limited in the fact that they are only able to cover timescales in the scope of seconds to minutes while using a tolerable amount of computational power. However, the time spectrum for solid deposit formation is minutes to hours. Scania is one of Sweden’s biggest developers of SCR after-treatment, with the technology being incorporated directly into its silencers. AVL Fire is the main UWS spray simulation tool for engineers at Scania at the moment. One major drawback of using AVL Fire for UWS spray simulations is that it is deemed too time-consuming to set up new cases and too unstable during simulation, which makes it too costly in terms of expensive engineering hours. This project has investigated the potential of using STAR-CCM+ for UWS spray simulations at Scania instead. A standard method has been evaluated, as well as parameters that will prove useful in further investigations of a potential speedup method. The studied method in STAR-CCM+ is easy to setup and the simulation process is robust and stable. Various other perks come from using STAR-CCM+ as well, such as: a user-friendly interface, easy and powerful mesh-generation and great post-process capabilities. Several different parameters have been investigated for their impact on the studied method, such as mesh refinement of the spray injector area and the number of parcels injected every time-step through the spray injector (simply put the resolution of the spray). A possible speedup by freezing the momentum equations when allowed and lowering the amount of inner iterations has also been investigated. A handful of operating conditions have been studied for two different geometries. The attained simulation results display correlations with physical measurements, but further assessment for identifying the risk of solid deposit needs to be performed on the studied cases to assess the full accuracy of solid deposit prediction of the studied method. Recommendations for future work includes fully implementing and evaluating the speedup method available for spray simulations in STAR-CCM+ as well as directly comparing how the accuracy and performance of the method relates to that of the method used in AVL Fire for spray simulations.Dieselmotorer producerar under körning stora mängder kväveoxider (NOx). Kväve-oxider är starkt giftiga föreningar som även bidrar till att öka mängden marknära ozon. Allt strängare lagstiftning gällande mängden kväveoxider som får släppas ut från fordon med dieselmotorer har lett till att tillverkare av dieselmotorer blivit tvingade att utveckla efterbehandlingssystem som renar avgasen från motorn. En av huvudkomponenterna i ett sådant system idag är selective catalytic reduction (SCR; på svenska selektiv katalytisk reduktion), där kväveoxider omvandlas till kvävgas och vatten med hjälp av ammoniak. För att producera ammoniak används en lösning av urea och vatten (t.ex. AdBlue®), som introduceras till efterbehandlingssystemet via spray. Denna process har dock en stor nackdel, då det under omvandlingsprocessen kan finnas risk för klumpbildning av ämnen som biuret, ammelid och ammelin ifall flödesförhållandena är ogynnsamma. Riskfaktorer för klumpbildning inkluderar höga temperaturer samt låg dynamik och hög tjocklek för den vätskefilm som bildas när sprayen med urea-lösning kommer i kontakt med ytor i efterbehandlingssystemet. Det är därför av stor vikt för tillverkare av efterbehandlingssystem som använder SCR att känna till hur mycket urealösning som kan sprayas in för varje givet flöde. Experimentella tester används till stor del för att utvärdera detta, men är väldigt dyra och kan endast göras för ett fåtal prototyper under en produkts utveckling. För att kunna utvärdera ett större antal koncept och geometrier tidigare i utvecklingsstadiet av en ny produkt används därför ofta datorkraft med simuleringsverktyg som CFD (Computational Fluid Dynamics). En av de mest beräkningstunga processerna att simulera i ett efterbehandlingssystem med SCR är sprayandet av urea-lösning och dess interaktion med ytor, där korrekta förutbestämmelser av huruvida det finns risk för klumpbildning eller inte är av stor betydelse. De flesta CFD modeller som används i detta syfte har förhållandevis god noggrannhet och används i stor utsträckning i den bransch där efterbehandling med SCR tillämpas. Däremot är dessa modeller begränsade i att de endast kan åstadkomma simuleringar (med en acceptabel mängd datorkraft) som sträcker sig i tidsintervallet sekunder till minuter. Bildningen av klump är dock en process som kan ta upp till flera timmar. Scania är en av Sveriges största tillämpare av SCR, då tekniken används i de efterbehandlingssystem som finns inbyggda i tillverkarens ljuddämpare. Scania använder främst AVL Fire för simulering av spray med urea. AVL Fire anses dock vara för tidskrävande vid skapelsen av nya simuleringsfall och för instabilt under simulering. Detta projekt har därför undersökt möjligheten att använda STAR-CCM+ för simulering av spray med urea hos Scania. Den metod i STAR-CCM+ som utvärderats är enkel att använda då nya simuleringsfall ska skapas, samtidigt som den är robust och stabil under simulering. Relevanta parametrar för en potentiell uppsnabbningsmetod har också undersökts. STAR-CCM+ i sin helhet är användarvänligt, där verktyget för att skapa och generera mesh är enkelt att använda såväl som kraftfullt när mer avancerade operationer krävs. Möjligheterna för postprocessing är väldigt smidiga för transienta förlopp, vilket är ett stort plus för simuleringar med urea-spray, vars injektion och resulterande processer är väldigt transienta skeenden i sig. Flera olika parametrar har undersökts, för att granska hur stor påverkan de har på prestandan och noggrannheten hos den studerade metoden. Två av dessa är tätheten av beräkningsnoder i den region där spray-munstycket är placerat samt antalet paket med urea-vatten lösning som injiceras varje tidssteg via spray-munstycket. En möjlig uppsnabbning av metoden, som går ut på att frysa ekvationerna för bevarelse av rörelsemängd (eng - momentum equations) när det är tillåtet och samtidigt minska antalet inre iterationer för varje tidssteg, har också undersökts. Ett flertal olika flödesförhållanden har också undersökts för två olika geometrier. De erhållna resultaten tyder på korrelation med data från fysiska experiment. Dock bör ytterligare hydrodynamiska utvärderingar tillämpas för att ordentligt kunna redogöra för hur väl STAR-CCM+ kan användas för att förutse risken för klump- bildning i en spray-process med urea-vatten lösning. Framtida arbete borde fokusera på att utvärdera den uppsnabbningsmetod som finns för spray-simuleringar i STAR-CCM+, samt direkt jämföra hur väl metodens noggrannhet och prestanda står sig gentemot den metod som används i AVL Fire för spray-simuleringar.
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Choi, Hong Fei. "Numerical simulation of atrium fire using two CFD tools." Thesis, University of Macau, 2007. http://umaclib3.umac.mo/record=b1694321.
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Al-Far, Salam H. "Indirect fired oven simulation using computational fluid dynamics (CFD)." Thesis, London South Bank University, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.618655.
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Risberg, Daniel. "CFD simulation of indoor climate in low energy buildings." Licentiate thesis, Luleå tekniska universitet, Energivetenskap, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-18432.
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In this thesis computational fluid dynamics (CFD) was used for simulation of the indoor climate of low-energy buildings in cold climate. The heat consumption in newly built houses was reduced drastically. Along with the different classification systems for low-energy buildings the demand for the indoor climate has increased, which causes a need to investigate buildings even before they are built. Than CFD is of importance in studies of different heating systems and how new construction solutions can affect the indoor environment. The work focus was on investigating the computational setup, such as grid size and boundary conditions in order to solve the indoor climate problems in an accurate way and compare different heating systems. A limited number of grid elements and knowledge of boundary settings is therefore essential in order to obtain reasonable calculation time.The models show that radiation between building surfaces has a large impact on the temperature field inside the building, with the largest differences at the floor level. An accurate grid edge size of around 0.1 m was enough to predict the climate. Different turbulence models were compared with only small differences in the indoor air velocities and temperatures. To explore the viability of this approach, the indoor climate in a building was studied considering three different heating systems: an underfloor heating system, air heating through the ventilation system and an air heat pump installation. The underfloor heating system provided the most uniform operative temperature distribution and was the only heating system that fully satisfies the recommendations to achieve tolerable indoor climate set by the Swedish authorities. On the contrary, air heating and the air heat pump created a relatively uneven distribution of air velocities and temperatures, and none of them fulfils the specified recommendations. From an economic point of view, the air heat pump system is cheaper to be installed but produces a less pleasant indoor environment then distributed heating systems. The most widely used turbulence model for indoor CFD simulations, the k-ε model, has exhibited problems with treating natural convective heat transfer, while other turbulence models have shown to be too computationally demanding. One paper therefore studies how to deal with natural convective heat transfer for a radiator in order to simplify the simulations, reduce the numbers of cells and the simulation time. By adding user-defined wall functions, to the k-ε model the number of cells can be reduced considerably compared with the k-ω SST turbulence model. The user-defined wall function proposed can also be used with a correction factor for different radiator types without the need to resolve the radiator surface in detail. Compared to manufacturer data the error was less than 0.2% for the investigated radiator height and temperature.Godkänd; 2015; 20150915 (danris); Nedanstående person kommer att hålla licentiatseminarium för avläggande av teknologie licentiatexamen. Namn: Daniel Risberg Ämne: Energiteknik/Energy Engineering Uppsats: CFD Simulation of Indoor Climate in Low Energy Buildings Examinator: Professor Lars Westerlund, Institutionen för teknikvetenskap och matematik, Luleå tekniska universitet Diskutant: Professor Thomas Olofsson, Institutionen för samhällsbyggnad och naturresurser, Luleå tekniska universitet Tid: Måndag 2 november 2015 kl 10.00 Plats: E632, Luleå tekniska universitet
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Strasser, Clemens. "Simulation of progressive flooding of damaged ships by CFD." Thesis, University of Strathclyde, 2010. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=12422.
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Vollmer, Thees, and Ludger Frerichs. "Development of hydraulic tanks by multi-phase CFD simulation." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-199968.
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Hydraulic tanks have a variety of different tasks. The have to store the volume of oil needed for asymmetric actors in the system as well as to supply the system with preconditioned oil. This includes the deaeration as air contamination is affecting the overall system performance. The separation of the air in the tank is being realized mainly by passive methods, improving the guidance of the air and oil flow. The use of CFD models to improve the design of hydraulic tank is recently often discussed. In this paper, a design method for hydraulic tanks using CFD is presented and discussed. First the different requirements on a hydraulic tank are described as well as the motivation changing the tank designs. Additionally, a quick overview on different calculation models for the behavior of air in oil as well as the capabilities of CFD to reproduce them is given. After this the methodology of tank design applying CFD is presented. The method is then used in an example.
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Muttenthaler, Lukas, and Bernhard Manhartsgruber. "Optimizing hydraulic reservoirs using euler-eulerlagrange multiphase cfd simulation." Technische Universität Dresden, 2020. https://tud.qucosa.de/id/qucosa%3A71100.
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Well working hydraulic systems need clean hydraulic oil. Therefore, the system must ensure the separation of molecular, gaseous, liquid and solid contaminations. The key element of the separation of contaminants is the hydraulic reservoir. Solid particles are a major source of maintenance costs and machine downtime. Thus, an Euler-Euler-Lagrange multiphase CFD model to predict the transport of solid particles in hydraulic reservoirs was developed. The CFD model identifies and predicts the particle accumulation areas and is used to train port-to-port transfer functions, which can be used in system models to simulate the long-term contamination levels of hydraulic systems. The experimental detection of dynamic particle contamination levels and particle accumulation areas validate and confirm the CFD and the system model. Both models in combination allow for parameter and design studies to improve the fluid management of hydraulic reservoirs.
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Subramanya, Shreyasu. "Modelling and Simulation of Fan Performance using CFD Group." Thesis, Linköpings universitet, Mekanisk värmeteori och strömningslära, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-171106.
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Performance of vacuum cleaners are affected by factors such static pressure, airflow rate and efficiency. In this thesis work, attempt has been made to design a fan to meet the requirements of suction static pressure and air flow rate and in the process understand the fan design parameters that affect these performance parameters. Parametric study has been conducted for the same, by choosing six fan design parameters. Additionally, ways to increase the fan efficiency has been investigated during the parametric study. Computational Fluid Dynamics is used to visualize the flow inside the fan casing and further to simulate fan performance at an operational point. Steady state RANS and moving reference frames was used to model the turbulence in the fluid flow and rotation of the fan, respectively. Performance curve showing the relation between static suction pressure and mass flow rate is plotted for the base model is in proximity to the required performance. Parametric study was conducted on the six fan design parameters: Fan diameter, number of impeller blades, blade outlet angle, radius of the curve connecting inlet to outlet section of the fan, diffuser exit length and splitter blade length. The range for each parameter analysis was restricted so that static pressure values are around the required performance. Greater performance variation was found with design parameters: fan diameter, blade outlet angle, radius of the curve connecting inlet to outlet section of the fan and diffuser exit length. This variation at low mass flow rate can be majorly attributed to the randomness in the flow captured by entropy contours. At high mass flow rate, blockage in the flow visualized by pressure contours reasoned for the performance variation. Greater performance variation was not when design parameters such as number of blades and splitter blade length were varied. Larger variation of these parameters is required to see better variation.
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Wahlbom, Hellström Victoria, and Frida Alenius. "Investigation of Scale Adaptive Simulation (SAS) Turbulence Modelling for CFD-Applications." Thesis, Linköpings universitet, Mekanisk värmeteori och strömningslära, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-96363.
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Fluid dynamics simulations generally require large computational recourses in form of computer power and time. There are different methods for simulating fluid flows that are more or less demanding, but also more or less accurate. Two well known computational methods are the Reynolds Averaged Navier-Stokes (RANS) and Large Eddy Simulation (LES). RANS computes the timeaveraged flow properties, while LES resolve the large structures (eddies) of the flow directly and model the small ones. Hybrid models are combinations of these two models which have been developed to improve the RANS solutions and shorten the simulation time compared to LES computations. One such model is the Scale Adaptive Simulation (SAS) model which uses the RANS model in steady flow regions, such as close to walls, and a LES like model in unsteady regions with large fluctuations. This study was done for evaluating the SAS model compared to Unsteady RANS (URANS) and LES and their performance compared to measurements from an engineering point of view. This was done by running simulations on two different test cases, one external and one internal flow situation. The first one was flow around a wall-mounted cylinder and the second one was flow through an aorta with a coarctation in the descending aorta. The first test case was used to thoroughly evaluate the SAS model by running many simulations with URANS, SAS and LES with different element types, element sizes and flow parameters. The element types that have been analyzed are; tetrahedral, hexahedral and polyhedral. The results were compared with experiments done by Sumner et al. [7, 8, 9, 10]. The second test case was used for evaluating the SAS model even further on another flow situation. For this test case, only two SAS simulations were performed on two different grids; a structured hexahedral and an unstructured polyhedral. These results were compared with Magnetic Resonance Imaging (MRI) measurements obtained from Linköping University. No conclusion of which one of the simulated cases gives the best overall agreement with experimental results could be concluded from the obtained results. The best prediction of the drag coefficient for the cylinder was obtained for the coarsest polyhedral mesh that was run with LES, with the disagreement 0.4 percent. The best prediction of the Strouhal number was obtained for a URANS simulation performed on the coarsest mesh with an improved grid close to the cylinder surface, generating less than one, with a disagreement of 3 percent compared to measurements. For the meshes used, it was found that the polyhedral mesh gave the best overall results and the tetrahedral mesh gave the worst results for the cylinder case. For the aorta case the SAS model produced velocity components that had acceptable agreement with the MRI-measurements, but gave very poor results for the turbulent kinetic energy. The main conclusion of this thesis was that the SAS model performed better than URANS, but took longer time to compute simulations than LES, which was the model that generated the best overall results.
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ZUZUL, JOSIP. "Characterization of thunderstorm downburst winds through CFD techniques." Doctoral thesis, Università degli studi di Genova, 2022. http://hdl.handle.net/11567/1081542.
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The characteristic wind field of a certain region is mostly governed by the climatology of its larger scale area. In the case of mid-latitude regions (e.g. Europe), their climatology is determined by the extra-tropical cyclones at the larger synoptic scale. Atmospheric boundary layer (ABL) winds based on synoptic-scale structures are hence considered as the foundation for codes and standards used to assess the wind loading of structures and to design structures to prevent wind-related damage accordingly. In addition to the ABL winds, the mid-latitude regions are also prone to winds of a non-synoptic origin at the mesoscale level, with thunderstorm outflows or downbursts being the representative of such non-synoptic wind action. Since they are determined by a set of features that makes them fundamentally different from the ABL winds, downbursts can produce the corresponding wind action that is often fatal to low-rise and mid-rise structures. On these grounds, a comprehensive initiative to enable a better understanding of fundamental downburst flow features relevant for the structural loading was framed under the umbrella of the ERC THUNDERR Project. The present thesis, as the numerical modeling part of the THUNDERR Project framework, aims to address the physical characteristics of thunderstorm downbursts through the application of Computational Fluid Dynamics (CFD) technique. The focus of this work is placed on the CFD reconstruction of experimental tests of the reduced-scale thunderstorm downbursts carried out in the WindEEE Dome Research Institute (University of Western Ontario, Canada). Although they recreate the downburst flow field, the experimental analysis is restricted to the limited number of probe points. In that perspective, CFD allows expanding the analysis of experimental tests to the entire flow field, which can reveal phenomenological aspects that are either challenging or impossible to retrieve from experimental tests only. Two fundamental downburst scenarios were analyzed: (i) an isolated vertical downburst, and (ii) a downburst embedded inside the approaching ABL flow. For that purpose, three CFD approaches of a ranging complexity level were adopted. The unsteady Reynolds-Averaged Navier-Stokes (URANS), hybrid Scale-Adaptive Simulations (SAS), and Large-Eddy Simulations were used, and their overall reliability was examined. Theimplications of the WindEEE Dome specific geometrical features (i.e. bell-mouth inflow nozzle) on the downburst flow reconstruction by the facility were further discussed. The bulk of the thesis discusses the dominant flow features of the downburst with the particular emphasis on the dynamics of dominant vortex structures (i.e. primary vortex, secondary vortex, trailing ring vortices) and their spatio-temporal influence on the vertical profiles of radial velocity component. The non-dimensional flow characteristics of interest were evaluated such as the trajectory of the primary vortex and the spatial dependence of the velocity of primary vortex propagation. Analyses were further extended for the case of a joint downburst and ABL wind interaction to address the dynamics between two different wind fields, and the genesis of the worst condition in terms of the maximum radial velocity due to the ABL wind entrainment was discussed. The flow field was analyzed across various azimuth angles with respect to the ABL flow to report on the flow asymmetry, and general implications of such downburst configuration on spatio-temporal evolution of wind velocity profiles which can produce severe conditions for low-rise and mid-rise structures.
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Quillatre, Pierre. "Simulation aux grandes échelles d'explosions en domaine semi-confiné." Phd thesis, Toulouse, INPT, 2014. http://oatao.univ-toulouse.fr/11851/1/quillatre.pdf.
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Dans le contexte actuel de croissance continue de la demande mondiale en combustible fossile, la sécurité de la production, du transport, ainsi que du stockage de l'énergie est un défi majeur de ce début de XXIème siècle. Les produits manipulés étant extrêmement volatils et inflammables, les éventuelles fuites qui peuvent survenir malgré les lourdes mesures de sécurité mises en place, peuvent engendrer des explosions désastreuses. Il existe donc un fort besoin d'être capable de prédire ces explosions afin de limiter les dégâts potentiels et d'assurer la sécurité des personnes et des biens. Dans cette optique, l'augmentation régulière des puissances de calcul permet à la CFD (Computational Fluid Dynamics) de se présenter comme une alternative intéressante aux expériences qui peuvent s'avérer couteuses et dangereuses. Les explosions sont des phénomènes multi-physiques qui sont principalement dirigés par la turbulence et la combustion et qui prennent place sur une très large gamme d'échelles nécessitant ainsi d'être modélisées. Aujourd'hui, des codes basés sur une approche URANS (Unsteady Reynolds Averaged Navier Stokes) sont généralement utilisés afin de simuler des explosions de gaz dans des configurations à échelle industrielle. Cependant, l'émergence de la LES (Large Eddy Simulation), qui a déjà montré son potentiel à donner des prédictions plus fiables que le URANS sur des configurations instationnaires complexes, ouvre de nouvelles perspectives pour le domaine de la sécurité explosion. Le but principal de cette thèse est d'évaluer l'apport des méthodes LES et de développer une méthodologie pour la prédiction des phénomènes réactifs turbulents transitoires que sont les explosions. Tout au long de cette étude, un intérêt particulier a été porté à l'approfondissement de la compréhension des phénomènes d'explosion ainsi qu'à la mise en valeur des points cruciaux de modélisation qui permettent une reproduction correcte des phénomènes considérés. Notre approche peut alors se résumer en deux temps : - Dans un premier temps nous nous sommes concentrés sur l'étude LES des déflagrations dans une chambre de combustion de petite échelle : la configuration expérimentale de l'Université de Sydney. La LES associée à un modèle de flamme épaissie a ainsi été appliquée à cette configuration à l'aide du code AVBP (développé par le CERFACS et l'IFP-EN) et a permis de mettre en place une méthodologie de calcul. Une étude de Quantification d'Incertitude (UQ) a ensuite été réalisée sur ces simulations afin d'évaluer la fiabilité de ces résultats, ce qui est primordial dans ce contexte d'étude de sécurité. - Dans un second temps, le but a été d'extrapoler les résultats obtenus sur la configuration de petite échelle à des configurations de plus grande échelle, plus représentatives des configurations industrielles réelles de plateformes pétrolières ou de dépôts de carburants qui constituent l'objectif final visé. Une campagne expérimentale a ainsi été lancée afin de construire des répliques de la configuration de Sydney à des échelles plus importantes et de les étudier numériquement grâce à la méthodologie LES mise en place sur la configuration de petite échelle. Afin de replacer notre étude dans le contexte actuel et de le relier à l'état-de-l'art en matière d'étude de risque d'explosions, d'autres calculs de ces configurations d'explosion ont été réalisés en parallèle de l'étude LES, premièrement avec un code phénoménologique développé dans le cadre de cette thèse, ainsi qu'avec le code URANS FLACS. Ceci a permis de mettre en évidence leurs limitations ainsi que l'apport de la LES pour ce type d'étude.
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Aguirre, John. "Study of 3-Dimensional Co-Flow Jet Airplane and High-Rise Building Flow Using CFD Simulation." Scholarly Repository, 2009. http://scholarlyrepository.miami.edu/oa_theses/181.
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The purpose of this thesis is to design and study an aircraft which implements the Co-Flow Jet (CFJ) airfoil concept, as well as to study the CAARC standard highrise building. The design concept is verified mainly by the use of a Computational Fluid Dynamics (CFD) package. A thorough methodology for geometry and mesh generation is developed, and subsequently applied to the two cases. The first case studied is that of the CFJ Airplane (CFJA). It consists of a threedimensional, highly blended, ying wing geometry implementing the Co-Flow Jet airfoil concept. Though a thorough comparison to a baseline geometry, it is shown that usage of the CFJ airfoil cross-section greatly improves aircraft performance by increasing lift, reducing drag, and providing a source of thrust over the operational range of angles of attack. A steady state CFD simulation is used for this case, as the air ow around an airfoil cross-section is inherently steady for attached ows. CFD results are used to support the Engineless Aircraft" concept, where the CFJ airfoil is used as the sole form of propulsion. The second case studied consists of a rectangular high-rise building undergoing a wind condition with Mach number of 0:1 and a Reynolds number of 160000. Due to the non-streamlined geometry of the building cross-section, aerodynamic instabilities due to uid separation are present, and therefore an unsteady CFD analysis is necessary to fully resolve all of the ow phenomena. Preliminary steady state results are presented, and a plan is laid down for the future study of this highly complex case. Results are presented for a variety of angles of attack in the case of the CFJA, and for the main ow direction in the case of the CAARC building. Results are compared with baseline geometry in the case of the CFJ Airplane. The CFJ Airplane case is simulated using a 3rd order steady state scheme, which is sufficient to achieve valid results for the ow regime. The CAARC building, which has inherent ow separation, requires the use of high order schemes.
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Stoakes, Preston John. "Simulation of Airflow and Heat Transfer in Buildings." Thesis, Virginia Tech, 2009. http://hdl.handle.net/10919/35690.
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Energy usage in buildings has become a major topic of research in the past decade, driven by the increased cost of energy. Designing buildings to use less energy has become more important, and the ability to analyze buildings before construction can save money in design changes. Computational fluid dynamics (CFD) has been explored as a means of analyzing energy usage and thermal comfort in buildings. Existing research has been focused on simple buildings without much application to real buildings. The current study attempts to expand the research to entire buildings by modeling two existing buildings designed for energy efficient heating and cooling. The first is the Viipuri Municipal Library (Russia) and the second is the Margaret Esherick House (PA). The commercial code FLUENT is used to perform simulations to study the effect of varying atmospheric conditions and configurations of openings. Three heating simulations for the library showed only small difference in results with atmospheric condition or configuration changes. A colder atmospheric temperature led to colder temperatures in parts of the building. Moving the inlet only slightly changed the temperatures in parts of the building. The cooling simulations for the library had more drastic changes in the openings. All three cases showed the building cooled quickly, but the velocity in the building was above recommended ranges given by ASHRAE Standard 55. Two cooling simulations on the Esherick house differed only by the addition of a solar heat load. The case with the solar heat load showed slightly higher temperatures and less mixing within the house. The final simulation modeled a fire in two fireplaces in the house and showed stratified air with large temperature gradients.Master of Science
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Zaki, Afifa Adel. "Using tightly-coupled CFD/CSD simulation for rotorcraft stability analysis." Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/43579.
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Dynamic stall deeply affects the response
of helicopter rotor blades, making its modeling accuracy very important. Two commonly used dynamic stall models were implemented
in a comprehensive code, validated, and contrasted to provide improved analysis
accuracy and versatility. Next, computational fluid dynamics and computational structural dynamics loose coupling methodologies are reviewed, and a general tight coupling approach was implemented and tested. The tightly coupled
computational fluid dynamics and computational structural dynamics methodology is then used to assess the stability characteristics of complex rotorcraft problems. An aeroelastic analysis of rotors must include an assessment of
potential instabilities and the determination of damping ratios for all modes of interest. If
the governing equations of motion of a system can be formulated as linear, ordinary
differential equations with constant coefficients, classical stability evaluation
methodologies based on the characteristic exponents of the system can rapidly and
accurately provide the system's stability characteristics. For systems described by linear,
ordinary differential equations with periodic coefficients, Floquet's theory is the preferred
approach. While these methods provide excellent results for simplified linear models with
a moderate number of degrees of freedom, they become quickly unwieldy as the number
of degrees of freedom increases. Therefore, to accurately analyze rotorcraft aeroelastic
periodic systems, a fully nonlinear, coupled simulation tool is used to determine the
response of the system to perturbations about an equilibrium configuration and determine
the presence of instabilities and damping ratios. The stability analysis is undertaken using
an algorithm based on a Partial Floquet approach that has been successfully applied with
computational structural dynamics tools on rotors and wind turbines. The stability analysis approach is computationally
inexpensive and consists of post processing aeroelastic data, which can be used with any
aeroelastic rotorcraft code or with experimental data.
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Wiese, Jens [Verfasser]. "DEM/CFD-Simulation und experimentelle Untersuchungen von Holzpelletfeuerungen / Jens Wiese." Aachen : Shaker, 2016. http://d-nb.info/1081885742/34.
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Asyikin, Muhammad Tedy. "CFD Simulation of Vortex Induced Vibration of a Cylindrical Structure." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for bygg, anlegg og transport, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-18814.
Full textAbstract:
This thesis presents the investigation of the flow characteristic and vortex induced vibration (VIV) of a cylindrical structure due to the incompressible laminar and turbulent flow at Reynolds number 40, 100, 200 and 1000. The simulations were performed by solving the steady and transient (unsteady) 2D Navier-Stokes equation. For Reynolds number 40, the simulations were set as a steady and laminar flow and the SIMPLE and QUICK were used as the pressure-velocity coupling scheme and momentum spatial discretization respectively. Moreover, the transient turbulent flow was set for Re 100, 200 and 1000 and SIMPLE and LES (large Eddies Simulation) were selected as the pressure-velocity coupling solution and the turbulent model respectively. The drag and lift coefficient (Cd and Cl) were obtained and verified to the previous studies and showed a good agreement. Whilst the vibration frequency (fvib), the vortex shedding frequency (fv), the Strouhal number (St) and the amplitude of the vibration (A) were also measured.
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Taskin, Ertan M. "CFD simulation of transport and reaction in cylindrical catalyst particles." Link to electronic thesis, 2007. http://www.wpi.edu/Pubs/ETD/Available/etd-081507-135028/.
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Hosain, Md Lokman. "CFD Simulation of Jet Cooling andImplementation of Flow Solvers inGPU." Thesis, KTH, Numerisk analys, NA, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-123971.
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In rolling of steel into thin sheets the final step is the cooling of the finished product on the Runout Table. In this thesis, the heat transfer into a water jet impinging on a hot flat steel plate was studied as the key cooling process on the runout table. The temperature of the plate was kept under the boiling point. Heat transfer due to a single axisymmetric jet with different water flow rate was compared to cases of a single jet and two jets in 3D. The RANS model in ANSYS Fluent was used with the k −ε model in transient simulation of the axisymmetric model and steady flow for the 3D cases. Two different boundary conditions, constant temperature and constant heat flux were applied at the surface of the steel plate. The numerical results were consistent between 2D and 3D and compared well to literature data. The time dependent simulation for the 3D model requires very large computational power which motivated an investigation of simpler flow solvers running on a GPU platform. A simple 2D Navier-Stokes solver based on Finite Volume Method was written using OpenCL which can simulate flow and heat convection. A standard CFD problem named "Lid Driven Cavity" in 2D was chosen as validation case and for performance measurement and tuning of the solver.När stål valsas till plåt är det sista steget att kyla den färdiga produkten på utrullningsbordet (ROT). I detta arbete studeras värmetransporten i en vattenstråle som faller in mot en varm plan platta som är den viktigaste kylprocessen på utrullningsbordet. Plattans temperatur hölls under kokpunkten. Värmeövergång i en ensam rotationssymmetrisk stråle med olika hastighet jämförs med en och två strålar i 3D modeller. RANS-modellering i ANSYS Fluent med k −ε turbulensmodell används för transientberäkning för rotationssymmetri och för stationär beräkning för 3D-fallen. Två olika randvillkor, konstant temperatur och konstant värmeflöde, används vid plattan. De numeriska resultaten är konsistenta mellan rotationssymmetri och 3D och jämförbara med litteratur-data. Transient simulering av 3D modellerna kräver stora datorresurser vilket motiverar en undersökning om enklare strömningsmodeller som kan köra på GPU-plattform. En enkel 2D Navier-Stokes-lösare baserad på Finita Volym-metoden implementerades i OpenCL för simulering av konvektiv värmetransport. Lid Driven Cavity-problemet i 2D valdes för verifiering och tidtagning.
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Maré, Charl Francois. "An investigation of CFD simulation for estimation of turbine RUL." Diss., University of Pretoria, 2018. http://hdl.handle.net/2263/69152.
Full textAbstract:
Turbines encounter blade failures due to fatigue and creep. It has been shown in the literature that the primary cause of steam turbine blade failures worldwide can be ascribed to fatigue in low pressure (LP) turbine blades. The failure and damage to these blades can lead to catastrophic consequences. Some utilities use empirical methods to determine the forces experienced by turbine blades but desire more accurate methods. The inaccurate
prediction of high-cycle fatigue (HCF), thermal durability and stage performance
is introduced when one does not consider blade row interaction. Blade row interactions can, however, be accounted for by means of computational fluid dynamics (CFD). Furthermore, modern high- fidelity CFD tools would be able to contribute greatly in predicting the forces experienced by turbine blades.
Numerical tools such as CFD and nite element analysis (FEA) can greatly contribute to the estimation of the remaining useful life (RUL) of turbine blades. However, in this estimation process, there are various uncertainties and aspects that affect the estimated RUL. Understanding the sensitivity of the estimated RUL to these various uncertainties and aspects is of great importance if RUL is to be estimated as accurately as possible.
In this dissertation, a sensitivity analysis is performed with the purpose of establishing the sensitivity of the estimated RUL of the last stage rotor of an LP steam turbine, to the number of harmonics used in a nonlinear harmonic (NLH) CFD simulation. The sensitivity of the estimated RUL is evaluated in the HCF regime, where the cyclic stresses occur below the yield strength of the turbine blade. A CFD model, FE model, and fatigue model were therefore developed in such a manner that would suffice, regarding the purpose of the sensitivity analysis. The CFD model is validated by comparing the predicted CFD power to that of actual generated power of a dual 100MW LP steam turbine. The sensitivity analysis is performed for 3 operation conditions, and for each operational condition the aerodynamic forces were computed using 1, 2, and 3 harmonics in an NLH simulation.
The estimation process considers a weak coupling between the CFD model and FE model. NLH simulations are firstly performed to calculate the unsteady static surface pressure distributions on the last stage rotor. This is followed by the mapping thereof to the FE model, for which a transient structural analysis is performed. Finally, the RUL is estimated by performing a fatigue analysis on the stress history obtained from the transient structural analysis.
Based on the results of the sensitivity analysis, the following recommendations were made, from a conservative point of view. Firstly, in general, if the RUL is to be estimated with reasonable accuracy, just using 1 harmonic in an NLH simulation will not be sufficient and 2 harmonics should be used. Secondly, if the RUL has to be estimated with high accuracy, 3 harmonics should be used.Dissertation (MEng)--University of Pretoria, 2018.
National Research Foundation (NRF)
Mechanical and Aeronautical Engineering
MEng
Unrestricted
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Janic, Aljaz. "CFD Simulation of Particles in Pipe Flow and Mixing Tank." Thesis, Linköpings universitet, Mekanisk värmeteori och strömningslära, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-168488.
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This project aimed to investigate the capability of the STAR CCM+ software when predicting the flow with particles using Lagrangian Particle Tracking and Discrete Element Method. The first part pertained to rectangular channel flow, with ratio between height of the channel and particle diameter (2h/Dp ) of 15. It was found out that simulations of particles in a channel come with many diculties. Such as, obtaining accurate pressure drop results using DEM when comparing to DNS simulations including particles within a reasonable computational time. The second part consisted of a simulation of the off-centred mixing tank. As the use of DEM caused numerical issues, another modeling approach was used. Therefore, the Lagrangian Particle Tracking was used. The outcome of the project is the sensitivity study of the forces which can be applied to the particles. The finding was that the Shear Lift force and the Virtual Mass force have a negligible contribution in regards to the particles distribution. In addition to this, it was also discovered that the turbulence model has a large effect on the particles in the near-wall region. Choosing an isotropic turbulence model resulted in clustering of the particles near the wall, therefore an anisotorpic turbulence model needed to be used.
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Hill, Hugh Edward. "2D CFD Simulation of a Circulation Control Inlet Guide Vane." Thesis, Virginia Tech, 2007. http://hdl.handle.net/10919/30994.
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This thesis presents the results of two 2-D computational studies of a circulation control Inlet Guide Vane (IGV) that takes advantage of the Coanda effect for flow vectoring. The IGV in this thesis is an uncambered airfoil that alters circulation around itself by means of a Coanda jet that exhausts along the IGV's trailing edge surface. The IGV is designed for an axial inlet flow at a Mach number of 0.54 and an exit flow angle of 11 degrees. These conditions were selected to match the operating conditions of the 90% span section of the IGV of the TESCOM compressor rig at the Compressor Aero Research Laboratory (CARL) located at Wright-Patterson AFB. Furthermore, using the nominal chord (length from leading edge of the IGV to the jet exit) for the length scale, the Reynolds number for the circulation control IGV in this region was 5e5. The first study was a code and turbulence model comparison, while the second study was an optimization study which determined optimal results for parameters that affected circulation around the IGV. Individual abstracts for the two studies are provided below.
To determine the effect of different turbulence models on the prediction of turning angles from the circulation control IGV, the commercial code GASP was employed using three turbulence models. Furthermore, to show that the results from the optimization study were code independent a code comparison was completed between ADPAC and GASP using the Spalart-Allmaras turbulence model. Turbulence models employed by GASP included: two isotropic turbulence models, the one equation Spalart-Allmaras and the two-equation Wilcox 1998 k-ω. The isotropic models were then compared to the non-isotropic stress transport model Wilcox 1998 Stress-ω. The results show good comparison between turning angle trends and pressure loss trends for a range of blowing rates studied at a constant trailing edge radius size. When the three turbulence models are compared for a range of trailing edge radii, the models were in good agreement when the trailing edge is sufficiently large. However, at the smallest radius, isotropic models predict the greatest amount of circulation around the IGV that may be caused by the prediction of transonic flow above the Coanda surface.
The optimization study employed the CFD code ADPAC in conjunction with the Spalart-Allmaras turbulence model to determine the optimal jet height, trailing edge radius, and supply pressure that would meet the design criteria of the TESCOM (TESt COMpressor) rig while minimizing the mass flow rate and pressure losses. The optimal geometry that was able to meet the design requirements had a jet height of h/Cn = 0.0057 and a trailing edge Radius R/Cn = 0.16. This geometry needed a jet to inflow total pressure ratio of 1.8 to meet the exit turning angle requirement. At this supply pressure ratio the mass flow rate required by the flow control system was 0.71 percent of the total mass flow rate through the engine. The optimal circulation control IGV had slightly lower pressure losses when compared to the cambered IGV in the TESCOM rig.
Master of Science
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Crozon, Clément. "Coupling flight mechanics and CFD : numerical simulation of shipborne rotors." Thesis, University of Liverpool, 2015. http://livrepository.liverpool.ac.uk/2030079/.
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This thesis demonstrates the use of Computational Fluid Dynamics (CFD) for the simulation of manoeuvring helicopters. Results are presented for the problem of shipborne operations, for which a literature survey showed that little work has been carried out. The CFD solver HMB2 was first validated using available experimental data for isolated ship wakes and helicopter loads at low advance ratios. A rotorcraft flight mechanics model was then developed and integrated into HMB2. The model includes a trimming method and a linearisation routine based on finite differences. The linear model of the aircraft can be used to estimate the controls applied by the pilot during a prescribed manoeuvre via the use of the SYCOS inverse-simulation method or via an LQR auto-pilot. The methods developed in the framework of this thesis include a general multi-body grid motion and an alternative formulation for earth-fixed frame of reference in the CFD. A study of the ship/rotor wake interaction was carried out using the actuator disc method that approximated the effect of the rotor, in a steady fashion and without resolving the flow around the blades. Various positions and thrust of the rotor were tested and the flowfield obtained via coupled simulations were compared with those obtained by super-imposing isolated rotor and ship flowfields. The results show that the superposition principle is not valid and leads to flowfields that have little to do with the real flow that is dominated by the interaction of helicopter and ship airwakes. The case of a rotor hovering in close proximity to a frigate deck was reproduced with fullyresolved blades, and the results shows a significant reduction of thrust due to the flow topology behind the hangar. The Helicopter Flight Mechanics (HFM) method was tested by simulating the aircraft response to a collective pilot input, using simplified models and coupled with CFD. Then, the coupled HFM/HMB2 method was used, in conjunction with the LQR auto-pilot, to simulate the phase of landing of a Sea King helicopter. Simulations were carried-out in free-air and above the frigate deck and the specified trajectories were followed adequately. Results for the ship landing show that the wake of the ship alters the obtained landing trajectory and that the current method captures some of the effects of the wake interaction.
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Cha, Jeesung Jeff. "CFD Simulation of Multi-Dimensional Effects in Inertance Tube Pulse Tube Cryocoolers." Thesis, Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/5229.
Full textAbstract:
Inertance Tube Pulse Tube Cryocoolers (ITPTC) are a class of rugged and high-endurance refrigeration systems that operate without a moving part at their low temperature end, and are capable of reaching 4 K or lower. ITPTCs are suitable for application in space vehicles, and attempts are underway worldwide to improve their performance and miniaturize their size. The thermo-fluidic processes in ITPTC are complicated, however, and the details of the mechanisms underlying their performance are not well understood. Elucidation of these underlying processes is the objective of this investigation.
In this study, the commercial computational fluid dynamic (CFD) package Fluent䵠was utilized for modeling the entire large ITPTC system that includes a compressor, an after cooler, a regenerator that is represented as a porous medium, a pulse tube, cold and warm heat exchangers, an inertance tube, and a reservoir. The simulations represent a fully-coupled system operating in steady periodic mode, without any arbitrary assumptions. The objective was to examine the extent of multi-dimensional flow effects in an inertance tube pulse tube cryocoolers, and their impact on the performance of these cryocoolers.
Computer simulations were performed for two complete ITPTC systems that were geometrically similar except for the length-to-diameter ratios of their regenerators and pulse tubes. For each ITPTC system three separate simulations were performed, one with an adiabatic cold-end heat exchanger (CHX), one with a known cooling heat load, and one with a pre-specified CHX temperature. Each simulation would start with an assumed uniform system temperature, and continue until steady periodic conditions were achieved.
The results indicate that CFD simulations are capable of elucidating the complex periodic processes in PTCs very well. The simulation results also show that a one-dimensional modeling of PTCs is appropriate only when all the components of the PTC have very large aspect ratios (i.e., L/D >>1). Significant multi-dimensional flow effects occur at the vicinity of component-to-component junctions, and secondary-flow recirculation patterns develop, when one or more components of the PTC system have small aspect ratios. The simulation results, although limited in scope, also suggest that ITPTCs will have a better overall performance if they are made of components with large aspect ratios.
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Ilie, Katherine-Rodica, and Katherine ilie@rmit edu au. "Modelling, Simulation and Optimisation of Asymmetric Rotor Profiles in Twin-screw Superchargers." RMIT University. Aerospace, Mechanical and Manufacturing Engineering, 2007. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20080213.144857.
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There is a growing recognition worldwide of the need for more powerful, smaller petrol engines, capable of delivering the higher picking power of larger engines, yet still being economical and environmentally friendly when used for day-to-day driving. An engineering solution for more efficient engines has been considered by research so far. It has been identified that superchargers can potentially improve the performance of automotive engines; therefore research has focused on developing superchargers and supercharger components with higher efficiency. Of particular interest to the research presented in this thesis has been the twin-screw supercharging compressor with design adapted for automotive use (the twin-screw supercharger). The performance of this supercharger type depends on the volume and total losses of the air flow through the supercharger rotors more than on any other aspects of its behaviour. To accurately predict the efficiency of the twin-screw su percharger for matching a particular engine system, accurate supercharger design is required. The main objective of this research was the investigation of the existing limitations of twin-screw superchargers, in particular leakage and reduced efficiency, leading to the development of optimal asymmetric rotor profiles. This research has been completed in four stages defining an innovative rotor design method. The parametric three-dimensional geometric model of twin-screw supercharger rotors of any aspect ratio was developed. For model validation through visualisation, CAD rotor models with scalable data were generated in commercial CAD software and calibrated experimentally by Laser Doppler Velocimetry (LDV) tests. Calibrated rotor profile data can be transferred into CAD-CFD interface for flow simulation and performance optimisation. Through the application of this new rotor design method, new opportunities are created for the twin-screw supercharger design practice, making it a part of the engineering solution for more efficient engines.
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Ratnam, Edward. "Indoor air quality simulation and feedback control." Thesis, Glasgow Caledonian University, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.388935.
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Prasser, Horst-Michael, Tobias Sühnel, Christophe Vallée, and Thomas Höhne. "Experimental investigation and CFD simulation of slug flow in horizontal channels." Forschungszentrum Dresden, 2010. http://nbn-resolving.de/urn:nbn:de:bsz:d120-qucosa-28061.
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For the investigation of stratified two-phase flow, two horizontal channels with rectangular cross-section were built at Forschungszentrum Dresden-Rossendorf (FZD). The channels allow the investigation of air/water co-current flows, especially the slug behaviour, at atmospheric pressure and room temperature. The test-sections are made of acrylic glass, so that optical techniques, like high-speed video observation or particle image velocimetry (PIV), can be applied for measurements. The rectangular cross-section was chosen to provide better observation possibilities. Moreover, dynamic pressure measurements were performed and synchronised with the high-speed camera system. CFD post-test simulations of stratified flows were performed using the code ANSYS CFX. The Euler-Euler two fluid model with the free surface option was applied on grids of minimum 4∙105 control volumes. The turbulence was modelled separately for each phase using the k-ω based shear stress transport (SST) turbulence model. The results compare well in terms of slug formation, velocity, and breaking. The qualitative agreement between calculation and experiment is encouraging and shows that CFD can be a useful tool in studying horizontal two-phase flow. Furthermore, CFD pre-test calculations were done to show the possibility of slug flow generation in a real geometry and at relevant parameters for nuclear reactor safety. The simulation was performed on a flat model representing the hot-leg of the German Konvoi-reactor, with water and saturated steam at 50 bar and 263.9°C. The results of the CFD-calculation show wave generation in the horizontal part of the hot-leg which grow to slugs in the region of the bend.