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1
Carmack, Andrew Cardin. "Heat Transfer and Flow Measurements in Gas Turbine Engine Can and Annular Combustors." Thesis, Virginia Tech, 2012. http://hdl.handle.net/10919/32466.
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A comparison study between axial and radial swirler performance in a gas turbine can combustor was conducted by investigating the correlation between combustor flow field geometry and convective heat transfer at cold flow conditions for Reynolds numbers of 50,000 and 80,000. Flow velocities were measured using Particle Image Velocimetry (PIV) along the center axial plane and radial cross sections of the flow. It was observed that both swirlers produced a strong rotating flow with a reverse flow core. The axial swirler induced larger recirculation zones at both the backside wall and the central area as the flow exits the swirler, and created a much more uniform rotational velocity distribution. The radial swirler however, produced greater rotational velocity as well as a thicker and higher velocity reverse flow core. Wall heat transfer and temperature measurements were also taken. Peak heat transfer regions directly correspond to the location of the flow as it exits each swirler and impinges on the combustor liner wall.
Convective heat transfer was also measured along the liner wall of a gas turbine annular combustor fitted with radial swirlers for Reynolds numbers 210000, 420000, and 840000. The impingement location of the flow exiting from the radial swirler resulted in peak heat transfer regions along the concave wall of the annular combustor. The convex side showed peak heat transfer regions above and below the impingement area. This behavior is due to the recirculation zones caused by the interaction between the swirlers inside the annulus.<br>Master of Science
2
Tse, David Gar Nile. "Flow and combustion characteristics of model annular and can-type combustors." Thesis, Imperial College London, 1988. http://hdl.handle.net/10044/1/8941.
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Kao, Yi-Huan. "Experimental Investigation of Aerodynamics and Combustion Properties of a Multiple-Swirler Array." University of Cincinnati / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1406881553.
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4
Spencer, A. "Gas turbine combustor port flows." Thesis, Loughborough University, 1998. https://dspace.lboro.ac.uk/2134/6883.
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Competitive pressure and stringent emissions legislation have placed an urgent demand on research to improve our understanding of the gas turbine combustor flow field. Flow through the air admission ports of a combustor plays an essential role in determining the internal flow patterns on which many features of combustor performance depend. This thesis explains how a combination of experimental and computational research has helped improve our understanding, and ability to predict, the flow characteristics of jets entering a combustor. The experiments focused on a simplified generic geometry of a combustor port system. Two concentric tubes, with ports introduced into the inner tube's wall, allowed a set of radially impinging jets to be formed within the inner tube. By investigating the flow with LDA instrumentation and flow visualisation methods a quantitative and qualitative picture of the mean and turbulent flow fields has been constructed. Data were collected from the annulus, port and core regions. These data provide suitable validation information for computational models, allow improved understanding of the detailed flow physics and provide the global performance parameters used traditionally by combustor designers. Computational work focused on improving the port representation within CFD models. This work looked at the effect of increasing the grid refinement, and improving the geometrical representation of the port. The desire to model realistic port features led to the development of a stand-alone port modelling module. Comparing calculations of plain-circular ports to those for more realistic chuted port geometry, for example, showed that isothermal modelling methods were able to predict the expected changes to the global parameters measured. Moreover, these effects are seen to have significant consequences on the predicted combustor core flow field.
5
Asere, Abraham Awolola. "Gas turbine combustor wall cooling." Thesis, University of Leeds, 1986. http://etheses.whiterose.ac.uk/2590/.
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The need for better methods of cooling gas turbine combustors and a review of current cooling techniques have been presented. Three cooling methods are investigated: (a) Full Coverage Discrete Hole Film Cooling (Effusion), (b) Impingement/Effusion Hybrid Cooling Systems, and (c) Transpiration Cooling. The aim of these cooling techniques is to effectively and efficiently cool gas turbine combustors with a significant reduction in current cooling air requirements. The range of test conditions were coolant temperature, Tc, of 289 < Tc 710 K and combustion gases temperature, Tg, of 500 Tg N< 1900 K. The discharge coefficients of the effusion and the impingement/effusion systemshave also been studied. A detailed analysis has been made of the heat transfer of the cooling systems, jet penetration into the cross-stream, prediction of the cooling jet temperatures at various stages in the cooling process and the cooling film heat transfer coefficient. The results of the discharge coefficient (Cd) indicate a decreasing C with increasing wall thickness to diameter ratio, t/D, and a weak effect of cross-stream flow. The results of both the effusion and the impingement/effusion hybrid systems indicate a high cooling performance of similar magnitude to that of the transpiration system. Graphical design correlations for the cooling wall have been made. The optimum hole geometries for both cooling configurations have been developed. The influence of the coolant to hot gas density ratio has been studied over the range 1.4-3.4. In the design of effusion and impingement/effusion cooling systems, wall thickness, hole density, hole diameter and wall design pressure loss are significant parameters for cooling performance maximisation.
6
Murthy, J. N. "Gas turbine combustor modelling for design." Thesis, Cranfield University, 1988. http://hdl.handle.net/1826/2626.
Full textAbstract:
The design and development of gas turbine combustors is a crucial but uncertain part of an engine development process. Combustion within a gas turbine is a complex interaction of, among other things, fluid dynamics, heat and mass transfer and chemical kinetics. At present, the design process relies upon a wealth of experimental data and correlations. The proper use of this information requires experienced combustion engineers and even for them the design process is very time consuming.
Some major engine manufacturers have attempted to address the above problem by developing one dimensional computer programs based on the above test and empirical data to assist combustor designers. Such programs are usually proprietary. The present work, based on this approach has yielded DEPTH, a combustor design program. DEPTH ( Design and Evaluation of Pressure, Temperature and Heat transfer in combustors) is developed in Fortran-77 to assist in preliminary design and evaluation of conventional gas turbine combustion chambers.
DEPTH can be used to carry out a preliminary design along with prediction of the cooling slots for a given metal temperature limit or to evaluate heat transfer and temperatures for an existing combustion chamber. Analysis of performance parameters such as efficiency, stability and NOx based on stirred reactor theories is also coupled. DEPTH is made sufficiently interactive/user-friendly such that no prior expertise is required as far as computer operation is concerned. The range of variables such as operating conditions, geometry, hardware, fuel type can all be effectively examined and their contribution towards the combustor performance studied. Such comprehensive study should provide ample opportunity for the designer to make the right decisions. It should also be an effective study aid. Returns in terms of higher thermal efficiencies is an incentive to go for combined cycles and cogeneration. In such cases, opting for higher cycle pressures together with a second or reheat combustor promise higher thermal efficiencies and exhaust temperatures and hence such designs are likely to be of interest. The concepts that are needed for understanding a double or reheat combustor are also addressed using the programme. A specific application of the programme is demonstrated through the design of a double combustor.
7
Bengtsson, Karl. "ThermoacousticInstabilities in a Gas Turbine Combustor." Thesis, KTH, MWL Marcus Wallenberg Laboratoriet, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-226530.
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Stationary gas turbines are widely used today for power generation and mechanical drive applications. The introduction of new regulations on emissions in the last decades have led to extensive development and new technologies used within modern gas turbines. The majority of the gas turbines sold today have a so called DLE (Dry Low Emission) combustion system that mainly operates in the leanpremixed combustion regime. The lean-premixed regime is characterized by low emission capabilities but are more likely to exhibit stability issues compared to traditional non-premixed combustion systems. Thermoacoustic instabilities are a highly unwanted phenomena characterized by an interaction between an acoustic eld and a combustion process. This interaction may lead to self-sustained large amplitude oscillations which can cause severe structural damage to the gas turbine if it couples with a structural mode. However, since a coupled phenomena, prediction of thermoacoustic stability is a complex topic still under research. In this work, the mechanisms responsible for thermoacoustic instabilities are described and a 1- dimensional stability modelling approach is applied to the Siemens SGT-750 combustion system. The complete combustor is modelled by so called acoustic two-port elements in which a 1-dimensional ame model is incorporated. The simulations is done using a generalized network code developed by Siemens. The SGT-750 shows today excellent stability and combustion performance but a deeper knowledge in the thermoacoustic behaviour is highly valued for future development. In addition, measurement data from an engine test is evaluated, post-processed and compared with the results from the 1-dimensional network model. The results are found to be in good agreement and the thermoacoustic response of the SGT-750 is found to be dominated by both global modes including all cans as well as local modes within the individual cans.
8
Main, A. D. J. "Annular turbine cascade aerodynamics." Thesis, University of Oxford, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.239350.
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9
Poppe, Christian. "Scalar measurements in a gas turbine combustor." Thesis, Imperial College London, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.264987.
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10
Zheng, Qing-ping. "Soot production in a tubular gas turbine combustor." Thesis, Cranfield University, 1994. http://hdl.handle.net/1826/3910.
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Soot production in gas turbine combustors is not desirable since it is the major source
of exhaust smoke emission and its thermal radiation to the combustor liner deteriorates the liner
durability. Soot formation involves comparatively slow chemistry and equilibrium can not be
applied to soot modelling in the combustor flow field.
. The exact sooting process in the
combustor is poorly understood given both the complexity and the limited experimental data
available. The work reported in this thesis seeks to first develop in-situ techniques for
retrieving spatially-resolved soot properties, mainly soot particle volume fraction, from within
the combustor and also to apply the measured results to comparisons with predicted soot
concentrations.
Two probing methods have been demonstrated which also incorporate a laser absorption
technique. The sight probe proves to be more reliable in the present measurements. The
evaluation of the physical probing techniques in sooty laboratory flames reveals that the flame
structure will not be substantially distorted by the probe. The disturbance caused by the probe
is localised, a feature which is evident in the reported water flow visualization test. The
necessary inert gas purge can be minimised to reduce the local aerodynamic perturbation. The
measured soot volume fraction distributions are comparable with sooting levels reported in
flame studies in the literature. The peak soot volume fractions are located off-axis,
characteristic of the fuel atornization. The measurementsin the primary zone are restricted by
the multi-phase character of the flow, where soot absorption can not be readily discriminated
from fuel droplet scattering. Measurements are reported over a range of air-fuel ratios, inlet
pressures and temperatures.
Time-averageds calard istributionsa t the nominald ilution sectionh ave beeno btained
in addition to the soot measuremenut sing probe sampling and standard gas analysis.
Correlationso f carbond ioxide with mixture fraction reveala clear relationshipa t overall lean
conditionsc onsistenwt ith widely usedm odelleda ssumptions.T here are less well-correlated
relationshipsb etweent emperaturea ndm ixture fraction, possiblyd ue to the influenceo f scalar
fluctuationsa nda lsoo f the scalard issipationr ate. Sootl oadingi n the presentf low conditions
is characteristicallylo w, basedo n the mixture fraction ands ootv olumef raction data. Thermal
radiation in the visible spectrum shows a distinct narrow band spectra in addition to the soot
continuum, which is believed to arise fromC2radical emission. The mean radiation intensities,
predictedb y usingt he measuredte mperaturea nds ootc oncentrationre sults,a rei n generallo wer
than the measured mean intensities. Temperature fluctuation levels may be particularly
influential in some of these calculations.
Sootm odellingi n the combustohr asb eenu ndertakenb y applyinga n extendedla minar
flamelet concept. The two-equations oot formation model has beenp rimarily developedo n
laminar flames. The comparisono f the computationa nd measuremenstu ggeststh at this soot
model holds promise in the context of prediction in the combustor. In the absenceo f a
satisfactoryt heoreticald escriptiono f the fuel-air burning in the combustor,w heret he liquid
kerosinee mployedis replacedb y gaseoups ropane,t he computeds calarp rofiles are inconsistent
in some importantr espectsw ith the measuredo nes. This exerts a major effect on the soot
predictioni n terms of the quantitatived etail in the computationw, hich is howeverc rucial for
the soot model development. The original flow field modelling needs to be improved for the
purpose of further soot model refinement.
11
Da, Palma Jose Manuel Laginha Mestre. "Mixing in non-reacting gas turbine combustor flows." Thesis, Imperial College London, 1989. http://hdl.handle.net/10044/1/47606.
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12
Koutmos, P. "An isothermal study of gas turbine combustor flows." Thesis, Imperial College London, 1985. http://hdl.handle.net/10044/1/37748.
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13
Stitzel, Sarah M. "Flow Field Computations of Combustor-Turbine Interactions in a Gas Turbine Engine." Thesis, Virginia Tech, 2001. http://hdl.handle.net/10919/30992.
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The current demands for higher performance in gas turbine engines can be reached by raising combustion temperatures to increase thermal efficiency. Hot combustion temperatures create a harsh environment which leads to the consideration of the durability of the combustor and turbine sections. Improvements in durability can be achieved through understanding the interactions between the combustor and turbine. The flow field at a combustor exit shows non-uniformities in pressure, temperature, and velocity in the pitch and radial directions. This inlet profile to the turbine can have a considerable effect on the development of the secondary flows through the vane passage.
This thesis presents a computational study of the flow field generated in a non-reacting gas turbine combustor and how that flow field convects through the downstream stator vane. Specifically, the effect that the combustor flow field had on the secondary flow pattern in the turbine was studied. Data from a modern gas turbine engine manufacturer was used to design a realistic, low speed, large scale combustor test section. This thesis presents the results of computational simulations done in parallel with experimental simulations of the combustor flow field.
In comparisons of computational predictions with experimental data, reasonable agreement of the mean flow and general trends were found for the case without dilution jets. The computational predictions of the combustor flow with dilution jets indicated that the turbulence models under-predicted jet mixing. The combustor exit profiles showed non-uniformities both radially and circumferentially, which were strongly dependent on dilution and cooling slot injection. The development of the secondary flow field in the turbine was highly dependent on the incoming total pressure profile. For a case with a uniform inlet pressure in the near-wall region no leading edge vortex was formed. The endwall heat transfer was found to also depend strongly on the secondary flow field, and therefore on the incoming pressure profile from the combustor.<br>Master of Science
14
Stuttaford, Peter J. "Preliminary gas turbine combustor design using a network approach." Thesis, Cranfield University, 1997. http://hdl.handle.net/1826/1038.
Full textAbstract:
Gas turbine combustor design represents an ambitious task in numerical and
experimental analysis. A significant number of competing criteria must be optimised
within specified constraints in order to satisfy legislative and performance requirements.
Currently, preliminary combustor flow and heat transfer design procedures, which by
necessity involve semi-empirical models, are often restricted in their range of
application.
The objective of this work is the development of a versatile design tool able to model all
conceivable gas turbine combustor types. A network approach provides the foundation
for a complete flow and heat transfer analysis to meet this goal.
The network method divides the combustor into a number of independent
interconnected sub-flows. A pressure-correction methodology solves the continuity
equation and a pressure-drop/flow-rate relationship. A constrained equilibrium
calculation, incorporating mixing and recirculation models, simulates the combustion
process. The new procedures are validated against numerical and experimental data
within three annular combustors and one reverse flow combustor. A full conjugate heat
transfer model is developed to allow the calculation of liner wall temperature
characteristics. The effects of conduction, convection and radiation are included in the
model. Film cooling and liner heat pick-up effects are included in the convection
calculation. Radiation represents the most difficult mode of heat transfer to simulate in
the combustion environment. A discrete transfer radiation model is developed and
validated for use within the network solver. The effects of soot concentration on
radiation is evaluated with the introduction of radial properties profiles. The accuracy of
the heat transfer models are evaluated with comparisons to experimental thermal paint
temperature data on a reverse flow and annular combustors.
The resulting network analysis code represents a powerful design tool for the
combustion engineer incoporating a novel and unique strategy.
15
Ruggles, Adam. "Flame Behaviour in an Acoustically Forced Gas Turbine Combustor." Thesis, Cranfield University, 2009. http://hdl.handle.net/1826/3760.
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A swirl stabilised dump combustor capable of imposing flow perturbations
creating combustion instabilities has been designed and commissioned. The
capability of supplying different fuel mixtures (methane hydrogen blends) has
been incorporated. Additional capability is the facility to preheat the combustion
air prior to chamber entry and to be able to introduce dilution air into the
chamber. The chamber itself is of fused silica quartz to allow non-intrusive
optical diagnostics.
High speed CH* Chemiluminescence has been performed to qualitative
characterise the unstable heat release rate of pure methane and methane
hydrogen blended flames to allow analysis of the mean deconvoluted flame
structure. High speed Stereoscopic Particle Imaging Velocimetry (SPIV) has been
used to acquire the flow field throughout the chamber and focusing upon the
Annulus entry. These diagnostics have been phase locked to the imposed
perturbation.
A selection of conditions is presented with three different perturbation
frequencies within the low frequency range. These reveal vastly different
reacting and flow field structures. The difference of structures is attributed to
behaviour of the IRZ (Internal Recirculation Zone) and CRZ (Corner
Recirculation Zone) in altering the flame shape. All conditions exhibited the
axisymmetric/bubble vortex breakdown mechanism responsible for stabilisation.
Both single cell and double cell structures were observed in the mean flow field
vector maps. The mechanism of oscillating heat release rate is attributed to
oscillations of flame surface area. Profiles of integrated heat release rate and
flame exhibit the same profile shape and behaviour correlating very well. The
inclusion of hydrogen had no quantifiable impact upon the mean reacting or flow
field structures using the current diagnostics. Investigation into the nature of the
turbulence of the shear layers close to the annulus is presented for three
perturbation frequencies. This highlighted periodic structures within the
turbulence corresponding to the imposed perturbation frequency. It was found
that excitation of both shear layers for all turbulent components was not always
true and depended upon the perturbation frequency and flow structure close to
the annulus. Two oppositely rotating vorticity structures were revealed attached
to the outer and inner circumference of the annulus. These structures protruded
into the chamber and spread radially. Frequency analysis of these two structures
revealed both were oscillating at the perturbation frequency indicating vorticity
shedding. The mean vorticity structures are shown to be influenced also by the
behaviour of the recirculation zones.
16
Abdulsada, Mohammed. "Flashback and blowoff characteristics of gas turbine swirl combustor." Thesis, Cardiff University, 2011. http://orca.cf.ac.uk/24193/.
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Gas turbines are extensively used in combined cycle power systems. These form about 20% of global power generating capacity, normally being fired on natural gas, but this is expected in the future to move towards hydrogen enriched gaseous fuels to reduce CO2 emissions. Gas turbine combined cycles can give electrical power generation efficiencies of up to 60%, with the aim of increasing this to 70% in the next 10 to 15 years, whilst at the same time substantially reducing emissions of contaminants such as NOx. The gas turbine combustor is an essential and critical component here. These are universally stabilized with swirl flows, which give very wide blowoff limits, and with appropriate modification can be adjusted to give very low NOx and other emission. Lean premixed combustion is commonly used at pressures between 15 to 30 bar, these even out hot spots and minimise formation of thermal NOx. Problems arise because improving materials technology/improved cooling techniques allow higher turbine inlet temperatures, hence higher efficiencies, but with the drawback of potentially higher emissions and stability problems. This PhD study has widely investigated and analysed two different kinds of gas turbine swirl burners. The research has included experimental investigation and computational simulation. Mainly, the flashback and blowoff limits have been comprehensively analysed to investigate their effect upon swirl burner operation. The study was extended by using different gas mixtures, including either pure gas or a combination of more than one gas like natural gas, methane, hydrogen and carbon dioxide. The first combustor is a 100 kW tangential swirl combustor made of stainless steel that has been experimentally and theoretically analysed to study and mitigate the effect of flashback phenomena. The use of a central fuel injector, cylindrical confinement and exhaust sleeve are shown to give large benefits in terms of flashback resistance and acts to reduce and sometimes eliminate any coherent structures which may be located along the axis of symmetry. The Critical Boundary Velocity Gradient is used for characterisation of flashback, both via the original Lewis and von Elbe formula and via new analysis using CFD and investigation of boundary layer conditions just in front of the flame front. Conclusions are drawn as to mitigation technologies. It is recognized how isothermal conditions produce strong Precessing Vortex Cores that are fundamental in producing the ii final flow field, whilst the Central Recirculation Zones are dependent on pressure decay ratio inside the combustion chamber. Combustion conditions showed the high similarity between experiments and simulation. Flashback was demonstrated to be a factor highly related to the strength of the Central Recirculation Zone for those cases where a Combustion Induced Vortex Breakdown was allowed to enter the swirl chamber, whilst cases where a bluff body impeded its passage showed a considerable improvement to the resistance of the phenomenon. The use of nozzle constrictions also reduced flashback at high Reynolds number (Re). All these results were intended to contribute to better designs of future combustors. The second piece of work of this PhD research included comprehensive experimental work using a generic swirl burner (with three different blade inserts to give different swirl numbers) and has been used to examine the phenomena of flashback and blowoff in the swirl burner in the context of lean premixed combustion. Cylindrical and conical confinements have been set up and assembled with the original design of the generic swirl combustor. In addition to that, multi-fuel blends used during the experimental work include pure methane, pure hydrogen, hydrogen / methane mixture, carbon dioxide/ methane mixture and coke oven gas. The above investigational analysis has proved the flashback limits decrease when swirl numbers decrease for the fuel blends that contain 30% or less hydrogen. Confinements would improve the flashback limit as well. Blowoff limits improve with a lower swirl number and it is easier to recognise the gradual extinction of the flame under blowoff conditions. The use of exhaust confinement has created a considerable improvement in blowoff. Hydrogen enriched fuels can improve the blowoff limit in terms of increasing heat release, which is higher than heat release with natural gas. However, the confinements complicate the flashback, especially when the fuel contains a high percentage of hydrogen. The flashback propensity of the hydrogen/methane blends becomes quite strong. The most important features in gas turbines is the possibility of using different kinds of fuel. This matter has been discussed extensively in this project. By matching flashback/blowoff limits, it has been found that for fuels containing up to 30% of hydrogen, the designer would be able to switch the same gas turbine combustor to multifuels whilst producing the same power output.
17
Almutlaq, Ahmed N. "Density-based unstructured simulations of gas-turbine combustor flows." Thesis, Loughborough University, 2007. https://dspace.lboro.ac.uk/2134/13892.
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The goal of the present work was to identify and implement modifications to a density-based unstructured RANS CFD algorithm, as typically used in turbomachinery flows (represented here via the RoIIs-Royce 'Hydra' code), for application to Iow Mach number gas-turbine combustor flows. The basic algorithm was modified to make it suitable for combustor relevant problems. Fixed velocity and centreline boundary conditions were added using a characteristic based method. Conserved scalar mean and variance transport equations were introduced to predict scalar mixing in reacting flows. Finally, a flarnelet thermochemistry model for turbulent non-premixed combustion with an assumed shape pdf for turbulence-chemistry interaction was incorporated. A method was identified whereby the temperature/ density provided by the combustion model was coupled directly back into the momentum equations rather than from the energy equation. Three different test cases were used to validate the numerical capabilities of the modified code, for isothermal and reacting flows on different grid types. The first case was the jet in confined cross flow associated with combustor liner-dilution jetcore flow interaction. The second was the swirling flow through a multi-stream swirler. These cases represent the main aerodynamic features of combustor primary zones. The third case was a methane-fueled coaxial jet combustor to assess the combustion model implementation. This study revealed that, via appropriate modifications, an unstructured density-based approach can be utilised to simulate combustor flows. It also demonstrated that unstructured meshes employing nonhexahedral elements were inefficient at accurate capture of flow processes in regions combining rapid mixing and strong convection at angles to cell edges. The final version of the algorithm demonstrated that low Mach RANS reacting flow simulations, commonly performed using a pressure-based approach, can successfully be reproduced using a density-based approach.
18
Hollis, David. "Particle image velocimetry in gas turbine combustor flow fields." Thesis, Loughborough University, 2004. https://dspace.lboro.ac.uk/2134/7640.
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Current and future legislation demands ever decreasing levels of pollution from gas turbine engines, and with combustor performance playing a critical role in resultant emissions, a need exists to develop a greater appreciation of the fundamental causes of unsteadiness. Particle Image Velocimetry (PIV) provides a platform to enable such investigations. This thesis presents the development of PIV measurement methodologies for highly turbulent flows. An appraisal of these techniques applied to gas turbine combustors is then given, finally allowing a description of the increased understanding of the underlying fluid dynamic processes within combustors to be provided. Through the development of best practice optimisation procedures and correction techniques for the effects of sub-grid filtering, high quality PN data has been obtained. Time average statistical data at high spatial resolution has been collected and presented for generic and actual combustor geometry providing detailed validation of the turbulence correction methods developed, validation data for computational studies, and increased understanding of flow mechanisms. These data include information not previously available such as turbulent length scales. Methodologies developed for the analysis of instantaneous PIV data have also allowed the identification of transient flow structures not seen previously because they are invisible in the time average. Application of a new `PDF conditioning' technique has aided the explanation of calculated correlation functions: for example, bimodal primary zone recirculation behaviour and jet misalignments were explained using these techniques. Decomposition of the velocity fields has also identified structures present such as jet shear layer vortices, and through-port swirling motion. All of these phenomena are potentially degrading to combustor performance and may result in flame instability, incomplete combustion, increased noise and increased emissions.
19
Whiteman, Michael. "Reducing the pressure loss in a gas turbine combustor." Thesis, University of Sheffield, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.266000.
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Aksit, I. M. "A stochastic model for aircraft gas turbine combustor emissions." Thesis, Cranfield University, 1995. http://dspace.lib.cranfield.ac.uk/handle/1826/11118.
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The emission of NOx from aero-gas turbine combustors, which in the present generation of
designs consists mainly of thermal NOx ' is of great concern due to its potential damage to the
stratospheric ozone layer. Soot production in gas turbine combustors is also undesirable since
it is both the major source of exhaust smoke and, more importantly, the principal agent in
thermal radiation to the combustor liner. Furthermore thermal radiation from the soot redistributes
energy in the combustor, modifying the temperature field. This consequently
affects the production of other pollutants, notably that of thermal NOx> since the production
rate is especially sensitive to temperature.
Mathematical models for predicting gas turbine combustor emissions can be divided, in
general terms, into two main groups, Methods based on zonal (or modular) approach and on
CFD modelling. CFD modelling allows the use of computation intensive multi-dimensional
Navier-Stokes codes but cannot account for detailed chemistry which is responsible for
emissions. On the other hand, although the modular approaches make significant assumptions
about the mean flowfield and mixing, they employ detailed chemical kinetics.
The work reported in this thesis seeks to develop a model for emission predictions in the gas
turbine combustor which combines the advantage of both the modular approach and CFD
modelling. The strategy was based on a pdf calculation using the Monte-Carlo simulation
technique because the chemical source term is in closed form for the approach and the
solution procedure requires a CFD based calculation. Averaging of the particle properties was
on an extended zonal or planar basis in order to reduce computational effort. The predictions
are evaluated against available experimental results and other predictions employing more
conventional approaches.
Since the pdf method allows the modelling of slow chemistry and simultaneous influence of
multiple scalars, the thermal NO x production rate was implemented considering the effect of
NO concentration itself. Predicted exit NOx concentration was higher than the measured exit
level. It has been thought that this discrepancy is mainly due to neglecting radioactive heat loss
for temperature calculations.
The modelling of soot formation and oxidation has proved more problematic since the
assumption that soot is simply perturbation to the gaseous field, analogous to the NO
concentration, and temperature may be accurately described by single adiabatic flamelet are
no longer valid at elevated pressure and temperature conditions. Soot bum-out is
under-predicted. The computed mean soot oxidation is less than 10% of the maximum
production levels, even when OH is considered to be oxidising species in addition to
O2 ••
Although high soot formation rate was predicted as a result of neglecting radioactive loss and
using single perturbed flamelet calculation, the main uncertainties come from instantaneous
soot oxidation rate and the particle size effect which influence the particle surface area.
21
Ubhi, G. S. "Emissivity measurement of gas turbine combustor ceramic coatings and its influence on combustor design." Thesis, Cranfield University, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.378890.
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Caley, Thomas. "Numerical Modeling of Gas Turbine Combustor Utilizing One-Dimensional Acoustics." University of Cincinnati / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1491562189178949.
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Day, Charles. "Aerodynamics of an annular film-cooled turbine cascade." Thesis, University of Oxford, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.362028.
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Knost, Daniel G. "Parametric Investigation of the Combustor-Turbine Interface Leakage Geometry." Diss., Virginia Tech, 2008. http://hdl.handle.net/10919/29145.
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Engine development has been in the direction of increased turbine inlet
temperatures to improve efficiency and power output. Secondary flows develop
as a result of a near-wall pressure gradient in the stagnating flow approaching
the inlet nozzle guide vane as well as a strong cross-passage gradient within the
passage. These flow structures enhance heat transfer and convect hot core flow
gases onto component surfaces. In modern engines it has become critical to cool
component surfaces to extend part life.
Bypass leakage flow emerging from the slot between the combustor and
turbine endwalls can be utilized for cooling purposes if properly designed. This
study examines a three-dimensional slot geometry, scalloped to manipulated
leakage flow distribution. Statistical techniques are used to decouple the effects
of four geometric parameters and quantify the relative influence of each on
endwall cooling levels and near-wall total pressure losses. The slot geometry is
also optimized for robustness across a range of inlet conditions.
Average upstream distance to the slot is shown to dominate overall cooling
levels with nominal slot width gaining influence at higher leakage flow rates.
Scalloping amplitude is most influential to near-wall total pressure loss as formation
of the horseshoe vortex and cross flow within the passage are affected.
Scalloping phase alters local cooling levels as leakage injection is shifted laterally
across the endwall.<br>Ph. D.
25
Skidmore, F. W., and n/a. "The influence of gas turbine combustor fluid mechanics on smoke emissions." Swinburne University of Technology, 1988. http://adt.lib.swin.edu.au./public/adt-VSWT20070420.131227.
Full textAbstract:
This thesis describes an experimental program covering the development of certain
simple combustion chamber modifications to alleviate smoke emissions from the
Allison T56 turboprop engines operated by the Royal Australian Air Force.
The work includes a literature survey, smoke emission tests on two variants
of the T56 engine, flow visualisation studies of the combustion system in a
water tunnel and combustion rig tests of a standard combustor and four possible
modifications. The rig tests showed that reductions in smoke emissions of
80% were possible by simple modifications that reduced the primary zone
equivalence ratio and improved mixing in that zone.
26
Eriksson, Sara. "Development of methane oxidation catalysts for different gas turbine combustor concepts." Licentiate thesis, Stockholm, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-311.
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Awosope, Iyiola Olumide. "Flameless oxidation combustion modelling and application to a gas turbine combustor." Thesis, Imperial College London, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.419936.
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Griffiths, Julian P. "Measurements of the flow field in a modern gas turbine combustor." Thesis, Loughborough University, 1999. https://dspace.lboro.ac.uk/2134/12714.
Full textAbstract:
A detailed investigation into the aerodynamics of a modern gas turbine combustor is reported in this thesis. The main objectives of this work were to examine the interactions between the various features of the internal flow field, and between the external and internal aerodynamics, and to obtain sufficient flow field data for validation of CFD codes. A new experimental facility was developed to allow optical access for high quality internal and external measurements of the isothermal flow field in a three sector segment of an annular gas turbine combustor whose geometry is typical of the combustors in use in current turbofan engines. A specialised traverse system was designed to enable measurements of the flow field by a three component Laser Doppler Anemometry (LDA) system, and a considerable effort was made to maximise the accuracy of the LDA system. Measurements of three orthogonal mean velocity components and all six Reynolds stresses were obtained throughout a burner sector of the combustor. A set of data has been obtained that is sufficiently extensive for use as a benchmark data set for CFD validation. Measurements in the feed annuli showed that the behaviour of the flow was as expected. Internal measurements revealed a strong coupling between the flow in the feed annuli and the flow entering the flame tube through primary and secondary ports. Differences in the geometries and flow splits in the inner and outer annuli caused significant differences between the opposed jets inside the flame tube. The initial pitch angle and axial and radial momentum components of the jets were found to be strongly dependent on the ports' feed conditions. Differences between the opposed jets, due to differences in their feed conditions, affected the location of their impingement and the trajectory of the jet fluid after impingement. The impingement process was also found to be unstable. The centre primary jets, which are downstream of the fuel injector, displayed a dramatically increased sensitivity to their feed conditions, caused by the low pressure in the recirculation induced by the swirler. This caused the jets to be deflected in opposite directions, with no impingement. The flow field in the primary zone was thus substantially altered, with serious implications for the performance of the combustor. These results also demonstrate the importance of coupling the internal and external flows in all experimental and computational models.
29
Wright, Andrew D. "Acoustic boundary condition estimation in a near-scale gas-turbine combustor." Thesis, This resource online, 1996. http://scholar.lib.vt.edu/theses/available/etd-08222008-063430/.
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Aslanidou, Ioanna. "Combustor and turbine aerothermal interactions in gas turbines with can combustors." Thesis, University of Oxford, 2015. https://ora.ox.ac.uk/objects/uuid:b1527fd0-8e54-4831-8625-32722141511e.
Full textAbstract:
As the research into the improvement of gas turbine performance progresses, the combustor-turbine interface becomes of increasing importance. In new engine designs components come closer together and the study of the combustor and turbine interactions can prove to be valuable for the improvement of the aerothermal performance of the vane. This thesis presents an experimental and numerical investigation of the aerodynamic and heat transfer aspect of the interactions between the combustor and the nozzle guide vane. In the gas turbine studied the trailing edge of the combustor transition duct wall is found upstream of every second vane. In the experimental measurements carried out in a purpose-built high speed experimental facility, the wake of this wall is shown to increase the aerodynamic loss of the vane. On the other hand, the wall alters secondary flow structures and has a protective effect on the heat transfer in the leading edge-endwall junction, a region that has proven to be detrimental to component life. The effect of different clocking positions of the vane relative to the combustor wall are tested experimentally and shown to alter the aerodynamic field and the heat transfer to the vane. The experimental methods and processing techniques adopted in this work are utilized to highlight the differences between the different cases studied. A new concept of using the combustor wall to shield the nozzle guide vane leading edge is introduced, followed by a proposed design that is numerically analysed, including a new cooling system. This uses continuous cooling slots on the upstream combustor wall to cool the vane leading edge. Coolant to the endwalls is provided from continuous slots on the combustor-turbine interface. The reduction of secondary flow through the removal of the horseshoe vortex in the new design results in improved cooling of the endwalls, with a higher average adiabatic effectiveness than in the original case, using the same coolant mass flow rate. The vane surface and suction side are also successfully cooled using less air than that required for a showerhead. The new vane is tested in the experimental facility. The improved aerodynamic and thermal performance of the shielded vane is demonstrated under engine-representative inlet conditions. The new design is shown to have a lower average total pressure loss than the original vane for all inlet conditions. The heat transfer on the vane surface is overall reduced for all inlet conditions and the peak heat transfer on the vane leading edge-endwall junction is moved further upstream, to a region that can be effectively cooled from the upstream cooling slots on the combustor wall trailing edge and the endwalls.
31
Wolf, Pierre. "Large Eddy Simulation of thermoacoustic instabilities in annular combustion chambers." Thesis, Toulouse, INPT, 2011. http://www.theses.fr/2011INPT0111.
Full textAbstract:
La conception des turbines à gaz est aujourd'hui contrainte par des normes d'émissions de plus en plus draconiennes, couplées à l'urgente nécessité d'économiser les ressources en carburant fossile. Les choix technologiques adoptés pour répondre à ces exigences entraînent parfois l'apparition d'instabilités de combustion. Dans les chambres de combustion annulaires, ces instabilités prennent souvent la forme de modes azimutaux. Prédire ces modes reste un défi à l'heure actuelle et impose de considérer la totalité de la géométrie annulaire, ce qui n'est rendu possible, dans le domaine de la simulation numérique en mécanique des fluides, que par l'avènement très récent des supercalculateurs massivement parallèles. Dans ce travail de thèse, les modes azimutaux pouvant apparaître dans les chambres de combustion annulaires sont abordés avec plusieurs approches: un modèle analytique 1D, un solveur acoustique de Helmholtz 3D et enfin des Simulations aux Grandes Echelles. Combiner ces méthodes permet une meilleure compréhension de la structure de ces modes et peut amener à considérer des solutions innovantes pour concevoir des chambres inconditionnellement stables<br>Increasingly stringent regulations and the need to tackle rising fuel prices have placed great emphasis on the design of aeronautical gas turbines. This drive towards innovation has resulted sometimes in new concepts being prone to combustion instabilities. Combustion instabilities arise from the coupling of acoustics and combustion. In the particular field of annular combustion chambers, these instabilities often take the form of azimuthal modes. To predict these modes, one must consider the full combustion chamber, which, in the numerical simulation domain, remained out of reach until very recently and the development of massively parallel computers. In this work, azimuthal modes that may develop in annular combustors are studied with different numerical approaches: a low order model, a 3D Helmholtz solver and Large Eddy Simulations. Combining these methods allows a better understanding of the structure of the instabilities and may provide guidelines to build intrinsically stable combustion chambers
32
Khandelwal, Bhupendra. "Development of gas turbine combustor preliminary design methodologies and preliminary assessments of advanced low emission combustor concepts." Thesis, Cranfield University, 2012. http://dspace.lib.cranfield.ac.uk/handle/1826/9157.
Full textAbstract:
It is widely accepted that climate change is a very serious environmental
concern. Levels of carbon dioxide (CO2) and other emissions in the global
atmosphere have increased substantially since the industrial revolution and now
increasing faster than ever before. There is a thought that this has already led
to dangerous warming in the Earth’s atmosphere and relevant changes around.
Emissions legislations are going to be stringent as the years will pass. Hydro
carbon fuel cost is also increasing substantially; more over this is non-
renewable source of energy.
There is an urgent need for novel combustor technologies for reducing emission
as well as exploring alternative renewable fuels without effecting combustor
performance. Development of novel combustors needs comprehensive
understanding of conventional combustors. The design and development of gas
turbine combustors is a crucial but uncertain part of an engine development
process. At present, the design process relies upon a wealth of experimental
data and correlations. Some major engine manufacturers have addressed the
above problem by developing computer programs based on tests and empirical
data to assist combustor designers, but such programs are proprietary. There is
a need of developing design methodologies for combustors which would lead to
substantial contribution to knowledge in field of combustors. Developed design
methodologies would be useful for researchers for preliminary design
assessments of a gas turbine combustor.
In this study, step by step design methodologies of dual annular radial and axial
combustor, triple annular combustor and reverse flow combustor have been
developed. Design methodologies developed could be used to carry out
preliminary design along with performance analysis for conventional combustion
chambers. In this study the author has also proposed and undertaken
preliminary studies of some novel combustor concepts.
A novel concept of a dilution zone less combustor has been proposed in this
study. According to this concept dilution air would be introduced through nozzle
guide vanes to provide an optimum temperature traverse for turbine blades.
Preliminary study on novel dilution zone less combustor predicts that the length
of this combustor would be shorter compared to conventional case, resulting in
reduced weight, fuel burn and vibrations. Reduced fuel burn eventually leads to
lower emissions.
Another novel concept of combustor with hydrogen synthesis from kerosene
reformation has been proposed and a preliminary studies has been undertaken
in this work. Addition of hydrogen as an additive in gas turbine combustor
shows large benefits to the performance of gas turbine engines in addition to
reduction in NOx levels. The novel combustor would have two stages,
combustion of ~5% of the hydrocarbon fuel would occur in the first stage at
higher equivalence ratios in the presence of a catalyst, which would eventually
lead to the formation of hydrogen rich flue gases. In the subsequent stage the
hydrogen rich flue gases from the first stage would act as an additive to
combustion of the hydrocarbon fuel. It has been preliminary estimated that the
mixture of the hydrocarbon fuel and air could subsequently be burned at much
lower equivalence ratios than conventional cases, giving better temperature
profiles, flame stability limits and lower NOx emissions.
The effect of different geometrical parameters on the performance of vortex
controlled hybrid diffuser has also been studied. It has been predicted that
vortex chamber in vortex controlled hybrid diffuser does not play any role in
altering the performance of diffuser.
The overall contribution to knowledge of this study is development of combustor
preliminary design methodologies with different variants. The other contribution
to knowledge is related to novel combustors with a capability to produce low
emissions. Study on novel combustor and diffuser has yielded application of two
patent applications with several other publications which has resulted in a
contribution to knowledge. A list of research articles, two patents, awards and
achievements are presented in Appendix C.
33
Kunstmann, Sébastien [Verfasser]. "A Contribution to Gas Turbine Combustor Cooling Using Complex Configurations / Sébastien Kunstmann." München : Verlag Dr. Hut, 2012. http://d-nb.info/102110390X/34.
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Venkatesh, Vishnu P. (Vishnu Pravin). "Thermal design and analysis of a recuperative combustor for gas-turbine combustion." Thesis, Massachusetts Institute of Technology, 1993. http://hdl.handle.net/1721.1/101313.
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Sharma, Anshu. "Numerical Investigation of a Swirl Induced Flameless Combustor for Gas Turbine Applications." University of Cincinnati / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1613731788158991.
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Fannin, Christopher A. "Linear Modeling and Analysis of Thermoacoustic Instabilities in a Gas Turbine Combustor." Diss., Virginia Tech, 2000. http://hdl.handle.net/10919/28400.
Full textAbstract:
A dynamic model is developed for the purpose of predicting stability characteristics of an industrial-scale, swirl-stabilized premixed combustor located at the National Energy Technology Laboratory (NETL) in Morgantown, WV. The model consists of modular blocks that assemble into an open-loop transfer function depicting the frequency response of the thermoacoustic system. These blocks include the system acoustic response to unsteady heat release forcing, the air-side coupling of acoustic particle velocity to inlet fuel mass fraction, transport delays present in the mixing nozzle and combustion chamber, and dynamic heat release excitation from unsteady inlet fuel mass fraction. By examing the frequency response with linear stability techniques, the existence of limit cycles due to linear instabilities is predicted. Further, the frequency response analysis is used to predict limit cycle frequencies in the case of predicted instability. The analysis predictions are compared with the results of tests performed at NETL, demonstrating a capability of replicating many of the observed stability characteristics.<br>Ph. D.
37
Barringer, Michael David. "Design and Benchmarking of a Combustor Simulator Relevant to Gas Turbine Engines." Thesis, Virginia Tech, 2001. http://hdl.handle.net/10919/35519.
Full textAbstract:
An experimental facility was designed and benchmarked that could simulate the non-uniformities in the flow and thermal fields exiting real gas-turbine combustors. The design of the combustor simulator required analyses of the flow paths within a real combustor in a gas turbine engine. Modifications were made to an existing wind tunnel facility to allow for the installation of the combustor simulator. The overall performance of the simulator was then benchmarked through measurements of velocity, pressure, temperature, and turbulence using a straight exit test section to provide a baseline set of data. Comparisons of the measured quantities were made between two test cases that included a flow field with and without dilution flow.One of the major findings from this study was that the total pressure profiles exiting the combustor simulator in the near-wall region were different from a turbulent boundary layer. This is significant since many studies consider a turbulent boundary layer as the inlet condition to the turbine. Turbulent integral length scales were found to scale well with the dilution hole diameters and no dominant frequencies were observed in the streamwise velocity energy spectra. Dilution flow resulted in an increase in turbulence levels and mixing causing a reduction in the variation of total pressure and velocity. Adiabatic effectiveness levels were significantly reduced for the case with dilution flow in both the near combustor exit region and along the axial length of the straight exit test section.<br>Master of Science
38
Liljenberg, Scott Alan. "Modeling and Stability Analysis of Thermoacoustic Instabilities in Gas Turbine Combustor Sections." Thesis, Virginia Tech, 2000. http://hdl.handle.net/10919/35469.
Full textAbstract:
In order to predict the linear stability of combustion systems in industrial-scale gas turbines, a stability analysis was completed using models generated for each of the major dynamic components. Changes in the combustion process of gas turbines to reduce emissions has resulted in large amplitude pressure oscillations associated with a coupling between the natural acoustic modes of the combustor and the unsteady heat release from the flame. Detailed models of the acoustics and the heat release processes were created and assembled, with a time delay element and the appropriate scaling, into a system block diagram to investigate the stability of the system using linear system theory. Wherever possible the analytical models were validated with experimental data. The main goal of this work was to create a design methodology which could be used by industry to predict where instabilities were likely to occur during the design phase. Results show that the system based stability analysis can predict some of the instability frequencies seen in the experimental data, but more refined models are needed to predict every instability. Future work will involve designing experiments to validate and refine the dynamic models already developed.<br>Master of Science
39
Luff, John K. "Numerical prediction of flow, thermal and stress fields in gas turbine combustor components." Thesis, Loughborough University, 2003. https://dspace.lboro.ac.uk/2134/15458.
Full textAbstract:
In this work an integrated set of numerical methods is developed for the analysis of gas turbine combustors, which can predict the flow, temperature and stress fields in modern geometrically complex combustor walls. A key problem for accurate flow and temperature field prediction is the wide range of geometric length scales within modern combustor components. These components typically contain multiple small-scale cooling features such as pedestals and effusion cooling holes, which cannot be resolved by a computational mesh without incurring huge penalties in terms of computer processor and memory requirements. In this work a sub-grid-scale model is developed, which accounts for the effects of small-scale features such as pedestals without resolving them in the computational mesh. Validation of this model using experimental results from the literature shows that the pressure drop, turbulence generation and heat transfer effects of pedestal arrays can be successfully modelled using this approach. Another difficulty in the analysis of combustors is coupling the interdependent temperature field predictions in the fluid and solid regions. This has led to a unified approach to conjugate heat transfer prediction being adopted in this work, whereby a structured finite volume solver is used to predict temperature fields throughout fluid and solid domains. A new conjugate heat transfer discretisation scheme is developed, which can cope with the demanding combination of strong temperature gradient discontinuities and highly skewed grids. Several test cases are presented which demonstrate the accuracy of this new scheme, as well as demonstrating the inadequacy of conventional treatment of the diffusive fluxes for the solution of conjugate problems. The assembled numerical methods are used to predict the flow, thermal and stress fields in a geometrically complex combustor heatshield/backplate assembly, typical of that found in modern engines. This calculation shows that a viable route to computational life prediction has been established.
40
Relation, Heather L. "Application of a modified k-[epsilon] turbulence model to gas turbine combustor geometries." Thesis, This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-10312009-020353/.
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Söderberg, Jakob. "CAE of Gas Turbine Combustor Chamber : Improving workflow in product lifecycle management systems." Thesis, Linköpings universitet, Maskinkonstruktion, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-168687.
Full textAbstract:
This thesis seeks to improve the workflow in the product development process when using the Product Lifecycle Management (PLM) system PLM2020, incorporated at Siemens Energy. Focus is on three problem cases that emerge when working with Computer Aided Engineering (CAE) data during the development process. Apart from solving these problems, a current situation analysis was conducted, and possible solutions of these problems were investigated on how they affect the lead time in the product development process. The problems consist of exploration of an unused function and solving of two problematic situations that can occur while using PLM2020 during development work. A case study was established to investigate the problems, using participatory observations and interviews. The interviews established the current situation of Siemens work methodology to handle these situations and how PLM2020 is used. During the observations, the problems were attempted to be solved using an arbitrary Computer Aided Design (CAD) model while exploring different functions in a sandbox environment. During the interviews, it was discovered that there exist different ways of working in PLM2020 and that some approaches nullifies the benefits of using a PLM system. The participatory observations revealed that that there exist functions in the PLM system that solves the problems encountered. A set of proposed solutions are presented to Siemens
42
Scrittore, Joseph. "Experimental Study of the Effect of Dilution Jets on Film Cooling Flow in a Gas Turbine Combustor." Diss., Virginia Tech, 2008. http://hdl.handle.net/10919/28171.
Full textAbstract:
Cooling combustor chambers for gas turbine engines is challenging because of the complex flow fields inherent to this engine component. This complexity, in part, arises from the interaction of high momentum dilution jets required to mix the fuel with effusion film cooling jets that are intended to cool the combustor walls. The dilution and film cooling flow have different performance criteria, often resulting in conflicting flow mechanisms.
The purpose of this study is to evaluate the influence that the dilution jets have on the film cooling effectiveness and how the flow and thermal patterns in the cooling layer are affected by both the dilution flow and the closely spaced film cooling holes. This study also intends to characterize the development of the flow field created by effusion cooling injection without dilution injection. This work is unique because it allows insight into how the full-coverage discrete film cooling layer is interrupted by high momentum dilution jets and how the surface cooling is affected.
The film cooling flow was disrupted along the combustor walls in the vicinity of the high momentum dilution jets and the surface cooling effectiveness was reduced with increased dilution jet momentum. This was due to the secondary flows that were intensified by the increased jet momentum. High turbulence levels were generated at the dilution jet shear layer resulting in efficient mixing. The film cooling flow field was affected by the freestream turbulence and complex flow fields created by the combined dilution and effusion cooling flows both in the near dilution jet region as well as downstream of the jets. Effusion cooling holes inclined at 20Ë created lower coolant layer turbulence levels and higher surface cooling effectiveness than 30Ë cooling holes. Results showed an insensitivity of the coolant penetration height to the diameter and angle of the cooling hole in the region downstream of the dilution mixing jets.
When high momentum dilution jets were injected into crossflow, a localized region in the flow of high vorticity and high streamwise velocity was created. When film cooling air was injected the inlet flow field and the dilution jet wake were fundamentally changed and the vortex diminished significantly. The temperature field downstream of the dilution jet showed evidence of a hot region which was moderated appreciably by film cooling flow. Differences in the temperature fields were nominal compared to the large mass flow increase of the coolant.
A study of streamwise oriented effusion film cooling flow without dilution injection revealed unique and scaleable velocity profiles created by the closely spaced effusion holes. The effusion cooling considered in these tests resulted in streamwise velocity and turbulence level profiles that scaled well with blowing ratio which is a finding that allows the profile shape and magnitude to be readily determined at these test conditions. Results from a study of compound angle effusion cooling injection showed significant differences between the flow field created with and without crossflow. It was found from the angle of the flow field velocity vectors that the cooling film layer grew nearly linearly in the streamwise direction. The absence of crossflow resulted in higher turbulence levels because there was a larger shear stress due to a larger velocity difference between the coolant and crossflow. The penetration height of the coolant was relatively independent of the film cooling momentum flux ratio for both streamwise oriented and compound angle cooling jets.<br>Ph. D.
43
Melia, Thomas. "Heat transfer characteristics of pulse combustors for gas turbine engines." Thesis, Loughborough University, 2012. https://dspace.lboro.ac.uk/2134/10278.
Full textAbstract:
Conventional gas turbine combustors operate with a designed drop in pressure over the length of the device. This is desired in order to encourage mixing within the combustor. Compared to this, pulse pressure gain combustors are an alternative to the conventional combustor that produces an increase in static pressure between the inlet and exhaust of the device. The removal of the combustor pressure loss increases the efficiency of the combustion process by increasing the amount of work produced. Many types of pulsed pressure gain combustors exist. Of these, the valveless pulse combustor is the simplest featuring no moving parts. Whilst some research has been conducted into investigating the performance and workings of a pulse combustor, little has been conducted with the view of cooling the combustor. This has been the focus for the research contained herein. The research has focussed on establishing an understanding of the heat transfer characteristics within a pulse combustor tailpipe. This has involved experimental, analytical and computational research on a pulse combustor as well as on a cold-flow model of a pulse combustor tailpipe. This has enabled a study into the feasibility of cooling a pulse combustor to be conducted. The research has found that for conditions where the unsteady velocity amplitude within the cold-flow model of the pulse combustor tailpipe exceeds the mean velocity, an enhancement to the heat transfer coefficient is measured compared to the value expected in a similar non-oscillating flow. When there is no enhancement to the heat transfer coefficient, the cyclic variation of the unsteady heat flux follows the variation of the unsteady pressure within the device. However, at times of enhancement, the instantaneous heat flux structure shows a large deviation from the structure of the pressure field driving the oscillations. This change is shown to be caused by the reversal in the near-wall velocity and may indicate a mechanism for the enhancement in the mean heat flux. The cooling feasibility study showed that with further investigation, it may be possible to cool a pulse combustor within a gas turbine engine.
44
Tokekar, Devkinandan Madhukar. "Modeling and simulation of reacting flows in lean-premixed swirl-stabilized gas turbine combustor." Cincinnati, Ohio : University of Cincinnati, 2005. http://www.ohiolink.edu/etd/view.cgi?acc%5Fnum=ucin1141412599.
Full textAbstract:
Thesis (M.S.)--University of Cincinnati, 2005.<br>Title from electronic thesis title page (viewed Apr. 18, 2006). Includes abstract. Keywords: Large Eddy Simulation; LES; Lean Pre-mixed; LPM; Gas Turbine Combustor; Combustion; Reacting Flows. Includes bibliographical references.
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Chua, Khim Heng. "Experimental characterisation of the coolant film generated by various gas turbine combustor liner geometries." Thesis, Loughborough University, 2005. https://dspace.lboro.ac.uk/2134/12704.
Full textAbstract:
In modern, low emission, gas turbine combustion systems the amount of air available for cooling of the flame tube liner is limited. This has led to the development of more complex cooling systems such as cooling tiles i.e. a double skin system, as opposed to the use of more conventional cooling slots i.e. a single skin system. An isothennal experimental facility has been constructed which can incorporate 10 times full size single and double skin (cooling tile) test specimens. The specimens can be tested with or without effusion cooling and measurements have been made to characterise the flow through each cooling system along with the velocity field and cooling effectiveness distributions that subsequently develop along the length of each test section. The velocity field of the coolant film has been defined using pneumatic probes, hot-wire anemometry and PIV instrumentation, whilst gas tracing technique is used to indicate (i) the adiabatic film cooling effectiveness and (ii) mixing of the coolant film with the mainstream flow. Tests have been undertaken both with a datum low turbulence mainstream flow passing over the test section, along with various configurations in which large magnitudes and scales of turbulence were present in the mainstream flow. These high turbulence test cases simulate some of the flow conditions found within a gas turbine combustor. Results are presented relating to a variety of operating conditions for both types of cooling system. The nominal operating condition for the double skin system was at a coolant to mainstream blowing ratio of approximately 1.0. At this condition, mixing of the mainstream and coolant film was relatively small with low mainstream turbulence. However, at high mainstream turbulence levels there was rapid penetration of the mainstream flow into the coolant film. This break up of the coolant film leads to a significant reduction in the cooling effectiveness. In addition to the time-averaged characteristics, the time dependent behaviour of the .:coolantfilm was. also investigated. In particular, unsteadiness associated with large scale structures in the mainstream flow was observed within the coolant film and adjacent to the tile surface. Relative to a double skin system the single skin geometry requires a higher coolant flow rate that, along with other geometrical changes, results in typically higher coolant to mainstream velocity ratios. At low mainstream turbulence levels this difference in velocity between the coolant and mainstream promotes the generation of turbulence and mixing between the streams so leading to some reduction in cooling effectiveness. However, this higher momentum coolant fluid is more resistant to high mainstream turbulence levels and scales so that the coolant film break up is not as significant under these conditions as that observed for the double skin system. For all the configurations tested the use of effusion cooling helped restore the coolant film along the rear of the test section. For the same total coolant flow, the minimum value of cooling effectiveness observed along the test section was increased relative to the no effusion case. In addition the effectiveness of the effusion patch depends on the amount of coolant injected and the axial location of the patch. The overall experimental data suggested the importance of the initial cooling film conditions together with better understanding of the possible mechanisms that results in the rapid cooling film break-up, such as high turbulence mainstream flow and scales, and this will lead to a more effective cooling system design. This experimental data is also thought to be ideal for the validation of numerical predictions.
46
Miller, Michael N. "Comparison between measured and predicted chemical species concentration from within a gas turbine combustor." Thesis, University of Reading, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.395245.
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Wang, Liang. "Experimental and Computational Investigation of Thermal-Flow Characteristics of Gas Turbine Reverse-Flow Combustor." ScholarWorks@UNO, 2010. http://scholarworks.uno.edu/td/1212.
Full textAbstract:
Reverse-flow combustors have been used in heavy land-based gas turbines for many decades. A sheath is typically installed to provide cooling at an expense of large pressure losses, through small jet impingement cooling and strong forced convention channel flow. With the modern advancement in metallurgy and thermal-barrier coating technologies, it may become possible to remove this sheath to recover the pressure losses without melting the combustor chamber. However, without the sheath, the flow inside the dump diffuser may exert nonuniform cooling on the combustion chamber. Therefore, the objective of this project is to investigate the flow pattern, pressure drop, and heat transfer in the dump-diffuser reverse-flow combustor with and without sheath to determine if the sheath could be removed. The investigation was conducted through both experimental and computational simulation. The results show that 3.3% pressure losses could be recovered and the highest wall temperature will increase 18% without the sheath.
48
Abraham, Santosh. "Heat Transfer and Flow Measurements on a One-Scale Gas Turbine Can Combustor Model." Thesis, Virginia Tech, 2008. http://hdl.handle.net/10919/35177.
Full textAbstract:
Combustion designers have considered back-side impingement cooling as the solution for modern DLE combustors. The idea is to provide more cooling to the deserved local hot spots and reserve unnecessary coolant air from local cold spots. Therefore, if accurate heat load distribution on the liners can be obtained, then an intelligent cooling system can be designed to focus more on the localized hot spots. The goal of this study is to determine the heat transfer and pressure distribution inside a typical can-annular gas turbine combustor. This is one of the first efforts in the public domain to investigate the convective heat load to combustor liner due to swirling flow generated by swirler nozzles. An experimental combustor test model was designed and fitted with a swirler nozzle provided by Solar Turbines Inc. Heat transfer and pressure distribution measurements were carried out along the combustor wall to determine the thermo-fluid dynamic effects inside a combustor. The temperature and heat transfer profile along the length of the combustor liner were determined and a heat transfer peak region was established.
Constant-heat-flux boundary condition was established using two identical surface heaters, and the Infrared Thermal Imaging system was used to capture the real-time steady-state temperature distribution at the combustor liner wall. Analysis on the flow characteristics was also performed to compare the pressure distributions with the heat transfer results. The experiment was conducted at two different Reynolds numbers (Re 50,000 and Re 80,000), to investigate the effect of Reynolds Number on the heat transfer peak locations and pressure distributions. The results reveal that the heat transfer peak regions at both the Reynolds numbers occur at approximately the same location. The results from this study on a broader scale will help in understanding and predicting swirling flow effects on the local convective heat load to the combustor liner, thereby enabling the combustion engineer to design more effective cooling systems to improve combustor durability and performance.<br>Master of Science
49
TOKEKAR, DEVKINANDAN MADHUKAR. "MODELING AND SIMULATION OF REACTING FLOWS IN LEAN-PREMIXED SWIRL-STABLIZED GAS TURBINE COMBUSTOR." University of Cincinnati / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1141412599.
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Dsouza, Jason Brian. "Numerical Analysis of a Flameless Swirl Stabilized Cavity Combustor for Gas Turbine Engine Applications." University of Cincinnati / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1627663015527799.
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