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1
Kurz, Rainer. "Natural Gas." Mechanical Engineering 133, no. 04 (2011): 52. http://dx.doi.org/10.1115/1.2011-apr-7.
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This article discusses the importance of gas turbines, centrifugal compressors and pumps, and other turbomachines in processes that bring natural gas to the end users. To be useful, the natural gas coming from a large number of small wells has to be gathered. This process requires compression of the gas in several stages, before it is processed in a gas plant, where contaminants and heavier hydrocarbons are stripped from the gas. From the gas plant, the gas is recompressed and fed into a pipeline. In all these compression processes, centrifugal gas compressors driven by industrial gas turbines or electric motors play an important role. Turbomachines are used in a variety of applications for the production of oil and associated gas. For example, gas turbine generator sets often provide electrical power for offshore platforms or remote oil and gas fields. Offshore platforms have a large electrical demand, often requiring multiple large gas turbine generator sets. Similarly, centrifugal gas compressors, driven by gas turbines or by electric motors are the benchmark products to pump gas through pipelines, anywhere in the world.
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Manservigi, Lucrezia, Mauro Venturini, and Enzo Losi. "Optimal selection of pumps as turbines for maximizing electrical energy production." E3S Web of Conferences 238 (2021): 01005. http://dx.doi.org/10.1051/e3sconf/202123801005.
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A Pump as Turbine (PAT) is a renewable energy technology that can be a cost-effective and reliable alternative to hydraulic turbines in micro and small hydropower plants. In order to further favour PAT exploitation, a general procedure that allows the identification of the most suitable turbomachine to install is required. To this purpose, this paper develops a novel methodology aimed at selecting the best PAT that, among several alternatives, maximizes energy production. The methodology comprises two steps, which only require the knowledge of the best efficiency point of the considered pump and the hydraulic parameters of the site. The novel methodology is validated in this paper by calculating the electrical energy production of a simulated water distribution network coupled with several PATs, whose performance curves, both in direct and reverse modes, are taken from the literature. For the sake of generality, the considered turbomachines account for different geometrical characteristics, rotational speeds and operating ranges.
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Arsiri, Vasyl, and Oleg Kravchenko. "Reconstruction of Turbomachines on the Basis of the Flow Structure Visual Diagnostics." Mechanics and Mechanical Engineering 22, no. 2 (2020): 405–14. http://dx.doi.org/10.2478/mme-2018-0032.
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AbstractThe indicator of the quality of modern turbomachines is only the coefficient of efficiency, which characterizes the ratio of the useful work of compressors or fans to the energy expended on the drive. For the analysis of the quality of the motion, processes in flow parts, the values of resistances are used which are difficult to be considered as an indicator of the efficiency of dynamic processes. The report presents the results of visual diagnostics of the structure of flows during the movement in the elements of turbomachines, as well as options for improving the geometry of the flow parts - in the inlet pipes, impellers.For the analysis of the efficiency of the motion of liquids and gases in flowing parts, a calculated index is proposed - the coefficient of hydraulic efficiency of dynamic processes. The joint use of two indicators - the efficiency of transformation of different types of energy (efficiency of turbomachines) and the efficiency of dynamic processes in flowing parts allows us to develop and to analyze the results of reconstruction of turbomachines. Reconstruction of turbomachines with the purpose of improving the geometry of the flow parts provides an increase in productivity of turbines, compressors, fans and pumps, while reducing the specific energy consumption for the processes of compression and transport of liquids and gases. Optimization of turbomachines flow parts based of flow structure visual diagnostics allows to reduce noise and vibration, as well as to solve other problems.
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Venturini, Mauro, Stefano Alvisi, Silvio Simani, and Lucrezia Manservigi. "Comparison of Different Approaches to Predict the Performance of Pumps As Turbines (PATs)." Energies 11, no. 4 (2018): 1016. http://dx.doi.org/10.3390/en11041016.
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This paper deals with the comparison of different methods which can be used for the prediction of the performance curves of pumps as turbines (PATs). The considered approaches are four, i.e., one physics-based simulation model (“white box” model), two “gray box” models, which integrate theory on turbomachines with specific data correlations, and one “black box” model. More in detail, the modeling approaches are: (1) a physics-based simulation model developed by the same authors, which includes the equations for estimating head, power, and efficiency and uses loss coefficients and specific parameters; (2) a model developed by Derakhshan and Nourbakhsh, which first predicts the best efficiency point of a PAT and then reconstructs their complete characteristic curves by means of two ad hoc equations; (3) the prediction model developed by Singh and Nestmann, which predicts the complete turbine characteristics based on pump shape and size; (4) an Evolutionary Polynomial Regression model, which represents a data-driven hybrid scheme which can be used for identifying the explicit mathematical relationship between PAT and pump curves. All approaches are applied to literature data, relying on both pump and PAT performance curves of head, power, and efficiency over the entire range of operation. The experimental data were provided by Derakhshan and Nourbakhsh for four different turbomachines, working in both pump and PAT mode with specific speed values in the range 1.53–5.82. This paper provides a quantitative assessment of the predictions made by means of the considered approaches and also analyzes consistency from a physical point of view. Advantages and drawbacks of each method are also analyzed and discussed.
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Barrio, R., J. Fernández, E. Blanco, J. Parrondo, and A. Marcos. "Performance characteristics and internal flow patterns in a reverse-running pump–turbine." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 226, no. 3 (2011): 695–708. http://dx.doi.org/10.1177/0954406211416304.
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Vaneless centrifugal pumps are reversible turbomachines that can operate also as centripetal turbines in low and very low-head power plants. However, the general performance in reverse mode is difficult to predict since the internal flow patterns are different from pump mode and the performance characteristics are not usually provided by manufacturers. This article presents numerical and experimental investigations on the operation of a reverse-running pump–turbine. The numerical calculations were carried out by solving the full unsteady Reynolds-averaged Navier–Stokes equations with the commercial code Fluent for several flowrates between 20 per cent and 160 per cent of rated conditions and both modes of operation. A complementary series of experimental measurements were performed in a test rig in order to obtain the general characteristics of the machine in pump and turbine modes, with the purpose of validating the numerical predictions. Once validated, the numerical model was used to investigate the flow patterns at some significant locations by means of pressure and velocity contours, and also by vector maps. Additionally, the model allowed the estimation of the steady load on the impeller as a function of flowrate in both modes of operation. It was concluded that, while the radial load in reverse mode is three times smaller than in pump mode, the axial load can be up to 1.6 times larger.
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Sazonov, Yuri Appolonievich, Mikhail Albertovich Mokhov, Inna Vladimirovna Gryaznova, et al. "Prototyping and Study of Mesh Turbomachinery Based on the Euler Turbine." Energies 14, no. 17 (2021): 5292. http://dx.doi.org/10.3390/en14175292.
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This paper presents a scientific development aimed at improving the efficiency of turbomachines through the joint use of rotary-vane and vortex workflows. In the well-known Euler turbine, the rotor flow channels represent a set of curved pipes. The authors propose to consider in more detail the possibilities of using such rotating pipes in the implementation of an ejection (vortex) workflow. A hybrid pump was considered with the conclusion that its workflow can be described using two Euler equations. The results of computer simulation indicate that hybrid turbomachines are promising. The use of additive technology allowed the creation of micromodels of the Euler turbine with various rotor designs. Laboratory hydraulic tests showed that the liquid inlet to the rotor is possible in pulse mode. Laboratory tests of micromodels using compressed air showed that gas (or liquid) motion through curved pipes could be carried out from the rotor periphery to its center and then back, albeit through another curved pipe. The research results demonstrated that the scientific and technical potential of the Euler turbine is not yet fully unlocked, and research in this direction should continue. The study results are applicable in various industries including the energyeconomy, robotics, aviation, and water transport industries.
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Hasmatuchi, Vlad, Alin Bosioc, Sébastien Luisier, and Cécile Münch-Alligné. "A Dynamic Approach for Faster Performance Measurements on Hydraulic Turbomachinery Model Testing." Applied Sciences 8, no. 9 (2018): 1426. http://dx.doi.org/10.3390/app8091426.
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During the design and optimization of hydraulic turbomachines, the experimental evaluation of hydraulic performances beyond the best efficiency point and for off-design conditions remains essential to validate the simulation process and to finalize the development. In this context, an alternative faster method to measure the efficiency of hydraulic turbomachines using a dynamic approach has been investigated. The so-called “sliding-gate” dynamic measurement method has been adapted and implemented on the hydraulic test rig of the HES-SO Valais//Wallis, Sion, Switzerland. This alternative approach, particularly gainful for small-hydro for which the investment devoted to development is limited, has been successfully assessed on two cases for drinking water networks energy recovery. A 2.65 kW double-regulated laboratory prototype of a tubular axial micro-turbine with two independent variable speed counter-rotating runners and a 11 kW multi-stage centrifugal pump-as-turbine (PAT) with variable speed have been selected. The hydraulic efficiency results obtained by dynamic measurements are compared to the ones obtained by the classical steady point-by-point method. This dynamic method, suitable not only for hydraulic machinery, allows: (i) reducing significantly (up to 10×) the time necessary to draw the complete efficiency characteristics of a hydraulic machine; (ii) rapidly detecting the hydrodynamic instabilities within the operating range of the machine.
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Kumar, M. Sarath, and B. S. Prabhu. "Rotating Machinery Predictive Maintenance Through Expert System." International Journal of Rotating Machinery 6, no. 5 (2000): 363–73. http://dx.doi.org/10.1155/s1023621x00000348.
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Modern rotating machines such as turbomachines, either produce or absorb huge amount of power. Some of the common applications are: steam turbine-generator and gas turbine-compressor-generator trains produce power and machines, such as pumps, centrifugal compressors, motors, generators, machine tool spindles, etc., are being used in industrial applications. Condition-based maintenance of rotating machinery is a common practice where the machine's condition is monitored constantly, so that timely maintenance can be done. Since modern machines are complex and the amount of data to be interpreted is huge, we need precise and fast methods in order to arrive at the best recommendations to prevent catastrophic failure and to prolong the life of the equipment. In the present work using vibration characteristics of a rotor-bearing system, the condition of a rotating machinery (electrical rotor) is predicted using an off-line expert system. The analysis of the problem is carried out in an Object Oriented Programming (OOP) framework using the finite element method. The expert system which is also developed in an OOP paradigm gives the type of the malfunctions, suggestions and recommendations. The system is implemented in C++.
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Teo, C. J., and Z. S. Spakovszky. "Modeling and Experimental Investigation of Micro-hydrostatic Gas Thrust Bearings for Micro-turbomachines." Journal of Turbomachinery 128, no. 4 (2005): 597–605. http://dx.doi.org/10.1115/1.2219760.
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One major challenge for the successful operation of high-power-density micro-devices lies in the stable operation of the bearings supporting the high-speed rotating turbomachinery. Previous modeling efforts by Piekos (2000, “Numerical Simulation of Gas-Lubricated Journal Bearings for Microfabricated Machines,” Ph.D. thesis, Department of Aeronautics and Astronautics, MIT), Liu et al. (2005, “Hydrostatic Gas Journal Bearings for Micro-Turbo Machinery,” ASME J. Vib. Acoust., 127, pp. 157–164), and Spakovszky and Liu (2005, “Scaling Laws for Ultra-Short Hydrostatic Gas Journal Bearings,” ASME J. Vib. Acoust. 127, pp. 254–261) have focused on the operation and stability of journal bearings. Thrust bearings play a vital role in providing axial support and stiffness, and there is a need to improve the understanding of their dynamic behavior. In this work, a rigorous theory is presented to analyze the effects of compressibility in micro-flows (characterized by low Reynolds numbers and high Mach numbers) through hydrostatic thrust bearings for application to micro-turbomachines. The analytical model, which combines a one-dimensional compressible flow model with finite-element analysis, serves as a useful tool for establishing operating protocols and assessing the stability characteristics of hydrostatic thrust bearings. The model is capable of predicting key steady-state performance indicators, such as bearing mass flow, axial stiffness, and natural frequency as a function of the hydrostatic supply pressure and thrust-bearing geometry. The model has been applied to investigate the static stability of hydrostatic thrust bearings in micro-turbine generators, where the electrostatic attraction between the stator and rotor gives rise to a negative axial stiffness contribution and may lead to device failure. Thrust-bearing operating protocols have been established for a micro-turbopump, where the bearings also serve as an annular seal preventing the leakage of pressurized liquid from the pump to the gaseous flow in the turbine. The dual role of the annular pad poses challenges in the operation of both the device and the thrust bearing. The operating protocols provide essential information on the required thrust-bearing supply pressures and axial gaps required to prevent the leakage of water into the thrust bearings. Good agreement is observed between the model predictions and experimental results. A dynamic stability analysis has been conducted, which indicates the occurrence of instabilities due to flow choking effects in both forward and aft thrust bearings. A simple criterion for the onset of axial rotor oscillations has been established and subsequently verified in a micro-turbocharger experiment. The predicted frequencies of the unstable axial oscillations compare well with the experimental measurements.
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Vásquez, Diego Penagos, Jonathan Graciano Uribe, Sebastián Vélez García, and Jorge Sierra del Rio. "Characteristic Curve Prediction of a Commercial Centrifugal Pump Operating as a Turbine Through Numerical Simulations." Journal of Advanced Research in Fluid Mechanics and Thermal Sciences 83, no. 1 (2021): 153–69. http://dx.doi.org/10.37934/arfmts.83.1.153169.
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In this work, we seek to predict the characteristic curve of a commercial centrifugal radial flow pump operating as a turbine, applying a novel methodology based on the state of the art. Initially, the characteristic curve in pump mode is validated through numerical simulations. The results obtained are approximate to the points awarded by the manufacturer, with an error of less than 7% at the best efficiency point. Subsequently, the characteristic curve is generated in turbine mode, obtaining an error of less than 10% respect to mathematical model. Then, velocity and pressure contours are evaluated to validate the fluid dynamic behavior. Finally, the site operating conditions for electricity generation are obtained. With this, it is proposing a methodology for the selection of these turbomachines, applying an economic technology for zones that do not have access to the electrical energy, since it was not found a method that is being applied for its correct election in the hydroelectric generation at low scale.
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Amirante, R., F. De Bellis, E. Distaso, and P. Tamburrano. "An Explicit, Non-Iterative, Single Equation Formulation for an Accurate One Dimensional Estimation of Vaneless Radial Diffusers in Turbomachines." Journal of Mechanics 31, no. 2 (2014): 113–22. http://dx.doi.org/10.1017/jmech.2014.72.
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AbstractThe present paper proposes a very simple one dimensional (1-D) model that accounts for the energy loss caused by the fluid dynamic losses occurring in the vaneless diffusers of centrifugal compressors and pumps. Usually, the present techniques to design turbomachines (pumps, compressors and turbines) emphasize numerical methods and their use is relatively complex because several parameters need to be chosen and a lot of time is required to perform the calculation. For this reason, it is relevant to perform an accurate preliminary design to simplify the numerical computation phase and to choose a very good initial geometry to be used for accelerating and improving the search for the definitive geometry. However, today 1-D modeling is based on the classical theory that assumes that the angular momentum is conserved inside a vaneless diffuser, although the flow evolution is considered as non-isentropic. This means that fluid-dynamic losses are taken into account only for what concerns pressure recovery, whereas the evaluation of the outlet tangential velocity incoherently follows an ideal behavior. Starting from such considerations, a new conservation law for the angular momentum is analytically derived, which incorporates the same fluid-dynamic losses modeled by the thermodynamic transformation law that is employed for correlating pressure recovery with enthalpy increase. Similar arguments hold for incompressible flows. Detailed and very accurate three-dimensional flow simulations are employed to analyze if the new model is capable of predicting the outlet tangential velocity more accurately than the classical theory. Results provided for both compressible (centrifugal compressors) and incompressible (centrifugal pumps) flows and for different inlet velocity profiles show a significant accuracy improvement of the new conservation law in the prediction of the outlet flow conditions when compared with the classical theory, thus demonstrating that the proposed model can be employed in the preliminary design of vaneless diffusers (i.e., in the estimation of the outlet diameter) more effectively than the classical ideal theory. Furthermore, the model is validated against industrial experimental campaigns. Even further experimental data, reported in a previous paper by the same authors, confirm the reliability of the employed approach.
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Zemanová, Lucie, and Pavel Rudolf. "Turbulence Models for Simulation of the Flow in a Rotor-Stator Cavity." EPJ Web of Conferences 213 (2019): 02104. http://dx.doi.org/10.1051/epjconf/201921302104.
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Modelling of the flow in the cavities between rotor and stator in turbomachines (e.g. pumps or turbines) is a task of great interest. Correctly evaluated pressure and velocity fields enable calculation of the disk losses and therefore assessment of efficiency. It is also crucial for determination of axial thrust and thus design of the bearings. The study demonstrates abilities of various turbulence models to describe the flow in a narrow gap between rotating and stationary disks. Numerical simulations were performed in order to find out the ability of particular models to capture unstable structures appearing during specific operating conditions as well as to calculate the velocity profiles precisely. Large Eddy Simulation (LES), Scale Adaptive Simulation (SAS), Detached Eddy Simulation (DES), Reynolds stress model (RSM) and SST k – ω model were used. Obtained results were also compared with experimental measurement published by Viazzo et al. [1]
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Song, J. W., A. Engeda, and M. K. Chung. "A modified theory for the flow mechanism in a regenerative flow pump." Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy 217, no. 3 (2003): 311–21. http://dx.doi.org/10.1243/095765003322066538.
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The regenerative flow pump (RFP) and regenerative flow compressor (RFC) are turbomachines capable of developing high pressure ratios in a single stage. They are also known by other names, such as peripheral, side channel, turbine, traction and vortex compressor/pump. Even though the efficiency of RFP/RFC is usually less than 50 per cent based on past design experience, they have found wide applications in automotive and aerospace fuel pumping, booster systems, water supply, agricultural industries, shipping and mining, chemical and food stuffs industries, and regulation of lubrication and filtering. RFCs have been proposed for use in hydrogen gas pipelines and as helium compressors for cryogenic applications in space vehicles. RFTs are used as accessory drives on aircraft and missiles. With the aim of improving the performance and efficiency of an RFP, this paper proposes an improved and modified theoretical model that can explain the change in the circulatory velocity caused by variation in channel area. All previous works concentrated on the fully developed flow region in the RFP and this work expands consideration to the developing region. Furthermore, in order to make the above-suggested model a closed problem, several loss models were assumed and the results of predictions were compared with experimental and CFD data.
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Simão, Mariana, Modesto Pérez-Sánchez, Armando Carravetta, and Helena Ramos. "Flow Conditions for PATs Operating in Parallel: Experimental and Numerical Analyses." Energies 12, no. 5 (2019): 901. http://dx.doi.org/10.3390/en12050901.
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Micro-hydro systems can be used as a promising new source of renewable energy generation, requiring a low investment cost of hydraulic, mechanical, and electrical equipment. The improvement of the water management associated with the use of pumps working as turbines (PATs) is a real advantage when the availability of these machines is considered for a wide range of flow rates and heads. Parallel turbomachines can be used to optimize the flow management of the system. In the present study, experimental tests were performed in two equal PATs working in parallel and in single mode. These results were used to calibrate and validate the numerical simulations. The analysis of pressure variation and head losses was evaluated during steady state conditions using different numerical models (1D and 3D). From the 1D model, the installation curve of the system was able to be defined and used to calculate the operating point of the two PATs running in parallel. As for the computational fluid dynamics (CFD) model, intensive analysis was carried out to predict the PATs′ behavior under different flow conditions and to evaluate the different head losses detected within the impellers. The results show system performance differences between two units running in parallel against a single unit, providing a greater operational flow range. The performance in parallel design conditions show a peak efficiency with less shock losses within the impeller. Furthermore, by combining multiple PATs in parallel arrangement, a site’s efficiency increases, covering a wide range of applications from the minimum to the maximum flow rate. The simulated flow rates were in good agreement with the measured data, presenting an average error of 10%.
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Rakibuzzaman, Md, Keum-Young Jung, and Sang-Ho Suh. "A study on the use of existing pump as turbine." E3S Web of Conferences 128 (2019): 06004. http://dx.doi.org/10.1051/e3sconf/201912806004.
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Cavitation is an abnormal physical phenomenon which occurs in relatively low–pressure regions in turbomachinery such as pumps and hydraulic turbines. A comparison between the pump and turbine cavitation behavior is a significant and essential process. The work investigates feasibility of turbineusing existing pump and a comparative study of the cavitation characteristics on a centrifugal pump asturbine numerically and experimentally. The current work adopted the Rayleigh–Plesset cavitation model as the source term for inter–phase mass transfer to predict cavitation characteristics.The experimental data were compared with the numerical results and were found to be in good agreement.Results of the comparative study showed that cavitation first occurred at the suction leading edge on the impeller blades and attached cavitation observed on the impeller blade at the lower suction head in pump mode; however, for the turbine mode, the development of vortex cavitation happened at the runner outlet near thetrailing edge on the impeller blades. Also, in the pump, the cavitation became largerfromshroud to the hub and the cavitation rapidly extended from the suction side to the pressure side. On the other hand in the turbine mode, as the cavitation number decreased more vapor bubbles are drawnup at the runner outlet near trailing edge on the blade suction side.
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Visser, F. C., J. J. H. Brouwers, and R. Badie. "Theoretical analysis of inertially irrotational and solenoidal flow in two-dimensional radial-flow pump and turbine impellers with equiangular blades." Journal of Fluid Mechanics 269 (June 25, 1994): 107–41. http://dx.doi.org/10.1017/s0022112094001503.
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Using the theory of functions of a complex variable, in particular the method of conformal mapping, the irrotational and solenoidal flow in two-dimensional radialflow pump and turbine impellers fitted with equiangular blades is analysed. Exact solutions are given for the fluid velocity along straight radial pump and turbine impeller blades, while for logarithmic spiral pump impeller blades solutions are given which hold asymptotically as (r1/r2)n→0, in whichr1is impeller inner radius,r2is impeller outer radius andnis the number of blades. Both solutions are given in terms of a Fourier series, with the Fourier coefficients being given by the (Gauss) hypergeometric function and the beta function respectively. The solutions are used to derive analytical expressions for a number of parameters which are important for practical design of radial turbomachinery, and which reflect the two-dimensional nature of the flow field. Parameters include rotational slip of the flow leaving radial impellers, conditions to avoid reverse flow between impeller blades, and conditions for shockless flow at impeller entry, with the number of blades and blade curvature as variables. Furthermore, analytical extensions to classical one-dimensional Eulerian-based expressions for developed head of pumps and delivered work of turbines are given.
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Kosoy, A. S., S. V. Monin, and M. V. Sinkevich. "Contemporary approaches to research supporting the development of microturbine power generation systems." Journal of «Almaz – Antey» Air and Space Defence Corporation, no. 1 (March 30, 2018): 72–79. http://dx.doi.org/10.38013/2542-0542-2018-1-72-79.
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The paper provides an analysis of how much it is possible to improve the efficiency of low-power gas-turbine engines. We show that refining those features of the main blading section units that affect the gas dynamics significantly enhances engine performance. We present a new concept of developing highly efficient turbomachinery, pumps and propellers using modern additive manufacturing technology. We describe a unique research and testing facility for studies, per-node refinement and testing concerning gas-turbine engine components, which should ensure low cost and high efficiency of gas-turbine engine design.
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Tiainen, Jonna, Ahti Jaatinen-Värri, Aki Grönman, Petri Sallinen, Juha Honkatukia, and Toni Hartikainen. "Validation of the Axial Thrust Estimation Method for Radial Turbomachines." International Journal of Rotating Machinery 2021 (February 24, 2021): 1–18. http://dx.doi.org/10.1155/2021/6669193.
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The fast preliminary design and safe operation of turbomachines require a simple and accurate prediction of axial thrust. An underestimation of these forces may result in undersized bearings that can easily overload and suffer damage. While large safety margins are used in bearing design to avoid overloading, this leads to costly oversizing. In this study, the accuracy of currently available axial thrust estimation methods is analyzed by comparing them to each other and to theoretical pressure distribution, numerical simulations, and new experimental data. Available methods tend to underestimate the maximum axial thrust and require data that are unavailable during the preliminary design of turbomachines. This paper presents a new, simple axial thrust estimation method that requires only a few preliminary design parameters as the input data and combines the advantages of previously published methods, resulting in a more accurate axial thrust estimation. The method is validated against previously public data from a radial pump and new experimental data from a centrifugal compressor, the latter measured at Lappeenranta-Lahti University of Technology LUT, Finland, and two gas turbines measured at Aurelia Turbines Oy, Finland. The maximum deviation between the estimated axial thrust using the hybrid method and the measured one is less than 13%, while the other methods deviate by tens of percent.
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Иванов, Андрей, and Andrey Ivanov. "INFLUENCE OF GAP FORM IN NON-CONTACT SEAL OF HIGH-SPEED TURBOMACHINE UPON ITS PARAMETERS." Bulletin of Bryansk state technical university 2016, no. 4 (2016): 39–45. http://dx.doi.org/10.12737/23161.
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Consolidation is one of the most significant elements in any turbomachine defining both economy and capacity for work of a unit. In high-speed pumps and turbines which belong turbo-pump units (TPU) of liquid-propellant engines (LPE) to, one uses mainly non-contact seals and in the first place groove seals. A radial seal gap its value and a form is a basic factor defining parameters and characteristics of sealing. In the paper there is shown the influence of geometrical characteristics of a non-contact seal gap in a high-speed turbomachine upon its characteristics. The influ-ence of the form of a sealing gap upon carrying capacity in it is analyzed that is particularly significant at the definition of seal influence upon critical frequencies of rotor rotation. The mutual misalignments in rotor and stator elements of a seal result in rotor stability reduction, the occurrence of additional radial loads upon bearings. Deviations in a surface form and deformations of sealing elements result in the pressure redistribution in a seal gap that, in its turn, changes forces character affecting a rotor from the side of a seal and, hence, its dynamic characteristics. The analysis of the influence upon carrying capacity in a seal gap of such factors as ellipse, obliquity, barreling, saddling is carried out. The results shown in the paper allow defining the tolerances influence upon manufacturing and deformations of sealing elements upon dynamic characteristics of a high-speed turbomachine rotor at the stage of designing a “rotor-bearings-seals” system.
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Najjar, Yousef S. H. "Review of Aerothermally Induced Vibrations in Gas Turbine Engines." Energy & Environment 6, no. 2 (1995): 143–57. http://dx.doi.org/10.1177/0958305x9500600205.
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High or changing vibration amplitude patterns in turbomachines are signs of impending failure or a machines deterioration. If properly diagnosed, this information can help improve performance, reliability; reduce maintenance cost; and avoid serious outages. Vibrations could be caused by structural or aerodynamic excitations, in addition to combustion pulsations. Methods of decreasing vibrations are mentioned, where selection of proper materials plays an important role. These areas are reviewed briefly in this work.
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Lazarovski, Nikolay, Paskal Novakov, and Anastas Yangyozov. "Mass Transfer Modeling into Disk Spaces of Heat Turbomachines." Defect and Diffusion Forum 362 (April 2015): 1–12. http://dx.doi.org/10.4028/www.scientific.net/ddf.362.1.
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The thermal aerodynamic analysis of the processes in thermal turbomachinery is of great importance when it comes their design and operation in order to achieve reliable and trouble-free operation in the required turbo-power range. The distribution of kinematic and thermodynamic parameters of the working medium around heavy loaded working disks and labyrinth seals has a significant influence on heat-mass exchange and energy transformation processes. Object of this work is thermo-aerodynamic research of mass exchange processes associated with the movement of the working medium in typical complex clearances between the rotor and stator of the steam turbines of disk type and determining axial forces in the rotor. Results based on one-dimensional and two-dimensional formulations of the problem are analyzed and compared with the results of field experiment of turbine P12-90 / 18, which before the reconstruction had problems with unstable axial loading during operation in wide power range. After proper reconstruction the turbine is in a sustainable balance throughout the whole range of operation modes. There is consistency in the results in quantitative and qualitative terms regarding the extreme conditions of axial loading. There is a three-dimensional approach to solving the problem of distribution of axial loading on the structural elements of the rotor, whose advantage is the obtaining of a detailed picture of the passing fluid in the clearances between the rotor and stator of the aggregate and diaphragm-disk spaces, and a detailed presentation of the uneven distribution of the axial forces on the front surfaces. The applied thermal aerodynamic approach allows to predict the main characteristics of steam turbines at different axial and radial clearances, changing during the operation in case of wear of the the crest of the labyrinth seals. This approach can serve as a thermo-aerodynamic diagnosis of the condition of the flow part of different thermal turbomachinery and in variable working modes.
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Denton, J. D. "The Calculation of Three-Dimensional Viscous Flow Through Multistage Turbomachines." Journal of Turbomachinery 114, no. 1 (1992): 18–26. http://dx.doi.org/10.1115/1.2927983.
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The extension of a well-established three-dimensional flow calculation method to calculate the flow through multiple turbomachinery blade rows is described in this paper. To avoid calculating the unsteady flow, which is inherent in any machine containing both rotating and stationary blade rows, a mixing process is modeled at a calculating station between adjacent blade rows. The effects of this mixing on the flow within the blade rows may be minimized by using extrapolated boundary conditions at the mixing plane. Inviscid calculations are not realistic for multistage machines and so the method includes a range of options for the inclusion of viscous effects. At the simplest level such effects may be included by prescribing the spanwise variation of polytropic efficiency for each blade row. At the most sophisticated level viscous effects and machine performance can be predicted by using a thin shear layer approximation to the Navier–Stokes equations and an eddy viscosity turbulence model. For high-pressure-ratio compressors there is a strong tendency for the calculation to surge during the transient part of the flow. This is overcome by the use of a new technique, which enables the calculation to be run to a prescribed mass flow. Use of the method is illustrated by applying it to a multistage turbine of simple geometry, a two-stage low-speed experimental turbine, and two multistage axial compressors.
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Damle, S. V., T. Q. Dang, and D. R. Reddy. "Throughflow Method for Turbomachines Applicable for All Flow Regimes." Journal of Turbomachinery 119, no. 2 (1997): 256–62. http://dx.doi.org/10.1115/1.2841108.
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A new axisymmetric throughflow method for analyzing and designing turbomachines is proposed. This method utilizes body-force terms to represent blade forces and viscous losses. The resulting equations of motion, which include these body-force terms, are cast in terms of conservative variables and are solved using a finite-volume time-stepping scheme. In the inverse mode, the swirl schedule in the bladed regions (i.e., the radius times the tangential velocity rVθ) is the primary specified flow quantity, and the corresponding blade shape is sought after. In the analysis mode, the blade geometry is specified and the flow solution is computed. The advantages of this throughflow method compared to the current family of streamline curvature and matrix methods are that the same code can be used for subsonic/transonic/supersonic throughflow velocities, and the proposed method has a shock capturing capability. This method is demonstrated for designing a supersonic throughflow fan stage and a transonic throughflow turbine stage.
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Asuaje, M., F. Bakir, S. Kouidri, R. Noguera, and R. Rey. "Computer-aided design and optimization of centrifugal pumps." Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy 219, no. 3 (2005): 187–93. http://dx.doi.org/10.1243/095765005x7556.
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Improvement in computer power and the development of numerical computational methods over the last few years have allowed the emergence of computational fluid dynamic (CFD) codes, making possible the numerical simulation of flow and energy transfer in turbomachines. To improve the efficiency of these tools, fast design software must be used. Within the framework of the optimization process of centrifugal pumps, HELIOX software was developed. It is a tool for design and performance analysis of centrifugal pumps. HELIOX allows quick design of new pumps and improvement of existing ones. HELIOX's performance analysis has been validated through many industrial cases: approximately 100 machines of different sizes and mechanical power. Heliox can be linked to quasi-and three-dimensional analysis tools; these tools enable a better understanding of physical phenomena so as to control the flow fields inside pumps.
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Siddique, M. Hamid, Arshad Afzal, and Abdus Samad. "Design Optimization of the Centrifugal Pumps via Low Fidelity Models." Mathematical Problems in Engineering 2018 (June 21, 2018): 1–14. http://dx.doi.org/10.1155/2018/3987594.
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Low fidelity model assisted design optimization of turbomachines has reduced the total computational and experimental costs. These models are called surrogate models which mimic the actual experiments or simulations. The surrogate models can generate thousands of approximate results from a few samples, making it easy to locate the optimal solution. Ample articles reported surrogate assisted design optimization of centrifugal pumps. In this article, the authors try to give a brief overview of the surrogate based optimization technique along with its historical applications and trend of the recent use. The various key design parameters which affect the performance of the centrifugal pump have also been discussed. The effectiveness of the surrogate based optimization technique and corresponding performance metrics have been discussed.
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Sharma, Chirag, Siddhant Kumar, Aanya Singh, et al. "Comprehensive Review on Leading Edge Turbine Blade Cooling Technologies." International Journal of Heat and Technology 39, no. 2 (2021): 403–16. http://dx.doi.org/10.18280/ijht.390209.
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Developments in the gas turbine technology have caused widespread usage of the Turbomachines for power generation. With increase in the power demand and a drop in the availability of fuel, usage of turbines with higher efficiencies has become imperative. This is only possible with an increase in the turbine inlet temperature (TIT) of the gas. However, the higher limit of TIT is governed by the metallurgical boundary conditions set by the material used to manufacture the turbine blades. Hence, turbine blade cooling helps in drastically controlling the blade temperature of the turbine and allows a higher turbine inlet temperature. The blade could be cooled from the leading edge, from the entire surface of the blade or from the trailing edge. The various methods of blade cooling from leading edge and its comparative study were reviewed and summarized along with their advantages and disadvantages.
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Acosta, Allan J., Yoshinobu Tsujimoto, Yoshiki Yoshida, Seiji Azuma, and Paul Cooper. "Effects of Leading Edge Sweep on the Cavitating Characteristics of Inducer Pumps." International Journal of Rotating Machinery 7, no. 6 (2001): 397–404. http://dx.doi.org/10.1155/s1023621x01000343.
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It is well known that leading edge sweep has a favorable effect on the cavitation of turbomachines. However, the mechanisms of the improvement have not been made clear. It has been shown that the lift and the drag on a cavitating swept single hydrofoil can be correlated fairly well based on the velocity component normal to the leading edge. In the present paper, such correlations for swept cascades are derived and the results are examined, neglecting the full geometrical effects of the inducer rotor. It is shown that the correlations can simulate the developments of various types of cavitation, including alternate blade cavitation, rotating cavitation, and cavitation surge. This result is based on the observation that the steady cavity length, as well as the developments ofvarious types ofcavitation, is fairly well predicted by the correlation.
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Wang, Zhengming. "A Method for Aerodynamic Design of Blades in Quasi-Three-Dimensional Calculation of Turbomachines." Journal of Turbomachinery 110, no. 2 (1988): 181–86. http://dx.doi.org/10.1115/1.3262178.
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A special inverse problem is formulated in which the shape of the mean streamline and the circumferential thickness distribution of the profile are given. On the basis of the series expansion method on a selected streamline, in quasi-three-dimensional aerodynamic design, the blade profile thickness is automatically fulfilled by computer. Six radial sections of a turbine blade are designed by this method.
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Barmpalias, Konstantinos G., Ndaona Chokani, Anestis I. Kalfas, and Reza S. Abhari. "Data Adaptive Spectral Analysis of Unsteady Leakage Flow in an Axial Turbine." International Journal of Rotating Machinery 2012 (2012): 1–7. http://dx.doi.org/10.1155/2012/121695.
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A data adaptive spectral analysis method is applied to characterize the unsteady loss generation in the leakage flow of an axial turbine. Unlike conventional spectral analysis, this method adapts a model dataset to the actual data. The method is illustrated from the analysis of the unsteady wall pressures in the labyrinth seal of an axial turbine. Spectra from the method are shown to be in good agreement with conventional spectral estimates. Furthermore, the spectra using the method are obtained with data records that are 16 times shorter than for conventional spectral analysis, indicating that the unsteady processes in turbomachines can be studied with substantially shorter measurement schedules than is presently the norm.
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Walker, P. J., and W. N. Dawes. "The Extension and Application of Three-Dimensional Time-Marching Analyses to Incompressible Turbomachinery Flows." Journal of Turbomachinery 112, no. 3 (1990): 385–90. http://dx.doi.org/10.1115/1.2927671.
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Conventional time-marching flow solvers perform poorly when integrating compressible flow equations at low Mach number levels. This is shown to be due to unfavorable interaction between long-wavelength errors and the inflow and outflow boundaries. Chorin’s method of artificial compressibility is adopted to extend the range of Denton’s inviscid flow solver and Dawes’ three-dimensional Navier–Stokes solver to zero Mach number flows. The paper makes a new contribution by showing how to choose the artificial acoustic speed systematically to optimize convergence rate with regard to the error wave–boundary interactions. Applications to a turbine rotor and generic water pump geometry are presented.
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Guinzburg, A., C. E. Brennen, A. J. Acosta, and T. K. Caughey. "Experimental Results for the Rotordynamic Characteristics of Leakage Flows in Centrifugal Pumps." Journal of Fluids Engineering 116, no. 1 (1994): 110–15. http://dx.doi.org/10.1115/1.2910217.
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In recent years, increasing attention has been given to fluid-structure interaction problems in turbomachines. The present research focuses on just one such fluid-structure interaction problem, namely, the role played by fluid forces in determining the rotordynamic stability and characteristics of a centrifugal pump. The emphasis of this study is to investigate the contributions to the rotordynamic forces from the discharge-to-suction leakage flows between the front shroud of the rotating impeller and the stationary pump casing. An experiment was designed to measure the rotordynamic shroud forces due to simulated leakage flows for different parameters such as flow rate, shroud clearance, face-seal clearance and eccentricity. The data demonstrate substantial rotordynamic effects and a destabilizing tangential force for small positive whirl frequency ratios; this force decreased with increasing flow rate. The rotordynamic forces appear to be inversely proportional to the clearance and change significantly with the flow rate. Two sets of data taken at different eccentricities yielded quite similar nondimensional rotordynamic forces indicating that the experiments lie within the linear regime of eccentricity.
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Lee, Donghyun, Byungock Kim, Mooryong Park, Hyungsoo Lim, and Euisoo Yoon. "Development of Pump-Drive Turbine Module with Hydrostatic Bearing for Supercritical CO2 Power Cycle Application." Applied Sciences 10, no. 19 (2020): 6824. http://dx.doi.org/10.3390/app10196824.
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The turbomachinery used in the sCO2 power cycle requires a high stable rotor-bearing system because they are usually designed to operate in extremely high-pressure and temperature conditions. In this paper, we present a pump-drive turbine module applying hydrostatic bearing using liquid CO2 as the lubricant for a 250 kW supercritical CO2 power cycle. This design is quite favorable because stable operation is possible due to the high stiffness and damping of the hydrostatic bearing, and the oil purity system is not necessary when using liquid CO2 as the lubricant. The pump-drive turbine module was designed to operate at 21,000 rpm with the rated power of 143 kW. The high-pressure liquid CO2 was supplied to the bearing, and the orifice restrictor was used for the flow control device. We selected the orifice diameter providing the maximum bearing stiffness and also conducted a rotordynamic performance prediction based on the designed pump-drive turbine module. The predicted Campbell diagram indicates that a wide range of operation is possible because there is no critical speed below the rated speed. In addition, an operation test was conducted for the manufactured pump-drive turbine module in the supercritical CO2 cycle test loop. During the operation, the pressurized CO2 of the 70 bar was supplied to the bearing for the lubrication and the shaft vibration was monitored. The successful operation was possible up to the rated speed and the test results showed that shaft vibration is controlled at the level of 2 μm for the entire speed range.
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Presas, Alexandre, David Valentin, Carme Valero, Monica Egusquiza, and Eduard Egusquiza. "Experimental Measurements of the Natural Frequencies and Mode Shapes of Rotating Disk-Blades-Disk Assemblies from the Stationary Frame." Applied Sciences 9, no. 18 (2019): 3864. http://dx.doi.org/10.3390/app9183864.
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Determining the natural frequencies and mode shapes of rotating turbomachinery components from both rotating and stationary reference frames is of paramount importance to avoid resonance problems that could affect the normal operation of the machine, or even cause critical damages in these components. Due to their similarity to real engineering cases, this topic has been experimentally analyzed in the past for disk-shaft assemblies and rotor disk-blades assemblies (bladed-disk or blisk). The same topic is less analyzed for disk-blades-disk assemblies, although such configurations are widely used in centrifugal closed impellers of compressors, hydraulic pumps, pump-turbines, and runners of high head Francis turbines. In this paper, experimental measurements, varying the rotating speed of a disk-blade-disk assembly and exciting the first natural frequencies of the rotating frame, have been performed. The rotating structure is excited and measured by means of PZT patches from the rotating frame and with a Laser Doppler Vibrometer (LDV). In order to interpret the experimental results obtained from the stationary frame, a method to decompose the diametrical mode shapes of the structure in simple diametrical components (which define the diametrical mode shapes of a simple disk) has been proposed. It is concluded that the resonant frequencies detected with a stationary sensor correspond to the ones predicted with the decomposition method. Finally, a means to obtain equivalent results with numerical simulation methods is shown.
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Kyparissis, Spyridon D., and Dionissios P. Margaris. "Experimental Investigation and Passive Flow Control of a Cavitating Centrifugal Pump." International Journal of Rotating Machinery 2012 (2012): 1–8. http://dx.doi.org/10.1155/2012/248082.
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Passive flow control techniques are used to improve the flow field and efficiency of centrifugal pumps and turbomachines, in general. An important phenomenon that mechanical engineers have to take into account is cavitation. It leads to the decrease of the pump performance and total head. In the present experimental study, a centrifugal pump is investigated in cavitating conditions. A passive flow control is realized using three different blade leading edge angles in order to reduce the cavitation development and enhance the pump performance. The experiments are carried out in a pump test rig specially designed and constructed, along with the impellers. The head drop and total efficiency curves are presented in order to examine the effect of the blade leading edge angle on the cavitation and pump performance. Finally, the vapour distribution along with the blades is illustrated for the tested blade leading edge angles.
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Zemanová, Lucie, and Pavel Rudolf. "Flow Inside the Sidewall Gaps of Hydraulic Machines: A Review." Energies 13, no. 24 (2020): 6617. http://dx.doi.org/10.3390/en13246617.
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The paper critically reviews the current state of the art in flow inside sidewall gaps of hydraulic pumps and turbines. It describes the consequences of the presence of this type of flow in turbomachinery and then relates it to other physical phenomena that determine the behavior, operating characteristics, and overall performance of the machine. Despite the small dimensions of the rotor-stator spaces, the flow in these regions can significantly affect the overall flow field and, consequently, efficiency. The circulation of the fluid inside the gaps and secondary flow that is caused by rotating elements influences the disk friction losses, which is of great importance, especially in the case of low specific speed pumps and turbines. The flow pattern affects the pressure distribution inside a machine and, thus, generates axial thrust. The presence of secondary flow also significantly changes the rotordynamics and can bring about undesirable vibrations and acoustics issues. This article aims to review and summarize the studies that were conducted on the mentioned phenomena. Experimental and numerical studies are both taken into consideration. It proposes some requirements for prospective research in order to fill current gaps in the literature and reveals the upcoming challenges in the design of hydraulic machines.
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Mobarak, A., M. G. Khalafallah, A. M. Osman, and H. A. Heikal. "Experimental Investigation of Secondary Flow and Mixing Downstream of Straight Turbine Cascades." Journal of Turbomachinery 110, no. 4 (1988): 497–503. http://dx.doi.org/10.1115/1.3262223.
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The purpose of this paper is to investigate the flow field downstream of turbine cascades of low aspect ratio, often used in vehicles and small turbomachines. Experimental investigation was carried out to study the flow downstream of three sets of turbine cascades having the same blade turning angle of about 83 deg but different profiles. The total energy losses were measured at several planes downstream of the cascade of blades in order to determine the changes in gross secondary flow loss coefficient and the growth of the mixing loss with distance downstream. Influence of inlet boundary layer thickness, aspect ratio, and exit Mach number on the nature of the flow at the exit plane of the cascade and total energy loss were studied. The tests were performed with four values of aspect ratio: 1.16, 0.8, 0.5, and 0.25. Some new correlations were deduced that predict energy loss coefficients as a function of distance downstream, aspect ratio, and exit Mach number as well as the upstream boundary layer thickness. The test results compare well with other published correlations.
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Capata, Roberto. "New Power Train Concept for a City Hybrid Vehicle." Proceedings 58, no. 1 (2020): 6. http://dx.doi.org/10.3390/wef-06926.
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This research aims to test the feasibility of a prototype of a newly designed thermal engine for a hybrid propulsion vehicle. This study consists of the implementation of an innovative supercharger for city car ICE (900cc). The preliminary proposal presented here is to mechanically disconnect the compressor/turbine device, supporting the rotation of the compressor with a dedicated electric motor and connecting a turbine to a generator. Mechanical decoupling will allow both machines to be designed for operating closer to their maximum performance point, for most of the expected real field of operation. Specifically, the turbine is likely to have a slightly lower rotation speed than the original group and will, therefore, be slightly larger. The advantage is that, while in the current supercharger groups the surplus at high regimes is discharged through the waste-gate valve without expanding in a turbine, in the configuration proposed, all the energy of the combustible gases is used by the turbine to generate electrical power that can be used where required. Once the motorization of the vehicle (999 cc) has been fixed, the two turbomachines will have to be studied and designed, looking, where possible, for commercial components. Finally, a CFD will be needed to verify the validity of the choice, followed by careful experimentation campaigns.
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Najjar, Yousef S. H. "Relative effect of pressure losses and inefficiencies of turbomachines on the performance of the heat-exchange gas turbine cycle." Applied Thermal Engineering 16, no. 8-9 (1996): 769–76. http://dx.doi.org/10.1016/1359-4311(95)00031-3.
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Capata, Roberto. "Preliminary Analysis of a New Power Train Concept for a City Hybrid Vehicle." Designs 5, no. 1 (2021): 19. http://dx.doi.org/10.3390/designs5010019.
Full textAbstract:
This research aims to test the feasibility of a prototype of a newly designed thermal engine for a hybrid propulsion vehicle. This study consists of the implementation of an innovative supercharger for city car internal combustion engine ICE (900 cc). The preliminary proposal presented here is to mechanically disconnect the compressor/turbine device, supporting the rotation of the compressor with a dedicated electric motor and connecting a turbine to a generator. Mechanical decoupling will allow both machines to be designed for operating closer to their maximum performance point, for most of the expected real field of operation. Specifically, the turbine is likely to have a lower rotation speed than the original group and will, therefore, be slightly larger. The advantage is that, while in the current supercharger groups the surplus at high regimes is discharged through the waste-gate valve without expanding in a turbine, in the configuration proposed, all the energy of the combustible gases is used by the turbine to generate electrical power that can be used where required. Once the motorization of the vehicle (999 cc) has been fixed, the two turbomachines will have to be studied and designed, looking where possible, for commercial components. Finally, a computational fluid dynamic CFD will be needed to verify the validity of the choice, followed by careful experimentation campaigns.
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Ng, E. Y. K., and Miao Yi. "Computation of Q3D Viscous Flows in Various Annular Turbine Stages with Heat Transfer." International Journal of Rotating Machinery 4, no. 1 (1998): 25–33. http://dx.doi.org/10.1155/s1023621x98000037.
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A better understanding of the flow inside the multi-stage turbomachines will be very useful to both the designer and operator. The numerical calculation for single blade row has been well established with the time marching computation of the Navier-Stokes equations. But there will exist much more difficulties for the multi-blade rows due to the rotor-stator interaction. The major problems are related to the unsteady flow which will inevitably exist in the blade passages due to the different rotating speed and possible the different in blade number. A method is presented for simulating various turbine blade rows in single-stage environment. A solver has been developed for studying the complex flow analysis of ‘proposed high pressure turbine’ (HPT) using quasi-3-D Reynolds-averaged Navier-Stokes (Q3D RNS) equations. The code achieves good quality solutions quickly even with relatively coarse mesh sizes. The work is first validated both with UTRC's and Zeschky and Gallus' subsonic turbine test cases covering inlet boundary conditions and Reynolds-averaged values. A H-type grid is adopted as it is easy to generate and can readily extend to 3D application. When rows are closely spaced, there can be a strong interaction which will impact the aerodynamic, thermal and structural performance of the blade.
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Matsunuma, Takayuki, and Takehiko Segawa. "Effects of Input Voltage and Freestream Velocity on Active Flow Control of Passage Vortex in a Linear Turbine Cascade Using Dielectric Barrier Discharge Plasma Actuator." Energies 13, no. 3 (2020): 764. http://dx.doi.org/10.3390/en13030764.
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Passage vortex exists as one of the typical secondary flows in turbomachines and generates a significant total pressure loss and degrades the aerodynamic performance. Herein, a dielectric barrier discharge (DBD) plasma actuator was utilized for an active flow control of the passage vortex in a linear turbine cascade. The plasma actuator was installed on the endwall, 10 mm upstream from the leading edge of the turbine cascade. The freestream velocity at the outlet of the linear turbine cascade was set to range from UFS,out = 2.4 m/s to 25.2 m/s, which corresponded to the Reynolds number ranging from Reout = 1.0 × 104 to 9.9 × 104. The two-dimensional velocity field at the outlet of the linear turbine cascade was experimentally analyzed by particle image velocimetry (PIV). At lower freestream velocity conditions, the passage vortex was almost negligible as a result of the plasma actuator operation (UPA,max/UFS,out = 1.17). Although the effect of the jet induced by the plasma actuator weakened as the freestream velocity increased, the magnitude of the peak vorticity was reduced under all freestream velocity conditions. Even at the highest freestream velocity condition of UFS,out = 25.2 m/s, the peak value of the vorticity was reduced approximately 17% by the plasma actuator operation at VAC = 15 kVp-p (UPA,max/UFS,out = 0.18).
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Borges, J. E. "A Three-Dimensional Inverse Method for Turbomachinery: Part II—Experimental Verification." Journal of Turbomachinery 112, no. 3 (1990): 355–61. http://dx.doi.org/10.1115/1.2927667.
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The performance of an impeller of a low-speed radial-inflow turbine, designed using a three-dimensional inverse technique, was evaluated experimentally. This performance was compared with that achieved by a rotor typical of the present technology. Besides measuring overall quantities, in special efficiency, some traverses of flow velocity were carried out. The results of the tests showed that the new design had a peak total-to-static efficiency 1.4 points better than the conventional build. The traverses indicated that the level of swirl at exhaust of the new impeller was only half as big as that for the conventional rotor, in spite of the fact that both impellers were designed to have zero swirl at outlet. It is also shown that the rotor loss for the new impeller is considerably lower than for the conventional wheel. This research points to the desirability of using a three-dimensional inverse method for the design of turbomachines with significant three-dimensional flows.
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Ismail, Mohd Azlan, Al Khalid Othman, and Hushairi Zen. "Numerical Investigation of Rotational Speed on Pump as Turbine for Microhydro Applications." Applied Mechanics and Materials 833 (April 2016): 11–18. http://dx.doi.org/10.4028/www.scientific.net/amm.833.11.
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Pump as Turbine (PAT) always has been a favourable solution to generate electricity in rural areas when there is a potential microhydro site. Such systems have lower capital cost, and they are easier to maintain than commercially-available microhydro turbines. Normally, PAT is designed to run at a rated rotational speed so it can directly couple with an induction generator in order to match the synchronous speed. In an actual scenario, the PAT’s rotational speed changes and fluctuates with respect to flow rate due to the absence of a hydraulic control mechanism. It is essential to understand how the PAT behaves under different rotational speeds in order to design good microhydro systems. The aim of this study was to conduct simulation analysis of the effect of rotational speed on PAT’s performance curve over a range of flow rates. ANSYS CFX software was used as the Computational Fluid Dynamic (CFD) simulation tool in this study. Three distinct flow domains was modelled by Computer Aided Design (CAD) software and assembled as the computational fluid domains. Mesh independence analysis and convergence criteria were set to ensure the accuracy of the model. The torque generated by the impeller was collected from the simulation data and presented in the PAT performance curve. It was observed that the pressure head and torque generated increased at higher rotational speeds, thus maintaining the efficiency value. The results showed that the efficiency of the PAT was maintained around 76.5% for rotational speeds between 1350 to 1650 RPM, but the best efficiency point shifted to lower flow rate for lower rotational speed. The outcomes of this study will be useful for turbomachinery researchers, microhydro users, and project engineers for predicting the PAT performance for designing microhydro systems.
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Marin, G. E., B. M. Osipov, and A. R. Akhmetshin. "Technical and economic assessment of the parameters of thermal schemes of thermal power plants with a hydrogen generator." Power engineering: research, equipment, technology 23, no. 2 (2021): 84–92. http://dx.doi.org/10.30724/1998-9903-2021-23-2-84-92.
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THE PURPOSE. The study is aimed at studying the effect of fuel gases of various component composition on the environmental performance of the GE 6FA gas turbine unit. Consider using hydrogen as primary sweat to minimize emissions and improve performance of the GE 6FA gas turbine. METHODS. To achieve this goal, the ASGRET (Automated system for gas-dynamic calculations of power turbomachines) software package was used. RESULTS. The article discusses promising directions for the utilization of CO2 using highly efficient technologies with further use or disposal. A mathematical model of a GE 6FA gas turbine unit, diagrams of changes in the main characteristics and the composition of emissions when operating on various types of fuel, including hydrogen, are presented. CONCLUSION. The studies carried out show that a change in the component composition of the gas affects the energy characteristics of the engine. The method for determining the quantitative composition of COx, NOx, SOx in the exhaust gases of a gas turbine plant is presented. The transition to the reserve fuel kerosene leads to an increase in the amount of emissions, which must be taken into account when designing systems for capturing harmful emissions with a dual-fuel fuel gas supply system. The use of hydrogen as a fuel for gas turbines allows to reduce not only the cost of fuel preparation, but also to minimize emissions and improve the performance of the gas turbine plant.
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Leguizamón, Sebastián, and François Avellan. "Open-Source Implementation and Validation of a 3D Inverse Design Method for Francis Turbine Runners." Energies 13, no. 8 (2020): 2020. http://dx.doi.org/10.3390/en13082020.
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The hydraulic design of Francis turbines and pump-turbines is an expensive project-specific engineering effort that typically involves a direct iterative exploration of the design space. An inverse design method for turbomachinery has been previously introduced in the literature, and several recent applications have demonstrated its advantages; however, only a commercial implementation of the method is currently available. In this work, an open-source implementation of the inverse design method is introduced. First, the governing equations in cylindrical and curvilinear coordinate systems are derived, consolidating the somewhat inconsistent formulations that are available in the literature. Then, a convergence analysis of the method is performed in order to characterize the behavior of the discretization error and deduce the mesh resolution requirements. A validation of the method output with respect to high-fidelity computational fluid dynamics simulations is then presented; it is demonstrated that the velocity fields are well predicted, the pressure distribution on the blades is reasonably well approximated, and the flow angular momentum extraction is achieved in the prescribed manner. Possible improvements to the open-source implementation of the method are discussed.
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Shao, Ziyi, Wen Li, Yangli Zhu, et al. "Tip leakage flow analysis of an axial turbine under the effect of separation at low Reynolds number." Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy 234, no. 6 (2019): 751–65. http://dx.doi.org/10.1177/0957650919882877.
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The tip clearance flow could lead to work reduction and loss generation in turbomachines. However, the effect of separation at low Reynolds number on leakage flow is seldom studied. The previous method for evaluating tip leakage characteristics should also be further researched. Thus, numerical investigations on the tip clearance flow in an unshrouded axial-inflow turbine are conducted at low Reynolds number (3.5 × 104 of the rotor outlet at the designed condition) in the present study. The flow patterns and leakage mass flow rate of the clearance have been analyzed in detail. It is found that the tip clearance flow is greatly affected by the flow separation caused by low Reynolds number. The scraping ratio adopted in previous references does not accord with the clearance flow characteristics at low Reynolds number, especially in the front part of the clearance. A coefficient by −0.70 power of the Reynolds number is proposed to modify the scraping ratio in the present study. The synergy between the velocity and the pressure gradient is innovatively employed to research the tip clearance flow characteristics, and it gives a reliable criterion of indicating the flow patterns in the tip clearance.
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Chasoglou, Alexandros C., Michel Mansour, Anestis I. Kalfas, and Reza S. Abhari. "A novel 4-sensor fast-response aerodynamic probe for non-isotropic turbulence measurement in turbomachinery flows." Journal of the Global Power and Propulsion Society 2 (May 17, 2018): UALS07. http://dx.doi.org/10.22261/jgpps.uals07.
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Abstract In modern computational studies for turbomachinery applications, time, length scales and isotropy of turbulent structures are important for representative modelling. To this end, experimental data are essential to validate the numerical tools. The current article presents the development and application of a newly designed 4-sensor Fast Response Aerodynamic Probe (FRAP-4S) enabling time-resolved measurement of the three-dimensional unsteady flow velocity vector in turbomachines. The miniature multi-sensor probe demonstrates a 4 mm probe-tip. In the first part of this article the design, manufacturing and calibration results of the FRAP-4S are presented in detail. To assess the newly developed probe accuracy, comparison against traditional instrumentation developed at the Laboratory for Energy Conversion is also provided. In the second part of this work, measurements are performed at the rotor exit of a one-and-a-half stage, unshrouded and highly-loaded axial turbine configuration. The results showed increased level of unsteadiness and turbulence levels with peak-to-peak fluctuation from 5 to 35%. More importantly, in some regions stream-wise unsteadiness was found to be ten times higher, compared to the cross-wise components, an indication of the high degree of anisotropy.
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Kupferschmied, Peter, Pascal Ko¨ppel, Christian Roduner, and Georg Gyarmathy. "On the Development and Application of the Fast-Response Aerodynamic Probe System in Turbomachines—Part 1: The Measurement System." Journal of Turbomachinery 122, no. 3 (1999): 505–16. http://dx.doi.org/10.1115/1.1303702.
Full textAbstract:
This contribution gives an overview of the current state, performance, and limitations of the fast-response aerodynamic probe measurement system developed at the Turbomachinery Lab of the ETH Zurich. In particular, the following topics are addressed: • Probe technology: Miniature probes with tip diameter ranging from 0.84 to 1.80 mm (one-sensor and three-sensor probes, respectively) have been developed. New technologies derived from microelectronics and micromechanics have been used to achieve an adequate packaging of the microsensor chips used. Both the sensor packaging and the sensor calibration (time-independent and time-dependent) are crucial issues for the DC accuracy of any measurement. • Aerodynamic probe calibration: The methods used for the sensor calibration and the aerodynamic probe calibration, the pertinent automated test facilities, and the processing of the output data are briefly presented. Since these miniature probes are also capable of measuring the mean flow temperature, aspects related to the effective recovery factor and the self-heating of the probe tip are treated and some recommendations related to sensor selection are given. • Measurement system and data evaluation: The early measurement chain described in Gossweiler et al. (1995) has evolved into the fast-response aerodynamic probe system. This automatic system incorporates dedicated measurement concepts for a higher accuracy and a more efficient operation in terms of time and failures. An overview of the data evaluation process is given. The fast-response aerodynamic probe system has been tested in real-sized turbomachines under industrial conditions within the temperature limits of 140°C imposed by the sensor technology (axial-flow turbofan compressor, axial-flow turbine, centrifugal compressor). These applications confirmed the potential of the system and encouraged its further development. Now, the system is routinely used in the facilities of the Turbomachinery Lab and in occasional measurement campaigns in other laboratories. Part 2 of this contribution (Roduner et al.) will focus on the application of the fast-response aerodynamic probe system in a transonic centrifugal compressor of the ETH Turbomachinery Laboratory, while Part 3 (Ko¨ppel et al.) treats more sophisticated data analysis methods. [S0889-504X(00)01003-5]
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Carscallen, W. E., T. C. Currie, S. I. Hogg, and J. P. Gostelow. "Measurement and Computation of Energy Separation in the Vortical Wake Flow of a Turbine Nozzle Cascade." Journal of Turbomachinery 121, no. 4 (1999): 703–8. http://dx.doi.org/10.1115/1.2836723.
Full textAbstract:
This paper describes the observation, measurement, and computation of vortex shedding behind a cascade of turbine nozzle guide vanes that have a blunt trailing edge. At subsonic discharge speeds, periodic wake vortex shedding was observed at all times at a shedding frequency in the range 7–11 kHz. At high subsonic speeds the wake was susceptible to strong energy redistribution. The effect was greatest around an exit Mach number of 0.95 and results are presented for that condition. An unusually cold flow on the wake centerline and hot spots at the edges of the wake were measured. These were found to be a manifestation of Eckert–Weise effect energy separation in the shed vortex street. Experimental identification of these phenomena was achieved using a new stagnation temperature probe of bandwidth approaching 100 kHz. Using phase-averaging techniques, it was possible to plot contours of time-resolved entropy increase at the downstream traverse plane. Computational work has been undertaken that gives qualitative confirmation of the experimental results and provides a more detailed explanation of the fine scale structure of the vortex wake. The topology of the wake vortical structures behind blunt trailing-edged turbine blades is becoming clearer. These measurements are the first instantaneous observations of the energy separation process occurring in turbine blade wake flows. This was also the first demonstration of the use of the probe in the frequency, Mach number, and temperature ranges typical of operation behind the rotors of high-performance turbomachines such as transonic fans.
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van de Wall, Allan G., Jaikrishnan R. Kadambi, and John J. Adamczyk. "A Transport Model for the Deterministic Stresses Associated With Turbomachinery Blade Row Interactions." Journal of Turbomachinery 122, no. 4 (2000): 593–603. http://dx.doi.org/10.1115/1.1312802.
Full textAbstract:
The unsteady process resulting from the interaction of upstream vortical structures with a downstream blade row in turbomachines can have a significant impact on the machine efficiency. The upstream vortical structures or disturbances are transported by the mean flow of the downstream blade row, redistributing the time-average unsteady kinetic energy (K) associated with the incoming disturbance. A transport model was developed to take this process into account in the computation of time-averaged multistage turbomachinery flows. The model was applied to compressor and turbine geometry. For compressors, the K associated with upstream two-dimensional wakes and three-dimensional tip clearance flows is reduced as a result of their interaction with a downstream blade row. This reduction results from inviscid effects as well as viscous effects and reduces the loss associated with the upstream disturbance. Any disturbance passing through a compressor blade row results in a smaller loss than if the disturbance was mixed-out prior to entering the blade row. For turbines, the K associated with upstream two-dimensional wakes and three-dimensional tip clearance flows are significantly amplified by inviscid effects as a result of the interaction with a downstream turbine blade row. Viscous effects act to reduce the amplification of the K by inviscid effects but result in a substantial loss. Two-dimensional wakes and three-dimensional tip clearance flows passing through a turbine blade row result in a larger loss than if these disturbances were mixed-out prior to entering the blade row. [S0889-504X(00)01804-3]