- Fluid and Power Machinery
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Entropy production analysis for hump characteristics of a pump turbine model
Chinese Journal of Mechanical Engineering volume 29, pages 803–812 (2016)
Abstract
The hump characteristic is one of the main problems for the stable operation of pump turbines in pump mode. However, traditional methods cannot reflect directly the energy dissipation in the hump region. In this paper, 3D simulations are carried out using the SST k-ω turbulence model in pump mode under different guide vane openings. The numerical results agree with the experimental data. The entropy production theory is introduced to determine the flow losses in the whole passage, based on the numerical simulation. The variation of entropy production under different guide vane openings is presented. The results show that entropy production appears to be a wave, with peaks under different guide vane openings, which correspond to wave troughs in the external characteristic curves. Entropy production mainly happens in the runner, guide vanes and stay vanes for a pump turbine in pump mode. Finally, entropy production rate distribution in the runner, guide vanes and stay vanes is analyzed for four points under the 18 mm guide vane opening in the hump region. The analysis indicates that the losses of the runner and guide vanes lead to hump characteristics. In addition, the losses mainly occur in the runner inlet near the band and on the suction surface of the blades. In the guide vanes and stay vanes, the losses come from pressure surface of the guide vanes and the wake effects of the vanes. A new insight-entropy production analysis is carried out in this paper in order to find the causes of hump characteristics in a pump turbine, and it could provide some basic theoretical guidance for the loss analysis of hydraulic machinery.
References
Int. Energy Agency (IEA). Renewable Energy Essentials: Hydropower [R]. Paris, France: IEA, 2010.
Int. Energy Agency (IEA). Technology Roadmap: Hydropower[R], Paris, France: IEA, 2013.
GENTNER CH, SALLABERGER M, WIDMER CH. Numerical and experimental analysis of instability phenomena in pump turbines[C/CD]//26th IAHR Symposium on Hydraulic Machinery and Systems - Session 1: Hydraulic Turbines and Pumps, Beijing, China, August 19–23, 2012. IOP Conference Series: Earth and Environmental Science, v15, n PART 3.
LIU Jintao, LIU Shuhong, WU Yulin, et al. Numerical investigation of the hump characteristic of a pump-turbine based on an improved cavitation model[J]. Computer & Fluids, 2012, 68: 105–111.
YANG J, PRAVESI G, YUAN S, et al. Experimental characterization of a pump-turbine in pump mode at hump instability region[J]. Journal of Fluids Engineering, 2015, 137 (051109): 1–11.
LI Deyou, WANG Hongjie, XIANG Gaoming, et al. Unsteady simulation and analysis for hump characteristics of a pump turbine model[J]. Renewable Energy, 2015, 77: 32–42.
BRAUN O, KUENY J L, AVELLAN F. Numerical analysis of flow phenomena related to the unstable energy-discharge characteristic of a pump-turbine in pump mode[C]//2005 ASME Fluid Engineering Division Summer Meeting and Exhibition, Houston, TX, USA, June 19–23, 2005. New York: ASME, v2005: 944–949.
YIN Junlian, LIU Jintao, WANG Leqin, et al. Performance prediction and flow analysis in the vaned distributor of a pump-turbine under low flow rate in pump mode [J]. Science China Technological Sciences, 2010, 53(12): 3302–3309.
RAN Hongjuan, LUO Xianwu, ZHU Lei, et al. Experimental study of the pressure fluctuations in a pump turbine at large partial flow conditions[J]. Chinese Journal of Mechanical Engineering, 2012, 25(6): 1205–1209.
HERWIG H, GLOSS D, WENTERODT W. A new approach to understanding the influence of wall roughness on friction[J]. Journal of Fluid Mechanical, 2008, 613: 35–53.
ZHANG H C, SCHMANDT B. HERWIG H. Determination of loss coefficients for micro-flow devices: a method based on the second law analysis (SLA)[C]//ASME 2009 2nd Micro/Nanoscale Heat & Mass Transfer International Conference, Shanghai, China, December 18–21, 2009. Proceedings of the ASME Micro/Nanoscale Heat and Mass Transfer International Conference 2009: MNHMT2009, 2010, v2: 545–552.
NATERER G F, CAMBEROS J A. Entropy-based design and analysis of fluids engineering systems[M]. CRC Press, Boca Raton, 2008.
GHASEMI E, MCELIGOT D M, NOLAN K P. Entropy generation in a transitional boundary layer region under the influence of free stream turbulence using transitional RANS models and DNS[J]. International Communications in Heat and Mass Transfer, 2013, 41: 10–16.
MCELIGOT D M, WALSH E J, LAURIEN E, et al. Entropy generation in the viscous part of turbulent boundary layers[J]. Journal of Fluids Engineering, 2008, 106 (6): 061205–1–12.
MCELIGOT D M, NOLAN K P, WALSH E J, LAURIEN E. Effects of pressure gradients on entropy generation in the viscous layers of turbulent wall flows[J]. International Journal of Heat and Mass Transfer, 2008, 51: 1104–1114.
MCELIGOT D M, BRODKEY R S, ECKELMANN H. Laterally converging duct flows: part 4.Temporal behavior in the viscous layer[J]. Journal of Fluid Mechanics, 2009, 634: 433–461.
GLOSS D, HERWIG H. Wall roughness effects in laminar flows: an often ignored though significant issue[J]. Experiments in Fluids, 2010, 49: 461–470.
GONG Ruzhi, WANG Hongjie, CHEN Lixia, et al. Application of entropy production theory to hydro-turbine hydraulic analysis[J]. Sci. China Tech. Sci., 2013, 56(7): 1636–1643.
BEJAN A. Entropy production through heat and fluid flow[M]. New York: John Wiley & Sons, 1994.
BEJAN A. Entropy production minimization: the method of thermodynamic optimization of finite-time systems and finite-time processes[M]. Boca Raton, FL: CRC Press, 1996.
SCHMANDT B, HERWIG H. Internal flow losses: a fresh look at old concepts[J]. Journal of Fluids Engineering, 2001, 133(5): 1–10.
KOCK F, HERWIG H. Local entropy production in turbulent shear flows: a high Reynolds number model with wall functions[J]. International Journal of Heat and Mass Transfer, 2004, 47: 2205–2215.
MATHIEU J, SCOTT J. An introduction to turbulent flow[M]. Cambridge: Cambridge University Press, 2000.
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Supported by National Key Technology R&G Program (Grant No. 2012BAF03B01-X), and Innovative Research Groups of National Natural Science Foundation of China (Grant No. 51121004)
LI Deyou, born in 1986, is currently a PhD candidate at School of Energy Science and Engineering, Harbin Institute of Technology, China. He received his bachelor and master degree from Harbin Institute of Technology, China, in 2010 and 2012, respectively. His research interests include numerical simulation and experimental investigation of hydraulic machinery, such as pump turbine, turbine and pump; modeling and simulation of hydraulic system control, and testing technology of hydraulic machinery.
GONG Ruzhi, born in 1977, is currently a lecturer at School of Energy Science and Engineering, Harbin Institute of Technology, China. He received his PhD degree on engineering thermal physics from Harbin Institute of Technology, China, in 2013.
WANG Hongjie, born in 1962, is currently the Vice President and a professor at School of Energy Science and Engineering, Harbin Institute of Technology, China.
XIANG Gaoming, born in 1992, is currently a master candidate at School of Energy Science and Engineering, Harbin Institute of Technology, China.
WEI Xianzhu, born in 1966, is currently the Vice Chief Designer and the Director of Hydraulic Turbine Research Department at Harbin Institute of Large Electrical Machinery, Harbin, China. And also, he is a part time professor at School of Energy Science and Engineering, Harbin Institute of Technology, China.
QIN Daqing, born in 1965, is currently the Vice Chief Engineer and the Vice president at Harbin Institute of Large Electrical Machinery, China. And also, he is a part time professor at School of Energy Science and Engineering, Harbin Institute of Technology, China.
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Li, D., Gong, R., Wang, H. et al. Entropy production analysis for hump characteristics of a pump turbine model. Chin. J. Mech. Eng. 29, 803–812 (2016). https://doi.org/10.3901/CJME.2016.0414.052
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DOI: https://doi.org/10.3901/CJME.2016.0414.052