Instability analysis of a model pump-turbine in vaneless space with different openings of guide vanes

27th IAHR Symposium on Hydraulic Machinery and Systems

Liu, J.^1 ; Liu, S.^2 ; Zuo, Z.^2 ; Wu, Y.^2

Beijing Institute of Control Engineering, China Aerospace and Technology Corporation, Beijing

100190, China^1

State Key Laboratory of Hydroscience and Engineering, Tsinghua University, Beijing

100084, China^2

关键词: Difference schemes;    Instability analysis;    Non-linear methods;    Partially averaged navier stokes;    Pressure fluctuation;    Pump-turbines;    RANS turbulence models;    Simulating flows;   

Others  :  https://iopscience.iop.org/article/10.1088/1755-1315/22/3/032047/pdf
DOI  :  10.1088/1755-1315/22/3/032047

来源: IOP

【 摘 要 】

Pump-turbines were always running at partial condition with the power grid changing. Flow separations and stall phenomena were obvious in the pump-turbine. Most of the RANS turbulence models solved the shear stress by linear difference scheme and they were isotropous, so they couldn't capture all kinds of vortexes in the pump-turbine well. At present, Partially-Averaged Navier-Stokes (PANS) has been found better than LES in simulating flow regions especially those with poor near-wall resolution. In this paper, a new nonlinear PANS turbulence model was proposed, which was modified from RNG k-∈ turbulence model and the shear stresses were solved by Ehrhard's nonlinear methods. The nonlinear PANS model was used to study the instability of «S» region of a model pump-turbine with misaligned guide vanes (MGV). The opening of pre-opened guide vanes had great influence on the «S» characteristics. Pressure fluctuations in the vaneless space for different opening of pre-opened guide vanes were analyzed. It is found that the «S» characteristics and instability can be improved when the relative pre-opening of MGV is 50%.