Analysis of Pressure Fluctuations in a Prototype Pump-Turbine with Different Numbers of Runner Blades in Turbine Mode

In pump-turbines, high pressure fluctuation is one of the crucial instabilities, which is harmful to the stable and effective operation of the entire unit. Extensive studies have been carried out to investigate pressure fluctuations (amplitude and frequency) at specific locations. However, limited research was conducted on the distribution of pressure fluctuations in turbine mode in a pump-turbine, as well as the influence of the number of runner blades on pressure fluctuations. Hence, in this study, three dimensional numerical simulations were performed to predict the distribution of pressure fluctuations with different numbers of runner blades in a prototype pump-turbine in turbine mode using the shear stress transport (SST) k-ω turbulence model. Three operating points with the same hydraulic head and different mass flow rates were simulated. The distribution of pressure fluctuation components of blade passing frequency and its harmonics in the direction along the whole flow path, as well as along the circumferential direction, was presented. The mass flow rate and number of runner blades have great influence on the distribution of pressure fluctuations, especially at blade passing frequency along circumferential direction. The mass flow rate mainly affects the position of peak pressure fluctuations, while the number of runner blades mainly changes the number of peak pressure fluctuations. Additionally, the number of runner blades influences the dominant frequencies of pressure fluctuations especially in the spiral casing and draft tube.

[1]  Yulin Wu,et al.  Instability study of a pump-turbine at no load opening based on turbulence model , 2012 .

[2]  Christophe Nicolet,et al.  One-Dimensional Modeling of Rotor Stator Interaction in Francis Pump-Turbine , 2006 .

[4]  Zhengwei Wang,et al.  Numerical analysis of misaligned guide vanes effect pressure oscillations in a prototype pump turbine , 2013 .

[5]  P C Guo,et al.  3-D Simulation of a prototype pump-turbine during starting period in turbine model , 2013 .

[6]  Bernd Nennemann,et al.  CFD prediction of unsteady wicket gate-runner interaction in Francis turbines: A new standard hydraulic design procedure , 2005 .

[7]  Yuekun Sun,et al.  Pressure fluctuations in the vaneless space of High-head pump-turbines—A review , 2015 .

[8]  Daqing Qin,et al.  Mechanism of high amplitude low frequency fluctuations in a pump-turbine in pump mode , 2018, Renewable Energy.

[9]  Yulin Wu,et al.  S-shaped characteristics on the performance curves of pump-turbines in turbine mode – A review , 2016 .

[10]  Joaquin Fernandez-Francos,et al.  The Effect of the Operating Point on the Pressure Fluctuations at the Blade Passage Frequency in the Volute of a Centrifugal Pump , 2002 .

[11]  Daqing Qin,et al.  Entropy production analysis of hysteresis characteristic of a pump-turbine model , 2017 .

[12]  Jun Liu,et al.  Unsteady flow characteristics regarding hump instability in the first stage of a multistage pump-turbine in pump mode , 2018, Renewable Energy.

[13]  Leqin Wang,et al.  Three-dimensional flow simulation of transient power interruption process of a prototype pump-turbine at pump mode , 2013 .

[14]  Shouqi Yuan,et al.  Experimental Characterization of a Pump–Turbine in Pump Mode at Hump Instability Region , 2015 .

[15]  Jintao Liu,et al.  Distribution of Pressure Fluctuations in a Prototype Pump Turbine at Pump Mode , 2014 .

[16]  Yuning Zhang,et al.  A review of rotating stall in reversible pump turbine , 2017 .

[17]  Christophe Nicolet,et al.  Hydroacoustic Modeling of Rotor Stator Interaction in Francis Pump-Turbine , 2006 .

[18]  Leqin Wang,et al.  Pressure fluctuation propagation of a pump turbine at pump mode under low head condition , 2014 .

[19]  Bryan W. Karney,et al.  Three-dimensional transient simulation of a prototype pump-turbine during normal turbine shutdown , 2017 .

[20]  Li Deyou,et al.  Unsteady simulation and analysis for hump characteristics of a pump turbine model , 2015 .

[21]  Shuhong Liu,et al.  Flow-Induced Instabilities in Pump-Turbines in China , 2017 .

[22]  Deyou Li,et al.  Dynamic analysis on pressure fluctuation in vaneless region of a pump turbine , 2015 .

[23]  Daqing Qin,et al.  Numerical investigation on transient flow of a high head low specific speed pump-turbine in pump mode , 2015 .

[24]  Yuning Zhang,et al.  Experimental Study of Load Variations on Pressure Fluctuations in a Prototype Reversible Pump Turbine in Generating Mode , 2017 .

[25]  Xin Wang,et al.  Experimental study of the pressure fluctuations in a pump turbine at large partial flow conditions , 2012 .

[26]  Daqing Qin,et al.  Transient characteristics during the closure of guide vanes in a pump-turbine in pump mode , 2018 .