Influence of cavitation on hump characteristics in a pump-turbine model

29th IAHR Symposium on Hydraulic Machinery and Systems

Li, D.Y.^1 ; Lin, S.^1 ; Wang, H.J.^1 ; Fu, W.W.^1 ; Chen, J.X.^1 ; Wei, X.Z.^1^2 ; Qin, D.Q.^1^2

School of Energy Science and Engineering, Harbin Institute of Technology, Harbin

150001, China^1

State Key Laboratory of Hydro-Power Equipment, Harbin Institute of Large Electrical Machinery, Harbin

150040, China^2

关键词: Characteristic frequencies;    Guide vane openings;    Hump characteristic;    Low frequency pressure;    Performance characteristics;    Pressure fluctuation;    Pump-turbines;    Specific speed;   

Others  :  https://iopscience.iop.org/article/10.1088/1755-1315/240/7/072031/pdf
DOI  :  10.1088/1755-1315/240/7/072031

来源: IOP

【 摘 要 】

The hump characteristic in pump mode is one of unique instabilities in pump-turbines. Recently, it is found that the cavitation has a large influence on hump characteristic. Hence, in this paper, a specific speed (n q=36.1) pump-turbine model was investigated experimentally in pump mode under different guide vane openings to verify the influence of cavitation on hump characteristic. Firstly, performance characteristic experiments were carried out to obtain the hump characteristics under three cavitation coefficients. The influence of cavitation on hump characteristics was analysed. Then, observation of cavitation at the runner inlet was conducted using the high speed camera. The cavitation at the runner inlet was presented. Finally, pressure fluctuation experiments were performed to analyse the characteristic frequencies and their variation with the cavitation coefficient. Through the analysis of pressure fluctuations, the hump characteristic is related to the low frequency pressure fluctuations, Analysis reveals that the strength of cavitation at the runner inlet has an obvious influence on low frequency pressure fluctuations, which leads to the change of the hump characteristic.