非设计工况下混流式水轮机尾水管压力脉动研究

Study on pressure fluctuation in Francis turbine draft tubes under off-design condition

本文对非设计工况下水轮机尾水管流动进行数值研究。通过求解雷诺时均N-S方程和DES(Detached Eddy Simulation)湍流方程,分析了尾水涡带的形态及其引起的压力脉动特性。研究结果表明,尾水涡带的长度、偏心距及转动方向与水轮机运行条件有关:锥管上游测点周期性压力脉动比较规律,压力脉动幅值基本相同且主频突出;锥管下游同一平面上的不同测点压力脉动的幅值差异较大,而且压力脉动的频率成分增多。

In this paper, numerical study on the flow of water turbine draft tube in off - design conditions is carried out. The shape of the draft tube vortex and pressure pulsation characteristics induced by the vortex are analyzed by solving the Renault N - S equation and the DES （ Detached Eddy Simulation） turbulence equation. T h e results show that the length, eccentricity and rotation direction of the draft tube vortex are related to the operating condi-tions of the turbine; the periodic pressure pulsation of the upper taper tube is relatively regulatory, amplitude of the pressure pulsation is basically the s a m e and the mai n frequency is prominent. W h i l e, the amplitude of the pressure fluctuation at the same level of the lower taper tube is rather different, and the frequency component of the pressure pulsation increases.