贯流式水轮机压力脉动及流场特性数值模拟

Numerical Simulation of Pressure Pulsation Characteristics and Flow of Shaft Tubular Hydro-power Turbines

鉴于目前国内关于竖井贯流式水轮机压力脉动方面的研究工作较少,以某水电站模型水轮机为对象,运用计算流体动力学(CFD)数值模拟,通过改变水轮机导叶和叶片安装角度,揭示导叶角度与叶片角度的变化对竖井贯流式水轮机能量特性的影响规律。通过采用"Second Order Backward Euler"法对水轮机进行非定常模拟,研究在额定工况、小流量及大流量工况下,竖井贯流式水轮机压力脉动变化特征。计算结果表明:随着导叶角度的增大,水轮机效率先减小后增大,但效率变化范围很小;叶片角度的改变对水轮机效率影响较大,在某一角度下,水轮机达到高效率点,并基本保持稳定。额定工况下,压力脉动从进水流道到转轮区,脉动频率基本稳定,出水流道的脉动频率会有所增加,且由尾水管部分产生的压力脉动由尾水管到转轮区、导叶区向前部传递。本文的研究工作为预测竖井贯流式水轮机能量及压力脉动特性提供参考。

As little domestic research on shaft tubular turbine pressure fluctuations has been done,special attention is paid to the effect of the vane angle and blade angle on the energy characteristics of shaft tubular turbine via numerical simulation of computational fluid dynamics（ CFD）,with a hydro-power station model turbine as the object. Based on＂Second Order Backward Euler＂method,our analysis is focused on the variation of pressure pulsation of shaft tubular turbine under unsteady small,rated and mass flow conditions. As a result,with the increase in the angle of the guide vane,the efficiency of the turbine decreases first and then increases,but the efficiency range is very small,while the change of the blade angle has a greater influence. At a certain angle,the turbine reaches an high and relatively stable efficiency level,accompanied by better flow characteristics. From the inlet to the turbine region,the pulsating frequency is roughly stable,while the pulsating frequency in outlet channel increases,and noting that the effect of pressure pulsation generated by the draft tube will expand to the turbine,guide vane region. The research will be a theoretical reference for predicting the energy and pressure pulsation behavior of shaft tubular turbine.