水泵水轮机无叶区压力脉动产生机理研究

抽水蓄能电站厂房振动问题是影响电站及电网安全稳定运行的关键技术难题。本文首先介绍了水泵水轮机无叶区压力脉动的幅值和频率特性,总结出无叶区压力脉动幅值大于其它位置、水轮机工况无叶区压力脉动幅值大于水泵工况、水泵水轮机水轮机工况大于常规混流式水轮机等规律性特征,指出了无叶区压力脉动的主频为叶片通过频率。其次,本文应用自由涡环量等于常数原理,通过对水泵水轮机水轮机最优工况远离运行区、水轮机工况转轮叶片进口速度三角形、飞逸转速工况压力脉动幅值最大等问题的深入分析,提出了水泵水轮机水轮机工况无叶区高幅值压力脉动源自于转轮叶片进水边正面脱流产生的自由涡这一机理性认识。

Study on generating mechanism of pressure fluctuation in the vaneless region of the pump-turbine

The powerhouse vibration of pumped storage power station is a critical technical challenge, which influences the safe and stable operation of powerhouse and grids. This paper first describes the amplitude and frequency characteristics of pressure fluctuation in the vaneless region of pump-turbine, drawing conclusions that the amplitude of pressure fluctuation in the vaneless region is higher than other regions, the amplitude of pressure fluctuation in the vaneless region under turbine mode is higher than that under pump mode and the amplitude of pump-turbine under turbine mode is higher than that of normal Francis turbine. It states that the main frequency of pressure fluctuation in the vaneless region is blade passing frequency. Secondly, by using the theory of free vortex, the paper presents the cognition that high amplitude pressure fluctuation in the vaneless region of pump-turbine under turbine mode originates from free vortex separating from front inlet edge of the runner blades based on the in-depth analysis on turbine optimum condition of pump-turbine away from operating area, inlet velocity triangle of runner blades under turbine mode and the amplitudes of pressure fluctuation reaching maximum under runaway speed condition.