液力透平非定常压力脉动的数值计算与分析

液力透平内部流场的非定常压力脉动是影响机组运行稳定性的关键因素之一,为了研究液力透平内部压力脉动,采用流场分析软件CFX对液力透平内部流场进行了三维非定常数值模拟,通过设置监测点,得到了不同位置处的压力脉动结果,并对压力脉动进行了频域分析。结果表明,液力透平内部压力沿着流道逐渐减弱;蜗壳环形部分入口位置和割舍处压力脉动较小,割舍前端和蜗壳中部位置处压力脉动较大,压力脉动主频为转频的2倍;叶轮内部的压力脉动在液力透平各过流部件的脉动中最为强烈,最大压力脉动发生在叶轮中间位置,压力脉动主频为叶频的2倍;尾水管内的压力脉动沿着尾水管流道逐渐减弱,压力脉动主频与蜗壳内部的压力脉动主频相同,为转频的2倍。

Simulation and analysis of unsteady pressure fluctuation in hydraulic turbine

Pressure pulsation of internal flow field within pump as turbine is one of the major factors affecting the stability of turbine unit. To research the unsteady pressure field in pump as turbine, computational fluid dynamics software CFX was adopted in the unsteady flow field analysis. Pressure pulsation results at various monitoring points were acquired and frequency analyses were performed based on these results. Results show that the pressure value decreases along the flow channel of hydraulic turbine. The pressure pulsations at volute cut water and the inlet of volute spiral development part are small. The main frequency of pressure pulsation in volute is two times of the impeller rotational frequency. The most intensive pressure pulsation of hydraulic part in hydraulic turbine is impeller and the most intensive location happens at the middle of impeller passage. The main frequency of impeller pressure pulsation is two times of the blade passing frequency. The pressure pulsation in outlet pipe gradually decreases along the pipe, and its main frequency of pressure pulsation is two times of the impeller rotational frequency.