模型可逆式水泵水轮机S区压力脉动测试

S-shape Region Pressure Pulsation Measurement of Model Reversible Pump-Turbine

S区特性是影响可逆式水泵水轮机过渡过程工况运行稳定的重要影响因素,通过研究模型水泵水轮机S区压力脉动可以为准确预测真机过渡过程工况下的特性奠定基础,为设计和运行提供有效指导。本文在某模型水泵水轮机特性试验的基础上,对S区包括蜗壳进口、无叶区、尾水锥管和尾水肘管等测点的压力脉动进行了测试,获得了各测点压力脉动混频幅值的分布与频率成分变化情况。测试结果表明:在等开度线上,飞逸工况时各测点的压力脉动混频幅值达到最大;同一工况点,无叶区压力脉动大于蜗壳进口压力脉动;沿流道方向,无叶区、锥管0.4D2、锥管1.0D2和肘管压力脉动依次减小;S区部分工况点存在主频为0.63fR的旋转失速频率;0.18fR频率成分广泛分布于S区内各工况点和测点中,引起这方面的原因可能是尾水管中的低频涡带、低频振荡或装置固有频率。

The characteristics of S-shape region are one of the most important factors that influence stable operation of reversible pump-turbines in transient processes.The research on pressure pulsation of S-shape region of the model pump-turbines can lay a foundation for accurate predication of the characteristics of the prototype pump-turbine in the transient processes and provide effective guidance for design and operation of pump-turbines.In this paper,based on the characteristic test of a model pump-turbine,the pressure pulsations at measuring points of S-shape,including volute inlet,vaneless zone,cone tube and elbow tube,etc.were measured,and the distribution of frequency mixing amplitudes of pressure pulsations at measuring points and changes in frequency components were obtained.The test results show that for identical guide vane opening,the frequency mixing amplitude value of pressure pulsation at each measuring point under runaway operating conditions reaches maximum value.For the same operating point,the pressure pulsation in vaneless zone is bigger than that in volute inlet;the pressure pulsations in vaneless zone,cone tube 0.4D2,cone tube 1.0D2 and elbow tube decrease sequentially along the flow passage.At some specified operating points in S-shape region,there exists the rotating stall frequency of 0.63fR.Frequency component of 0.18f R is widely distributed at all operating points and measuring points of S-shape region and this component may be induced by the low frequency vortex strip and low frequency oscillation in draft tube or inherent frequency of the test rig.