【作者】 徐洪泉； 李铁友； 王万鹏； 廖翠林；

【Author】 XU Hong-quan;LI Tie-you;WANG Wan-peng;LIAO Cui-lin;China Institute of Water Resources and Hydropower Research;

【机构】 中国水利水电科学研究院；

【摘要】 本文首先论述了锯齿波在水力机械的压力脉动和振动波形中大量存在,说明了对其进行深入研究的必要性。然后分析了锯齿波压力脉动产生的两大可能原因,其一是涡带空腔及周围自由涡带来的压力速升速降或空化空腔快速收缩-膨胀带来的冲击,其二是大幅值压力波在传播过程中因密度变化而产生的波形畸变;而对于尾水管涡带压力脉动而言,其主要原因是前者。在对锯齿波压力脉动进行快速傅里叶分析时,会分析出与主频压力脉动频率呈整数倍关系的所谓倍频分量,其实是一种假象。更多还原

【Abstract】 This paper first discusses a large number of sawtooth waves in pressure fluctuation and vibration waveform of hydraulic machinery,and explains the necessity of in-depth study on such sawtooth waves,and then analyzes two major possible causes of sawtooth wave pressure fluctuation:the first one is rapid pressure rise and drop caused by vortex strip cavities and surrounding free vortex strips or impact caused by rapid shrinkage – expansion of cavitation cavities;the second one is waveform distortion of large-amplitude pressure waves caused by density fluctuation in the propagation process.For the vortex strip pressure fluctuation of draft tube,the former is the main cause.The so-called frequency multiplication component,which is in an integral multiple relation with the dominant-frequency pressure fluctuation frequency and obtained through fast Fourier analysis on sawtooth wave pressure fluctuation,is a false impression.更多还原