间隙空化对贯流式水轮机压力脉动特性的影响

许多贯流式水电站机组振动严重、噪声大，部分电站难以正常运行。目前的贯流式水轮机稳定性研究多侧重于转速频率和涡带频率，对高倍转速频率压力脉动危害性及其成因关注较少。本文将空腔危害水力机械稳定性理论应用于灯泡贯流式水轮机间隙空化研究，采用理论分析和原、模型试验验证相结合的方法，论证分析了间隙空化和高倍转速频率压力脉动的联系。本文介绍了贯流式水轮机原、模型尾水管压力脉动和真机振动的频率特性及工况条件，指出其产生原因是转轮叶片或导叶端面间隙空化，证明1倍、2倍或3倍叶片通过频率压力脉动产生于叶片内、外侧端面间隙空化，导叶通过频率压力脉动来自于导叶端面间隙空化。

Effect of clearance cavitation on pressure pulsation characteristics of bulb turbine

Severe vibration and noise of bulb turbines at hydropower stations is the main cause of unstable operation.Up to the present,the previous research of bulb turbine stability has focused on rotational frequency and vortex frequency rather than the harm of high power rotational frequency pressure pulsations and their causes.In this paper,the theory of destructive effect of cavitation on hydraulic mechanical stability is applied to study clearance cavitation in bulb turbines,and the relationship between clearance cavitation and such pressure pulsations is demonstrated and analyzed by combining theoretical analysis with prototype and model test verification.This paper describes the pressure pulsations in the draft tubes of model and prototype bulb turbines,along with the vibration frequency characteristics and working conditions in prototype;and points out that the cause for the high power rotational frequency pressure pulsations is the occurrence of cavitation at runner blade tip clearances and guide vane tip clearances.This study proves that the blades passing frequency pressure pulsations and their second and third harmonics are induced by the clearance cavitation between the blade tips and the discharge ring or runner hub,and the guide vanes passing frequency pressure pulsations induced by the guide vane tip clearance cavitation.