空腔危害水力机械稳定性理论Ⅲ——空腔对尾水管涡带压力脉动的影响和作用

Theory of cavitation bubbles conglomeration endangering stability of hydraulic machinery.Ⅲ.Effects on pressure fluctuations of vortex rope coming from cavitation bubbles conglomeration in draft tube

本文首先介绍了水轮机尾水管涡带压力脉动的研究现状及重要性,从涡旋流的特性入手分析了涡带空腔的产生机理及和转轮出口环量之间的关系,论证了涡带偏心距和蜗壳、固定导叶及尾水管之间的基本关系,并通过空腔尺寸的大小分析对原模型涡带压力脉动相似性进行了比较深入的探讨。

In this paper the state-of-art and significance of study on vortex rope pressure fluctuations in the draft tube of hydraulic turbine are discussed first. Then a basic relationship between vortex rope eccentric torque and flow passage components （including volute, stay vanes and draft tube） is demonstrated through an analysis on the vortex flow behaviors and the relationship between the mechanism of cavitation bubbles conglomeration in the vortex rope and the circulation at the runner outlet. Finally, through a comparison of the sizes of cavitation bubbles conglomeration, a more in-depth examination on similarity of vortex rope pressure fluctuations between prototype and model turbines is presented.