摘要
本文在定义空泡、空腔并分析它们和常压气泡区别的基础上,探讨了组成空腔的空泡所具有的快速溃灭和生成之特性会进一步放大压力脉动的可能性,论述了水力机械气液两相流中空泡、空腔的低压及可压缩性带来的影响及其差别,分析了尾水管涡带空腔的组成,以空腔能否形成合力为突破口着重探讨了涡带空腔"连续"与"散碎"的区别及原因,并提出了"压力脉动可能会增强空蚀甚至使超空化转变为对流道边壁的空蚀"这一新见解。尽管当涡带空腔大部分和尾水管边壁接触时涡带的"削波"现象表面上使测试的压力脉动幅值减小,但其给稳定性带来的危害可能更大。
Definitions of cavitation bubbles and cavitation cavity are presented and their differences from normal air bubbles of atmospheric pressure are analyzed. Then the possibility of pressure fluctuations intensified by cavitation bubbles of rapid collapse and generation is discussed, and the effects of cavitation bubbles and cavitation cavity in air-water two-phase flows due to their lower pressure and compressibility and the resulting differences are demonstrated. Through an analysis on the composition of vortex rope cavitation cavity in turbine draft tube, based on whether or not a resultant force can be formed by cavitation cavity, the difference between ＂continuum＂ and ＂fragmentariness＂ of vortex rope cavitation cavity and a reason for this difference are discussed. We put forward a new view： pressure fluctuations can strengthen cavitation erosion and even change super-cavitation into a condition of cavitation erosion on flow passage wall. The measured amplitudes of pressure fluctuations are reduced ostensibly through a ＂clipping＂ phenomenon of vortex rope when most part of vortex rope cavitation cavity come in contact with draft tube wall, but such clipping would possibly endanger flow stability more severely.
出处
《水力发电学报》
EI
CSCD
北大核心
2014年第4期250-254,共5页
Journal of Hydroelectric Engineering
关键词
水力机械
气液两相流
空泡
空腔
压力脉动
稳定性
空蚀
hydraulic machinery
air-water two-phase flows
cavitation bubbles
cavitation cavity
pressure fluctuation
stability
cavitation erosion
