云状空化的非定常流体动力特性

发布时间：2018-04-03 10:45

本文选题：云状空化　切入点：流体动力　出处：《船舶力学》2016年Z1期

【摘要】：基于高速全流场显示和动态压力测量技术,实现了非定常空化空穴形态和壁面压力的同步测量。采用该方法,同步观察和测量了收缩—扩张流道内云状空化形态的准周期性变化及其对应的壁面压力波动特性,分析了压力信号频谱,讨论了非定常空穴形态变化和壁面压力波动的关系。结果表明:扩张段内云状空穴的发展过程呈现出附着型空穴生长,附着型空穴断裂、脱落以及脱落型空穴聚合、生长、溃灭的准周期过程。壁面压力波动的主导频率约为21 Hz,对应附着型空穴的准周期生长、断裂和大尺度脱落型空穴生长、溃灭;次级频率约为42Hz,对应小尺度脱落型空穴非定常变化。同时发现空穴变化和压力波动存在如下关系:在附着型空穴的生长阶段,其空穴前部稳定附着区域的压力波动较小,其尾部非稳定区域的压力波动较大;当附着型空穴发展至最大长度时,其尾部空泡的非定常波动会使得相应区域压力波动更加剧烈。伴随着反向射流的发展,附着型空穴断裂、脱落产生许多小尺度脱落型空穴,其生长、溃灭等非定常变化会使得相应区域的压力波动变得复杂。小尺度脱落型空穴逐渐聚合、生长形成单一的大尺度脱落型空穴,伴随着其不断的向下游移动,相关区域被其覆盖时压力波动减小,脱离其覆盖或者经历其溃灭过程时压力波动显著增大。
[Abstract]:Based on high speed full flow field display and dynamic pressure measurement, the unsteady cavitation cavity shape and wall pressure are measured synchronously.By using this method, the quasi-periodic variation of cloud cavitation and its corresponding wall pressure fluctuation characteristics in the contract-expansion channel are observed and measured synchronously. The pressure signal spectrum is analyzed.The relationship between unsteady cavity morphology and wall pressure fluctuation is discussed.The results show that the development process of cloud holes in the expansion section shows a quasi-periodic process of attachment hole growth, adherent hole fracture, shedding and abscission hole aggregation, growth and collapse.The dominant frequency of the wall pressure fluctuation is about 21 Hz, which corresponds to the quasi-periodic growth of the attached hole, the growth and collapse of the fracture and the large scale shedding hole, and the secondary frequency is about 42 Hz, corresponding to the unsteady variation of the small scale shedding hole.At the same time, the relationship between hole variation and pressure fluctuation is found as follows: in the growth stage of the attached hole, the pressure fluctuation of the stable attachment region in the front part of the hole is small, and the pressure fluctuation in the unstable region of the tail hole is larger;When the attached cavity reaches the maximum length, the unsteady fluctuation of the tail cavitation will make the pressure fluctuation in the corresponding region more intense.With the development of the reverse jet, the attached hole breaks and the shedding produces a lot of small scale shedding holes. The unsteady changes such as growth and collapse will make the pressure fluctuation in the corresponding region more complicated.The small scale shedding holes gradually converge and grow into a single large scale shedding hole. Along with its continuous movement downstream the pressure fluctuation decreases when the relevant area is covered by it.The pressure fluctuation increases significantly when it is removed from its coverage or experienced its collapse process.
【作者单位】：北京理工大学机械与车辆学院;
【基金】：国家自然科学基金项目(51209004);国家自然科学基金项目(11172040)
【分类号】：O35

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