开放空腔壳体入水扰动流场结构及空泡失稳特征

发布时间：2018-03-26 06:29

本文选题：开放空腔壳体　切入点：扰动　出处：《物理学报》2017年06期

【摘要】：采用高速摄像实验和数值计算相结合的方法,对开放空腔壳体入水过程中空腔内气体涨缩对入水空泡的扰动机理和扰动作用下空泡局部失稳特征开展研究.基于实验观测结果,对比开放空腔和封闭空腔两种壳体入水空泡形态差异性,获得开放空腔壳体入水空泡波动特征,并根据能量守恒定律和能量转化关系,定性分析空腔自激扰动机理和扰动引起的空泡波动机理.基于数值计算结果,结合实验观测到的空泡阶段性局部失稳现象,定量分析空泡局部的结构性失稳特征和流动性失稳特征,并参照边界层理论和漩涡理论,揭示了空泡局部失稳机理.结果表明:入水冲击压缩空腔气体形成扰动源,对流场结构形成周期性扰动,导致空泡波动;撞水前空腔气体经冲击压缩密度升高,导致入水后气体首次膨胀阶段部分气体外泄,改变分离点流动,空泡局部结构失稳;空泡壁面流动具有类边界层流动特性,波动形态空泡形成多级回流现象,并逐级作用在空泡凹陷位置,使局部掺混区厚度增加,产生涡旋、转捩流动,空泡局部云化失稳;空泡逐级在波谷位置闭合、脱落,伴随大尺度漩涡生成,脱落过程形成拟序结构流场,漩涡导致脱落空泡迅速溃灭,但不会对附着空泡的流动产生影响.
[Abstract]:By using the method of high speed camera experiment and numerical calculation, the perturbation mechanism of gas inflation and shrinkage in open cavity shell and the local instability characteristics of cavitation under disturbance are studied, and the experimental results are based on the experimental results. Comparing the difference between open cavity and closed cavity, the fluctuating characteristics of open cavity shell entering water bubble are obtained, and according to the law of conservation of energy and the relation of energy transformation, The mechanism of cavity self-excited disturbance and the mechanism of cavitation fluctuation caused by perturbation are qualitatively analyzed. Based on the numerical results, combined with the experimental observation of the local instability of cavitation, The structural and fluidity instability characteristics of cavitation are quantitatively analyzed, and the mechanism of local instability of cavitation is revealed by referring to the boundary layer theory and vortex theory. The results show that the gas in the cavity compressed by water shock forms a disturbance source. The periodic disturbance of the structure of the flow field leads to the cavitation fluctuation, and the increase of the air pressure density before the water impingement results in the release of some gases during the first expansion stage of the gas after entering the water, which results in the instability of the local structure of the cavitation due to the change of the flow at the separation point. The cavitation wall flow has the characteristics of boundary layer flow, the fluctuating cavitation forms multi-stage backflow phenomenon, and it acts step by step in the cavitation depression, which increases the thickness of the local mixing zone, produces vortex, transition flow, and the local cloud instability of the cavitation. The cavitation gradually closes in the trough position, shedding, accompanied by large-scale vortex formation, the shedding process forms the flow field of the quasi-sequence structure, the vortex causes the exfoliated cavitation to collapse rapidly, but has no effect on the flow of the attached cavitation.
【作者单位】：哈尔滨工业大学航天学院;
【基金】：国家自然科学基金(批准号:11672094) 黑龙江省自然科学基金(批准号:A201409) 哈尔滨市科技创新人才研究专项基金(批准号:2013RFLXJ007)资助的课题~~
【分类号】：O35

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