物理学报Issue(1)：014704-1-014704-15,15.DOI:10.7498/aps.65.014704
基于高速摄像实验的开放腔体圆柱壳入水空泡流动研究∗
An exp erimental study of water-entry cavitating flows of an end-closed cylindrical shell based on the high-sp eed imaging technology
摘要
Abstract
The objective of this present study is to address the cavitating flow patterns and regimes in the water-entry cavity. For this purpose, an experimental study of vertical water-entry cavity of an end-closed cylindrical shell is investigated by using high-speed video cameras and visualization technique. According to the cavitating flows as observed in the experiments, two flow pattern forms of fluctuation cavitation and cloud cavitation are found around the body. A further insight into the characteristics of the cavity shape and the variation in the cavity fluctuations parameters is gained by analyzing the image data. Furthermore, the experiments at different impact velocities are conducted to analyze the effects of impact velocity on the flow patterns and parameters. Finally, the formation mechanisms of cavitation fluctuations and cavitation clouds are studied based on the basic theory of fluid mechanics. The obtained results show that the cavitation flow pattern form of fluctuation cavitation occurs under the impact velocity condition of low speed, and the cloud cavitation occurs under the velocity condition of high speed. As fluctuation cavitation, the maximal extension diameters of cavitation fluctuate periodically along the water depth, and the speeds of extension and shrinkage are both proportional to the extension diameter. The collapses are different for the two flow pattern cavitations, i.e., the fluctuation cavitation, which is of deep closure and closed at the trough of wave cavitation more than once, and the cloud cavitation, which falls off and forms the leading edge of the cylindrical shell. The frequency fluctuation is independent of the impact velocity, the corresponding pinch-off time decreases with increasing the impact velocity, and the pinch-off time decreases in a nearly linear relation with Froude number. The water poured to the cylindrical shell causes the internal air to compress and expand, and as a consequence of these effects, periodic disturbances of pressure distribution and velocity field occur around the leading edge of the cylindrical shell, then the extended intensity of the cross section of the cavity shows variation in this process, which can be defined as fluctuation cavitation pattern. It appears that the re-entrant flow after the pinch-off at the trailing edge of cavity, then the laminar-turbulent transition is waken as a consequence of the re-entrant flow moving upstream, which flow pattern involved in this structure occurs as cloud cavitation.关键词
开放腔体圆柱壳/空泡波动/空泡云化/入水实验Key words
an end-closed cylindrical shell/fluctuation cavity/cloud cavity/water-entry experiment引用本文复制引用
路中磊,魏英杰,王聪,孙钊..基于高速摄像实验的开放腔体圆柱壳入水空泡流动研究∗[J].物理学报,2016,(1):014704-1-014704-15,15.基金项目
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)和中央高校基本科研业务费专项资金(批准号：HIT.NSRIF.201159)资助的课题.* Project supported by the Natural Science Foundation of Heilongjiang Province, China (Grant No. A201409), the Spe-cial Foundation for Harbin Science and Technology Innovation Talents of China (Grant No.2013RFLXJ007), and the Fundamental Research Funds for the Central Universities, China (Grant No. HIT. NSRIF.201159) （批准号:A201409）
