绕水翼云状空化流动特性的研究

采用高速全流场显示技术分别观测了绕超空化水翼和Clark-Y型水翼的云状空化.结果表明:绕超空化水翼和Clark-Y型水翼的云状空化具有相同的变化过程,即:生成、成长、膨胀、脱落和消失溃灭五种状态,两种空化云流动都具有明显的脱落周期和脱落轨迹.在翼型尾部存在的反方向射流,致使空化旋涡脱落;尽管模型尺度、来流速度和空化数基本相同,但由于超空化水翼与Clark-Y型水翼断面形状不同,使翼型尾部的反方向射流强度不同,故与来流相互作用强度不同,导致绕两种水翼的空化云脱落周期不同.在本文实验条件下,绕超空化水翼空化云和Clark-Y型水翼空化云的脱落频率分别为13.5 Hz和19 Hz.

EXPERIMENTAL STUDY OF CLOUDY CAVITATING FLOWS AROUND HYDROFOILS

The cloudy cavitating flows around a Supercavitation foil and a Clark-Y foil have been experimentally studied by means of high-speed fluid visualization. The purpose of this paper is to compare the configurations and the flow mechanism of the cloudy cavity around two kinds of foils. Based on the observation on the patterns of the cloud cavitations around two foils, it shows that the cloud cavitations of two kinds of foil have a distinctly quasi-periodic pattern, respectively. The development process of the cloudy flows consists of five phases, which are generation, growth, expansion, dispersion and vanishment sequentially. A re-entrant jet flow around the rear region of the hydrofoil is induced. Even though the model scale, mainstream velocity and cavitation number are similar for the two kinds of the foil section, the shedding frequency is different. The shedding frequencies of the Supercavitation foil and the Clark-Y foil are 13.5 Hz and 19 Hz in our experiments, respectively.