绕水翼空化流场的数值模拟与试验研究

采用试验研究与数值模拟相结合的方法研究绕水翼ys930的非定常空化流场结构,试验采用高速数码拍摄技术观察在10°攻角下的片状和云状空化随时间的结构变化;数值模拟针对应用较多的RNG k-二方程湍流模型做适当修正,分析片状空化及云状空化时的非定常空化流场结构、流动特性及空泡演化过程。结果表明,数值模拟得到的水翼空化流动现象和试验观察到的结果基本一致,验证计算模型和数值方法的可靠性;在片状空化阶段,空泡长度变化不明显,空穴尾部边界存在小幅度波动,空穴总体相对比较稳定;云状空化阶段,空穴分为两部分:一部分为空泡主体,稳定地附着在水翼吸力面上,随时间推移逐渐长大,达到最大空泡长度后出现回缩;另一部分为空泡附体,为周期性非定常汽液两相运动区域。云状空泡的形成和发展过程均伴有压力的波动,在一个空泡生长周期内,压力面压力系数几乎不受空泡变化的影响,吸力面压力系数在空化数的负值附近小幅度波动。

Numerical and Experimental Study of Cavitating Flows around Hydrofoils

To study the cavitation mechanism in the cavitation flow field around a hydrofoil,by using high-speed degrees photography,the partial and cloud cavitation at an angle of attack of 10,and simulating with a corrected RNG k-ε turbulence model is observed.And the structure and evolution process of the sheet and cloud cavitation of unsteady cavitation flows is analyzed.The results show that there is little fluctuation near the boundary of the hydrofoil under the sheet cavitation.The cloud cavitation can be divided into two areas,the former part of main body,adhering to the hydrofoil of the suction surface stably,and its inner part is filled with water vapor.The second part of cavitation is vacuolus appendage and it is periodic and unsteady two-phase movement area.Development of cavitation is accompanied by pressure fluctuations.The pressure coefficient under the surface is hardly effected by cavitation,and the pressure coefficient at the surface have small fluctuations in nearby cavitation numbers.