非对称通气空泡多相流场特性研究

通气空泡的非对称介质分布将影响其水动力特性,继而影响空泡稳定控制,目前对其流动特性的认识较为局限。为揭示非对称通气空泡的流动机理,基于循环水洞实验及数值仿真开展了多相流场特性研究。结果表明:非对称流动导致空泡形成非对称沾湿区,依据流动介质的不同,非对称沾湿区可分为透明气相区、水气混合区及沾湿区。水气混合边界由底端母线向顶端母线发展过程中,滞止高压减小,空泡厚度增加,液体进入空泡内部方式从主要由轴向进入转化为主要由周向进入,同时水气混合物在来流作用下逐渐聚集,水气混合区面积随之增大。随着空泡闭合点逐渐靠近顶端母线,沿周向流动的液体层发展至顶端母线,顶端母线处则形成低速、高压、水气掺混区,湍流特性增强,并伴有大量细碎空泡涡的脱落。

Study on the Characteristics of Asymmetrical Ventilated Cavitating Flows

The asymmetric medium distribution of ventilated cavitating will affect their hydrody?namic force and then the cavitating stability control.In recent years,the understanding of the flow characteristics is relatively limited.The flow characteristics of asymmetric ventilated cavity is demon?strated by experimental and numerical methods.The results show that the asymmetric flow leads to the formation of asymmetric wet zone.On the basis of different flow media,asymmetric wetted region can be compartmentalized into transparent gas zone,water vapor mixing zone and wetted zone.As the boundary of water vapor mixing zone develops from incident flow axis to back flow axis,the relatively high pressure decreases,cavity thickness increases,the way that the liquid entering into the cavity is gradually transformed from the axial direction to the circumferential direction,and the area of water vapor mixing increases.In the water-gas mixture flow,with the liquid layer formed along the circum?ferential direction developing to the back flow axis,a low speed,high pressure and water vapor mix?ing area is formed at the back flow axis.Furthermore this area has enhanced turbulent characteristics accompanied by large shedding of cavitating vortex.