绕水翼超空化阶段汽液混合体动态特性的实验观测

为深入了解超空化流动机理,采用高速录像和数字粒子图像测速系统( DPIV)对绕hydronautics水翼的超空化流场进行了观测.结果表明:在两相共存超空化阶段,水汽混合相和汽相的分布决定了超空化区域速度场和涡量场的分布特性;水汽混合区的速度相对较低,而汽相区则与主流区有着相近的速度分布,而且空化区与主流区交界面处有着较大的速度梯度;在水汽混合区与主流区的交界处形成了上下涡带,其涡量分布表现出了明显的时间依赖性.

Experimental measurements on the characteristics of water-vapor mixture in supercavitating flows around a hydrofoil

The patterns of supercavitating flows around a hydronautics foil have been observed by means of a high-speed video camera and the digital particle image velocimetry(DPIV).The results show that the cavitation structure depends on the interaction of the water-vapor mixture phase and the vapor phase.Several features are obtained at the two-phase coexisting stage.Firstly,the velocity in the vapor region approaches the free stream level,while it is noticeably lower in the two-phase mixture region,and a large velocity gradient exists around the interface between the cavitation area and the free stream.Secondly,the upper and lower vortex bands form near the interface between the water-vapor mixture region and the free stream,and distinct time-resolved characteristics of the vorticity distribution are observed.