热力学效应对液氢非定常空化流动的影响

Effects of thermodynamic on unsteady cavitation flow of liquid hydrogen

为研究热力学效应对低温流体非定常空化流动的影响,以液氢为研究对象,采用大涡模拟计算了热力学和等温条件下液氢绕回转体的非定常空化流动。计算结果表明:热力学效应延长了液氢的空化周期,增强了空化的非定常特性,抑制了空化的发展。热力学条件下的空泡团内部包含更细、更小的气泡,呈现出多孔质特征,且使整个流域存在1.5K左右的温度波动。通过旋涡运动分析发现,热力学效应使旋涡结构由空穴交界面向空穴内部移动。基于涡量传输方程分析了热力学和等温条件下空穴和旋涡的交互作用,发现在热力学条件下,旋涡伸长项的作用位置主要位于空穴前端和尾端的交界面处,旋涡扩张项和斜压扭矩项主要位于空穴内部;在等温条件下,旋涡伸长项和旋涡扩张项主要位于空穴上方交界面处,斜压扭矩项主要位于空穴尾端。

In order to investigate the effects of thermodynamics on the unsteady cavitation flow of cryogenic fluid,the unsteady cavitation flow of the liquid-hydrogen around the Ogive body was studied by using the large eddy simulation under thermodynamics and isothermy.The results showed that the thermodynamics prolonged the cavitation period of liquid hydrogen,enhanced the unsteady characteristics and suppressed the cavitation.In addition,compared with isothermy,the cavitation in thermodynamics containd finer bubbles.A temperature depression about 1.5 Kwas detected because of thermodynamics.Besides,the vortex structure moved from the cavity interface to the inner of the cavity due to the thermodynamics.The interaction between cavitation and vortex structure was also studied based on the vorticity transfer equation under thermodynamics and isothermy.In thermodynamics,the vortex stretching term is mainly located at the front and the end of the cavity,and the vortex dilation term and baroclinic torque term are mainly located inside the cavity.In isothermy,the vortex stretching term and vortex dilation term are mainly located at the interface of cavity,and the baroclinic torque term is located at the end of cavity.