水蒸气跨声速流动中非平衡相变与激波的耦合作用

Coupling Effect of Shock and Non-Equilibrium Phase Change of Transonic Steam flow

引入水蒸气非平衡相变的动力学模型和水蒸气真实物性模型,建立了水蒸气跨声速非平衡流动的守恒型数值计算模型,采用Roe-FDS计算格式数值捕捉了水蒸气超声速流动中的非平衡相变与激波效应,在此基础上开展了气动激波与凝结激波的耦合计算,分析了气动激波波锋面与凝结激波波锋面相遇时,气动激波与非平衡相变之间的相互作用规律。研究显示,随着背压的不断升高,气动压缩激波不断向喷管喉口位置推移。当气动激波发生在凝结激波的下游位置时,气动激波的耗散效应使得喷管内的液相质量分数逐渐减小而不会对上游的非平衡相变和凝结激波产生影响。当气动激波随背压继续上行与气动激波交汇时,气动激波强烈的耗散效应使得凝结激波特征迅速减弱,非平衡相变逐渐退化到喷管边界区域,而气动激波由于受到凝结激波的强烈干扰,激波强度迅速减弱,显现出明显的斜弱激波特征.当气动激波上行至喷管喉口附近时,X型凝结激波逐渐消退,非平衡相变在喷管主流区消失。

In the present study,a conservative compressible numerical model coupling with dynamic model for non-equilibrium phase change and Virial Equations of steam,is developed and used to predict the non-equilibrium phase change and shock effect in the transonic steam flow.In order to capture the transient characteristics of the supersonic flow and the condensation shock effect,the improved high resolution Roe-FDS scheme is used.Based on the simulation,the coupling effect of the non-equilibrium phase change and aerodynamic shock is researched when the condensation shock and the normal aerodynamic shock meet.It is shown that,with the back pressure increases,the normal aerodynamic shock will move toward the nozzle throat.When the location of the aerodynamic shock locates at downstream of the condensation shock,the wetness fraction will decrease because of the energy dissipation of shock.But the downstream aerodynamic shock would not affect the non-equilibrium phase change and the condensation shock.With the aerodynamic shock moving, when the condensation shock and the aerodynamic shock meet,the energy dissipation of shock makes the condensation weaken obviously.And the non-equilibrium phase change fades rapidly to the boundary region.The aerodynamic shock will weaken obviously at the same time.With the aerodynamic shock moving to the throat,the non-equilibrium condensation even not occurs at all in the main flow region of the nozzle.