振动激发对激波反射的影响

定常激波反射分为规则反射和马赫反射,在不同条件下2种反射结构之间会相互转变。高超声速流动中的激波反射问题常面临高温气体效应,随着温度逐渐升高,最先出现的是空气分子振动激发。通过理论分析和定量计算,研究了振动激发对激波反射及其转变规律的影响。首先给出考虑振动激发的空气热力学模型,并分析其与量热完全气体的差异以及对激波关系的影响;接着分析在规则反射和马赫反射中,振动激发对激波反射流场的影响规律;最后讨论振动激发对激波反射转变2个准则点的影响。研究结果表明,振动激发使激波极线的整体轮廓变大,且这种差异在经过一次激波反射之后被明显放大,会对激波反射的流场产生重大影响;对于激波反射的转变,振动激发使转变的2个准则点都变大,且对规则反射向马赫反射转变的脱体准则影响更大。

Effects of vibration excitation on shock reflections

Steady shock reflections include regular reflection and Mach reflection,which can transit to each other under critical conditions.High-temperature gas effect is inevitable in hypersonic shock reflections.As temperature increases,the vibration excitation of air molecules comes first.Theoretical analysis and quantitative calculation are conducted to study the effects of vibration excitation on shock reflections and the transitions between regular reflection and Mach refection.A thermodynamic model for air with vibration excitation is presented and then compared with the calorically perfect gas model.The influences of vibration excitation on shock relations,on the flow fields in regular reflection and Mach reflection,and on the transition criteria between them are analyzed.The results show that vibration excitation may enlarge the overall profile of the shock polar as compared with the shock polar in the calorically perfect gas.In addition,the difference in the overall polar profiles is amplified significantly for the reflected shock,and may alter the reflection configuration.Regarding the shock reflection transition criteria,vibration excitation may cause increases of both transition angles,i.e.,the detachment criterion and yon Neumann criterion,and the increment of the former is much larger than the latter.