碳-酚醛材料烧蚀热解对再入流场特性影响的数值计算

数值模拟存在碳-酚醛材料烧蚀的高超声速再入流场,分析烧蚀和热解对流场热化学参数、电子数密度分布等的影响。采用19组元双温度的热化学模型,耦合热化学非平衡流Navier-Stokes方程组和烧蚀壁面边界条件,进行定常烧蚀流场求解;通过对比无烧蚀、非催化和辐射平衡壁温条件下的流场分析烧蚀的影响;讨论了壁面处碳-酚醛材料热解产物化学组成的确定方法,研究了不同热解率的影响。以RAM-C球锥的两个典型飞行条件(速度7.65km/s、高度61km和71km)为代表的研究表明:最主要的烧蚀热解产物是CO、H2、H,烧蚀产物和烧蚀的影响均局限于边界层内;烧蚀使原子和离子组元含量下降,当离子组元含量峰值出现在边界层内时,烧蚀使电子数密度峰值下降;随热解率增加烧蚀影响程度增强,烧蚀在后身区影响范围大于头部区,随飞行高度增加烧蚀影响范围扩大。

Numerical study for the effects of ablation andpyrolysis on the hypersonic reentry flow

Through solving the Navier-Stokes equations of thermochemical nonequilibrium flow coupled with the ablating boundary condition, the hypersonic flow over sphere-cone with ablation of heat shield made of carbon-carbon or carbon-phenolics is numerical simulated. 19 chemical species are considered in the flowfield calculation, and two-temperature model is taken to describe thermal nonequilibrium. The method to determine chemical composition of the pyrolysis-gas at the wall is discussed. Taking RAM-C at flight speed of 7.65km/s and altitude of 61km or 71km as examples, the flowfields without ablation, with ablation but without pyrolysis and with arbitrarily high rate of pyrolysis are calculated, the effects of ablation and pyrolysis on the thermochemical properties and electron densities of the flowfield in different flow zones under different flight conditions are analyzed.