运载高空发动机喷流热环境分析及飞行验证

Numerical Simulation and Flight Test Validation of a Launch Vehicle Altitude Engine Exhaust Plume Base Heating

为研究某运载火箭高空末子级发动机工作时对底部热环境的影响,对发动机底部喷流流场的Kn、温度、压力、速度分布进行数值建模分析,研究了贮箱、伺服机构、筒段等给定位置处的热流分布。结果表明在喷流主流区域Kn非常小,可视作连续介质流;高空状态下受外界低气压的影响,喷流迅速扩散,喷流压力和温度快速下降,形成的对流热流密度较小。用反向蒙特卡罗(RMC)法模型,根据HITRAN数据库计算气体红外辐射特性,获得辐射热流,结合喷管固体辐射,形成对给定位置的总热流。热流分析结果与运载火箭飞行试验结果吻合较好,一般误差小于10%,最大误差25%,满足工程研制需求。

In order to investigate the base heating environments of altitude engine exhaust plume,the exhaust plume flow fields of Kn,temperature,pressure and velocity,and the heat flux on stores,servo mechanism and wainscot were calculated in this paper.The flow field showed that the Kn of flow was small enough to regard as the continuum flow according to influence of altitude environment.The low environment pressure led to high velocity,low temperature and pressure of exhaust plume.The convective heat flux in the base region of the rocket engine was numerical simulated using Fluent software.The model using reverse Monte Carlo method was developed,and the infrared radiation characteristic of the plume gas was computed using HITRAN database to obtain the radiation heat flux in the same region.The total heat flux was obtained by adding the two fluxes.The total flux was measured with flight test of a launch vehicle.The results showed that the numerical results were in good agreement with the test,the difference of most points was about 10% and the max difference was about 25%,which could be accepted by engineering design.