整流罩层流换热瞬时温升计算及其结构改进

针对热障效应问题，采用流固耦合法计算了球形整流罩的瞬时温升，并对其进行了结构改进。首先，根据风洞及火箭撬实验，结合熵层涡干扰势分析，给出判别球型整流罩换热状态的临界来流雷诺数为2.7106，并分析了Van Driest层流换热公式对大张角球面处的适用性；再以Van Driest换热系数为边界条件，利用有限元法进行球形整流罩瞬时温升计算，结果表明其温升较快，需合理轨迹规划以规避热障效应；针对高速长航时应用需求，利用多孔陶瓷材料的低热导率设计了新型复合整流罩，能有效延长制导系统飞行时间；复合整流罩还具有光学窗口处的气动热冲击应力小以及气动阻力小的优点，可应用于低空、高马赫数条件下的光学精确制导。

Calculation of transient temperature rise of dome under laminar heat transfer condition and improvement of dome structure

Aiming at the problem of thermal barrier effect, transient temperature rise of sphere dome was calculated by fluid-solid coupling method, and then the structure of dome was improved. Based on wind tunnel and rocket sled tests, as well as analysis of the potential of vorticity interaction in entropy layer, the critical Reynolds number based on the free stream parameters and the diameter of dome which could be used to judge the flowing state over sphere dome was proposed as 2.7106. Compared with the experimental data, the laminar heat transfer formula of Van Driest based on isentropic relations was found to be applicable for the calculation of heat transfer for the most area of hemisphere dome. Based on Van Driest's formula and finite element method, the heat transfer of dome was calculated to obtain the transient temperature field of sphere dome. The results show that temperature rise of dome is relatively fast and the trajectory should be well designed to avoid thermal barrier effect. For the requirement of high speed long-endurance system, a composite optical dome structure was designed based on porous ceramic, which could extend the flight time significantly and compared with side-window system, the aero-optic effects caused by the new composite dome was small. The new composite optical dome is suitable for long wave infrared optical systems. Thermal shock stress in composite optical dome is smaller, and because of conformal shape, the aerodynamic drag of composite optical dome is smaller also. Then the composite optical dome can be flexibly applied under the flight conditions of high mach number and low altitude.