发动机喷流对飞行器底部流动影响数值模拟

针对发动机燃气喷流对底部流动的影响开展研究。建立冷喷与热喷计算方法，与经典的高压空气尾喷管喷流试验数据进行了对比，验证了本文建立的三维喷流方法的可靠性。对本文选用的飞行器外形采用冷喷与热喷方法开展了对比计算并与飞行试验值进行比较，分析了两种方法结果的差异。采用热喷方法对来流马赫数 2.5 ，不同飞行高度及喷管进口总压开展计算，研究飞行高度及喷管进口总压对发动机喷流及底部流场的影响。结果表明，保持飞行高度、来流马赫数不变，喷管进口总压增加，底部压力系数逐渐提高。燃气质量浓度最大值位于底部空腔的壁面处，且保持一个恒定值。保持喷管进口总压、来流马赫数不变，飞行高度增加，喷流高速区向后移动且中心区最大马赫数增加。在一定飞行高度下，底部压力系数由负转正，即飞行器底部会出现正推力，这对飞行器的射程会产生重要影响，需要提前评估。

Numerical Simulation of the Effect of Engine Jet on the Base Flow of Vehicle

The study on the effect of engine jet on base flow is performed and the method for both cold and hot jet is proposed. Compared with the experiment data of high-pressure nozzle jet, the computational results agree with it and the set of method is proved. The vehicle in this paper is computed by cold and hot jet method and the results on monitoring spot are compared with the flight data. The difference in results by two methods is analyzed. The hot jet method is utilized for Mach number at 2.5. The different flight altitudes and total pressures of nozzle inlet are chosen to be computed for exploring the effect on jet diffusion and base flow. The results show that with the increase of total pressure，the pressure coefficients on base swing up and the highest of the mass fraction of fuel gas lies on base wall and keeps a relative constant，and with the increase of flight altitude, the high-speed zone in jet moves downward and the max Mach number increases. In addition, at certain flight altitude, the pressure coefficient on base has changed to be positive from being negative, which will affect range of vehicle and should be assessed ahead.