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为了研究喷管结构形式对两级PDE性能的影响及作用规律,以氢气和空气混合物为例,采用FLUENT软件中的k-ε湍流模型,使用非平衡壁面函数、PISO算法及基于梯度的动态自适应网格加密方法,对收敛、扩张、收扩等不同喷管结构形式的凹面腔内环形向心射流聚心碰撞产生激波会聚起爆爆震波的过程进行了数值模拟,并对两级脉冲爆震发动机产生的推力和冲量进行了计算。通过对不同时间点凹面腔产生的推力和冲量、喷管产生的推力和冲量、两级PDE总的推力和冲量三者之间的对比和分析,发现凹面腔产生的推力和冲量是两级PDE总的推力和冲量的主要来源,不同喷管结构形式对两级PDE推力和冲量性能的影响有较大的差别。以冲量为例,收敛喷管可以提高凹面腔的冲量,但是由于自身同时产生过多负的喷管冲量,因而总冲量较小;扩张喷管虽然对凹面腔冲量的提高作用不大,但是由于其自身可以提供正的喷管冲量,所以总冲量较大;收扩喷管的收敛段也可以较小幅度的提高凹面腔冲量,但同时产生的负喷管冲量会和扩张段产生的正喷管冲量发生抵消,使总的喷管冲量比较低,发动机总冲量也较小。综合考虑各方面因素,扩张喷管性能最优。可见在两级PDE喷管结构形式的选择上,要同时考虑凹面腔冲量和喷管冲量,权衡两者,才能选择出合适的喷管。
In order to study the influence of nozzle structure on the performance of two-stage PDE and the law of action, taking the mixture of hydrogen and air as an example, the k-ε turbulence model in FLUENT software was used. The unbalanced wall function, PISO algorithm and gradient- According to the method of grid encryption, the process of convergent, expansion, expansion and contraction of the detonation wave of convergent and detonating waves in a concavo-convex annular cavity centripetal jet with different nozzle structures is numerically simulated. The thrust and impulse generated by the shock engine were calculated. By comparing the thrust and impulse generated by the concave cavity at different time points, the thrust and impulse generated by the nozzle, the total thrust and impulse of the two-stage PDE, it is found that the thrust and impulse generated by the concave cavity are two-stage PDE The main source of the total thrust and impulse, different nozzle structure on the two-stage PDE thrust and impulse performance are quite different. Taking the impulse as an example, the convergent nozzle can improve the impulse of the concave cavity, but the total impulse is small due to too much negative impulse at the same time. Although the expansion nozzle has little effect on the impulse of the concave cavity, Its own can provide a positive nozzle impulse, so the total impulse larger; convergent section of the expansion and contraction of the nozzle can also be a small margin to increase the concave cavity impulse, but at the same time the negative nozzle impulse and expansion of the positive section of the spray The offset of the tube offset cancels the overall jet impulse and the total engine impulse is small. Comprehensive consideration of various factors, the expansion of the best nozzle. Can be seen in the choice of two-stage PDE nozzle structure, to take into account the concave cavity impulse and nozzle impulse, weighing the two, in order to select a suitable nozzle.