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当火箭模式激光推进器在高空稀薄大气中飞行时,需要在激光聚焦区附近喷射稠密气体工质,从而利用激光聚焦击穿气体工质形成等离子体,为光船提供推力。为了分析该光船的推力产生过程,采用连续流体力学计算方法(CFD)和直接数值模拟蒙特卡洛方法(DSMC)耦合的混合算法,数值模拟飞行高度为80 km飞行马赫数为5的激光光船周围高温连续气体和稀薄环境大气耦合的非定常混合流场,并得到推力随时间的演化曲线。结果表明,稀薄效应明显增加了激波厚度,高温效应延迟了推力的产生,并导致冲量耦合系数和比冲的降低。
When a rocket-mode laser projectile is flown in a high-altitude, thin atmosphere, a dense gas working medium needs to be jetted near the laser focusing zone so that the laser is used to focus the breakdown gas on the plasma to provide a thrust for the bareboarder. In order to analyze the thrust generation process of the light craft, a hybrid algorithm of continuous fluid dynamics (CFD) and direct numerical simulation Monte Carlo (DSMC) coupling was used to numerically simulate laser light with flight altitude of 80 km and Mach number of 5 Unsteady mixing flow field coupled with the continuous high-temperature gas around the ship and the atmosphere of thin environment, and the evolution curve of thrust with time is obtained. The results show that the levitation effect obviously increases the thickness of the shock wave, and the high temperature effect delays the generation of the thrust force, resulting in the reduction of impulse coupling coefficient and specific impulse.