来流对吸气式激光推力器冲量耦合系数的影响

Effect of inflow on impulse coupling coefficient of air-breathing lightcraft

针对大气吸气模式激光推进的原理,采用二阶精度的Roe格式,在气体模型为完全气体时,分别对无来流以及来流马赫数为2.5和5的条件下,环聚焦激光推力器内外流场的演化过程进行了数值模拟。结果表明,无来流、来流马赫数为2.5和5时的冲量耦合系数分别为2.42×10-4N.s/J,1.00×10-4N.s/J和1.13×10-4N.s/J,无来流时激光推力器的冲量耦合系数高于同工况下有来流的情况,但来流马赫数为5时由于激波不会传播到推力器前体而产生负推力,因此冲量耦合系数较马赫数为2.5时高。研究结果可为激光推力器的构形设计以及实验模拟高空环境下推力器的飞行情况提供一定的理论指导。

Aimed at understanding the mechanism of air-breathing laser propulsion, with the Roe scheme of 2nd-order accuracy and perfect gas model adopted, the evolutive process of inner and outer fluid field of circular focusing laser lightcraft is simulated numerically with different inflow conditions. The results for the impulse coupling coefficients are obtained under the different conditions. It is obvious that the impulse coupling coefficient under the condition without inflow is higher than the one under the condition when inflow exits. However, when the inflow Mach number is 5, since shock wave cannot propagate to the front body of lightcraft and negative thrust cannot come into being, the impulse coupling coefficient is higher than that of Mach number 2.5. The results may provide some theoretical guidance for configuration design of laser lightcraft and experiments of lightcraft flight at high attitude.