喷管构形对多脉冲激光推进冲量耦合系数的影响

Effects of the nozzle configuration on the impulse coupling coefficient for multi-pulsed laser propulsion

关键词:  激光推进  吸气式  多脉冲  喷管构型  冲量耦合系数

Key words:  Laser propulsion  Air-breathing  Multi-pulsed  Nozzle configuration  Impulse coupling coefficient

摘要:

多脉冲激光推进中,后续脉冲的推进性能受到之前激波流场的影响。为了获得喷管构型参数对多脉冲推进性能的影响规律,针对圆台形喷管构形,数值模拟了频率为20,50,100Hz时多脉冲流场演化过程,得到了喷管顶部直径和长度对多脉冲冲量耦合系数的影响规律。结果表明:多脉冲冲量耦合系数随着顶部直径的增加而增加；一定范围内增加喷管长度利于冲量耦合系数的提高,但喷管过长将不利于喷管内气体的恢复,多脉冲冲量耦合系数提高不明显；不同频率下顶部直径和长度对冲量耦合系数的影响规律基本一致。研究结果为多脉冲条件下喷管参数优化和实验参数选择提供参考。

Abstract:

The propulsion performance of the followed pulse are influenced by the flow field induced by the previous pulse in multi-pulse propulsion. Aimed at achieving the relationship between the parameters of the nozzle configuration and propulsion performance, a conical nozzle is chosen. The details of the evolution process of the inner and outer flow fluids are simulated at the laser repeated rates of 0,0, 100Hz. The effects of the diameter of nozzle front wall and nozzle length on the impulse coupling coefficient have been studied. The results indicate that the multi-pulse impulse coupling coefficient increases with an increase in diameter of the front wall. In the certain range, a longer nozzle leads to a higher impulse coupling coefficient. However, the lengthening nozzle needs long time to breathe in and recover the air. So the impulse coupling coefficient is not sensitive to the nozzle length when it is too long. The results are very useful for the nozzle structure design and the selection of the experiment parameters in the air-breathing laser propulsion.