单脉冲能量对吸气式激光推进冲量耦合系数的影响
Effects of single pulse energy on impulse coupling coefficient in air-breathing laser propulsion
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摘要: 利用透镜聚焦，抛物面喷管约束，结合复摆和光指针测量系统研究了单脉冲能量对吸气式激光推进冲量耦合系数的影响，实验中通过调节激光器工作电压和硅片衰减实现了脉冲能量5~70 J范围的有效拓展；进一步采用纳秒分幅高速相机拍摄了24 J能量下的流场纹影照片。结果表明：在4~9 J低能量和32~70 J较高能量区间，冲量耦合系数均较稳定；9~32 J能量下冲量耦合系数呈线性增长趋势，变化范围(6.5~21.0)×10-5 N·s·J-1；纹影照片显示流场演化经历了激光支持爆轰波、爆燃波和激波3个阶段，耦合系数的变化规律源于不同单脉冲能量对应不同的能量沉积效率。Abstract: A lens and a paraboloid nozzle were used to focus pulsed CO2 laser and generate impulse. Effects of single pulse energy on impulse coupling coefficient was studied with a highaccuracy compound pendulum and a light figure system. Extension range of pulse energy from 5 J to 70 J was obtained through adjusting working voltage of the laser and energy attenuation of silicon combinations in the experiment. In addition, schlieren photographs were taken by a nanosecond framed high speed camera at the pulse energy of 24 J. The results indicate that the impulse coupling coefficient kept constant when pulse energy ranged from 4 J to 9 J and from 32 J to 70 J respectively. From 9 J to 32 J, it changed between 6.5 and 21×10-5 N·s·J-1 following a linear increment. The schlieren photographs show tha
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Key words:
- laser propulsion /
- pulse energy /
- impulse coupling coefficient /
- compound pendulum /
- light figure
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