脉冲激光能量降低高超声速波阻机理研究

Study on Mechanism of Hypersonic Wave Drag Reduction with Pulsed Laser Energy

关键词:  激光  高重频  准静态波  高超声速  波阻

Key words:  Laser  High-frequency repetitive  Quasi-stationary wave  Hypersonic  Wave drag

摘要:

高超声速飞行器面临较高的波阻问题。为揭示基于脉冲激光能量沉积的减阻机理，并为激光减阻新方法提供科学指导依据，在马赫数为5.0的高超声速激波风洞内开展了单脉冲激光与弓形激波相互作用过程的实验研究。结合数值模拟结果，揭示了单脉冲激光的减阻机理。通过数值模拟研究了高重频激光与弓形激波相互作用的减阻机理。结果表明:在脉冲激光引致的激波与弓形激波相互作用的特定时刻，钝头体表面附近形成了低压低密度通道，这是钝头体阻力降低的原因。高重频激光引致的激波串可在高超声速流场中追赶合并形成锥形的准静态波，准静态波与弓形激波相互作用增大了弓形激波的脱体距离，弓形激波后压力和温度重新分布，形成相对稳定的流场结构，减阻率达到19%。

Abstract:

High wave drag is a problem of the hypersonic flight. Pulsed laser energy deposition is demonstrated to be a promising solution to wave drag reduction. The purpose of this paper is to study the mechanisms of this new method，and a scientific guidance will be provided. Firstly，single puled laser was adopted in a Ma=5.0 shock tunnel to investigate its interaction with shock wave. Numerical simulation was combined to reveal the mechanism of wave drag reduction. Secondly，the mechanism of wave drag reduction by high-frequency repetitive laser interact with bow shock was studied by numerical simulation. The results showed that at a certain time，a low density and pressure region was formed near blunt body during the interaction of laser-induced detonation wave with bow shock，which caused the drag reduction. Merging of detonation waves induced by high-frequency repetitive laser contributed to the formation of cone shaped quasi-stationary wave. Stand-off distance of bow shock increased due to its interaction with so called quasi-stationary wave，distributions of pressure and temperature were reformed，reducing the pressure near blunt body. A quasi-stationary flow filed was obtained. Wave drag decreased by 19%.