激光引致激波演化数值研究

Numerical study on evolution of laser-induced shock wave

在高重复频率激光推进的研究中,激波的合并是发生在激波演化后期的,同时由于脉冲间隔短,脉冲宽度对流场演化的影响也需要详细研究。考虑了激光辐照过程对流场演化的影响,通过数值计算对激波演化特性进行了研究。结果表明,初期波阵面的椭球形状逐渐转化为一个球形,球心与击穿点的距离随时间逐渐减小并最终趋于稳定。基于激波合并的应用,当激波马赫数在1~2之间时,给出了激波波阵面半径随时间的变化规律,以及激波高压区长度和波峰压强随激波波阵面半径变化规律的经验公式。

Shock wave merging happens when the waves have damped,for repetitively pulsed laser irradiation induced waves.The influence of laser duration on the wave evolution becomes important as the laser pulse interval is small.Thus the evolution of the shock waves was numerically studied with laser incident process being taken into account.Results show that the shock wave front is ellipsoidal at the beginning,and then becomes spherical gradually.The distance from the sphere center to the breakdown point decreases gradually to a constant value.Based on the application of laser shock wave merging,shock waveradius,shock wave length,and overpressure as functions of time and shock wave front radius were derived at the Mach number from 1 to 2.