抛物形喷管的激光推进能量相似律数值研究

Numerical simulation of energy law of similitude of parabolic nozzles for laser propulsion

关键词:  激光推进  吸气式  抛物形喷管  相似律  冲量耦合系数

Key words:  Laser propulsion  Air-breathing mode  Parabolic nozzles  Law of similitude  Impulse coupling coefficient

摘要:

针对吸气式抛物形喷管,通过辐射输运方程和流体力学方程联立求解,计算激光能量沉积过程中的爆轰波流场,并采用高温平衡气体模型计算后续的激波流场,得到了不同构形的喷管在不同条件下的冲量和冲量耦合系数。提炼了耦合多种影响因素的无量纲因子,讨论了入射激光能量和喷管构形对推进性能参数的影响,建立了抛物形喷管激光推进的能量相似律。结果表明:当顶点到出口最外侧点连线和对称轴的夹角固定时,冲量和冲量耦合系数随无量纲因子先增大后减小,在0.37附近取得极大值;当无量纲因子固定时,冲量和冲量耦合系数均随夹角增大而减小,冲量随入射激光能量增加而增大,冲量耦合系数受能量的影响程度很小。

Abstract:

Laser supported detonation flow field for parabolic nozzles is computed by solving radiation transport equation and fluid dynamics equations simultaneously, and air model of high-temperature equilibrium gas is used to compute subsequent evolvement of shock wave. Impulse and impulse coupling coefficient for different nozzle sizes under different laser energies are gained. Effect of incident laser energy, nozzle geometry parameters on propulsion performance is discussed. A dimensionless factor is introduced, and energy law of similitude for parabolic nozzles is set up. The results show that when the angle between axis and line connecting apex and exit is fixed, impulse and impulse coupling coefficient firstly increase and then decrease, getting their maximum when the dimensionless factor is about 0.37. When the factor is fixed, impulse and impulse coupling coefficient both decrease with augment of the angle, while impulse increases with enhancement of incident laser energy and impulse coupling coefficient is independent of it.