高超声速飞行器气体辐射噪声计算方法

高超声速飞行器周围的激波层内高温气体会发生剧烈的物理化学变化，伴随强烈的光辐射过程，直接影响红外导引头的光学成像效果。采用流体力学Navier-Stokes方程和热化学非平衡模型模拟高温非平衡流动，考虑电子跃迁和振转跃迁以窄带法求解气体辐射特性参数，基于有限体积法离散辐射传输方程，在分别验证流场解算、辐射参数求解和辐射传输计算的基础上，进行了飞行器高速飞行的流动和辐射模拟。数值求解得到了飞行器流场特征和粒子数空间分布。计算的选定波长范围内的气体辐射发射系数空间分布显示其与激波形状和波后气体温度分布相似。通过传输得到的飞行器光学窗口视线路径上的气体辐射噪声成轴对称分布，发现辐射噪声和飞行速度、气体成分等密切相关，马赫数增加时气体辐射噪声显著增强。

Computational methods of gas radiative noise for hypersonic vehicles

When a vehicle flies at high velocity, the high temperature gas in shock layer undergoes strong physical and chemical change along with substantive optical radiation which will directly affect the imaging quality of an infrared seeker. Fluid dynamics Navier-Stokes equations with thermo-chemical non-equilibrium models were used to simulate the high temperature gas flow. Narrowband model accounting for both electronic and vibrational-rotational transition mechanisms was employed to obtain gas radiative characteristics. Radiative transfer equation was computed by finite volume method to acquire radiative intensity distribution. Based on validation of flow solver, radiative parameter calculation and radiative transportation computation, hypersonic flight vehicles were simulated. Flow structures and parameters and particles distributions were obtained. Emission coefficients in specific wavelength range were solved through the flow parameter. The distribution of the coefficients shows that is very similar to shock wave shape and gas temperature contours behind the shock. Gas radiative noises on optics window are axisymmetric, which is strongly related to flow velocity, gas species and so on. When Mach number increases, the gas radiative noises grow rapidly.