湍流脉动对发动机尾喷焰红外信号的影响

EFFECT OF TURBULENT FLUCTUATIONS ON THE INFRARED SIGNAL OF ENGINE PLUME

本文用简化的概率密度函数模拟温度的脉动,分析了轴对称火箭发动机尾喷焰湍流脉动对时均辐射信号的影响。分析结果表明,在不同的探测波长上,湍流脉动引起的时均辐射信号变化不同;由于光谱吸收系数总体上随温度的升高而降低,且降低的速率比Planck函数随温度的升高的速率大,从而导致随湍流温度脉动强度的升高尾喷焰时均辐射信号在不同波长处有不同程度的降低。

A simplified possibility density function is used to simulate the fluctuations of temperature in engine plume. The effects of turbulent fluctuation on the time-averaged infrared signal of plume are analyzed by the possibility density function. The results show that, the influences of turbulent fluctuation on time-averaged infrared signal in different wave band are different. Because the gas absorption coefficient generally decrease with temperature and the decreasing rate is larger than the increasing rate of Planck function with temperature, the time-averaged infrared signals are less then these calculated by the time-averaged temperature.