【摘要】 针对超音速飞行器在大气中飞行时所产生的湍流脉动气动光学效应进行了理论分析与计算,并对气动模糊图像进行了复原。首先根据计算流场时使用的湍流模型及其控制方程,计算脉动流场气动光学效应所对应的点扩散函数。计算结果表明,气动光学点扩散函数的幅度响应函数具有低通特征,使目标图像成像模糊。在相同飞行高度下,马赫数越高,图像模糊越严重。通过把气动光学效应传递函数应用于风洞实验吹风前图像,并将得到的气动模糊图像与吹风后实测图像的对比,验证了理论点扩展函数的正确性。最后,提出了一种改进的Landweber迭代图像复原方法对气动光学效应进行了校正。该方法在每一步迭代时对松弛因子进行修正,具有较快收敛速度和更好的复原效果。更多还原

【Abstract】 Computational analysis of the aero-optic effects caused by hyper-speed fluctuation fields was presented, and the blurred infrared image was restored. First, a time-averaged modulation transfer function (MTF) which represents the aero-optic effects was derived, experimental results show that the amplitude response of the transmission function of the aero-optical effect can be characterized as a low-pass filter, which results in the blurring of the objects in the acquired infra-red images. The higher speed, the more serious image was blurred at the same flight height. Furthermore, the correctness of the theoretical MTF was evaluated by wind tunnel experiment. Finally, an adaptive Landweber iteration method was proposed to restore the blurred images, which updated the relaxation factors at each iteration. Experiments demonstrated that the method has higher convergence rate and better restoration effect.更多还原