Numerical simulation of aero-optical effect of flow around typical optical windows

Delayed detached eddy simulation (DDES) is used to simulate the flow field around the conformal optical window turret and the flat optical window turret. The aero-optical effect and the far-field diffraction result of the two optical windows at 0°, 90° and 180° angles are quantitatively analyzed based on the flow field around the turret. Zernike polynomial is applied to fit the wavefront distortion, and the adaptive optics is used to analyze the propagation performance of the two optical windows. The results show that the beam transmission performance of the flat optical window is better than that of the conformal one at the angles of 0° and 180° without adaptive optical correction, while the beam transmission performance of the conformal window at 90° angle is better than that of the flat one. When the adaptive optics correct these low-order terms including piston, tilt, defocus and astigmatism, the beam transmission performance of the conformal optical window is better than that of the flat one at the angles of 90° and 180°. At the angle of 0°, the beam transmission performance of the two optical windows is similar. With the increase of the angle, the high-order terms of the two windows decrease continuously. It is worth noting that the peak intensity of the distorted beam after diffraction in the far field may be larger than that of the undistorted beam in the far field. Meanwhile, the location of the peak intensity will be seriously offset.