Flow feature and aero-optical effect for laser turret in transonic flow

Improved Delayed Detached Eddy Simulation (IDDES) is used to calculate the flow field around the turret in transonic flow. The ray tracing method is employed to calculate the aero-optical effect at different beam emission angles. The aero-optical effect affected by different flow structures is analyzed. The results indicate that the pressure distribution on the turret exhibits two main characteristics: a symmetric “breathing mode” and an antisymmetric “shifting mode”. Their peak frequency are at 0.26–0.41 and 0.11–0.22, respectively, and these two main features exhibit coherence in the frequency. The drag force of the turret is primarily determined by shear layer oscillation, the lateral force is largely due to the shock wave jitter, and the axial force is influenced by both shock wave jitter and shear layer oscillation. The high-order Optical Path Difference (OPD) is relatively small with little fluctuation when the beam passes through the attached flow region. However, when the beam traverses the shock wave region and the turbulent wake zone, the high-order OPD is significantly large, with the time-averaged OPD being about four times that of the attached flow region, and the peak OPD being 13 times greater than that of the attached flow. The high-order OPD of the beam passing through the shear layer and turbulent wake vortices shows similar energy ratio using Proper Orthogonal Decomposition (POD) analysis. In contrast, the OPD energy of beams passing through the shock wave is more concentrated in the first five modes.