关键词: 气动光学效应, 边界层, 流动控制, 数值模拟, 超声速流场

Abstract:

Optical imaging detection technology is an important subject in the study of precision guided weapons. The aero-optical effects has a big influence on the guidance precision, and it can make the vehicle off the target position, or even off the target. The interaction between the aircraft and the incoming flow leads to a very complex flow field structure around it. The existence of shock waves, expansion waves and turbulent boundary layer makes the refractive index of the flow field unevenly distributed in space and high frequency jitter in time. Among them, the aero-optical distortion caused by the boundary layer rotation process is the biggest problem to be solved urgently. Boundary layer transition, as a process of boundary layer flow from laminar to turbulent state, is a strong nonlinear complex flow physical phenomenon influenced by multi-factor coupling, and has been a hot topic in turbulence research field.The transition region of the supersonic boundary layer is very unsteady and random, and the pulsation frequency is high, so the refractive index distribution is extremely complex. The light passing through this layer will be deflected, and there will be imaging blur and energy dispersion which seriously affect the accuracy of imaging guidance. It is difficult to reduce this effect by optical correction. This paper attempted to reduce or even eliminate the effect of supersonic boundary layer transition on optical transmission performance by delaying boundary layer transition. Taking the boundary layer flow field around the optical window of the supersonic rotary vehicle as the research object, the study carried out numerical simulation on the variation law of the aero-optical effect of the boundary layer by using the flow control method of adding perturbation plates. The results show that with the increase of the angle of attack, the distribution of optical path difference gradually changes from the symmetrical distribution along the symmetry plane to the change along the flow direction, and gradually flattens. After the turbulence control is applied, the transition position of the boundary layer above the optical window moves backward, and the flow field above the window gradually changes from the transition area to the laminar flow area, which has a significant effect on suppressing the aero-optical effect.

Key words: aero-optical effect, boundary layer, flow control, numerical simulation, supersonic flow field