Flow characteristics of active control around a 3D turret

At high speeds the wake of a hemisphere turret is completely separated and fully turbulent. Within this region of separated flow large density fluctuations develop. The problem comes in with attempting to propagate light through the turbulent wake of the turret. As the a light beam passes through the wake and the shear layer of the turret, the beam becomes distorted. Distortion of the beam causes the intensity of the light to be reduced making a laser less effective. By manipulating the flow around the turret, in particular the region just over the laser aperture, the loss of light intensity can be minimized. Active flow control has been shown in pervious work to alter the flow characteristics around an object. In the effort to delay the onset of stall around an airfoil at high angles of attack Glauser et al (2004) and Ausseur et al (2005) were successful at showing that utilizing an active flow control system was a very effective means of control. The active flow control included open and closed loop control. For the closed loop control, a low dimensional analysis of the velocity field around the airfoil and the surface pressure along the airfoil, was fed back into a simple proportional controller. Closed loop flow control reduced the onset of stall as the angle of attack was increased. and the system also consumed less power to prevent stall than the open loop control. A pervious experiment perform under similar conditions and procedures was performed in the Syracuse University windtunnel. In this experiment open loop flow control was test on a quarter sized turret at a low freestream speed. After a large database of surface pressure and velocity measurements where obtain it was seen that there was a reduction in the unsteady fluctuating characteristics. In an effort to take this a step further and improve on the open loop control, the next step was to investigate the effects of open loop and closed loop control upon the flow and aero-optics of the system at a much higher Reynolds number. Like the pervious work before, the surface pressure based proportional closed loop control was found to have a positive effect upon the wake of the turret.