Effects of Three Types of Control Devices on Closed-Type Supersonic Cavity Flows

Abstract

Three types of devices were tested for their effects in reducing the strong adverse pressure gradient in a closed-type cavity with a depth of 8 mm and length-to-depth ratio of 15. The first type of control device consisted of embedding arrays of tubes longitudinally along the two sides of the cavity. It sought to move the high-pressure air at the recompression wake to the separation wake by creating a passage. The second type of control device consisted of installing a baffle plate laterally near the shock impingement line or the mid-part of the cavity floor. It aimed at changing the wave structure of the cavity flow through interfering with the reattaching or reattached boundary layer. With the third type of control device, we tried to increase the base pressure by supplementing external fluid with downstream blowing through side-holes along a lateral tube placed at the front corner of the cavity. Of the three types of control devices, the installation of tubes along the two sidewalls of the cavity was found to be the most effective in reducing adverse pressure gradient along the cavity centerline. Of the four combinations of plates installed laterally on the cavity floor, the 4-mm-high plate installed near the middle of the cavity was found to be the most effective. The relative ineffectiveness of downstream blowing near the cavity front corner is believed to be a result of the low blowing rate.