An investigation of the disturbances caused by a reflection plate in the working-section of a supersonic wind tunnel

Abstract

An investigation has been made of the disturbances caused by a reflection plate, mounted clear of the boundary layer in a supersonic tunnel. Static traverses were made, mainly at a Mach number of 1.4 above four reflection plates having different plan forms, with various conditions in the passage between the plate and the tunnel wall. In the region above the plate two main disturbances were found ; there was a small disturbance from the leading edge and a disturbance further downstream which had originated beneath the plate. Between the two there was a region of approximately constant pressure in which a model could be located. The forward disturbance seemed unavoidable. Increasing the area of the passage beneath the plate by a recess in the tunnel wall, was the most effective way of moving back and reducing the magnitude of the disturbance at the rear. With the best arrangement, at a Mach number, of 1.4, it was found possible to obtain a region of approximately constant pressure, extending downstream from the apex of the plate for a distance of about 0.66 times the height of the tunnel. A plate spanning the tunnel was found to be unsuitable because of disturbances originating at the extremities of the leading edge, in or near the tunnel boundary layer