An Experimental Investigation of Effects of Wall Porosity and Suction on the Flow Quality in a Transonic Wind Tunnel

A trisonic wind tunnel was modified to improve its flow quality when operating at transonic speeds through perforated walls and side suctions. The usefulness of such a perforated wall, already known. is reduction of the blockage effect as well as the shock elimination. Two types of perforated walls were used in this investigation. The first wall had a porosity of about 22% and the holes were drilled perpendicular to the surface. However, the second wall had a variable porosity. 0 to 6%, and the holes were drilled at an angle of 60 degrees with respect to the normal vector of the plate:. The flow in the test section of the wind tunned was surveyed extensively at various Mach numbers ranging from 0.6 up to 1.2. The effect of porosity was studied by comparing the results related to the present perforated with the pmvious closed wall data for various conditions. The amount of suction could be adjusted through the side walls. Flow quality along the nozzle and test section was studied by a long tube installed in the center of the wind tunned test section.