Development of a Diaphragmless shock Tunnel Using a Butterfly Valve

Abstract

A diaphragmless shock tunnel is developed using a butterfly valve, which has generally lower energy loss than that of a piston valve. The valve and its driving unit can be made from commercially available parts. Incident shock Mach numbers and stagnation pressures at the barrel end were measured and compared with those obtained when an aluminum diaphragm was used. The faster the velocity of opening of the valve (or the diaphragm), the larger the incident shock Mach number and the stagnation pressure. Moreover, uniformity of hypersonic flow in the test section was ensured by Mach number distribution based on Pitot pressure measurement. Those results show the feasibility of the valve mechanism.