Fast-Acting Valves for Use in Shock Tubes : Part 2, Formation of shock waves

Abstract

In the previous paper, two kinds of fast-acting valves were developed to replace diaphragm-breaking as a means of generating shock waves in the conventional shock tubes. One of them, called a type-H valve is used in a shock tube in this paper, and the strength of shock wave generated by the valve and the correlation between the shock formation distance and the opening time of the valve are experimentally clarified. Furthermore, the experiments where a diaphragm is used are also performed, keeping all other operating conditions equal, and the results are compared with those by the valve. When the initial pressure ratio is comparatively small, valve produces as strong a plane shock wave as the conventional diaphragm shock tubes, although the shock Mach numbers are less than those produced by the breaking of diaphragm at a larger initial pressure ratio.