The Characterization and Feasibility of a Low-Duty-Cycle Fast Valve for Impulse Facilities

Abstract

This paper describes the feasibility and characterization of a novel fast valve concept, which can replace the diaphragms in shock and Ludweig tube facilities. The proposed fast valve system consists of a rotating door and locking camshaft system. The concept was tested in a bench-top scale shock tube facility, which was operated over a driver gas (air) pressure range of 60 to 500 psig, with a duty cycle of 6 seconds. The measured wave speeds (M S = 1.7 -2.0) were within 3.1% of that predicted by ideal shock tube theory and a statistical repeatability within 7.9%. However, the post-shock driven gas pressures were approximately half that expected from ideal shock tube theory, which was attributed to losses associated with the mechanism (66% area increase) and incomplete shock wave formation. Nonetheless, these results show promise that the rotating door opening time may be sufficient for repeatable Ludweig tubes and shock wave generation given higher driver gas pressures and a longer test section.

Characterization of a novel open-ended shock tube facility based on detonation transmission tubing

“…The opening time of the rapid valve was on a timescale of 0.5 ms. Taylor [25] proposed a similar diaphragmless design concept, employing a shock wave generating mechanism that consists of a rotating door and a locking cam-shaft system. Furthermore, Janardhanraj and Jagadeesh [26] presented a novel concept to generate miniature shock waves using an in-situ oxyhydrogen generator.…”