Characteristics of an annular vertical diaphragmless shock tube

This paper reports on the characteristics of a compact vertical diaphragmle ss shock tube, which was constructed and tested in the Shock Wave Research Center to study experimentally the behavior of toroidal shock waves. It is 1.15m in height and has a self-sustained co-axial vertical structure consis ting of a 100 mm i.d. outer tube and an 80 mm o.d. inner tube. To create a ring shaped shock wave between the inner and outer tubes, a rubber sheet is inserted to separate a high pressure driver gas from a test gas, which is bulged with auxiliary high pressure helium from behind. When the rubber mem brane is contracted by the sudden release of the auxiliary gas so as to bre ak the seal, shock waves. are formed. Special design features of the shock tube are described and their role in producing repeatable shock waves is di scussed. Its special opening characteristics make possible the production o f annular shaped shock waves that are unlikely met with a conventional tube that uses rupturing diaphragms. Performance of the shock tube is evaluated in terms of the shock wave Mach numbers and the measured flow properties. It eventually showed a higher degree of repeatability and the scatter in th e shock wave Mach numbers Ms was found to be 0.2% for Ms ranging from 1.1 t o 1.8. The shock wave Mach number so far measured agreed very well with the simple shock tube theory.