Action on the obstacle of a shock wave discharged from a partly closed channel exit

Abstract

The pressure impulse on the obstacle of a shock wave discharged from an open and partly closed exit of a channel are compared. The high-speed imaging schlieren pictures series are compared with the measured pressure history on the obstacle. In the case of partly closed exit the additional pressure increase on the external obstacle was found when the incident shock wave Mach number was low enough. At higher shock wave Mach numbers the partly closing of exit leads to pressure decrease. The threshold of pressure impulse increasing/decreasing effect as a function of incident shock wave Mach number, relative obstacle location and exposure time is presented.