Experimental study of moving throat plug in a shock tunnel

Abstract

An experimental study has been carried out to investigate the flow in the KAIST shock tunnel with two moving throat plugs at a primary shock velocity of 1.19 km/s. The nozzle reservoir pressure and the Pitot pressure at the exit of the nozzle were measured to examine the influence of the moving throat plugs on the shock tunnel flow. To assess the present experimental results, comparisons with previous work using a stationary throat plug were made. The mechanism for closing the moving throat plug was developed and verified. The source of the force to move the plug was the pressure generated when the primary shock was reflected at the bottom of the plug. It was observed that the two plugs terminated the shock tunnel flow after the steady flow. .The time for the plugs to terminate the flow showed good agreement with the calculation of the proposed simple analytic solution. There was a negligible difference in flow values such as the reflected pressure and the Pitot pressure between the moving and the stationary plugs.