Effect of Partial Closure of the Channel on the Pressure Pulse in a Shock Wave Emerging from a Duct

Abstract

The temporal-spatial development of the flow pattern behind a shock wave emerging from open-ended and half-closed ducts at M0=1.15 to 3.0 Mach number is investigated both experimentally and numerically and the action of the diffracted wave on a barrier placed at different distances from the duct exit is studied. Flow toeplerograms are obtained and the pressure on the barrier is measured. The distinctive features of the interaction between the shock wave and a barrier mounted perpendicular to the duct axis are established. It is found that partial closing of the duct results in a decrease in the barrier pressure in the case of a strong shock (M0 > 2.2) and leads to a pressure decrease when a weak shock is diffracted (M0=1.1 to 1.7). A dependence characterizing the dynamic action of the shock wave on the barrier and specifying the threshold value of a combination of the shock Mach number and the distance from the barrier determining whether the pressure pulse on the barrier increases or decreases, is obtained.