Investigation on Rectangular-to-Circular Isolator Under Asymmetric Incoming Supersonic Flow

In order to adapt with the modularity design of the scramjet and the requirement of the circle combustor,the shape of the isolator must be designed from rectangular to circular. Based on the method of superelliptic curves for cross-section transition,a rectangular-to-circular isolator was designed,which was investigated with numerical simulation and experiment in a supersonic wind tunnel under an incoming asymmetric flow of Mach number 2.1. The results indicate that under the same back pressure,the total pressure recovery coefficient of rectangular-to-circular isolator are improved by 4% and 5% than the rectangular isolator at two kinds of incoming flow. Under incoming asymmetric flow,trends of the wall pressure in the two kinds of isolator are the same: the forepart of the top wall pressure of the isolator fluctuates up,the latter part of top wall pressure and bottom wall pressure both arises slowly up. The total pressure recovery coefficient decreases when the back pressure rises. The rectangular-to-circular isolator can withstand a maximum back pressure of 4.1 times static pressure.The total pressure recovery coefficient of outlet is 0.505 under the maximum back pressure.