Influence of the secondary flow control on the transverse gaseous injection flow field properties in a supersonic flow

The supersonic mixing process is a critical issue for the design of the scramjet engine. In this paper, the secondary flow control concept has been proposed and studied in order to strengthen the mixing process between the fuel and the incoming flow with the freestream Mach number being 3.75, and the influence of the secondary flow position on the mixing augmentation mechanism has been evaluated as well. The obtained results show that the secondary flow control concept has a great impact on the mixing augmentation mechanism in the transverse injection flow field, and the parameters should be properly selected, especially for the secondary flow position. When the upstream hole is close to the jet flow and the downstream hole is far away from the jet flow, the mixing process between the fuel and the incoming flow could be promoted, namely Case 1 is the best choice for the mixing augmentation in the range considered in the current study. This is due to the variation of the separation zone generated upstream of the fuel jet, and this issue should be evaluated quantitatively. The hydrogen plume shape changes from a "kidney" to a "lamp", and it is far away from the bottom wall in Case 1. The premature ignition phenomenon could be prevented properly in Case 1.