Experimental Study on the Characteristics of Sonic Gas Injection into Supersonic Crossflow with Ma2.0 and Ma3.0

The gaseous injection into a supersonic flow is one of the most fundamental methods of fuel mixing in scramjet engines. As the scramjet performs in a wide operating range of flight Mach number, the structure of the gaseous transverse jet flow also changes. This research combines NPLS (Nanoparticle-based Planar Laser Scattering) and oil flow experiments to study the flow structures of the transverse gaseous jet into a supersonic crossflow. The supersonic suction-type low turbulence wind tunnel of the National University of Defense Technology could provide inflow streams with different Mach numbers, including Ma2.0 and Ma3.0. We analyzed the instantaneous flow field structure by NPLS images and the near-wall friction characteristics by oil flow results, and compared the results with different dynamic pressure ratio under Ma2.0 and Ma3.0. Upstream the jet, the bow shocks under the inflow with Ma2.0 and the inflow with Ma3.0 vary significantly, especially the difference in shock angle. In the jet leeward, there is a V-shape separation zone. The characteristics of the separation zone under different conditions are analyzed. The results show that the bow shock angle and the separation angle are related to the inflow Mach number, but not to the jet dynamic pressure ratio J.