Hybrid RANS/LES Simulation And Experimental Research On The Flow Field Of Strut In Scramjet

The fuel injection and reaction flow field of scramjet with strut were studied in this paper. The attention was focused on the development of the fuel and the characteristics of the flow.Numerical simulation of the non-reaction flow with a strut was completed by employing the hybrid RANS/LES strategy. It was found that, the hybrid RANS/LES simulation method was capable of dealing with the interaction between the shock and boundary layer successfully. When injected from the rear of the strut, the fuel diffusion processes mainly depends on the development of shear layer down stream of strut. Due to the compressible effects, the shear layer in supersonic flow develops slowly, and the interaction of the reverse large eddy in shear layer on both side of the strut reduces the intensity of the vortical of the whole flow field, and that prevent the further mixing of fuel and air. When injected from the side of the strut, the vortical structure caused by fuel injection and downstream shear layer of the strut enhances the diffusion of fuel. The angle of fuel injection has important influence on its penetration into the air flow, but it has little effect on the whole flow field.Experimental investigations on the reaction flow of the strut show that, the shock induced by the strut or ramp in the supersonic reaction flow could promote both the ignition and reaction of the fuel. When thermal choke happened in the combustor, the drag caused by the strut would decrease greatly. The recirculation zone at the rear of the strut could also improve the local combustion much greatly. When the fuel was injected into the core region of the combustor by the strut, many new problems would be caused, and much attention should be paid to the interaction of the fuel injector and the flame holder. When injected in the incoming flame, the fuel could be ignited simultaneously, and the combustion efficiency in the strut-injection method is much better than that when injected from the wall of combustor. The flame in the supersonic flow propagates upstream and downstream frequently, in fact, it connects with the coupling process between the changed local flow state and the whole flow field, and it also has something to do with the interaction between the shock and the boundary layer.