Study of Interaction between Jets normal to Supersonic Flow and Porous Cavity

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The mixing enhancement in a field of supersonic flow is an important and applicable to industrial fields. The most promising application of the supersonic mixing is, so called, mixing enhancement in SCRAM jet engines. Moreover, it could be applied to a thermal spray, painting etc. One of the problems in such mixing is how well and quickly the mixing is achieved during the passing at the supersonic velocity, which means that there is no time to mixing. The ideal of this project is based on our patent for the supersonic mixing aiming at the utilization of the shock wave to the supersonic main flow and the bow shock wave. Then, the wall of the duct in which the supersonic flow passes is modified to the porous wall attached with a cavity underneath in order to make the supersonic main flow mixed well. As the result, it is found that the flow characteristics are clarified by means of the optical observations, two dimensional pressure distribution measurements, and tuft flow visualization. Moreover, the comparison of the experimental results with the three dimensional Navier-Stokes compressible numerical calculations suggests that the calculation is reasonable and provide us with important parameters such as the arrangement of the jets and rods, the displacement of the starting shock wave. The flow in the cavity is also affected by the jets and the rods, which is confirmed by the tuft flow visualization. One of the important factors for the devices is a pressure loss. The experiments and the calculations also show that the arrangement of the rods and the jets normal to the main supersonic flow achieved the worst pressure loss, which must be taken into account in designing the kind of devices. According to above all results, recirculation between the cavity and the main duct has been confirmed suggesting the possibility of the mixing enhancements in a supersonic flow.