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In this experiment, the effects of the combination of jets or rods and a porous cavity on the supersonic flow field are studied by means of visualization of schlieren method and the measurements of wall static pressures and the flow direction in the cavity with the thermal tuft probe. Three cases of jets or rods arrangements are tested in the experiments. As a result, a bow shock wave which is generated by the jets or rods is observed by mean of schlieren method. And it is confirmed that the expansion region appears downstream of the rods but is not in case of the jets pattern. Moreover the pressure ratios of starting shock wave passing through porous cavity for jets pattern differ from that of rods pattern. In the cavity, the flow direction at the measurement position in the cavity is always opposite to the main flow, as long as the starting shock wave is located upstream of the porous cavity for all cases. Difference in the backward flow ratio between the jets and rods patterns is observe after the starting shock wave passes through the porous cavity.

This paper investigates jets injection into supersonic main flow, where the jets are surrounded by the porous cavity. This application of the porous cavity to the jet injection aims for the supersonic mixing enhancement. Supersonic mixing technique is important for scramjet engines to improve combustion efficiency. This method using porous cavity has been experimentally studied. However, it is difficult experimentally to measure the mixing efficiency, total pressure loss, and a circulation between the main flow and the cavity flow. Therefore, this paper numerically studies this flow field. In the calculation, Navier-Stokes equations were solved using AUSMDV scheme with 3rd order MUSCL scheme and the four stage Runge-Kutta scheme. Two cases, with the porous cavity and without the porous cavity, were calculated. As a result, a circulation between the main flow and the porous cavity is confirmed. Moreover, it is found that the bow shock wave and the dead water region of the jet were the important factors of this circulation. In addition to the circulation, total pressure loss due to the porous cavity was revealed.

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As one of supersonic mixing techniques, a supersonic mixing technique using a cavity and a porous wall has been proposed. The cavity and the porous wall generate the low speed region in the cavity, which enhances mixing the main flow with the jets. In this study, numerical simulations were conducted to clarify the effects of backward inclined jets on the mixing technique using a porous wall and a cavity. In the numerical simulations, three patterns of jet injections which combined normal jets with backward inclined jets were studied. As a result, the combination of a backward inclined jet and a normal jet generates the suction flow behind the backward inclined jet, which is useful for making the injected jets flow into the cavity. In addition, the introduction of backward inclined jets reduces the total pressure loss. On the other hand, the mass flow rate through the porous holes decreases with increase in the number of the backward inclined jets.