The noise generated by supersonic jet is of primary interest in the high-speed flight. In several flight conditions jet exhaust of the propulsion system interacts with solid surfaces. For example, jet impingement on ground for a rocket lift-off, or interactions influenced by the integration of the engine with the airframe. Such complex applications require consideration of the role of acoustic-surface interactions on the noise generation of the jet and its radiation. Numerical analysis of supersonic jet noise involved in these scenarios is investigated by employing Hybrid Large Eddy Simulation โ Unsteady Reynolds Averaged Simulation approach to model turbulence.
First, the supersonic impinging jet noise reduction using aqueous injectors is investigated. The technique employed to suppress impingement noise, involves injecting liquid water from the ground surface. The Volume of Fluid model is adopted to simulate the two phase flow. The flow field and acoustic results agree well with the existing experimental data. The possible mechanisms of noise reduction by water injection are investigated.
Second, supersonic jet noise reduction by employing the shielding effect of a flat plate parallel to the jet is investigated. The numerical simulations model the shielding effect of the flat plate on the acoustics of supersonic jet, and results agree with the corresponding experimental data. The physical mechanisms involved in the flow-surface interactions are investigated. With understanding these mechanisms, a slightly wavy plate is proposed including theoretical background to determine the parameters needed for the way wall to provide acoustic reduction efficiently. Results show that the proposed wavy shield can effectively reduce both the level and extent of the jet noise source as compared to that of a flat shield
