The Use of a Noise Barrier with a Cut-out to Reduce Acoustic Levels During a Rocket Launch

This paper focuses on an investigation of noise sources present in a supersonic jet impinging on an inclined flat plate configuration, and the effects of a noise reduction method applied to it. Since the acoustic waves that are created during a rocket lift-off can be detrimental to the rocket launch vehicle because of the high acoustic loads and acoustic levels in the near and far-field have high impact on noise pollution around the launch site, investigations focusing on the noise generation mechanisms and ways to reduce the noise levels are very crucial during launch environment design. In this study, noise sources that are traveling upstream towards the launch vehicle and to the far-field are blocked by introducing a wall with a circular cut-out between the nozzle exit and the impingement plate. The geometry of this passive noise reduction method is designed in a way that the interaction between the jet flow and the wall with a cut-out will not create new high amplitude noise sources. The effects of the location of the wall on the flow field and the acoustic spectra in the near and far-fields are investigated using three configurations with different wall locations. A CFD solver using the Detached Eddy Simulation is used to calculate the flow fields and an acoustic solver based on the Ffowcs Williams and Hawkings method is used to calculate the acoustic spectra in the near and far-fields.