Recent efforts in rocket plume acoustics

Recent computational research in Japan on the acoustic waves generated by rocket plumes is summarized with brief remarks on CFD/CAA for jet acoustics. There are two approaches to improve the prediction accuracy of the pressure level of acoustic waves: 1) using CFD/CAA for direct computation of the acoustic waves from rocket plumes by considering an actual rocket launch site configuration; and 2) using CFD/CAA analysis of geometrically simple model problems, such as a free jet, and building a more reliable prediction method based on the results obtained. Research based on the first (engineering) approach was conducted by Tsusumi et a!., and low-frequency acoustic environments around Japanese rockets were discussed. Research with the second (academic) approach was conducted by Nonomura and Fujii. They investigated supersonic free jets in detail with highly resolved simulation. These researches will improve the prediction accuracy of pressure levels of acoustic waves from rocket plumes.