Rocket noise predicton models: An update.

Abstract

This paper summarizes revised or improved elements of rocket engine noise prediction models including overall sound power for rocket, noise source locations in undeflected/deflected rocket exhausts, sound power and/or pressure spectrum, and directivity for the rocket noise sources at, and after, launch with emphasis on locations on the launch tower. Finally, influence of the flow deflector and water injection on the rocket noise levels is considered. The data presented are from a number of previously published reports by the author, and others, including Eldred, Crocker, and Potter. The sound power of the rocket is predicted by a Lighthill theory‐consistent model as proportional to a flow‐dependent multiplier corresponding to the ratio of flow mechanical power at the supersonic core tip to mechanical power at nozzle exit. Data from 27 measurements of sound power of jets and rockets covering a range from 135 to 200 dB re 1 PW show a prediction accuracy of +/−2.8 dB. The model is a more robust approach to r...