Further development of a launch pad noise prediction model

Abstract

A model, PAD, has been developed for prediction of noise in the vicinity of launch vehicles, with specific application to the mobile launcher and tower for the Ares I launch vehicle. It follows the basic principles of a traditional NASA model (NASA SP-8072, 1971), with updated source components, including impingement and water suppression. The recent 5% scale Ares scale model acoustic test (ASMAT) exhibited sources not properly represented in PAD. These sources are noise increase associated with flat plate deflection of a supersonic plume, and generation of noise from impingement of the plume on an edge such as a launch mount or the edge of the exhaust hole in the launcher deck. New sources, based on ASMAT measurements, have been added to PAD to account for these effects. Treatment of the launch deck has also been generalized to permit full three dimensional launcher configurations, rather than a simple two dimensional arrangement with the tower over the flame trench. The prediction domain has also been expanded to include exhaust plume noise levels on the underside of the deck. (Work supported by the National Aeronautics and Space Administration.)