Extension of a launch pad noise prediction model to multiple engines and directional receivers

A model, PAD, has been developed for prediction of noise in the vicinity of launch vehicles, with original 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, water suppression and acoustic shielding by three dimensional launcher configurations. For application to Space Launch System, the model has been extended to multi-engine vehicles, using the plume merging model developed by Kandula, Vu and Lindsay (AIAA Paper 2005-3091) and accommodating multiple flame holes in the deck. The capability has also been added to account for receiver directivity. This can be significant when predicting the load on the surfaces of enclosures on the launch tower. It is also an issue for model scale tests (such as ASMAT) where microphones and their mounts are not small enough to be omnidirectional, and thus do not measure free field levels. (Work supported by the Na...