Acoustic Measurement of 1:42 Scale Booster and Launch Pad

Abstract

This paper describes the acoustic measurement of the sub-scale booster and launch pad. The 1:42 scale solid propellant booster was settled over the launch pad model on a flat plate. Designed to deflect the hot and high speed jet plume, the launch pad model was expected to mitigate acoustic impact fed back toward the vehicle. The launch pad model plays a role in attenuating the sound due to the impingement of the plume and the deflector. To investigate the acoustic field with a different booster height, acoustic measurement was carried out. The measurement involved the conventional acoustic measurement and the sound source localization. The conventional measurement employed the near-field microphones around the booster model and the far-field microphones on an arc centered on the base of the launch pad. In the sound source localization, a phased array microphone system was settled to focus the deflector exit. The obtained acoustic data helped revise the design of the launch pad model.

Accurate simulation of the noise generated by a hot supersonic jet including turbulence tripping and nonlinear acoustic propagation

“…Based on measured data, three main components have been highlighted: the turbulent mixing noise, the broadband shock-associated noise and the Mach wave radiation. Numerous authors have contributed by studying specific mechanisms including nonlinearities and crackle, [5][6][7][8] screech and feedback effects, [9][10][11] interaction with obstacles 10,12 or with noise reduction devices. 13 Available experimental studies regarding imperfectly expanded hot supersonic jets at Mach number M > 3 14 are however limited.…”

Acoustic measurement of under-expanded jet and its numerical prediction

“…Fukuda et al [14] employed an implicit LES to predict the acoustic mechanism of the static firing experiments of an NAL-735 rocket motor, and their predictions exhibited better correlation with the measurements at the resolved frequencies compared with the methods given in NASA SP-8072. Ishii et al [24] experimentally investigated the noise of a 1/42-scale booster and the launch pad of an Epsilon launch vehicle. Measurements were conducted for various deflector designs and flight altitudes for the near/far-field using phased array microphones.…”