Acoustic characterization of sub-scale rocket nozzles

During launch, space vehicles are subject to violent vibro-acoustic loads caused by the intense sound pressure levels and transient side-loads produced during rocket engine ignition. A recent study conducted at The University of Texas at Austin has focused on characterizing the internal flow and acoustic signature of a thrust-optimized parabolic (TOP) and a truncated ideal contour (TIC) nozzle test article in order to develop a detailed understanding of the mechanisms responsible for producing main engine ignition noise. The studies are conducted for both transient and fixed nozzle pressure ratio (NPR) conditions. The former provides a more realistic representation of the full scale environment, while the latter allows for a statistical characterization of the various sources of main engine ignition (MEI) noise. Time-frequency analysis is performed on transient startup data.