Friday, April 10, 2015 4:00 p.m. in ETC 4.150
Aerospace Engineering & Engineering Mechanics
The University of Texas at Austin
A new methodology for quantifying acoustic wavefronts is proposed in the present study. Retroreflective shadowgraphy visualizations during the start-up of a cluster of two high area ratio rockets are being used to analyze particular regions of interest using the Radon Transform. Laboratory scale rocket nozzles are tested in the anechoic chamber and high-speed flow facility at The University of Texas at Austin. Thrust optimized parabolic contour nozzles exhibit different flow states during start-up, free shock separated flow, restricted shock separated flow and end-effects regime; which is the most important acoustic event during the start-up. By way of linking acoustic measurements, wall pressure measurements and RANS simulations with the new methodology using the Radon Transform, the goal of the study resides in understanding the sources of sound. Most sound waves are generated by the interaction of turbulence with shock cells located in the supersonic annular plume, which is shown to behave very unsteadily during the end-effects regime. This new technique using the Radon Transform on shadowgraphy images aims to better characterize the near-field acoustic environment, which means to improve the prediction on the acoustic loads during ignition.