Comparison of the acoustical emissions of multiple full-scale rocket motors

Abstract

Development of the next-generation space flight vehicles has prompted a renewed focus on rocket sound source characterization and near-field propagation modeling. Improved measurements of the sound near the rocket plume are critical for direct determination of the acoustical environment both in the near and far-fields. They are also crucial inputs to empirical models and to validate computational aeroacoustics models. Preliminary results from multiple measurements of static horizontal firings of Alliant Techsystems motors including the GEM-60, Orion 50S XLG, and the Reusable Solid Rocket Motor (RSRM) performed in Promontory, UT, are analyzed and compared. The usefulness of scaling by physical parameters such as nozzle diameter, velocity, and overall sound power is demonstrated. The sound power spectra, directional characteristics, distribution along the exhaust flow, and pressure statistical metrics are examined over the multiple motors. These data sets play an important role in formulating more realistic sound source models, improving acoustic load estimations, and aiding in the development of the next generation space flight vehicles via improved measurements of sound near the rocket plume.