Full-scale rocket motor acoustic tests and comparisons with models: Updates and comparisons with SP-8072

Abstract

Development of the next-generation space flight vehicles has prompted a renewed focus on rocket sound source characterization and near-field propagation modeling. Measurements taken during a static horizontal firing of Alliant Techsystems Orion 50S XLG are compared to the predicted levels produced from NASA’s SP-8072 Distributed Source Methods (DSM-1 and DSM-2). Two modifications to the SP 8072 prediction model are considered in regards to the source directivity and the source power spectral distribution. All models considered provide a good first-order approximation given an appropriate total acoustic sound power. However, a more physical model is needed to adequately map out the critical near-field region as well as the far-field propagation. A new intensity-based measurement system and corresponding procedures are currently being developed for determining this near field energy flow and for achieving source characterization capabilities beyond traditional pressure measurements. These advances are believed to be a step toward improved measurements and modeling of the rocket plume.