Abstract

Rocket sonic booms are produced when launch vehicles or boosters travel faster than the local speed of sound in the atmosphere, generating systems of conical shock waves. The purpose of this dissertation is to perform high-fidelity measurements of rocket sonic booms and to explain the physics behind the unique phenomena observed. After a thorough literature review on sonic booms produced during spaceflight operations, Part I of this dissertation deals with measurement and analysis challenges. One challenge is reducing contaminating noise effects on sonic boom perception metrics, addressed using a low-pass filtering method tied to the noise floor. A second challenge is analyzing turbulence-induced variability, addressed using measurements across a microphone array along with models and evaluating their agreement. The final chapter in Part I surveys additional sonic boom measurement and analysis methods, including hardware setup and signal processing. Part II focuses on reusable rocket booster flyback sonic booms, which are produced when a reusable rocket booster descends through the atmosphere to land safely. Two chapters describe field measurements from three flights, showing that the booms do not elongate with distance and that the overpressure plateaus near the landing pad, likely because the booster becomes subsonic several kilometers above the ground. Additionally, the measured flyback sonic boom overpressures exceed launch noise peak pressures for distances greater than 2 km from the landing pad. The next two chapters describe work predicting the unique triple sonic boom waveform also observed in the measurements. Using a combination of theory, nonlinear propagation, computational fluid dynamics, and photographic evidence, the triple sonic boom is shown to result directly from vehicle geometry, without invoking maneuvers or other effects. Part III examines rocket launch-ascent sonic booms, which can reach communities when launch trajectories are close to the coast. Simulations using NASA's PCBoom software demonstrate that seasonal trends in sonic boom footprints are driven by recurring seasonal weather variations. Subsequent modeling of launch-ascent sonic boom waveforms demonstrates that waveform shapes can be physically explained by the vehicle and plume geometry. Overall, this dissertation work demonstrates that sonic booms from rockets are an important phenomenon that must be understood as the global launch cadence continues to increase. Moving forward, it will continue to be important to make accurate measurements while simultaneously improving simulation and modeling capabilities to ensure that the physics are fully understood.

Degree

PhD

College and Department

Computational, Mathematical, and Physical Sciences; Physics and Astronomy

Rights

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