Shock Wave Response to Laser-Generated Localized Perturbations in Mach-4 Freestream

This work investigates the response of a cylinder-generated inviscid bow shock when locally perturbed with laser-generated thermal disturbances in a Mach-4 freestream. Using a pulse-burst laser system, controlled energy deposition introduced intermittent high-temperature, low-density disturbances upstream of the shock. The resulting interactions were captured via high-speed schlieren imaging, allowing for a time-resolved analysis of shock displacement, relaxation dynamics, and perturbation scaling effects. The standoff distance and relaxation time scales were directly influenced by perturbation frequency and energy deposition levels. The amplitude of the maximum shock transmission and subsequent relaxation times increased in proportion to the frequency and strength of the perturbation. These findings offer new insights into the dynamics of shock waves encountering freestream fluid inhomogeneities in high-speed flows, which directly impact our understanding of weather effects, aerodynamic stability, and hypersonic flow control.