A Comparative Study of Experimental and Simulation Data for Micrometer Particle Acceleration in a Low-Pressure Supersonic Jet Impingement System

Micrometer-sized particles impacting high-speed vehicles encounter a wide range of conditions, including gas rarefaction and high relative speeds, which significantly affect their drag. Recent attention has been given to understanding hypersonic vehicle behavior in particle laden environments, where accurate prediction of particle drag under a wide range pressure, temperature and gas velocities is paramount to predicting damage to surfaces. To this end, we design an experimental system to measure particle acceleration and declaration in a low pressure supersonic jet impingement with gas Mach reaching a value of 5. Pure nitrogen gas was used with gas pressure and gas temperature near standard conditions upstream of a de Laval nozzle and flow driven by a 266 Pa downstream pressure. Well controlled single sized solid spherical particles in the size range of 0.7 to 7 μm in diameter and density of 2.7 g cm ^-3 and 1.5 g cm ^-3 are generated by a vibrating orifice generator. The velocities of particles within the supersonic jet are measured using laser Doppler velocimetry at various downstream locations. Particle velocities are compared with numerical models that incorporate state-of-the-art drag laws suitable for the high Mach number and high Knudsen number regimes.