Vortex–Particle Coupling of Polydisperse Microparticles in Supersonic Transverse Jets

Understanding the spatiotemporal evolution and vortex–particle coupling mechanisms of polydisperse microparticles in supersonic transverse jets is a fundamental challenge in aerospace propulsion systems. This study uses a Mach 2.6 supersonic direct-connect experimental platform with a total temperature of [Formula: see text] and a velocity of [Formula: see text]. This platform is integrated with high-speed planar laser scattering and high-speed shadowgraph imaging. This setup is used to elucidate the dynamic behaviors of polydisperse microparticles (ranging in size from 0.1 to [Formula: see text]) in supersonic transverse jets. Experimental results show that the particle clusters form three quasi-coherent distribution patterns sequentially along the jet trajectory: a fluctuating distribution on the windward side, a trailing distribution on the leeward side, and a roller-type distribution near the injection wall. Analysis based on proper orthogonal decomposition shows that shear layer instability dominates the particle dispersion process, exhibiting multiscale transfer characteristics. The study points out that the particle distribution pattern is essentially a spatiotemporal representation of their clustering behavior during the dynamic evolution of the large-scale roller-type vortex. The degree to which the particle response time matches the vortex timescale (i.e., the Stokes number) determines the clustering pattern. These findings provide critical experimental insights into particle-laden dynamics within supersonic multiphase flows.