Spectral modulation and suppression of coherent vortex shedding by inertial particles in transonic shock-separated flows

The interaction between inertial particles and unsteady shock-induced separation represents a fundamental problem in compressible multiphase turbulence, yet the multiscale modulation mechanisms of coherent structures remain poorly understood. This study investigates the spatiotemporal evolution of transonic shock–boundary layer interactions laden with inertial particles using high-fidelity delayed detached-eddy simulation. By integrating proper orthogonal decomposition (POD) and spectral analysis, we identify a distinct spectral modulation mechanism governed by phase coupling. Results reveal that inertial particles act as a distributed momentum sink, smearing the Rankine–Hugoniot discontinuity and reducing the primary shock intensity by 20%–30%. This momentum deficit imposes a softer adverse pressure gradient, thereby delaying the topological bifurcation of the boundary layer. In the deep stall regime, the presence of particles suppresses the dominant tonal instability (Stc ≈ 0.2) associated with coherent vortex shedding, triggering a transition to broadband turbulence. POD reconstruction demonstrates that this spectral shift is driven by vortex fragmentation: particles trapped in the recirculation zone via inertial retention physically disrupt the integrity of large-scale stall cells, redistributing energy from organized shedding modes to smaller dissipative scales. These findings elucidate the microscopic pathway of turbulence modulation in rarefied flows, linking macroscopic shock dynamics to mesoscopic coherent structure breakdown.