Particle-size effects on transport, retained deposition, and roughness propensity in a transonic compressor

Particle ingestion can alter compressor aerodynamics, wall-impact patterns, deposition, and blade-surface roughness. This study investigates particle-size-dependent transport, wall interaction, retained deposition, and roughness propensity in NASA Stage 35 under an accelerated particle-loading condition. A sequential Eulerian–Eulerian/Eulerian–Lagrangian framework is employed. A steady two-way Eulerian gas–particle calculation first provides the particle-laden aerodynamic response and particle-conditioned mean carrier-flow field. The resulting mean gas-phase variables are then used for deterministic one-way Lagrangian tracking, in which the gas field affects particle motion but the Lagrangian parcels do not feed back to the gas phase. Particle trajectories and wall-impact kinematics are evaluated using a two-stage adhesion–retention criterion. Each impact event is first classified as initial adhesion or rebound and then as retention or non-retention according to the local time-averaged wall shear. Only particles satisfying both criteria contribute to the retained deposited volume, which is converted into equivalent deposition thickness and equivalent sand-grain roughness height through a quasi-steady accumulation procedure. Smaller particles mainly follow the carrier flow and produce relatively distributed wall-impact patterns, whereas larger particles exhibit stronger inertial deviation and preferential concentration near the tip/endwall region. The 5.0 μm case produces the strongest localized retained deposition and roughness propensity. The reported aerodynamic changes arise from two-way Eulerian gas–particle coupling under smooth-wall conditions. Because the predicted roughness is not fed back into the flow calculation, long-term fouling-induced performance degradation is not quantified. The predicted surface fields therefore represent time-averaged retained-deposition and roughness-propensity distributions rather than transient deposit-layer evolution.