DIRECT NUMERICAL SIMULATION OF PARTICLE-LADEN FLOW IN A LINEAR COMPRESSOR CASCADE: BLADE EROSION INDUCED BY UNSTEADY BOUNDARY LAYERS

We perform point-particle direct numerical simulations
(PP-DNS) of particle-laden flow through a linear compressor
cascade subjected to synthetic freestream turbulence. Monodisperse
particles are advanced in a one-way coupled Eulerian-
Lagrangian framework with drag-only dynamics. We quantify
blade-particle collisions and resulting blade erosion based on
high-fidelity data, and the erosion hotspots are predicted near the
leading edge and over the pressure side. On the pressure side,
for intermediate Stokes numbers, the onset of collisions correlates
with elevated boundary-layer intermittency associated with
bypass transition, whereas for larger particles impacts occur farther
upstream with a higher probability of multiple rebounds. On
the suction side, sparse collisions appear only for the smallest
particles and are phase-modulated by separation-induced vortex
shedding. Joint distributions of impact velocity and angle show
that leading-edge impacts are faster and span wider angles than
pressure-side impacts, explaining their greater erosive severity.
The present results highlight the role of unsteady boundary-layer
dynamics in affecting erosion in compressor cascades