Quantification of Multistage Particle Fragmentation in a Gas Turbine Axial Compressor

Abstract

Particle ingestion in gas turbine engines leads to erosion, fouling, and deposition, with the severity of damage being dependent on particle characteristics. As particles progress through the axial compressor, they undergo breakage, which results in a terminal size, at which particles cannot break any further. Existing literature lacks the spatial resolution to quantify where most of the breakage occurs and at what stage terminal size is reached. This study presents spatially resolved experimental measurements of particle size distribution at multiple radial positions within the six-stage axial compressor of a Rolls-Royce M250-C20C turboshaft engine. A novel sampling technique using double-sided Kapton tape, wrapped across the leading edge of stator vanes was used to collect particle samples representative of the gas path. Collected samples were imaged using a scanning electron microscope and segmented using the image analysis software MIPAR, which yielded up to 5,000 particles per SEM image. Results show that most of the breakage occurs at the first stage rotor, where the volume weighted average minor axis length drops by approximately 50. Particles impacting near the rotor tip reach terminal size by the first stage, while particles impacting near the hub take longer to reach their terminal size, chipping and fatiguing before completely fragmenting to sizes smaller than those at the tip by the third stage. These findings provide experimental data which can inform and improve dirt ingestion models and support manufacturer maintenance for engines operating in particle-laden environments.