Aerodynamical Performance Decay Due to Fouling and Erosion in Axial Compressor for GT Aeroengines

The ingestion of solid abrasive particles and/or foulants causes erosion of the compressor blades, resulting in a considerable reduction in the performance and working life of aviation/heavy duty GT and an increase in fuel consumption. The geometry variation at the Leading Edge (L.E. blunting) and Trailing Edge (T.E. thickness reduction), together with the general increase of airfoil surface roughness, depends on the characteristics of the incident particles, the geometry and the materials of the blade cascade, the dynamic parameters of the particles and on the type of impact. In order to rectify this degradation in performance, it is therefore necessary to re-profile the blades with machining that is highly critical for the performance of the engine, the life of the compressor blades and for maintenance costs. In order to determine an optimum and cost effective process of reprofiling, a series of tests reproducing the corresponding models of flow have been carried out on the Water Table Test Bench using Lamb’s hydraulic analogy relative to profiles of the VII and VIII stage HP of the compressor of the GT CF6-50 (G.E. Co.). The tests were carried out both on the isolated airfoil profile and on the blade cascade and both in the original conditions, at varied geometry (because of erosion and/or fouling) and after re-profiling. The trajectories of the particles have been visualised in several ways (like a false color photographic procedure), confirming results reported by various authors related to the model of impact and erosion. Particularly in the case of the dust aspiration during the arrival phase on the deck of an aircraft carrier. The test results have been discussed and compared with those available in scientific literature