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Experimental Investigation of the Influence of Fouling on Compressor Cascade Characteristics and Implications for Gas Turbine Engine Performance

This article describes the findings of a study which examined the influence of fouling on the behaviour of a cascade and by making use of these results the performance implications for gas turbine engines of exposure to airborne foulants. A suction-type compressor cascade tunnel with a plenum chamber was employed for investigating fouling blade effects. The tests showed that such a testing arrangement allows the extraction of pressure and corrected velocity distribution data downstream of the blades that is comparable with what can be obtained from blow-type cascade tunnels. This study presents experimental results for smooth clean cascade blades and for uniformly fouled blades. For all the cases considered, mid-span-corrected velocity distributions and pressure losses taken one chord downstream of the blades were investigated in order to identify the effects of fouling on the blades. The result of fouling on exit flow angle was investigated as well. In the present study, cascade clean and fouled cases were used to predict real engine performance. Results are obtained in terms of stage polytropic efficiency, thermal efficiency, useful power, and compressor efficiency deterioration. Roughening the cascade blades uniformly with particles of 254 μ m size, the compressor efficiency dropped by 7.7 percentage points.