NUMERICAL INVESTIGATIONS ON INFLUENCE OF UNIFORM BLADE SURFACE ROUGHNESS ON THE PERFORMANCE CHARACTERISTICS OF A TRANSONIC AXIAL FLOW COMPRESSOR STAGE

摘要

Application of surface roughness to rotating mechanical bodies will result into performance degradation. In Aviation Industry, one of the most affecting causes for performance or efficiency degradation of gas turbine engine is the blade surface roughness. The aerosols which are very small particles in the atmosphere having diameters in the microns, impinges to the compressor blade inside the aircraft engine at higher altitudes. The aerosols damages surfaces of the compressor blades. Despite of having small dimensions, due to higher velocity of the aircraft, aerosol's impinging creates roughened surfaces and fouling. This paper is an attempt to numerically evaluate the performance degradation of the single stage transonic axial flow compressor due to uniform roughness created by the aerosols. Various cases with different roughness on various sections of the blades are analyzed to study and identify which section of the blade is more influenced by roughness. The transonic axial flow compressor has a capability of producing 1.36 stage total pressure ratio, swallowing air mass flow rate of 23 kg/s at rated design speed of 12930 rpm is used for the steady state numerical analysis. A systematic steady state 3- dimensional numerical study using solver with SST k-ω turbulence model has been carried out to evaluate the impact of blade surface roughness on the performance of compressor stage. Moreover, cases with the aerosols having different dimensions and their resulting effect is also studied to find out how performance varies when the aircraft enters into atmosphere having big aerosols from the atmosphere having smaller one and vice-e-versa.