Numerical Study Of The Influence Of Blade Roughness On The Aerodynamic Characteristics Of A Centrifugal Compressor

The goals of high thrust-to-weight ratio,high efficiency and low fuel consumption of aeroengines places higher require higher performance of compressors.Civil aviation engines will inevitably inhale dust particles,sand,and even volcanic ash and insects during use,which will increase the surface roughness of the blades in compressors and turbine.Therefore,it is of great practical value to study the changes of the flow field and the aerodynamic parameters of the compressor before and after blade fouling.In this paper,the small turbofan engine DGEN380 centrifugal compressor is taken as the research object and uses numerical simulation to complete the grid independence test,and the validity of the compressor calculation model is verified.The aerodynamic characteristics of compressor blades under different uniform surface roughness are studied.It is found that when the blade surface roughness ks increases from 0 to 270 ?m,the efficiency of the peak efficiency point decreases 4.0%,and the pressure ratio decreases by 7.7% under relatively smooth conditions.The increase of roughness will make the boundary layer thicker,flow separation will present on the suction side,the wake range of the blade trailing edge will increase,and the flow loss will be enhanced.In order to reduce the degradation of the aerodynamic performance of centrifugal compressors caused by the increase of the blade surface roughness,a high-order Bessel curve is used to fit the stacking line of the centrifugal impeller blades,the lean and sweep modification were completed by controlling the blade stacking line;Using the total pressure ratio and isentropic efficiency of the compressor peak efficiency point as the objective functions,combined with artificial neural network and genetic algorithm,complete the automatic optimization of the centrifugal impeller blades with ks set to 150 ?m.The optimized blade adjusts the static pressure distribution,reduces the intensity of the leakage flow from the blade tip and the radial secondary flow in the passage,and improves the aerodynamic performance of the centrifugal impeller.After optimization,the isentropic efficiency of the compressor design point was increased 0.42%,and the working margin was increased 2.5%,which effectively reduced the influence of ks on the aerodynamic characteristics of centrifugal compressors.