Numerical Research On The Effects Of Blade Surface Roughness On Compressor Aerodynamic Characteristics

During the operating process,affected by ingested air contaminants and electrochemical corrosion,the gas turbine blades suffer the risk of local or overall damage,which will cause the power output and performance degradation.The direct representation form of compressor blade damage is the increasing of surface roughness height,and this increasing will go on as it is operating.At a microscopic view,surface roughness changes the blade geometric profile,and then the roughness elements promote the skin fraction and heat transfer rate,which leads more internal flow loss.Due to the complicated compressor internal flow field and the fact that the main affect by blade surface roughness is limited under the boundary layer,the reported literatures home and abroad mainly focus on cascade testes and numerical research on 3D compressor.Considering the above discussion,this paper has put its research contents on numerical investigation of T3 series flat plate test cases and NASA Stage35 core compressor by using commercial software ANSYS CFX.The following is the list of main research interests.1.Study on effects of surface roughness on boundary layer flow.By using adding the sensibility in the near wall functions and establishing a randomly rough wall with a Gauss distribution,respectively,the effects of surface roughness on boundary layer flow were studied on the T3 series flat plate.The skin fraction coefficients,boundary layer displacement thickness and shape factor were investigated on T3 flat plate with different roughness height,and the effects on transition process were also studied.At the same time,the comparison and evaluation between the two approaches on studying the rough surface flow was employed,which provided the basis of the research of effects of blade roughness on compressor aerodynamic characteristics.2.Study on effects of uniform surface roughness on compressor aerodynamic characteristics.On the basis of validation on the established Stage35 calculating model,numerical simulations under 100% design speed were carried out by imposing different roughness height on rotor and stator blades respectively.The effects of surface roughness on compressor overall performance and internal flow were analyzed.Combined with the wall functions method,a new fitted correlation of compressor loss parameters and dimensionlessroughness height was established.3.Study on effects of non-uniform surface roughness on compressor aerodynamic characteristics.Calculation models with chordwise and spanwise non-uniform roughness were established,respectively.The non-uniform roughness was imposed on rotor blade with definitized distribution regulations,and the impacts of blade roughness location on compressor overall performance and internal flow field were investigated.Also the effect laws of non-uniform roughness and compressor loss parameters were summarized.4.Study on effects of blade pressure side and suction side surface roughness.Different surface roughness were imposed the compressor rotor blade pressure side and suction side surface,respectively.The impacts of blade pressure side and suction side surface roughness on compressor overall performance and internal flow field were investigated and an averaged surface roughness was used to evaluate the effects of non-uniform roughness.