Aerodynamic Characteristics Analysis And Optimization Design Of Fan Rotor Airfoil Leading Edge Erosion

As a core component to ensure the safe flight of aircraft,civil aviation engines have great economic value for promoting social development.However,as the engine runs for a long time on the route,the fan rotor blades located at the foremost end will inevitably be affected by the erosion of foreign sand and gravel particles and the wind erosion effect,which changes the shape of the leading edge.What is more,it leads to the decline of the aerodynamic performance of the blades.At present,domestic civil aviation engine maintenance companies only manually polish the leading edge of the blade whose erosion has not reached the stall limit chord length.Therefore,the consistency of the leading edge of the blade is poor and the exploration of the recovery potential of the aerodynamic performance of the blade is also limited.In addition,the existing research on the design of the erosion front fails to fully consider the working condition and aerodynamic performance of the airfoil.So it is necessary to carry out multi-mode aerodynamic optimization design research for its design mode and large angle of attack conditions,in order to lay the foundation for the subsequent three-dimensional aerodynamic optimization design of the fan/compressor erosion blade.In this paper,based on the research on the leading edge erosion morphology of in-service fan rotor blades and manual polishing and maintenance,the research object is the 50% blade profile of the DGEN380 fan rotor blade of the small body large bypass ratio engine.The leading edge erosion plane cascade and three biased leading edge plane cascade models are established respectively,then numerically simulated with the help of NUMECA software to calculate their aerodynamic characteristics and flow fields.The calculation results show that,compared with the original airfoil,the low-loss angle of attack range of the leading edge erosion airfoil is reduced by 11.75%.After eroded leading edge is polished,it is not only beneficial to broaden the low-loss attack angle range of the airfoil to the level of the original airfoil.The leading edge biased to pressure surface airfoil can basically recover at least 60%of the total pressure loss increase caused by the leading edge erosion.Through the flow field analysis,it is understood that there is a great amount of high-energy fluid at the leading edge of the airfoil and momentum exchange occurs with the flow from the suction surface,so as to obtain sufficient energy to overcome the reverse pressure gradient of the air flow.The thickness of the boundary layer also maintains a relatively healthy development state,which helps airflow to be closer to the suction surface,ultimately effectively reduces the total pressure loss caused by the leading edge erosion and enhances the work pressurization ability of the airflow.However,manual grinding fails to give full play to the recovery potential of the aerodynamic performance of the eroded leading edge blade,so the research on the multi-mode condition and multi-objective optimization design for the eroded leading edge of the blade is carried out.The attack angles of 0°,+4° and +6° were selected as reference operating conditions,and the weight of each operating condition was established by the analytic hierarchy process.The FINE Turbo/Design 3D module was used to build a large radius annular cascade for optimal design.Numerical results show that leading edge optimization significantly improves the aerodynamic performance of leading edge erosion airfoil.The optimized airfoil can not only recover more than 60% of the increase of total pressure loss coefficient caused by erosion of the leading edge,but also reduce the total pressure loss by 4.3% compared with the original airfoil under +4° angle of attack.In addition,the optimization of the leading edge can inhibit the generation and growth of the separation bubble at the leading edge of the blade suction to a certain extent,so that the boundary layer thickness can maintain a relatively good development state and effectively reduce the flow loss inside the boundary layer.