Study On The Influence Of The Tip Clearance Of The Axial Fan On The Dyamic Stess Of The Blade And The Design Of The Blade Vibration Test Bench

The blade is the core component of the axial compressor and its safety is critical.The tip clearance affects the flow field distribution inside the compressor.The size of the tip clearance has an important influence on the pressure ratio,efficiency and aerodynamic damping of the compressor,and affects the reliability and service life of the blade by affecting the aerodynamic stress of the blade.Therefore,the factor of the tip clearance must be considered during the compressor design phase.This paper first introduces the theoretical basis of blade aeroelastic analysis based on "energy method",and puts forward a specific numerical calculation method.The method is verified by NASA Rotor67 as an example.Then,taking a mine axial flow compressor as an example,the aerodynamic damping ratio of the blade at 18°,30°and 45°into the air angle is calculated,and the aerodynamic damping of the blade at different tip clearances at each inlet angle is calculated.ratio.After obtaining the aerodynamic damping ratio of the compressor,the compressor is still the research object.Through the calculation of the unsteady value and the harmonic response analysis of the forced vibration,the angles of the three blades of 18°,30°and 45°are obtained.Unsteady aerodynamic forces and dynamic stresses under the tip clearance.The results show that with the change of the head clearance of the moving blade,the dynamic stress of the blade also changes.The size of the tip clearance is nonlinear with the dynamic stress.There is a tip clearance,which causes the blade to be affected by the tip clearance.The dynamic stress is the largest,and the risk of high circumferential fatigue of the blade is also higher.This conclusion can provide reference for the height control of axial flow and compression air tip clearance,and has important guiding significance for compressor design and fault analysis.In addition,the blade excitation test bench and the high-speed blade vibration monitoring test bench were established.After the composition and function of the test bench were introduced,the finite element analysis of the test bench was carried out.Comparing the numerical calculation results of the unsteady aerodynamic analysis of the blades of the high-speed blade vibration monitoring test bench with the experimental results,it is found that the numerical calculation results are very close to the experimental results and completely achieve the purpose of fault prediction.