| With the increasing number of subway construction projects,the performance and safety of the axial fan have become one of the most important topics in the research of the subway system.With the development of science and technology and the change of actual demand,many performances of turbomachinery are constantly improved,which will bring new challenges to the safety of the operation.Therefore,it is necessary to conduct numerical simulation for fan impeller based on fluid solid interaction,Based on that,the running state of impeller is analyzed,providing a reference for structural improvement and fault diagnosis.Taking the impeller of a condensing axial fan of a subway as the research object,the static analysis of the impeller under unidirectional fluid solid interaction is carried out on the basis of the steady calculation results of the fan.the analysis shows that centrifugal force plays a leading role in the size and distribution of the equivalent stress.Gravity can not be considered.Aerodynamic force has a certain effect.The maximum stress occurs near the location hole and the hub bending,and the maximum deformation occurs on the top of the blade;The maximum equivalent stress and maximum deformation of the impeller decrease with the increase of flow rate,and the sensitivity of the latter is greater than that of the former;The maximum deformation of impeller X and Y direction is 0.89485 mm and 0.85707 mm,which is smaller than the gap between impeller and shell,and the maximum equivalent stress is less than allowable stress.Therefore,the strength and stiffness of impeller structure meet the requirements.In this paper,the unsteady flow field is calculated on the basis of steady state analysis,the frequency of the air flow pulsation is obtained,and the resonance analysis is carried out with the results of the modal calculation of the impeller.The results show that the impeller is dominated by the blade vibration,the deformation of the blade is the smallest in the nodal line area,the deformation of the whole hub is smaller;After loading,the natural frequency of impeller increases by 18%,the natural frequency is mainly affected by centrifugal force,and the aerodynamic force has a certain effect.Gravity can be ignored;the fundamental frequency of theaerodynamic pulsation falls in the eighth to tenth order,and the local resonance near the top of the blade will produce local resonance.However,the equivalent stress in the region is much lower than the yield limit of Al5052,and the impeller will not cause resonance failure.In this paper,the Sines high cycle fatigue criterion is applied to predict the fatigue life of impeller by two calculation methods.The results show that the influence of aerodynamic force should be considered when analyzing fatigue life,and the surface condition of impeller has great influence on the life.Fatigue life of a impeller under unidirectional flow solid interaction is obtained when the size of the different positioning holes,Results show that the fatigue life of the impeller of the standard positioning hole to meet the design requirements,the increase of the size of the positioning hole will increase the equivalent stress amplitude and reduce life,nd can significantly improve the fatigue life of non hole;the machining coefficient of the surface of the positioning hole has a great influence on the fatigue life. |
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