Research On Influence Of Tip Clearance On Flow Field And Structural Characteristics Of Axial Flow Compressor Blades

Axial compressor is an important part of aero engine.Tip clearance is one of the key factors affecting its reliable and efficient operation.Therefore,when designing axial flow compressor blades,the structural strength should be taken into account while improving aerodynamic performance.Therefore,based on CFD/CSD coupling solution technology,it is of great academic significance and practical value to study the influence of tip clearance on the flow field and structural characteristics of axial flow compressor blades to ensure the reliability of blades.The main research work of this paper is as follows:（1）Finite element models of blade flow field and structure field with various mesh values were created using NASA Rotor 37 design tip clearance specifications.Grid independent analysis was used for the model,and then the flow field simulation results were compared with the experimental data in the literature to ensure the reliability of the numerical calculation method of the flow field.（2）The pressure field and temperature field of axial compressor are obtained by simulation under the design tip clearance.Then,the numerical interpolation technique is used to take it as the external load of the blade structure,and the flow field and stress deformation of the axial compressor blade under different mass flows are studied by the one-way thermal-fluidstructure coupling method.（3）According to the design blade top clearance,finite element models of the blade flow and structural fields were produced for 60%,80%,100%,120%,and 140% of the blade top clearance.Studing on the influence of tip clearance on flow field and stress deformation of axial compressor blade under different mass flow.The results show that,while decreasing the blade top clearance improves the compressor’s total pressure ratio and efficiency,it decreases the stall margin and increases stress and deformation.When it is larger than the design gap,the average value of the maximum stress increases with the increase of the gap,because the decrease of the centrifugal force is not enough to offset the increase caused by aerodynamic force and thermal stress.（4）The load spectrum obtained by transient solution is used to analyze the high cycle fatigue of the blade.Studying on the influence of different tip clearances on the fatigue life of axial compressor blades.The results show that the dangerous point of the blade with the designed tip clearance is located at the trailing edge root,and the minimum life of the blade near the design point is about 3389 hours.After leaving the stall condition,the fatigue life increases with the increase of the mass flow,while total pressure ratio decreases with the increase of the mass flow,so it is necessary to balance the fatigue life and total pressure ratio.Considering the factors of total pressure ratio,adiabatic efficiency,stress,deformation and fatigue life,it can be concluded that when the tip clearance is between the design tip clearance and 80% tip clearance,the performance can be improved without the fatigue life being greatly reduced.However,when the tip clearance is less than 80% or greater than the design tip clearance,the blade fatigue life is greatly reduced,which is not applicable.