Vibration And Dynamic Stress Safety Assessment Of Small High Pressure Ratio Centrifugal Compressor Blade

With the improvement of micro gas turbine technology,the development of small high pressure ratio high speed centrifugal compressor has been greatly promoted.High-speed rotating centrifugal compressor blades are affected by aerodynamic load,centrifugal load and other aspects.Under the combined action of these loads,vibration is easy to occur,and the degree of deformation and vibration frequency are increasing.When the response frequency of the vibration caused by the excitation force is equal to or in a multiple relationship with the natural frequency of the blade,the blade resonance is the main cause of the blade crack and fracture.In order to prevent blade safety accidents and improve the pressure ratio and overall efficiency of centrifugal compressor,the aerodynamic characteristics analysis,blade stressstrain and modal analysis of the modified Krain centrifugal impeller are carried out and related research is carried out.The main research contents are as follows :1.The flow field of the impeller of a small high pressure ratio centrifugal compressor is analyzed by ANSYS CFX software,and the distribution of flow field parameters in the impeller of a single channel small high pressure ratio centrifugal compressor is analyzed.By comparing with the experimental data,the feasibility and reliability of the research object and the numerical method adopted in this thesis are demonstrated.The numerical simulation is used to compare the performance of the impeller with three different leading edge installation angles of the splitter blade.The aerodynamic performance of the three schemes is studied,and the optimal angle of the leading edge installation angle of the splitter blade is given and the flow of the flow channel after the impeller is improved is analyzed.2.Based on the ANSYS Workbench simulation platform,the one-way fluid-solid coupling of a small high-pressure ratio centrifugal compressor is studied,and the maximum stress and strain of the centrifugal compressor blade and its position under the fluid-solid coupling are analyzed,and the stress and strain distribution of the main blade and the splitter blade are obtained.The allowable stress of blade material is calculated and compared with the maximum stress of blade.3.Finally,the modal analysis of the blade is carried out,and the vibration frequency of the first six orders of the blade is calculated.It is concluded that the centrifugal force enhances the stiffening effect of the blade,which increases the vibration frequency of the main blade and the splitter blade,and the resonance of the main blade and the splitter blade under different load conditions is judged.Through the above research,the aerodynamic performance of three different splitter blade leading edge installation angles of the centrifugal compressor is understood,the stress and strain of the main blade and the splitter blade are evaluated,and the blade resonance is analyzed.Prevent the blade from being destroyed during high-speed rotation.