Structural Design And Strength Study Of Tunnel-type Compressor

With the continuous strengthening of the engine,the pressure ratio and speed of the turbocharger are increasing,and the mechanical,aerodynamic and thermal loads of the compressor impeller are also increasing.In addition,the service life of compressor impeller is required to be longer and the cost is required to be lower,which greatly increases the material performance requirements of traditional impeller.As a kind of closed rotating machinery,the new tunnel-type impeller(tunnel-type impeller)has the advantages of higher strength,less leakage loss,larger space for streamline design optimization,higher speed adaptation and lower requirements for material properties.The tunnel-type impeller of compressor mainly bears high-speed centrifugal load,air aerodynamic load,temperature difference thermal load caused by heat of compressed air and vibration alternating load caused by interaction of uneven flow field in the working process.Therefore,in the study of the strength of the new tunnel-type impeller,it is necessary to comprehensively consider the aerodynamics,heat transfer,structure and strength,and adopt the method of multi physical field coupling to obtain more accurate stress and vibration of the tunnel-type impeller.Taking a newly designed single-stage low pressure ratio tunnel-type impeller as the research object,the paper calculates and analyzes the stress and vibration of the tunnel-type impeller under multi load and conditions by using the method of multi physical field coupling solution,which provides the basis for ensuring the safe and reliable operation of the streamline tunnel-type compressor.The main research contents are as follows:Firstly,according to the relevant parameters of the tunnel-type impeller,the inlet,diffuser and volute of the streamline tunnel-type compressor are designed,and the aerodynamic calculation model of the streamline tunnel-type compressor is established,the influence of different working conditions on the temperature and pressure distribution of tunnel-type impeller basin under constant speed was studied,the results show that the temperature and pressure at the exit of tunnel-type impeller will increase with the decrease of flow rate.Secondly,The finite element model of the working wheel of the streamline tunnel-type compressor is established,and according to the temperature and pressure distribution of the tunnel-type impeller basin obtained by aerodynamic calculation,the multi field coupling method is used to calculate the influence of different working conditions and loads on the stress and deformation of the tunnel-type impeller.The results show that: the influence degree of different loads on the stress size and distribution of tunnel-type impeller is centrifugal load,temperature load and aerodynamic load in turn;temperature load and aerodynamic load will increase the equivalent stress of tunnel-type impeller on the basis of centrifugal load;under different working conditions,the equivalent stress of tunnel-type impeller is the largest under small flow condition.Based on the above research results,the method of checking the strength of the tunnel-type impeller considering the load and working conditions is studied,and according to the method,the strength of the tunnel-type impeller is checked,and the critical speed and limit speed of the low cycle fatigue of the tunnel-type impeller are calculated.Finally,the influence of prestress produced by different loads on the modal of tunnel-type impeller is studied,and the results show that the influence of different loads on the modal of tunnel-type impeller can be ignored.