Research On Rotor Structure Characteristics Of Twin-screw Compressor Under Fluid-heat-solid Coupling

As a positive displacement compressor,twin-screw compressors are widely used in our country,especially in foodstuff,medical treatment,refrigeration and numerous other field of life.As the core component of the compressor,the screw rotor is particularly important to the performance of the compressor.At this stage,domestic and foreign twin-screw compressors are developing in the direction of high-speed,high-precision and high-efficiency,which causes the screw rotor to be in a high temperature and high pressure environment for a long time,which affects the damage of the rotor structure.According to statistics,70% of compressor failures are caused by the destruction of the screw rotor structure.In order to improve the service life of the screw rotor,the pressure field and temperature field generated during the compressor working process are comprehensively considered,the multi-field coupling numerical analysis of the twin-screw compressor is carried out to study the structural characteristics of the screw rotor.The main research step are as follow:(1)Establish the finite element model of the internal flow field of the twin-screw compressor,and obtain the pressure field and temperature field generated during the working process based on the finite volume method.The pressure field and temperature field of the compressor are used as the external load of the rotor through numerical interpolation technology,and the distribution law of the pressure load and temperature load on the surface of the screw rotor is studied.(2)By solving the static balance equation of the screw rotor structure,the distribution law of the screw rotor deformation and stress under the torque effect,fluid-solid coupling,thermo-solid coupling,and fluid-heat-solid coupling of the twin-screw compressor is studied.The deformation and stress changes of the compressor under different working conditions under these four conditions are analyzed.(3)On the basis of fluid-heat-solid coupling,the distribution of friction stress and contact pressure of the screw rotor is analyzed,and the law of axial bending deformation of the screw rotor under the action of fluid-heat-solid coupling is studied.The modal frequency of the screw rotor under fluid-heat-solid coupling and torque is compared,and the influence of the temperature field and pressure field generated by the compressor on the vibration characteristics of the screw rotor is obtained.(4)In the case of compressor fluid-thermal-solid coupling,the fatigue life of the screw rotor is analyzed by the linear cumulative damage theory and the nominal stress method,and the life distribution of the screw rotor under torque and fluid-thermal-solid coupling is obtained.The fatigue life of the screw rotor under different exhaust pressures is analyzed.The research results have certain theoretical references for the structural design and optimization of screw compressors.