Rotor Dynamics Analysis Of Turbine With Air Foil Bearings

The air circulation machine is the core component of the aircraft environmental control system.It is an important guarantee for the efficient and reliable operation of the aircraft cockpit and equipment cabin in a dry,clean and suitable temperature environment.As a typical turbo compressor rotor structure,dynamic analysis of the rotor system with air foil bearings of the air cycle machine is necessary to ensure equipment safety and improve operating efficiency.Based on the high-speed and light-weight requirements of aviation equipment,based on the optimization of the structure,the numerical simulation method is used to systematically analyze the dynamic characteristics of the air cycle machine,aiming at providing reference for the design and development of the rotor system with air foil bearings.The main research contents are as follows:Based on the Reynolds equation of compressible gas,the model of 360°circular self-acting gas bearing is established,and the variation law of static and dynamic characteristic coefficient with rotation speed is studied.The calculation results show that the eccentricity has a significant influence on the maximum film pressure,and it is found that there is a critical speed value in the change of the maximum film pressure.Based on the above conclusions,the influence of the radius clearance,the preload coefficient,the pivot positions coefficient and the applied load on the static and dynamic characteristics of the self-acting gas bearing is determined and the calculation parameters are determined.Finally,the stiffness and damping parameters of the selected gas bearing are obtained.The gas bearing-rotor system model with and without enhanced airflow excitation force is established and the first three critical speeds and modes are calculated.The accuracy of the model is verified by Abaqus.The calculation results show that:The presence of the airflow excitation force reduces the first two critical speeds of the rotor system.A steady-state synchronous response analysis of the turbine end and the compressor end imbalance was found to be more sensitive to the application of the unbalanced amount.The transient vibration characteristics under airflow excitation are obtained by numerical integration.Finally,the stability of the rotor system is analyzed and found to be poor in the starting stage of the rotor system.Based on the design flow chart of the air circulation machine,the selection of the gas bearing,the design of the test system and the structural design of the air cycle machine test bench were completed.According to the design flow chart of the air circulation machine,the selection of the gas bearing,the design of the test system and the structural design of the air cycle machine test bed are completed,which lays a foundation for the next experimental research.