Design And Experimental Study On Air Cycle Machine Rotor System Supported By Gas Foil Bearing

Air Cycle Machine is the core component of air condition in plane and is widely used in armored car.The rotor system that adopts gas foil bearings(GFB)as Air Cycle Machine has become the standard of aviation.GFB is a kind of aerodynamic gas bearing supported by flexible structure,which has several advantages over conventional rolling bearing and fluid film bearings.These advantages include stable operation at higher speeds and temperatures,reduced weight due to the elimination of the oil system,low power loss at high speeds and long life with little maintenance.However,there is only a few researches focusing on the performance test,manufacture and application of GFBs in China.Base on the project of Combined Cooling Heating And Power(CCHP)system with micro gas turbine,the thesis tries to develop a ACM of 13Kw cooling power depending on the theoretical research and manufacturing process of GFBs by our team.This thesis focuses on design,debugging and experimental study of ACM bearing-rotor system.Furthermore,a virtual instrument measuring system,which aims to monitor the operation process,display,store and analyze data,would be developed for testing GFB.The main contents of this dissertation are as follows:(1)Designing ACM bearing-rotor system.Structure parameter of ACM rotor and GFB is initially determined by experience in rotating machinery and GFB design to calculate its stiffness and damp coefficient.Then the results would be substituted in the dynamic model of rotor-bearing system and the Undamped Critical Speed Map,Rotordynamic Damped Natural Frequency Map and Unbalance response would be analyzed to adjust the parameters until it meets the ACM design requirements.(2)Developing a virtual instrument measuring system.The test system mainly consists of three optional modules to test the GFB:static characteristic,dynamic characteristic,bearing-rotor system.(3)Manufacturing gas foil journal bearings and thrust bearing.Performance experiments Which include dynamic and static characteristic are carried out for the manufactural bearings to meet the requirement of ACM.(4)Assembling,debugging and experimenting ACM prototype.According to the analysis of experiment and experimental data,the main reason why prototype rotor has the problem of excessive vibration is manufactural accuracy of Thrust disc and turbine housing,which makes the clearance between thrust disc and thrust bearing bigger than the design and arose radial force to the rotor when turn on the driven gas source.Through repeating the tests,analysis and modifications,the amplitude of rotor vibration was reduced to 10?m.