| Gas bearing relays on the gas dynamic pressure film that has formed with a certainstiffness in the bearing clearance to support the stator. Those advantages are that it doesnot require external air feeder, low friction, high speed, long service life, etc. It iswidely used in precision mechanic, space technology, delicate electronic instrument,medical equipment, nuclear engineering and so on. Disadvantages, of course, also exist.The disadvantages are the lower carrying capacity and the smaller gas film stiffness.Stability is major problem for high-speed gas bearing when the gas bearing reaches ahigh enough speed, because the lubrication is gas. It leads to self-excited vibrations.These vibrations are the basic obstacle to a widespread application of gas bearings.In order to solve the above problems, dynamic characteristic coefficients are solvedand stability of rotor-bearing system is analyzed. Experimental data compare withtheoretical calculation results by the method of theory and experimental study.Firstly, taking the conical spiral groove aerodynamic bearing as research object, thenonlinear dynamic lubrication characteristics of fluid are studied in the bearingclearance, and the lubrication model of the conical spiral groove aerodynamic bearingsstate can be derived in the micro scale.Secondly, the gas pressure distribution is calculated in the bearing clearance withthe locally finite difference method and transformation due to differential geometrytheory, which show the influence law of structure parameters and operating parameterson the gas film pressure distribution and the bearing capacity and so on. Secondly, thetransient Reynolds equation with respect to time equals the partial derivative isestablished to calculate unsteady gas film force and dynamic characteristic coefficients,and to reveal the mathematical relationship between whirl and dynamic coefficients.Finaly, the dynamic characteristics of aerodynamic bearing can be studied by newtheory and method. Finally, the mechanical mechanism of the stability of thebearing-rotor system can be revealed by studying dynamic characteristic coefficients and whirl. |
