Stability Analysis Of High Speed Aerostatic Bearing Rotor System

Gas bearing can provide more advantages than conventional bearings forpractical industrial applications. These advantages include elimination of thelubrication system, friction free operation and low vibration, long life cycle andlow maintenance costs. Hence gas bearing have been successfully applied toequipment such as centrifuges, milling machines, molecular vacuum pumps toincrease rotating speed, reduce energy loss, or increase precision of position.Disadvantages, of course, also exist. The disadvantage is the low carryingcapacity. Stability is major problem for high-speed gas bearing, because thelubrication is gas. When during the operation of rotors supported in gas bearingstheir rotational velocity reaches a sufficiently high value, the loss ofsteady-state stability occurs. It leads to self-excited vibrations. These vibrationsare the basic obstacle to a widespread application of gas bearings.In order to solve the above problem, this paper takes O rubber ringembedded between the body and bearings, to improve the stability of the system,therefore. This paper mainly studies the dynamic stability of gas bearing rotorsystem.First of all, on the basis of gas bearing Reynolds equation, and defining aseries of first order Taylor expansion of related variables, and at the same time,using linear perturbation method to formula the dynamic stiffness and dynamicdamping coefficient of gas bearing, and then using center finite differencemethod and successive super relaxation iteration method, to solve linear partialdifferential equations, the paper analyses the influence of the centrifugal rate,rotor rotation speed, whirling ratio, gas supply pressure, eccentricity on thedynamic characteristics coefficient of the gas bearing.And then, establishing bearing rotor system model, by combining thedynamic coefficient of the gas bearing obtained from the front, then establishingthe system dynamics equation, and at the same time, using the Routh-Hurwitzstability criterion, judge the stability of the system, and present the result of thedynamic properties of elastic supports having the form of rubber O-rings and theresult of the stability threshold of the gas bearing system. and analyzes theeffect of the gas supply pressure, centrifugal rate, whirling ratio on the stabilityof system, uses New-mark gradually integral method to solve the imbalanceresponse of the system.The last is about gas bearing-rotor system experimental established,experiment and the analysis of experimental results, test bench including:holding mechanism, electric spindle, test devices. Experiments including: accelerate test to get the critical speed and the amplitude of unbalance response.Large vibration of a rotor-bearing system excited by unbalance forces orexternal forces can deteriorate the performance and shorten the lifetime of thesystem. To reduce the vibration, properly designed gas bearing can be installed toprovide desirable damping and stiffness for the rotor-bearing system.