Analysis on film flow characteristics of high lifting air static thrust bearings
In order to clarify the static/dynamic characteristics of aerostatic bearing under high lifting,the transient model was used to analyze the formation and evolution of supporting gas film turbulence and the energy dissipation process.Then,the flow state evolution,temperature distribution,Mach number variation and vorticity characteristics in the characteristic region of the flow field were described by the method of bidirectional fluid-solid thermal coupling.Furthermore,the theoretical analysis and experimental test results were combined to clarify the characteristics of the internal flow field of the air bearing film,the bearing capacity,stiffness characteristics and micro-vibration characteristics of the system under high lifting.The results showed that there was a phenomenon of aerodynamic heating in the film flow field of air bearing with negative pressure under high lifting.The large pressure drop inside the gas film and the enhanced compressibility of the fluid led to the bad static characteristics of the air bearing.Considering the fluid-solid thermal coupling effect,the calculation accuracy of static characteristics of aerostatic thrust bearings can be effectively guaranteed under high lifting.Especially,the calculation errors of bearing capacity and stiffness were only 2.2％and 2.7％,respectively,when air was supplied with 50 μm film at 1 MPa.
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