Gas-Lubricated Bearings

The solution of Eqn 5-3 is greatly eased by adopting some physical assumptions regarding Eqn 5-1. Ausman [1] treated the lubricating film as an isentropic gas, for which by straightforward thermodynamics we can write 

Here h = h/h, where h is the minimum clearance between the boundina 

Sternlicht and Elwell [2] started with the following form of the generalized Reynolds equation. 

Here V is the bearing diameter, L its axial length, clearance, the average gas viscosity in the bearing, M the 

Analysis of the externally pressurized gas-lubricated journal bearing is involved, tedious and quite specific to the particular problem. Details can be found in the monograph by Pinkus and Sternlicht [4]. 

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Burgdorfer, A., The Influence of the Molecular Mean Free Path on the Performance of Hydrodynamic Gas Lubricated Bearings,"ASMC/. Basic Eng., Vol. 81,1959, pp. 94-100. 

Hsia, Y. T. and Domoto, G. A., An Experimental Investigation of Molecular Rarefaction Effects in Gas Lubricated Bearings... 

It should be noted that this analysis is not restricted to gas lubricated bearings it is applicable to journal bearings with any lubricant where the effects of lubricant inertia... 

Frechette LG, Nagle SF, Ghodssi R, Umans SD, Schmidt MA, Lang JH (2001) An electrostatic induction micromotor supported on gas-lubricated bearings. IEEE 14th Int Micro Electro Mechanical Systems Conf MEMS, Interlaken... 

A miniature canned centrifugal pump to circulate bismuth, ideally suited for in-pile work, has been developed by the Atomic Energy Research Establishment at Harwell, England. The over-all pump dimensions are 3 -in.-diameter by 24 in. long, with a 2-in.-diameter impeller. The bismuth flow is 1.5 gpm with a head of 9 ft. The motor rating is 0.75 hp and 2800 rpm. Two gas-lubricated bearings are utilized. The material of construction is 2j Cr-1 Mo. steel. 

Flow and horsepower sizes vary over a wide range. Turboexpanders with 4- to 6-in-diameter turbine wheels are typical. Ibrboexpanders have been built with wheel diameters over 17 in and as small as in. Miniature turboexpanders with wheel diameters below lin have a rotative speed above 100,000 rpm when only gas-lubricated bearings make a successfiil design possible. 

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