Abstract
The effect of capillary, orifice and flow-control valve compensation on the fluid film stiffness, ψ, and static instability (ψ = 0) of hydrostatic cylindrical-pad bearings has been examined both theoretically and experimentally. Equations derived from the basic bearing parameters allow the stiffness to be expressed in non-dimensional form and calculated at any load and eccentricity. The equations show that for the same load and eccentricity ψv> ψo> ψc>. For both orifice and capillary compensation the stiffness may reduce to zero and the shaft become unstable as the load and eccentricity are increased. This does not occur with flow-control valve compensation. Here the stiffness increases rapidly with eccentricity. For this type of compensation a greater stiffness is obtained with a smaller port. For a given orifice or capillary the port size determines the eccentricity when instability occurs. To obtain a maximum stable working range and also to increase the stiffness at any eccentricity a large port is preferred with these types of compensation. The size of the compensating element also affects the inception of instability. Maximum allowable values for various port sizes are derived for square ports.
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