60

Thus, the bearing is operating in the laminar regime. To become turbulent (assuming constant viscosity), the operating speed would have to increase to approximately 38,500 rpm.

The example cited is for a relatively high-speed, oil-lubricated bearing for pump applications. In general, most pump bearings operate in the laminar regime. Exceptions might occur when water is used as tbe lubricant because it its much less viscous than oil.

Evaluation of Frictional Losses It is often desirable to obtain a quick estimate of viscous drag losses that the journal bearings produce. If we consider shear forces again, we return to the laminar flow equation:

where F = viscous shear force, lb (N) m = viscosity, lb • s/in2 (Pa • s) A = surface area, in2 (m2) u = journal velocity, in/s (m/s) h = film thickness, in (m)

To obtain friction, we multiply both sides of Equation 21 by the journal radius R. Then the viscous frictional moment is

Survival Treasure

Survival Treasure

This is a collection of 3 guides all about survival. Within this collection you find the following titles: Outdoor Survival Skills, Survival Basics and The Wilderness Survival Guide.

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