The kinematic viscosity of oil of specific gravity .8 is .0005 .This oil is used for lubrication of shaft of diameter .4 m and rotates at 190 rpm. Calculate the power lost in the bearing for a sleeve length of 90mm. The thickness of the oil film is 1.5mm.

Answer 1

Power lost= torque * angular velocity
= force* radius* angular velocity
= shear stress * area* radius* angular velocity
Shear Stress = viscosity* velocity gradient
Power lost= 0.0005*0.8*1000* 2*3.142*190/60*0.2*3.142*0.23 * 190/60
= 477.65 Watts.