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Sample Examples ˗ Traditional Format ˗ Fluid Mechanics Problems

Example 1: A 25 mm diameter shaft is pulled through a cylindrical bearing as shown below.

The lubricant that fills the 0.33 mm gap between the shaft and the bearing is an oil having

a kinematic viscosity of 8.0 x 10-8 m2/sec and a specific gravity of 0.91. Find the force

P required to pull the shaft at a constant speed of 3 m/sec. Assume the velocity distribution

in the gap is linear. Length of the shaft, L, is 0.5 m.

Example 2: Water is supplied at 150 ft3/sec and 60 psi to a hydraulic turbine through a

3 ft inside-diameter inlet pipe as shown in the figure below. The turbine discharge pipe

has a 4 ft inside-diameter. The static pressure at section (2), 10 ft below the turbine

inlet, is 10 in Hg vacuum. The turbine develops 2500 hp. Find the power lost between

sections 1 and 2.