Question

An oil of viscosity 7 poise is used for lubrication between shaft and sleeve. The diameter of shaft is 0.6 m and it rotates at 360 rpm. Calculate the power lost in oil for a sleeve length of 160 mm. The thickness of oil film is 1 mm.

• A. 26.96 kW
• B. 50.62 kW
• C. 37.97 kW
• D. 12.65 kW

Answer 1

The correct option is A 26.96 kW

Power lost = torque $\times$ angular velocity
= Force $\times$ radius $\times \omega$
= shear stress $\times$ area $\times$ radius $\times \omega$

Shear stress = viscosity$\times$velocity gradient

Lost power $=0.7\times \frac{0.3\times 12\pi }{0.001}\times 2\pi \times {0.3}^2\times 0.16\times 12\pi$

Lost power = $26.96$ kW