Answer to Question #303855 in Molecular Physics | Thermodynamics for Naomi

Question

Dynamic viscosity of oil used for lubrication between a shaft and a sleeve is 0.8Ns/m². The shaft is of d=0.5m and rotates at 190rpm. Calculate the horsepower lost in bearing for a sleeve length of 0.1m. Thickness of oil film is 2mm

Answer 1

$u=\frac{\pi DN}{60}=3.98~\frac ms,$

$\tau=\mu\frac {du}{dy}=1592~\frac N{m^2},$

$F=\tau \pi Dl=180.05~N,$

$T=F\frac D2=36.01~Nm,$

$P=\frac{2\pi NT}{60}=716.48~W.$