Solve the following:
Q: A journal bearing has a clearance of 0.5 mm. The journal has a diameter of 100 mm and rotates at 3600 rpm within the bearing. The journal is lubricated by an oil having a density of 800 kg/m3, a viscosity of 0.01 kg/(ms), and a thermal conductivity of 0.14 W/(mK). Both the journal and the bearing temperatures are maintained at 60°C. Calculate the rate of heat transfer from the bearing and the power required for rotation per unit length.
GIVEN
A journal bearing
Diameter (D) = 100 mm = 0.1 m
Clearance (H) = 0.5 mm = 0.0005 m
Rotational speed (I?) = 3600 rpm
Oil properties
Density (I) = 800 kg/m3
Viscosity (1) = 0.01 kg/(ms)
Thermal conductivity (k) = 0.14 W/(m K)
Temperature of both surface (Tb) = 60°C
ASSUMPTIONS
Steady state
Uniform and constant surface temperatures
Constant fluidproperties
