Question

A journal bearing has shaft diameter of 40 mm and a length of 40 mm. The shaft is rotating at 20 rad/s and the viscosity of the lubricant is 20 mpa.S. The clearance is 0.020 mm. The loss of torque due to the viscosity of the lubricant is approximately

Answer 1

Answer:

0.040 nm

Step-by-step explanation:

Given  

A journal bearing has shaft diameter of 40 mm and a length of 40 mm. The shaft is rotating at 20 rad/s and the viscosity of the lubricant is 20 mpa.S. The clearance is 0.020 mm. The loss of torque due to the viscosity of the lubricant is approximately

We know that  

Shaft diameter 2r = 40 mm, l = 40 mm

There is a shear stress due to fluid friction.

We know that  

Torque = (τ A) r

T = τ x 2πrL x r

So τ = μV / C (2πr^2)L

       = μrw / C (2π r^2)L

    L = 2πμ / C r^3 WL

      = 2π (20 x 10^-3)(0.020)^3 x 20 x 0 / 0.02 x 10 ^-3

    L  = 0.040 Nm