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Viscous Torque and Power on Rotating Shafts Equations and Calculator

Viscous Torque and Power on Rotating Shafts Equations and Calculator

Rotating Shaft in Bearing

Preview: Viscous Torque and Power on Rotating Shafts Calculator (Membership Required: Premium).

Shear stress, τ = µ (du/dy) = µ (u/y), as linearity is assumed

u = π DN/60, y = h, clearance in m

τ = µ (πDN/60h), Tangential force = τ × A, A = πDL

Torque, T = tangential force × D/2 =µ (πDN/60h) (πDL) (D/2)

substituting T = µ π2NLD3/ 120 h

If radius is used, T = µπ2NLR3/15 h

As power, P = 2πNT/60,

P = µπ3N2LR3/450 h

Clearance h is also the oil film thickness in bearings.
End effects are neglected. Linear velocity variation is assumed.
Axial location is assumed.

Where:

L = Length (m)
R = Radius (m)
D = Diameter (m)
h = Clearance (m)
N = Revolutions per minute (rpm)
µ = Viscosity of fluid (Ns/m² or Pas).

The torque will be obtained in Nm and the power calculated will be in W.