Question

Which one of the following is criterion in the design of the hydrodynamic journal bearings?

• A. Rating life
• B. Specific dynamic capacity
• C. Sommerfeld number
• D. Rotation factor

Answer 1

The correct option is C Sommerfeld number

Sommerfeld number,
$S=\frac{ZN}{P}{\left(\frac{D}{C}\right)}^2$
It is called bearing characteristic number
where $Z$ = Absolute viscosity of lubricate
$N$ = Speed (RPM)
$P$ = Bearing pressure on projected bearing area $\left(N/m{m}^2\right)$
$D$= Diameter of the journal
$C=$ Diametral clearance