Sommerfeld Number
Sommerfeld number, abbreviated as S, a dimensionless number, is used extensively in hydrodynamic lubrication analysis. The Sommerfeld number is very important in lubrication analysis because it contains all the variables normally specified by the designer.
Sommerfeld Number formula |
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| \(\large{ S = \left( \frac{ r }{ c } \right)^2 \; \frac{ \mu\;n}{P} }\) | ||
| Symbol | English | Metric |
| \(\large{ S }\) = Sommerfield number | \(\large{dimensionless}\) | |
| \(\large{ \mu }\) (Greek symbol mu) = absolute viscosity | \(\large{\frac{lbf - sec}{ft^2}}\) | \(\large{ Pa - s }\) |
| \(\large{ P }\) = load per unit of projected bearing area | \(\large{\frac{lbf}{in}}\) | \(\large{\frac{N}{m}}\) |
| \(\large{ c }\) = radius clearance | \(\large{ft}\) | \(\large{m}\) |
| \(\large{ r }\) = shaft radius | \(\large{ft}\) | \(\large{m}\) |
| \(\large{ n }\) = shaft rotational speed | \(\large{\frac{r}{min}}\) | \(\large{\frac{r}{min}}\) |
Tags: Fluid