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Unformatted text preview: iven as a ratio of the head loss hm
through the device to the velocity head V2/(2g) of the associated piping system
V2/(2g) Loss coefficient K 1
V2 (6.98) Although K is dimensionless, it unfortunately is not correlated in the literature with the
Reynolds number and roughness ratio but rather simply with the raw size of the pipe
in, say, inches. Almost all data are reported for turbulent-flow conditions.
An alternate, and less desirable, procedure is to report the minor loss as if it were
an equivalent length Leq of pipe, satisfying the Darcy friction-factor relation
or f Leq V 2
Leq K V2
f (6.99) Although the equivalent length should take some of the variability out of the loss data,
it is an artificial concept and will not be pursued here.
A single pipe system may have many minor losses. Since all are correlated with
V 2/(2g), they can be summed into a single total system loss if the pipe has constant
htot hf hm V2 fL
2g d K (6.100) Note, however, that we must sum the losses separately if the pipe size changes so that
V2 changes. The length L in Eq. (6.100) is the total length of the pipe axis, including
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This note was uploaded on 10/27/2009 for the course MAE 101a taught by Professor Sakar during the Spring '08 term at UCSD.
- Spring '08