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7.48 E8 (1.1 E-5)(274,800)
0.5 274,800 6.05 ft/s Ans. We did not get 6.0 ft/s exactly because the 4.5-ft head loss was rounded off in Example 6.6. Iterative Solution
As in Eq. (6.9) the friction factor is related to velocity:
f hf d 2g
L V2 or (4.5 ft) 0.5 ft
200 ft V 2(32.2 ft/s2)
V2 0.7245/f Knowing /d 0.0008, we can guess f and iterate until the velocity converges. Begin with the
fully rough estimate f 0.019 from Fig. 6.13. The resulting iterates are
f1 | v v 354 | 0.019: e-Text Main Menu V1 | 0.7245/f1 6.18 ft/s Textbook Table of Contents Red1 | Vd 280,700 Study Guide 6.5 Three Types of Pipe-Flow Problems f2 0.0198: V2 6.05 ft/s f3 0.01982: V3 Red2 6.046 ft/s 355 274,900
Ans. The calculation converges rather quickly to the same result as that obtained through direct computation. Type 3 Problem: Find the Pipe
Diameter The Moody chart is especially awkward for finding the pipe size, since d occurs in all
three parameters f, Red, and /d. Further, it depends upon whether we know the vel...
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- Spring '08