Page 241 - Bird R.B. Transport phenomena

Problems 225

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7A.5 Force on a U-bend (Fig. 7A.5). Water at 68°F (p = 62.4 lb /ft , fx = 1 cp) is flowing in turbu-
m
lent flow in a U-shaped pipe bend at 3 ft /s. What is the horizontal force exerted by the water
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on the U-bend?
Answer: 903 \b f

Plane 2 = 19 psia
1 Pi
1
\
1 \
4" internal
diameter
1
1
—•!
Fig. 7A.5. Flow in a U-bend; both arms of the bend are at
Plane 1 = 21 psia the same elevation.

7A.6 Flow-rate calculation (Fig. 7A.6). For the system shown in the figure, calculate the volume
flow rate of water at 68°F.

Internal diameter
of all pipe is 5" "

Fig. 7A.6. Flow from a constant-head tank.

7A.7 Evaluation of various velocity averages from Pitot tube data. Following are some experi-
mental data for a Pitot tube traverse for the flow of water in a pipe of internal radius 3.06 in.:
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Distance from Local velocity Distance from Local velocity
Position tube center (in.) (ft/s) Position tube center (in.) (ft/s)
1 2.80 7.85 6 0.72 11.70
2 2.17 10.39 7 1.43 11.47
3 1.43 11.31 8 2.17 11.10
4 0.72 11.66 9 2.80 9.26
5 0.00 11.79
Plot these data and find out whether the flow is laminar or turbulent. Then use Simpson's
2
rule for numerical integration to compute (v)/v max/ {v^/v ^^, and {v )/v 3 max > Are these results
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consistent with the values of 50/49 (given just before Example 7.2-1) and 43200/40817 (given
just before Example 7.4-1)?

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B. Bird, С. Е. thesis, University of Wisconsin (1915).