Unformatted text preview: P5165 In turbulent ﬂow near a ﬂat wall, the local velocity 217 7 P628 3
v varies only with distance 3‘ from the wall, wall shear stress
7,... and ﬂuid properties p and u. The following data were
taken in the University of Rhode Island wind tunnel for
airﬂow, p = 0.0023 slug/r13, [.L = 3.81 57 slug/(ft  s),
and r“. : 0.029 Ibf/ftz: y, in 5 0.021 0.035 3 0.055 I 0.080 f 0.12 i 0.16
.2 7 l
u. ft/s i 50.6 54 l 5 .6 i 59.7 r635 i 65.9
((1) Plot these data in the form of dimensionless :1 versus
dimensionless y, and suggest a suitable powerlaw curve
ﬁt. (b) Suppose that the tunnel speed is increased until u = 90 ft/s at y = 0.11 in. Estimate the new wall shear
stress, in lbf/ftz. For straightening and smoothing an airﬂow in a SO—em
diameter duct, the duct is packed with a “honeycomb” of
thin straws of length 30 cm and diameter 4 mm, as in Fig.
P628. The inlet ﬂow is air at 110 kPa and 20°C, moving at an average velocity of 6 m/s. Estimate the pressure drop
across the honeycomb. Thousands
of straws P628 1.40ch P652 The pipe ﬂow in Fig. P652 is driven by pressurized air in the tank. What gage pressure 121 is needed to provide a
20°C water ﬂow rate Q = 60 mS/h? ﬂ 30m rt
Smooth pipe: Q = ——p
d 5 cm Open jet P652 P662 Water at 20°C is to be pumped through 2000 ft of pipe from
reservoir 1 to 2 at a rate of 3 ft3/s, as shown in Fig. P662.
If the pipe is cast iron of diameter 6 in and the pump is 75
percent gfﬁcient, what horsepower pump is needed? Pu
P662 ® mp t *P6.102 A 70 percent efﬁcient pump delivers water at 20°C from
one reservoir to another 20 ft higher, as in Fig. P6102.
The piping system consists of 60 ft of galvanized iron 2—
in pipe, 21 reentrant entrance, two screwed 90° longradius
elbows, a screwedvopen gate valve, and a sharp exit. What
is the input power required in horsepower with and with—
out a 6° well—designed conical expansion added to the
exit? The flow rate is 0.4 nS/s. 6° cone ...
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 Fall '08
 Schwartz,L

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