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Chemical Engineering 150A
Spring Semester, 2009
Homework 10: Turbulence & Intro to Heat Transfer
Problem 1
Water flows through a 150 mm diameter diameter pipe with an average velocity of 0.4 m/s.
Assuming that the velocity profile in turbulent flow is welldescribed by the empirical pwer
equation:
v
z
v
z
,max
=
1
"
r
R
#
$
%
’
(
1/
n
(Note that n is often set equal to 7; this result is equivalent to equation 16.64a in Denn.)
(a)
Determine the relationship between
v
z
and
v
z
,max
.
(b)
At what radial position should a pitot tube be placed if it is to measure the average velocity in
the pipe? For the case where n=7?
(c)
What is the shear stress at this radial position?
(d)
What fraction of the shear stress at this position is due to the turbulent or Reynolds stresses?
Problem 2
Water is flowing at 68
°
F through a smooth, horizontal tube of 2in ID at an average velocity of 5.0
ft/s. At a point 0.75 inches from the wall, calculate:
(a)
the timeaveraged velocity
(b)
the total shear stress
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This note was uploaded on 02/05/2010 for the course CHEM 150A taught by Professor Muller during the Spring '10 term at University of California, Berkeley.
 Spring '10
 Muller

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