ENGR 225
Name ______Key______________
December 3, 2007
Please Check One
Recitation: 8:30___; 10:00 ___; 1:15___
Short answer (2 pts. Each, for T/F and multiple choice
circle
the best answer of the choices given
, fill in the blank must be completed
with a meaningful word or phrase)
1.
The expression below represent a balance of _
mechanical
_ energy for 1D incompressible steady flow
˙
m
P
1
"
+
#
1
V
1
2
2
+
gz
1
$
%
&
’
(
)
+
˙
W
pump
=
˙
m
P
2
"
+
#
2
V
2
2
2
+
gz
2
$
%
&
’
(
)
+
˙
W
turbine
+
˙
E
mech
,
loss
2.
T
F
The expression given in Q. 1 can also be written as
P
1
"
g
+
#
1
V
1
2
2
g
+
z
1
+
h
pump
=
P
2
"
g
+
#
2
V
2
2
2
g
+
z
2
+
h
turbine
,
e
+
h
L
3.
The symbol ‘h’ in the expression given in Q. 2 represents
a)
enthalpy
b)
head
c)
height
d)
none of the above
4.
For internal flow of velocity, V, in a pipe of length L and diameter D ,
h
L
=
f
L
D
+
K
L
"
#
$
%
&
’
(
V
2
2
g
therefore
˙
E
mech
,
loss
=
˙
mgh
L
=
˙
mg f
L
D
+
K
L
"
#
$
%
&
’
(
V
2
2
g
___________________
5.
T
F
Depending on what you are trying to learn, different choices for points 1 & 2 are made when applying the expressions
given in Q.1 and Q.2 to a given situation.
6.
When there are minor losses for flow in a pipe
a)
K
L
values must be determined
b)
it is equivalent to a longer pipe
c)
mechanical energy is being converted to heat
d)
all of the above
e)
none of the above
7.
The friction factor, f, can be well approximated from the __
Moody
____ chart or the Haaland relation
1
f
" #
1.8log
6.9
Re
+
$
/
D
3.7
%
&
’
(
)
*
1.11
+
,

.
/
0
8.
T
F
For external flows, there are two net forces, drag and lift, that operate in two different directions that are 90
0
apart.
9.
Drag coefficients depend on
10.
A thermos bottle is a device that is designed to have a high thermal resistance for heat flow due any of the
_____
three
________ (
give a number
) modes of heat transfer.
11.
T
F
Convection is a complex process that is often analyzed using a heat transfer coefficient that is not a property of the
fluid, but is an experimentally determined parameter whose value depends on all the variables influencing convection
such as the surface geometry, the nature of the fluid motion, the properties of the fluid, and the bulk fluid velocity.
This preview has intentionally blurred sections. Sign up to view the full version.
View Full Document
12.
A valid expression for heat flow by radiation is
4
$
T
surr
4
(
)
2
+
T
surr
2
(
)
T
surf
+
T
surr
(
)
T
surf
$
T
surr
(
)
13.
The thermal conductivity of an aluminum window frame is roughly ___
100
_____ times larger than the thermal conductivity
of the glass that the window is made from.
14.
T
F
In the expression,
"
T
"
t
=
#
"
2
T
"
x
2
the symbol
α
refers to kinetic energy correction.
This is the end of the preview.
Sign up
to
access the rest of the document.
 Fall '08
 Landau
 Dynamics, Fluid Dynamics, Heat, Mass Transfer, Heat Transfer, heat transfer coefficient, TI

Click to edit the document details