SUGGESTED MINIMUM KNOWLEDGE OF FLUID MECHANICS AND FOR FE EXAM

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24 Οκτ 2013 (πριν από 3 χρόνια και 5 μήνες)

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SUGGESTED MINIMUM
KNOWLEDGE OF FLUID
MECHANICS AND
HEAT TRANSFER

FOR FE EXAM

F. Parsi

Winona State University

March 5, 2013

2 Hour Review


http://www.ncees.org/exams/study_materials/fe_handbook/


Exam Composition


Morning


120 Questions


4 hours


7% Fluid Mechanics



Afternoon (General Engineering)


60 Questions


15% Fluid Mechanics

Define and/or Explain


density


specific gravity


specific volume


pressure (absolute and gage)


vapor pressure


stress tensor


shear stress


shear rate


viscosity (dynamic and kinematic)


Newtonian and non
-
Newtonian fluids


dimensional analysis




Fluid Statics


u
-
tube manometer calculations


barometer calculations


hydrostatic pressure


force on submerged flat surface


point of application of the force


force on submerged curved surfaces


hydraulic ram


Archimedes's principle buoyancy


Fluid Dynamics


Reynolds number and its significance


laminar and turbulent flow


velocity distribution


conservation of mass (continuity equation)


Bernoulli equation


head loss


major head loss calculations in pipes


friction factors (Moody and Darcy)


minor head loss calculations in piping systems


pumping power calculation


hydraulic radius


drag coefficient and drag force



Fluid Measurement Devices


pitot tube


venturi meters


orifices



Example 1: Pressure


What is the atmospheric pressure on the
planet if the absolute pressure is 100 kPa
and a gage pressure is 10 kPa?


1. 10 kPa

2. 80 kPa

3. 90 kPa

4. 100 kPa

Example 2: static Pressure


What is the height of a column of tetrachloride
with a specific gravity of 1.56 that supports a
pressure of 1 lbf/in
2
?


1.
0.01 ft

2.
0.12 ft

3.
1.48 ft

4.
1.56 ft

5.
2.31 ft


Example 3: Viscosity


Kinematic viscosity cabn be expressed in
which of the following units?



1. m
2
/s


2. s
2
/m


3. kg.s
2
/m


4. kg/s





Example 4: Hydrostatic
Pressure


A pressure of 35
kPa

is measured 4 m
below the surface of an unknown liquid.
What is the specific gravity of the liquid?


1.
0.09

2.
0.89

3.
0.93

4.
1.85

Example 5: u
-
tube manometer


The specific gravity of mercury is 13.6, and the
specific gravity of
glycerine

is 1.26. For the
manometer shown, calculate the difference in
pressure between points A and B.

1.
35
kPa

2.
42
kPa

3.
55
kPa

4.
110
kPa


Example 6: U
-
Tube Manometer


The fluid in a manometer tube is 60% water
and 40% alcohol (specific gravity = 0.8). What
is the manometer fluid height difference if a 6.2
lbf/in2 pressure difference is applied across
the two ends of manometer?


1.
0.92 in

2.
15.5 in

3.
186 in

4.
215 in

5.
361 in


Example 7: Fluid Statics


What is the resultant force on the inclined
wall?


1.
222
kN

2.
395
kN

3.
503
kN

4.
526
kN

Example 8: Fluid Statics


What is the vertical force on the inclined
wall?


1.
197
kN

2.
392
kN

3.
486
kN

4.
544
kN

Example 9: Hydrostatic Force


A tank is filled with water to a depth of 10
ft. What is the total force on the gate?


1.
560 lbf

2.
5400 lbf

3.
5620 lbf

4.
6000 lbf

5.
6240 lbf

Example 10: Buoyancy


A crown is made of an alloy of gold and silver.
The crown weighs 1000 g in air and 940 g in
water. What percentage of gold was it? Density
of gold and silver are respectively 19.3 g/cm
3

and 10.5 g/cm
3
.

1.
53.1%

2.
67.4%

3.
81.2 %

4.
91.3%


Example 11: Buoyancy


A 24
-
in
-
long rod floats vertically in water. It has
a 1
-
in
2
cross section and a specific gravity of
0.6. What length L, is submerged?


1.
2.4 in

2.
9.6 in

3.
14.4 in

4.
18.0 in

5.
18.7 in

Example 12: Fluid Dynamics


Consider water flowing through a converging
channel as shown and discharging freely into
the atmosphere at the exit. What is the gage
pressure at the inlet? Assume the flow to be
incompressible and frictionless.

1.
102
kPa

2.
106
kPa

3.
113
kPa

4.
127
kPa


Example 13: Dimensionless
Numbers


A 500
-
ft
-
long surface vessel is modeled at
1:50. What speed must the model travel if a 25
mph similarity is desired?


1.
3.54 ft/sec

2.
5.0 ft/sec

3.
5.2 ft/sec

4.
7.07 ft/sec

5.
7.3 ft/sec



Example 14: Hydraulic radius


The hydraulic radius is


1.
The mean radius of the pipe

2.
The radius of the pipe bend on the line

3.
The wetted perimeter of a conduit divided
by the area of the flow

4.
The cross
-
sectional fluid area divided by
wetted perimeter


Example 15: Hydraulic radius


What is the hydraulic radius of the shown
open channel?


1.
b/4

2.
b/3

3.
b/2

4.
2b/3

Example 16: Pipe flow


A steel pipe with an inside diameter of 25 mm is
20 m long and carries water at a rate of 4.5
m3/h. Assuming the specific roughness of the
pipe is 0.00005 m, the water has an absolute
viscosity of 1.00 x 10
-
3 m2/s and a density of
1000 kg/m3, what is the friction factor?

1.
0.023

2.
0.024

3.
0.026

4.
0.028

Example 17: Head Loss


What is the expected head loss per mile of
closed circular pipe (17
-
in inside diameter,
friction factor of 0.03) when 3300 gal/min of
water flow under pressure?


1.
0.007 ft

2.
0.64 ft

3.
38 ft

4.
3580 ft

5.
1.9x10
7

ft

Example 18: Pipe Flow


The transition between laminar and turbulent
flow in a pipe usually occurs at a Reynolds
number of approximately


1.
900

2.
1200

3.
1500

4.
2100

5.
3900


Example 19: Pumping Power


A pump requires 75 kW to move water with a
specific gravity of 1.0 at a certain flow rate to a
given elevation. What power does the pump
require if the flow rate and elevation conditions
are the same, but the fluid pumped has a
specific gravity of 0.8?

1.
45 kW

2.
60 kW

3.
75 kW

4.
90 kW

Basic Heat Transfer


Conduction



Convection



radiation