FLUID MECHANICS 1
Fall 1998
Dr. Jess W. Everett
ROW335, 256-5326
Office Hours: M9-11 and any time my door is open
everett@rowan.edu
Dr. Everett's home page
Prerequisites (top)
Physics I and Math for Engineering Analysis II or equivalent
Text (top)
Franzini et al. (1997) Fluid Mechanics, WCB McGraw-Hill, NY, NY.
Goals (top)
The course deals with general fluid flow and with fluid flow in pipe
systems. Topics covered in the area of general fluid flow include hydrostatics,
laws of fluid motion, kinematics, dynamics, energy balance, and dimensionless
groups. Topics covered in the area of pipe flow include incompressible
flow, compressibility, pumps, viscosity, boundary layers, turbulence, and
losses. The course includes appropriate laboratory experiments and computer
applications.
Learning Activities (top)
Reading the text (before material is covered in class); listening
and responding to lecture (on materials not in the text, or that are difficult
to understand); watching demonstrations; discussing important
concepts; reviewing examples from the textbook; solving assigned
problems in class and/or at home (singly and in groups); and conducting
experiments.
Evaluation (top)
Multiple choice quizzes cover your knowledge of the textbook.
These occur before material is covered in class. The solutions to
assigned problems are used to evaluate your ability to define and solve
fluid mechanics problems. Laboratory reports are graded to assess
your ability to conduct experiments, perform the necessary calculations
and write a report. The exams test your comprehension of the course
topics. They are closed notes and books. You will be given any formulas,
conversions, or fundamental facts.
Grading (top)
Grades in the course will be based on the ten point scale (90-100
= A, 80-89 = B, etc.). Depending upon class performance, the scale
may be adjusted down, e.g., an 89 might be an A. Points will be awarded
according to the following percentages:
Quizzes, Problems, Participation, Laboratory
30 %
Semester Exam (Test 1)
35 %
Comprehensive Final Exam (Test 2)
35 %
It is possible to change the distribution, with agreement of all involved.
Turning in work (top)
To get full credit, you must have the correct answer and show appropriate work.
See the Homework Format and Grading document
for the format to be used in preparing your homework and for help in interpreting
grading. Assignments are due by the beginning of the designated lecture
period, unless otherwise indicated. Late assignments can be turned in
until solutions are posted, but will receive at least a 50 % grade reduction.
Some problems may require the use of spreadsheets or math solvers. If
you have ANY questions about a graded assignment, you must talk to me about
it within a week of my return of the assignment to the class. Please work
together on assignments, but do not copy!
Laboratory (top)
Laboratory time is spent watching demonstrations and conducting formal
and informal experiments. Because much of the laboratory equipment
is still on-order, this portion of the course will depend on equipment
availability. Additional lecture and class work will be substituted
for laboratory, if necessary.
Schedule (top)
A tentative quiz and test schedule available. Read the chapter
before the quiz!
Disabilities (top)
Any student in this course who has a disability that may prevent him
or her from fully demonstrating his or her abilities should contact me
personally as soon as possible so that we can discuss accommodations necessary
to ensure full participation and facilitate your educational opportunity.
Academic Misconduct (top)
You are encouraged to work together on assignments. However,
copying is not acceptable. Copied assignments will receive a zero
grade. Cheating on a test will cause the student to receive a zero grade,
at a minimum. If you are to miss an assignment due date, exam, quiz,
field trip, or laboratory session you must have a valid excuse and notify
me prior to the event.
ASCE (top)
You are encouraged to join the American Society of Civil Engineers
or other appropriate organization. If you join (show me your membership
card) and attend two on campus ASCE meetings, I will allow you to drop
your lowest non-zero quiz grade.
Tentative Quiz and Test Schedule, Fall 1998 (top)
Quiz / Test
Quiz on Chapter 1: Introduction
Quiz on Chapter 2: Fluid Properties
Quiz on Chapter 3: Statics
Quiz on Chapter 4: Basic Fluid Flow
Quiz on Chapter 5: Energy
Quiz on Chapter 6: Momentum and Forces
Test on Chapters 1 to 5
Quiz on Chapter 7: Similitude and Dimensional Analysis
Quiz on Chapter 8: Pressure Conduits, sections 1 - 16
Quiz on Chapter 8: Pressure Conduits, sections 17 - 28
Test on Chapters 6, 7, 8 |
Date
September 9
September 9
September 14
September 21
September 23
September 28
September 30
October 7
October 12
October 14
October 21 |
Last updated: September 24, 1998
Home work assignments for Dr. E's Fluid Mechanics,
Fall 98 (top)
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Assignment 1:
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2.8, 2.13, 2.18.
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Due Monday, September 14.
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Assignment 2:
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3.6 Change in diameter is at bottom of u-tube.
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3.12 The centroid of a triangle is?.
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3.18 Integrate to get vertical force and moment.
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3.23 Use moments about the buoyancy force to solve for W;
you don't know the specific weight of the fluid!
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Due Monday, September 21.
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Assignment 3:
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4.1 Graph velocity versus radii, then estimate total flow as nViAi,
using your best judgment; the mean velocity is total flow divided
by the total area of the pipe.
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4.3 Use the ideal gas law to estimate the specific weight;
note that the 50 psi is a gage pressure.
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4.12 Make a graph that has x from 0 to 3 and y from 0 to 4;
plot the x and y velocities at each node as arrows with length proportional
to magnitude; draw the resultant velocity at each point based on
the x and y values; determine the eaquations for the x and y accelerations
using equations 4.23 a and b; DON'T calculate the normal and tangential
accelerations;
DO draw some streamlines.
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Due Wednesday, September 23.
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Assignment 4:
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5.3 Use the relationship DI = (c/g)DT,
where c = specific heat of water = 1.0 Btu/lbmR = 25,000 ft2/s2R,
and lbm = pound-mass = mass of one pound under Earth gravity.
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5.6 Use Bernoulli's, make sure you state why you can assume hL
and Dz are zero.
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5.10 Use equation 5.27, get density and the speed of sound at 2000
m from Table A.3.
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5.11 Because it is a closed circuit, all of the power input
to the pump ends up as heat energy in the water: <a> calculate
the power imparted to the water by the pump, divide by the pump efficiency,
then multiply by one hour to convert from power to energy; <b>
since this energy all ends up as heat, use DI
= (c/g)(DT)--in the form Di
= c(DT), where i is energy per mass--to calculate
the temperature after one hour, c = 25,000 ftlb/slugR, you'll need to convert
gallons of water to slugs,
watch your units!
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5.11.2 Use Table A.1 to get the specific weight and vapor pressure
of water, solve using the method we used to solve 5.11.1 in class.
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Due Monday, September 28.
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Assignment 5:
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Assignment 6: NOTE: for moving blades/pumps/turbines, draw
velocity triangles when determining velocities. It helps!
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6.4 Hydraulic jumps occur under certain conditions [we'll
learn more in water resources, next semester]. Part <a>, solve
this just like problems 6.4.2 and 6.4.4. Use the continuity and impulse-momentum
equations. You can determine F1 as gamma x centroid of the area x
area, while F2 is gamma x centroid of area x area plus pressure x area.
Note, in calculating F2 you use both static pressure and the pressure measured
by the pressure gauge at the top of the pipe. The force exerted by
"something" on the water, F?/w, is zero because there
is nothing there to exert a force on the water! Now use continuity
to write Q, V1 and V2 all in terms of V1 and solve for V1. Use V1
to get Q. Part <b>, use Bernoulli's equation, remembering that
elevation for open channel flow [e.g., upstream of the hydraulic jump]
is the free water surface. After the hydraulic jump you should use
the top of the channel for the elevation [why? because that is where we
have a pressure measurement].
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6.9 First, use the continuity equation to determine the velocity
in the 8 inch pipe. Second, use Bernoulli's to determine pressure
in the 8 inch pipe [note that the head loss from the 8 inch pipe to either
exit point must be the same, for any type of flow. Because the flow
is frictionless for this problem, it is zero]. Apply Bernoulli's
from the 8 inch pipe to either exit--but not BOTH. Finally, determine
the forces using the impulse-momentum equation [as we did for 6.5.1 and
6.5.4, also see sample problem 6.2 to see what to do with split flows].
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6.33 Do the problem in metric units. Part (a) - determine
the Force exerted in the u direction. First determine the flows entering
and leaving the blades. Second, determine the velocity of the water
relative to the blades (v) at the point where they first "meet" (note:
for this system, V, v, u are all in the same direction where the water
enters blade system). The magnitude (though not the direction)
of the water's relative velocity (i.e., its speed) does not change in the
blade system, because the flow is assumed to be frictionless. Thus,
v exiting the blade (top and bottom) is equal to v where the water enters
the blade. Calculate the force in the u direction using equation
6.24, where vu is the relative velocity component
of the water in the u direction. Don't forget to calculate the force
resulting from each of the deflections caused by the blade.
Part (b) - the power transferred to the blades is simply the force from
part (a) times u, the velocity of the blades. Part (c)
Calculate the absolute velocity of the water entering and leaving
the blade (don't forget there are two velocities leaving the blade).
Absolute velocity is u + v. Do it in the x and y directions, then
calculate the resultant velocity as the "square-root of the squares".
Calculate head (all you've got is velocity head) entering and leaving the
blade. The head entering the blade is the velocity head of the jet.
The energy leaving the blade is 2/3 times the velocity head of the water
leaving the "top" of the blade plus 1/3 times the velocity head of the
water leaving the "bottom" of the blade. Why the 2/3 and 1/3?
Because we are calculating energy per weight of water, and the water was
split between the two exit points. The difference in head between
exit and entrance is the energy input to the blades. Calculate the
power input to the blades using equation 5.31 and compare to your earlier
calculation of power. Note: the head you will input to the
power equation is the difference between the water head entering and exiting
the blades.
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6.38 Read pages 219 and 220. Look at sample problem 6.6.
At each radius, determine u (the tangential velocity of the blades), Vr
(the radial velocity of the water), and Vu (the velocity
of the water in the direction of u). u is determined from u = wr.
Vr is determined from continuity in the radial direction,
assume here that the blades don't take up significant space. Vu
is u + Vr /tanb (see the
Figures on page 222 and re-read the second full paragraph on page 220).
Part (a): T = r Q (r1
Vu1 - r2 Vu2),
this is another version of equation 6.28. Part (b): Power =
FV = Tw. Part (c): Use equation
6.29, realizing the V1 Cosa1
= Vu1, etc. Check your power calculation, it
should equal g Q hm.
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Due Monday, October 12.
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Assignment 7:
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7.4 Look in Section 7.4
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7.6 Calculate Reynolds number for the water system.
Determine
g for the air, using Tables in Appendix
A and equation 2.5. Determine the kinematic viscosity of the air
as m/r, where m
is interpolated from a Table in Appendix A and r
is g/g. "Interpolation" means assuming
a linear relationship between two variables given in a table (e.g., viscosity
and temperature). A general equation for linear interpolation is
(Y2-Y1)/(X2-X1) = (U-Y1)/(Xu-X1), where Y2 and Y1 are the dependent variables
in a table (e.g., viscosity at 70 and 60 F), X2 and X1 are the independent
variables in a table (e.g., 70 and 60 F), U is the value to be determined
(e.g., viscosity at 68 F), and Xu is the given independent value (e.g.,
68 F). Determine the volumetric flow rate (Q) in the air
system that will give you the same Reynolds number you got for the water
system. Convert this to weight flow rate (G) using gQ.
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7.30 The important variables are h (rise in capillary tube),
r (radius of capillary tube), s (sufrace tension),
and
g (specific weight), therefore n = 4. Use
the FLT system. Determine m. Determine k. Determine the
number of P group, n-k. This should be
1, thus there is one P group. For the
single P group, determine the exponents that
make the group dimensionless. [Note: set the exponent on h to one.
Also, you will not be able to determine a unique number for the exponent
on specific weight; however, experiments have shown it to be one.]
Realize that if f(P) = 0, then P
= Constant. Call the constant Cr and solve the
equation for h. Looking at equation 2.12, what is Cr
for a given fluid?
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Due Monday, October 12.
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Assignment 8:
- Do problems 8.13.2, 8.37, and 8.39. There is one of each of the pipe
problems (type 1, 2, and 3). Solve them like we did in class, but
use a spreadsheet to solve the equations for type 2 and 3 problems, which
will require iteration. If you missed class or had trouble following what
we covered, read section 8.13 (pg. 294). Turn in your spreadsheet
solution for type 2 and 3 problems, making sure that you have documented
your work well enough for me to follow it. Follow all of the homework
guidelines and include explanations of the calculations used to create
each column in the spreadsheet. Feel free to turn in the usual hand-written
solution for type 1 problems.
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Due Monday, October 19.
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Assignment 9 (Last assignment!):
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Do problems 8.24.6, 8.82, and 8.107. Please note, we discussed the
last two problems in class on Wed. The first problem is a single
pipe with minor losses. This type of problem was discussed in class
on Wed.
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Due Monday, October 19.
Note: Homework solutions are posted on a bulletin board
across from my office
Study Guides and Test Review (top)
Two study guides for each chapter are provided. The Chapter
Question Guide contains a list of questions for each chapter. Reviewing
these questions before quiz-time should help you prepare. The Chapter
Review Guide contains a list of the concepts, variables, and relationships
you should learn from each chapter. Reviewing this guide could help for
quizzes and tests.
Test 1 Review: Know the following
topics: Viscosity, Surface Tension, Vapor Pressure, Pressure with
Fluid Height, Absolute and Gage Pressures, Barometers, Pressure Measuring
Devices, Force on Plane Areas, Center of Pressure, Force on Curved Areas,
Buoyancy and Stability, Types of Flow, Flow Rates, Mean Velocity, Equation
of Continuity, Velocity and Acceleration Fields, General Energy Equation,
Bernoulli's Equation, Relationship between internal energy and temperature,
Stagnation pressure, Head, Power, Cavitation, Energy and Hydraulic Grade
Lines. Definitely do not study sections: 2.8,
2.9, 4.10, 5.16-5.19.
Grades (top)
Review your grades at any time. (You need to
know your ID name.)
Dr. Everett's home page