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The University of Adelaide
SCHOOL OF MECHANICAL ENGINEERING
Level III
LABORATORIES
Semester 2 2013
COORDINATOR: ANTONI BLAZEWICZ (Room s310)
E-MAIL: [email protected]
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SAFETY REQUIREMENTS Students have to complete a compulsory OH&S quiz online before they are allowed
to do their lab classes. You need to read and understand SAFETY INDUCTION on
page 15 of the LABORATORY BOOK and the Safety Information on the Mech. Eng
School Website: www.mecheng.adelaide.edu.au/safety/
You will only be allowed to select lab groups if you answer correctly OH&S quiz
questions on the LAB Website:
https://labselect.mecheng.adelaide.edu.au/ You can follow the link from the Mech. Eng. Home page; Current Students/Lab
Management.
Students who have any OH&S related enquiries should contact Mr. Richard Pateman
(OH&S officer), room SG22 in the Mechanical Workshop.
GROUP ALLOCATION You need to enroll in lab groups during Week 1, during which there will be no
laboratory sessions. For further information about the group allocation see the Lab
Website:
https://labselect.mecheng.adelaide.edu.au/
NOTE: Times of individual lab sessions vary and it is important that you
carefully check the time of each session you have booked on the Lab Website.
NOTE: Level 2, 3 and 4 Pracs on Access Adelaide, which give you provisional lab
allocation, are the same as labs on the Lab Management, which you need to use to
book specific lab times.
INQUIRIES ABOUT LABORATORIES All specific inquiries about laboratories (submission dates, extensions, report formats
etc.) should be directed to lab demonstrators. Names of the demonstrators and their
contact details are given in the List of Laboratories on page 7. An updated list of the
demonstrators is available on the Lab Website.
LAB REPORTS
The lab reports should be submitted via corresponding Course Submission Boxes
located next to the School Office. For some labs students should submit group lab
reports. Details will be provided by lab demonstrators.
TURNITIN
Some reports will require electronic submission through Turnitin (software detecting
plagiarism). Labs for which this submission is required are listed in the List of
Laboratories on page 7. Please see Turnitin Submission on page 13 for further
details.
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CONTENTS
List of Laboratories 7
Important Information for Students 9
Laboratory Guidelines 10
Group Lab Reports & Peer-Assessment 12
Turnitin Submission 13
Emergency Action 14
Safety Induction 15
COURSES - LABORATORIES:
1. Applied Aerodynamics – Fluid Dynamics
- PART I 25
- PART II 33
2. Dynamics and Control 2 - Balancing Machinery 41
3. Dynamics and Control 2 - Vibrating Beam 49
4. Space Vehicle Design – Microgravity 57
5. Sports Engineering 2 – Lab 1 – info will be provided at the lectures
6. Sports Engineering 2 – Lab 1 – info will be provided at the lectures
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Level 3 LABORATORY LISTS;
No COURSE Laboratory Supervisor Demonstrator Sessions TURNITIN
Submission Location
1 Applied Aerodynamics Fluid Dynamics Richard Kelso Peter Lanspeary
Javad Farrokhi Derakhshandeh
1 No Holden Lab
2 Dynamics and Control 2 Balancing Machinery Gareth Bridges Aditya.Khanna
[email protected] 1/2 Yes S237
3 Dynamics and Control 2 Vibrating Beam Gareth Bridges Saksham Garg
[email protected] 1 Yes S311b
4 Space Vehicle Design Microgravity Min Kwan Kim Jesse Coombs [email protected]
1/2 Yes Holden Lab
5 Sports Engineering 2 LAB 1 Paul Grimshaw tba 1 No Sports Eng Lab
6 Sports Engineering 2 LAB 2 Paul Grimshaw tba 1 No Sports Eng Lab
Details of the labs and timetable can change and you should consult the Lab Website, MyUni and
the School notice board for updates.
NOTE: Times of individual lab sessions vary and it is important that you carefully check the time of each session you have
booked on the Lab Website.
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IMPORTANT INFORAMTION FOR STUDENTS – sem. 2
RULES (see LABORATORY GUIDELINES in your LAB book for details)
1 All SAFETY requirements must be satisfied during Lab sessions. Students have to
attend compulsory INTRODUCTORY MEETING on safety before they are allowed to
do their lab classes.
2 Students should attend ONLY THE LAB SESSIONS FOR THE COURSES IN WHICH
THEY ARE ENROLLED (labs and corresponding courses are listed in the LAB LIST).
3 LABORATORIES ARE COMPULSORY part of a course. If a class is missed or a lab
report not handed in or a student fails to get at least 35% of the total possible lab mark, then that is grounds for FAILURE of the entire course.
4 Unless specified otherwise by a course supervisor, the laboratories account for a total of
10% of the course assessment, irrespective of how many labs are included in the course.
5 Details of the TIMETABLE may change and you are requested to consult School’s
Undergraduate Notice Board, the lab website and MyUni for current arrangement.
6 If UNABLE TO ATTEND any specific Lab for an important reason, permission must
be sought from Lab Demonstrator to attend the next available lab session.
7 Students should be prepared for PRE-LABORATORY QUIZZES.
8 Each student must bring a WORKBOOK to each Lab session.
9 Depending on a lab students are required to submit either INDIVIDUAL or GROUP
REPORTS (as indicated in the List of Laboratories on p.7). More information will be
provided by lab demonstrators.
10 Length and format of a report depends on a specific lab. General guidelines are given in
the LABORATORY GUIDELINES. Rules for the GROUP REPORTS are given on next
page.
11 Unless specified otherwise you have ONE WEEK to submit a report. Report mark will
be reduced by 10% for each day of delay.
12 COPYING of lab reports or attempts to submit a report without attending a prac will be
penalized with 0 final mark for a prac.
13 Some reports will require electronic submission through TURNITIN (software detecting
plagiarism). Labs for which this submission is required are listed on page 7.
ASSESSMENT (see STUDENT GUIDLINES for details) Unless specified otherwise by a course supervisor:
• PRE-LABORATORY QUIZ and EXPERIMENTAL PERFORMANCE - 20% when class is less than 10 students, 10% otherwise.
• WORKBOOK - 20% • REPORT - 60% when class is less than 10 students, 70% otherwise
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LABORATORY GUIDELINES
Aims of the laboratory classes
• To demonstrate practical applications of the theoretical parts of the course. • To familiarise students with a range of engineering equipment, instrumentation and
computing applications.
• To develop the skill required for preparing, conducting and reporting an engineering investigation.
Rules of the laboratory class
• Laboratories are compulsory (if you are enrolled in a corresponding course). If a class is missed or a lab report not handed in or a student fails to get at least 35% of the total
possible lab mark, then that is grounds for failure of the entire course.
• If you can not attend a laboratory class for an important reason, permission must be sought from Lab Demonstrator to attend the next available lab session.
• Unless specified otherwise by a course supervisor, the laboratories account for a total of 10% of the course assessment, irrespective of how many labs are included in the course.
• Turn up to the laboratory class that you are timetabled to, on time. You will lose 10% of your mark if you turn up late or all marks if you do not turn up at all. Unless specified otherwise
you have one week to submit a report. Report mark will be reduced by 10% for each day of
delay. If your report submission is delayed for an important reason you should contact a lab
demonstrator to seek extension.
• Be familiar with all of the laboratory safety regulations (see Lab booklet). • Be sure that you know how the experimental equipment operates and how to switch it off in
case of an emergency (ask the demonstrator).
• All measurements, changes in operating conditions and supplementary data should be recorded in your work book as you proceed.
• Be involved in the laboratory. The more active you are during the laboratory class, the better mark you get for experimental performance (see assessment).
Work book
Each student MUST bring a workbook to each laboratory session. Loose sheets of paper are not
acceptable. The work book should include a brief summary of the laboratory, equipment
configurations and settings, experimental results, graphs and sketches, calculations, design ideas,
feedback and suggestions, etc. Do NOT tear out any pages – work, which is superseded, should
be crossed out with a comment as to the reason. Plan the experiment, use your work book
effectively and then it should be possible to write the majority of the report from the information
recorded in the work book. The workbook MUST be handed in at the end of the laboratory class
for assessment and will be handed back to you before you leave.
Assessment
Assessment will be based on pre-laboratory quizzes, experimental performance, workbook
records and the formal reports. Unless specified otherwise by a course supervisor, the
distribution of your mark for each laboratory will be as following:
• The pre-laboratory quiz and your experimental performance will count 20% of your mark when the laboratory class has less than 10 students. Otherwise, it will count 10% of your
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mark. Your experimental performance will be judged based on your involvement and
participation during the laboratory. The quiz questions are based on the information in the
laboratory handouts. The aim of the quiz is to encourage the students to prepare themselves
before attending the laboratory class.
• The work book records will count 20% of your mark
• The formal report will count 60% of your mark for the laboratory class, which has less than 10 students; otherwise it will count 70% of your mark.
Formal Report Structure
This material is provided as a general guide, the actual report layout will sometimes need to be
modified to suit a particular investigation.
a. Title of experiment, author, date and list of other group members.
b. Summary of the main results and conclusions. This is often presented first, but written last.
c. Introduction to the experiment, stating the aims.
d. Background information about the phenomenon, which was being investigated. This may include reference to existing theory or analysis techniques. Do not include mathematical
derivations unless their development was a key part of the experiment (i.e. dimensional
analysis).
e. Equipment which were used in the experiment. Often all that is required is an annotated sketch or line drawing of the test rig and instrumentation, plus a few sentences describing the
important features.
f. Procedures which was followed in the experimental program. This should not be detailed, but should be sufficient for someone else to duplicate your tests at a later date.
g. Results in descriptive, numerical, tabular and /or graphical form. Often this will involve a comparison of theoretical and experimental results. Use appendices for large volumes of
data.
h. Comments and Conclusions regarding the experiment. Explain your results, highlighting any weakness in the experimental technique, which may affect accuracy. If possible, propose
any enhancement to the technique to improve accuracy. State the overall conclusions for the
experiment. It may sometimes be appropriate to state other situations where the technique or
results may be applicable.
i. References which were mentioned in the body of the report.
j. Appendices.
The formal report should be a complete record of the experimental program, results and
conclusions.
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GROUP LAB REPORTS & PEER-ASSESSMENT
• For some labs students should submit group lab reports. A suitable size of a lab group will be determined by a lab demonstrator.
• If students are not happy with the contribution from their peers a peer-assessment form can be used to determine the contribution of individual students to the report preparation.
• A student SHOULD NOT submit the peer-assessment form if he/she thinks that all the group members contributed to the report preparations as expected. It will be
assumed that the student gives the full mark to all his/her group members.
• Standard peer-assessment forms will be available during lab sessions, from MyUni and from the School Office.
• The peer-assessment mark is confidential but a student has to put his/her name and ID number on a peer-assessment form.
• Students can give a mark out of 100 to all their group members except themselves: - a full mark of 100 if a group member has met all the expectations regarding his/her
contribution to a report preparations
- 0 mark if a group member did not contribute at all.
If a student does not give a group member a mark it will be assumed that the
student gives this group member the maximum mark of 100.
• Peer-assessment forms can be submitted to: - the course submission box or
- directly to a lab demonstrator.
• A report mark for an individual student will be calculated from an overall report mark and the peer-assessment marks. A lab supervisor/demonstrator has a final decision
regarding the student mark.
• A student can submit an individual report if he/she chooses to and the report mark will be assigned directly to the student.
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TURNITIN SUBMISSION
Reports for selected labs require electronic submission through Turnitin (software detecting
plagiarism). These labs with their Class ID's and passwords for each lab (you need these to login
to Turnitin) are as follows:
The webpage for Turnitin is - http://www.turnitin.com/static/index.html
You should look at TRAINING section if you want to learn more about Turnitin.
To create your login go to:
https://www.turnitin.com/newuser_type.asp
NOTE: You must provide both Class ID and password for a particular lab.
Please consult your lab demonstrators or course supervisors about specific requirements for
electronic reports.
General rules are
1. Students need to submit at the same time:
- an electronic, typed version of a report (in Word) to Turnitin (for group reports only one
student needs to submit report to Turnitin) and
- a hard copy of the report to a course submission box.
2. Students will not be able to see Turnitin reports.
Depending on a lab the reports can be individual or group. Unless specified otherwise by lab
demonstrators or supervisors reports can be submitted as an electronic version without equations
and diagrams which can be inserted by hand into the hard copy for marking.
Level COURSE Laboratory Class ID Password
2 Dynamics and Control 1 Linkage Analysis 6635224 Linan13
3 Dynamics and Control 2 Balancing Machinery 6635233 Vibe13
3 Dynamics and Control 2 Vibrating Beam 6635233 Vibe13
3 Space Vehicle Design Microgravity 6635235 Space13
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EMERGENCY ONLY
SECURITY – FIRE – MEDICAL - CHEMICAL
RING 35444
GIVE: TYPE OF EMERGENCY
BUILDING NAME
FLOOR NUMBER
ROOM NUMBER
NAME
TELEPHONE NUMBER
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UNDERGRADUATE SAFETY INDUCTION
Issue No. 07- 21/01/2011 Prepared by: R.Pateman
INSTRUCTIONS TO UNDERGRADUATE STUDENTS
WORKING IN LABORATORIES
Welcome to the School of Mechanical Engineering, We hope that your study here will be
stimulating and rewarding and that the experience will be of benefit to all concerned. Safety
induction into your new workplace is an important process. The school elected Health and Safety
Representative or the Safety Officer will guide and help you through the process of the safety
induction. Please use this guide and checklist as a reference as the HSW representative talks to
you about the safety provisions in place within the department to protect you.
Safety Items you will need in the laboratories:
Closed-in Footwear. “Mandatory”
Safety Glasses. “Mandatory” when provided for certain classes.
Hearing protection. “Mandatory” when provided for certain classes.
A knowledge of the safety provisions in this document. “Mandatory”.
Note: Before being allowed to attend future laboratory classes it is also mandatory that you
complete and sign the STUDENT CONFORMATION OF RECEIPT OF THE SAFETY
INFORMATION.
IN AN EMERGENCY.
SECURITY – FIRE – MEDICAL – CHEMICAL
RING 35444 GIVE: TYPE OF EMERGENCY
BUILDING NAME
FLOOR NUMBER
ROOM NUMBER
NAME
TELEPHONE NUMBER
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ENGINEERING SOUTH BUILDING
– EMERGENCY PROCEDURES
1. SOUND ALARM. If the situation is out of control, notify a FLOOR WARDEN or activate a BREAKGLASS ALARM located in the corridors. The alarm activates the
EMERGENCY WARNING SYSTEM and notifies the Fire Brigade.
ALERT TONE (Beep - Beep) sound: - This means standby – await further instructions. It
is not a signal to evacuate.
2. EVACUATE TONE (Whoop – Whoop) sound: - This means evacuate the building immediately.
TELEPHONE SECURITY: - Dial 35444. Explain the nature of the emergency.
After hours a telephone is available by the western ground floor entrance, on the second
floor near the lift and in the CATS suite.
3. EVACUATE: - When the Whoop – Whoop alarm sounds all occupants of the building must evacuate by the nearest exit or follow the directions of the Floor Wardens (Red
Hats). Leave doors unlocked and lights on. Take personal valuables with you. Mobility
impaired occupants should proceed to the most convenient exit point and seek the
assistance of a floor warden. DO NOT USE THE LIFTS. DO NOT RE- ENTER THE
BUILDING. Proceed to the ASSEMBLY AREA on the lawns outside the Napier Building. (see map
below)
4. Wait for the all clear from the Chief Warden.
FIRST AID.
First Aid. Is available from the departmental first aid officers:
Robert Dempster Engineering Workshop.
Steven Smith Engineering Workshop
Wendy Brown Administration, 1st Floor.
Marc Simpson Thebarton Laboratories.
HEALTH AND SAFETY OFFICER (HSO)
Richard Pateman Engineering Workshop Office
ELECTED HEALTH AND SAFETY REPRESENTATIVE.
Dr. Paul Medwell Room S205
ACCIDENTS AND INCIDENTS.
All accidents and incidents must be reported to the OH&S Representative or
your Supervisor as soon as possible, and if necessary an RMSS report completed
on the University RMSS website. In the case of a serious or notifiable accident
or incident this must be done immediately, refer to accident/incident information on
the HSW Web page. http://www.adelaide.edu.au/hr/ohs/rmss
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ENGINEERING WORKSHOP. The engineering workshop is a shared faculty facility, currently occupied by staff from both
Mechanical and Chemical engineering; it is also used by staff from Civil and Electrical
engineering. Undergraduate students who require workshop assistance are asked to refer their
request to Dr. Michael Riese, Workshop Manager or Richard Pateman, Technical and Projects
Officer or if he is not available, one of the other Mechanical staff members.
Access: The workshop is a limited access area, it must not be used as a thoroughfare from the
lift area to the laboratories. Closed Toe shoes must be worn when entering the workshop and
safety glasses MUST be worn if crossing any yellow lines to enter the general work areas. 2nd
year students may be allowed access to bench space in the student workshop to work on their
design project at designated times. 4th year students may also be allowed to do project work in
this area. Permission must be obtained from a workshop staff member prior to any work being
done, any instructions given by a staff member regarding safety or workshop use MUST be
carried out, you may only work when a mechanical staff member is present. Note: When in the
workshop You must not remove any tools or equipment from any toolbox, cupboard or drawer
without first asking a staff member, as staff have some personal tools for their own use.
Tools: There are a limited number of tool kits available for Undergraduate use, see Richard
Pateman for these, portable electric drills and hand tools may be available on request to a staff
member, but must be signed out and returned promptly. The machine tools in the workshop are
for use by the technical staff only and under no circumstances are the postgraduate students
allowed to use them.
Hours: The workshop is nominally open from 8.00am to 4.30pm, Monday to Thursday, and
until 3.00pm on Fridays. The workshop is also closed between 10.30am to 11.00 and from
1.00pm to 2.00pm each day. All persons except workshop staff are requested to leave 15minutes
prior to closing times.
THEBARTON CAMPUS.
Access. A security system is fitted to the Thebarton laboratories, which can only be deactivated
by authorised personnel. If you wish to work in these labs, check with Marc Simpson to make
sure the labs will be open. There is restricted after hours access for essential work, refer to the
Thebarton after hours policy.
Undergraduate Students:
Students who wish to plan their experiments or set up equipment, may do so with prior
arrangement with Marc Simpson, who will supervise them. Students who are going to carry out
experimental work MUST have a supervisor with them.
Tools. Some hand tools are available, see Marc Simpson for access to these.
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GENERAL LABORATORY SAFETY REGULATIONS.
Health and Safety issues in the Laboratory are of paramount importance to all people who use
laboratory facilities. Safety regulations apply equally to staff and students and are to be strictly
adhered to. Non compliance may result in exclusion from laboratories.
The University of Adelaide recognises its obligation to take all reasonable precautions to
safeguard the health, safety and welfare of its employees and students while they are at work.
When working in a laboratory, You MUST also take reasonable care to protect your own safety
at work and to avoid adversely affecting the health or safety of any other person, through any act
or omission.
School staff regularly review Laboratory practices and procedures with a view to identifying and
eliminating potential hazards. Notwithstanding this, staff and students must always approach
their laboratory work with due care and should make their own critical appraisal of each
situation. Any potential hazards so identified should be reported immediately.
Persons who fail to comply with these procedures will not be allowed to
work in the laboratory
The following regulations are basic requirements for laboratory safety and compliance with
them is an express condition of use of the laboratory.
1. FOOTWEAR. Closed-in Footwear must be worn.
• No Bare feet, Thongs or sandals are permitted.
2. FOOD AND DRINK:
• Eating, drinking and the application of cosmetics in laboratories is prohibited.
• Do not store food and/or drink in laboratory refrigerators or laboratory storage units.
• Never ingest or misuse any laboratory substance
3. SMOKING Is prohibited in all University buildings.
4. CLOTHING. Must give adequate protection to the body
• Appropriate protective clothing (for example overalls, laboratory coats, flame resistant clothing, etc) shall be worn where required. The requirement for protective
clothing and gloves will be at the discretion of the area and can be determined by
legislative requirements and/or risk assessment.
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5. PERSONAL PROTECTIVE EQUIPMENT. Is to be worn when required.
• Approved safety spectacles, goggles or safety shields must be worn in all areas where tools or substances such as chemicals, liquids, UV light or radiation may cause eye
injury.
• Cover all open wounds when handling chemicals. • Wash hands after work and before leaving the laboratory. • Use disinfectants after handling suspected infectious materials.
6. PROFESSIONAL CONDUCT. Is expected at all times in the laboratory.
• Do not run or indulge in horseplay
7. SAFETY SIGNS. Must be observed and obeyed at all times
8. PLAN. For safe laboratory work by identification and elimination or control of hazards using the hierarchy of control (Elimination, Substitution, Administration, Personal
Protection Equipment)
9. DRUGS AND ALCOHOL. Working whilst under the influence of non prescription drugs and alcohol is prohibited in the laboratory. Certain prescription drugs may also
impair your ability to work safely in the laboratory.
10. WORK OUTSIDE SCHEDULED TIMES. May only be carried out in accordance with the departmental after hours work policy.
11. EMERGENCY EXITS. Note the location of emergency exits, fire extinguishers, safety showers and eye wash stations when entering the laboratory.
12. WORKING ALONE. 2 people must be present when any hazardous work is being done or working after hours.
13. WORK AREAS. Must be kept neat and clean at all times, extension cords, air lines
etc are not to be on the floor.
14. WALKWAYS. Must be kept clear and accessible at all times.
• Keep fire escape routes clear at all times.
14.1 HOUSEKEEPING: Keep floors tidy and dry.
• Keep benches clean and free from chemicals and apparatus that are not being used.
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• Keep aisles and exits free from obstructions. • Clean working area and equipment thoroughly after use. • If contractors are working in your area, make known to them any hazards which may
exist in your area, ie flammable liquids.
• Chemical waste should not be disposed of via sinks, drains or stormwater channels. Departments must provide suitable waste disposal containers and are responsible for
their removal by an approved waste disposal contractor.
15. EXPERIMENTAL APPARATUS AND MACHINES. do not operate any of this
equipment until you have been instructed in and are familiar with the safe operating
procedure for that equipment, and you are authorised to use it.
16. NEW EXPERIMENTAL RIGS. No new rigs are allowed to be set up or experiments carried out until a risk assessment has been done and a safe
operating procedure written Both are to be approved by the Department safety
officer and health and safety representative.
17. DOORS: always exercise care in opening and closing doors, and entering or leaving the laboratory
18. REPORT ALL ACCIDENTS, HAZARDS AND INCIDENTS as soon as possible to Laboratory supervisor or Safety officer.
19. ELECTRICAL. Only approved personnel are permitted to carry out work on mains voltage electrical equipment.
• Switch off all electrical appliances when equipment is not in use. • Display a "LEAVE ON" sign on any equipment required to be left on for an
extended period.
• The use of double adapters is prohibited. • Only use University approved & tested equipment - Look for test tag • If no test tag - DON’T USE
20. LIFTING, Use correct lifting techniques and avoid lifting heavy objects, use help or Mechanical aids wherever possible.
• Use Trolleys where necessary.
21. CLIMBING, On any equipment or structure is strictly forbidden except with permission of laboratory staff.
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22. REGARD ALL SUBSTANCES AS HAZARDOUS, unless there is definite Information to the contrary. Always read labels and instructions carefully.
23.1 CHEMICALS: Clearly label all containers in use within the laboratory.
• Regard all substances as hazardous unless there is definite information to the contrary.
• Carry out work in fume cupboards if material is likely to give off toxic or unpleasant odours.
• Do not place objects near fume cupboard baffles so that airflow is prevented. • Do not allow flammable materials to accumulate in the laboratory. • Use the correct containers provided to dispose of glass, sharps, metal, paper,
infectious waste etc.
• Wash hands frequently and upon completion of work.
23. MATERIAL SAFETY DATA SHEETS, read the appropriate one before using any Substance, if it is not located in the laboratory, see the OH&S rep.
24. SPILLS. Clean up spills of non-hazardous materials immediately and thoroughly. For spills of hazardous materials, evacuate and isolate the area and report
immediately to the supervisor.
25. ALWAYS USE SAFETY CARRIERS, for transporting glass or plastic containers with a capacity of 2.5 litres or greater. Exercise special precautions when carrying
containers of mutually reactive, toxic, corrosive or flammable substances.
26. LASERS. Only trained and authorised persons are to operate lasers, when lasers are in use 2 people must be present.
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LAB 6: Fluid Dynamics - part I
Lift and drag of an aerofoil
1 Aim • Measure the pressure distribution on a NACA 0018 aerofoil.
• Calculate lift coefficients, drag coefficients and lift/drag ratios of the aerofoil.
• Find the stall angle of the aerofoil and observe the flow pattern of fully-stalled flow.
• Compare your results with those published in the engineering literature.
• Assess the accuracy of your results.
Note: The NACA 0018 aerofoil might be used in an aeroplane wing or in the blades of a wind turbine. Designers
of aeroplanes or wind turbines need to know the lift coefficients, drag coefficients and lift/drag ratios of the wings
or turbine blades.
The time available for measurements is only about 70 minutes, and so you can obtain data for only 4 or so angles
of attack. You will need to share data with ALL students in your group.
2 Background reading Before attempting this experiment, please read Sections 3.1, 3.2, 3.5, 9.1 and 9.4.1 of your text book,
Munson, Young and Okiishi [3]. A better text book [2] and a book on using wind tunnels [4] is in the
university library.
3 Apparatus 1. “Undergraduate” wind tunnel located on the ground-floor, Holden Laboratory. This is a “closed
return” wind tunnel with an open working section.
2. Pitot tube; to measure total (stagnation) pressure.
3. Aerofoil with a NACA 0018 cross-section. You will need to measure the chord length. A row of
pressure tappings is distributed along the upper and lower surfaces of the aerofoil. The
coordinates of the pressure tappings are given in Table 1.
4. Multi-tube inclined manometer. The accuracy and resolution of measurement depends on the
manometer inclination angle, which you will need to measure.
4 Calculations For each measurement of pressure distribution at the surface of the aerofoil, you can plot the distribution of the
static pressure coefficient
Cp=surface static pressure
dynamic pressure of freestream flow (1)
From these measurements and from the background-theory document following these notes, you can calculate the
lift coefficient and drag coefficient of the aerofoil. Plot lift coefficient, drag coefficient and lift/drag ratio as
functions of angle of attack, α . The measurements are obtained at a single, constant wind-tunnel flow speed (i.e. single, constant Reynolds number).
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Note that easiest way to do calculations is to use nondimensional quantities at the earliest possible stage. This
method avoids any need to calibrate the manometer. The lab demonstrator will describe the theory, will give
schematic examples of the results and will show you how to process the data both graphically and numerically.
The graphical method is very “illustrative”, so it is highly recommended. The recommended tools for numerical
computation are Matlab and Octave. Matlab and Octave are programmable matrix and vector processing
software. If you get to know one of them well, it will be your life-long friend. The demonstrator will give you
“head start” by providing some useful functions.
Table 1: Location of pressure tappings on the NACA 0018 aerofoil
x/c y/c x/c y/c x/c y/c
0.00 0.00000 0.15 0.08018 0.60 0.06845
0.0125 0.02841 0.20 0.08606 0.70 0.05496
0.025 0.03922 0.25 0.08912 0.80 0.03935
0.05 0.05332 0.30 0.09003 0.90 0.02172
0.075 0.06300 0.40 0.08705
0.10 0.07024 0.50 0.07941
Leading-edge radius is 3.56% of chord.
Note: y/c is negative on the lower surface.
x = distance from leading edge
y = distance from chord line
c = chord
5 Report: requirements and guidelines You must submit a formal report within two weeks of practical session. The report will be assessed principally on
its technical content, but also on presentation (10%). Reports may be handwritten. Please write mathematics by
hand unless your skill with your word processor can match the quality of formatting in the background-theory
document which follows these notes. The report should contain the following.
Aims: a list of aims (what you measured and calculated).
Apparatus: a description of apparatus, instrumentation and (especially) aerofoil. Give dimensions. Good
quality sketches are required. Photographs will not be accepted.
Theory: the theoretical basis of experimental method. The report must include any theory presented during
the practical session, including the results (Equations 17 – 20) but not including the derivation given in
the background-theory document following these notes.
Method/procedure: measurement procedure and numerical methods. These should be written as itemised
lists.
Results: presented in a standard (nondimensional) engineering format, including
1. statement of flow conditions, and geometric parameters,
2. tables (with captions) of lift and drag coefficients,
3. graphs (with captions) of pressure-coefficient distributions on the aerofoil ( pC vs.
c,x / pC vs. cy / ),
4. graphs of lift and drag coefficient as a function of angle of attack ( LC vs. α, CfC vs.α )
5. description of what is in the tables and graphs (but not analysis or discussion),
6. sketch of flow pattern over the fully stalled aerofoil.
Discussion:
1. Estimate the (numerical) accuracy of your results.
2. Show each of your results and the corresponding result published in N.A.C.A. TR-647 [6] on the
same graph. Make a (numerical) comparison between your results ( LC , CfC ) with the N.A.C.A.
TR-647 results.
27
3. Suggest why your results are not the same as in N.A.C.A. TR-647.
Conclusion: Make a brief summary of results; condense it all to just a few sentences and numbers.
References: list of cited articles and books. Format your references like those given below, and use numbers
in square brackets to make citations, as shown in Section 2.
Appendices: should contain the raw data and your Matlab or Octave scripts.
Important note: your report should be a technical document, not an essay. Please write in good, plain English.
Express your reasoning clearly and as briefly as you can. While there is no upper limit on the size of a report, the
assessor will ignore or penalise any irrelevant content.
6 References 1. Harry J. Goett and W. Kenneth Bullivant (1939): Tests of NACA 0009, 0012, and 0018 airfoils in the full-
scale tunnel, N.A.C.A. TR-647, Langley Research Center. (http://ntrs.nasa.gov/).
2. Philip M. Gerhart, Richard J. Gross and John Hochstein (1993): Fundamentals of Fluid Mechanics, 2nd
Ed., Addison Wesley.
3. Bruce R. Munson, Donald F. Young and Theodore H. Okiishi (1998): Fundamentals of Fluid Mechanics,
3rd Ed., Wiley, New York.
4. Jewel B. Barlow, William H. Rae and Alan Pope (1999): Low-Speed Wind Tunnel Testing, 2nd Ed.,
Wiley, New York.
28
Aerofoil theory: Calculating lift and form-drag
coefficients from measurements of surface pressure
Please note; if you wish to follow the mathematics of this document in detail, you may need to write some
intermediate steps and inspect Figure 2 rather carefully.
Figure 1: Schematic pressure distribution on a two-dimensional aerofoil at angle of attack α . Wall shear stress is
not shown. Total aerodynamic force on the aerofoil the sum of chordwise component, ,FC and normal
component, .NF ∞P is static pressure in the undisturbed flow.
1 Total force on a 2-D aerofoil This discussion is restricted to two-dimensional flow over a two dimensional body such as the aerofoil shown in
Figure 1. The stresses generated at the surface of a body by a flow over the body are:
• pressure p, acting normal to the surface, and
• shear stress τ, parallel to the surface.
The total aerodynamic force on the body, ,Fr is obtained by integrating the stress over the aerofoil surface area,
S :
( )dAtτ+np=FS
∫∫ ⋅⋅−rrr
(2)
where nr is the unit outward normal vector at the surface and t
r is the unit tangential vector in the direction of
flow adjacent to the surface. The definitions of the surface stresses and the coordinate system are indicated in
Figure 2(a). Note that the equations which follow depend on the definition of the angle θ , and so can vary from one text book to another. From the chordwise and normal components of pressure and wall shear stress given in
Figure 2(b), the total aerodynamic force on the aerofoil is
NC F+F=Frrr (3)
where
29
( )dAθτ+θp=FS
C ∫∫ sincos (4)
is the magnitude of the chordwise component of force, and
( )dAθτθp=FS
N ∫∫ − cossin (5)
is the magnitude of the component of force normal to the chord; at each point on the surface, θ is the angle subtended by the surface normal vector and the chord.
Figure 2: Definition of stresses acting on a surface
2 Stress and force coefficients Pressure and wall shear stresses can be nondimensionalised by dividing them by the dynamic pressure,
.2
1 2ρU=q (6)
The resulting force, pressure and skin friction coefficients characterise the behaviour of the aerofoil in a manner
which is independent of the free-stream flow speed. It is also very convenient experimentally because it removes
the need to measure density ( ρ ), to calculate free-stream air speed ( ∞U ), or even to use S.I. units when
measuring pressure.
pressure coefficient: Cp=p− p∞q
, (7)
skin friction coefficient: ,q
τ=C f (8)
where is the static pressure of flow undisturbed by the aerofoil. It now possible to dimensionalise the chordwise
and normal forces given in Equations 3 and 4:
( ) ,S
AdθC+θC=
qS
F=C
pS
fp
p
C
C ∫∫ sincos (9)
and
30
( ) ,S
AdθC+θC=
qS
F=C
pS
fp
p
C
C ∫∫ sincos (10)
where the plan area of the aerofoil,
S p= c× w= chord× span (11)
is much easier to measure than the surface area, S.
3 Experimental measurements of lift and drag For thin aerofoils and small angles of attack, the skin friction term in the integrand of Equation 9 is much smaller
than the pressure term. This is very convenient when measuring aerodynamic lift because it is much easier to
measure the distribution of pressure over the surface of the aerofoil than the wall shear stress. Neglecting the skin
friction term produces a fairly small experimental error:
,S
AθdCC
p
pN sin∫∫≈ (12)
On the other hand, because 1sin ≈θ neglecting the skin friction in Equation 8 can produce a large error when
measuring the total drag force on streamlined bodies. We therefore divide the drag into two components, form
drag due to the (normal) pressure distribution, and skin-friction drag due to the shear-stress distribution on the
surface of the aerofoil, so that
[ Total Drag Force] = [ Form Drag] + [ Skin Friction Drag] (13)
and we measure only the form drag coefficient, DfC . From Equation Error! Reference source not found., the
chordwise component of the form drag coefficient is
,S
AθdC=C
p
pCf cos∫∫ (14)
For a two-dimensional aerofoil in a two-dimensional free stream flow, the integration variable can be simplified
significantly. Rather than calculating a complicated surface integral, we define the infinitesimal surface area
element, dA , as a spanwise rectangular strip on the surface:
dA
Sp=
span× ds
chord× span (15)
where ds is defined in Figure 2, and c is the chord of the aerofoil. The aerodynamic force
coefficients NC and CfC now become line integrals around the closed-curve outline,C,of the aerofoil:
,S
AθdCC
p
pN sin∫∫≈ (16)
.cosc
sθdC=C pCf ∫ (17)
We then use θds=dy cos and θds=dx sin (see Figure 2(a)) to write
,c
xdCC pN ∫≈ (18)
31
,c
xdCC pN ∫≈ (18)
.c
xdC=C pCf ∫− (19)
Note that the sign (±) ofdx and dy depends on θ and, according to Figure 2(a),ds is positive if integration around
the pathC proceeds in the anticlockwise direction. Given the aerofoil profile as a set of (x,y) coordinates at zero
angle of attack ( ),=α 0 these closed-cycle line integrals are easy to approximate numerically using the trapezoidal
rule.
Finally, for angle of attack,α, the lift coefficient is
α,CαCC CfNL sincos −≈ (20)
and the form drag coefficient is
.cossin αC+αCC CfNDF ≈ (21)
4 Questions you might be asked 1. What are the independent parameters which determine the lift and drag coefficients of a wing ?
2. What is stall? How would you detect it?
3. What component of drag is not measured by the method described above?
4. Approximately how large would you expect this unmeasured drag component to be?
5. What data do you need to measure lift and form drag coefficients?
6. What units would you use? (trick question)
7. Explain in detail how you would use the experimental data to obtain a measurement of lift and form drag
coefficients.
32
33
Vw1
Vw2
r2
r1
Vr1
u2
u1
V1
ω
Vr2V2
CV
0
Vf2
β
α
1
2
1
α β2
Fluid Dynamics - part II
Pump Flow Laboratory
It is important that you prepare for this laboratory prior to the session. For your preparation, read:
Munson, Young & Okiishi, Sections 12.1 to 12.4.2 and and/or Thermo-Fluids I (Fluid Mechanics)
Lectures 14 and 15. Your knowledge will be tested in a brief quiz (10% of the final mark).
Aims
The aim of this laboratory is to enhance your knowledge and hands on experience of Pump Theory.
This is achieved by:
• measuring and presenting pump performance curves obtained from a practical measurement system;
• comparing a range of performance curves (head, power and efficiency) and correlating these with different impeller designs;
• understanding the concepts of head coefficient, capacity coefficient, specific speed and efficiency.
Theory
Euler's Pump and Turbine Equation
The following summarizes the velocity triangles and equations used to estimate the theoretical
performance of a pump. Note: the arrangement shows backward-curved vanes.
( )( ) ( )( ) ( )( )1122
111222
111222
0
.. ww
ww
s
VrVrmei
VrmVrm
VrmVrm
TM
−=
−=
×−×=
=∑
&
&&
rr&
rr&
r
This is Euler's Pump and Turbine
Equation.
Note that the torque T represents the torque on the contents of the control volume, i.e. the fluid. The
torque on the rotor itself is equal and opposite. Subscript 1 and 2 represent the inlet and outlet
respectively. V1 and V2 are the absolute velocity of the fluid entering the passage and are the vector
sums of the velocity of the blade and relative velocity within the blade passage. Vw is the tangential
velocity component and m& is the flow rate in kg/s.
34
Now we can express this equation in terms of the power input into the fluid, i.e. the work performed
per unit time by the shaft. However, noting the convention in Thermodynamics that work out is
positive, we include a negative sign:
( )( ) ω
ω
ω
ruecnisVuVum
VrVrm
TW
ww
ww
s
=−=
−=
=−
1122
1122
&
&
&
We can also express this equation in head terms to obtain the “Euler Head”, E. This is the theoretical
head developed by a pump.
E =1
gu2Vw2 − u1Vw1( )
Note that for Pumps: (u2Vw2 ) > (u1Vw1 )
The flow rate can be calculated from (where b1 and b2 are the impeller passage widths):
( ) ( ) 22221111 22 ff VbrVbrm πρπρ ==&
For incompressible flow: r1b1Vf1 = r2b2Vf 2
For the case where the inlet velocity is radial and the flow is aligned with the blade tips at entry and
exit, where β is the blade angle, we obtain the result:
cot β2 =u2 − Vw2Vf 2
i.e. Vw2 = u2 − Vf 2 cot β2
Therefore, Euler's Head and Power become:
( )
( ) ωβ
β
222222
2222
cot
cot
ruerehwVuumW
Vug
uE
fs
f
=−=−
−=
&&
Overall Efficiency
For a pump the overall efficiency is:
η =Fluid power output
Power input to shaft=ρgHQP
=Q∆p
P
In both cases H = the actual head difference between inlet and outlet in metres.
If 3-phase electrical power is supplied to the motor, then the electrical power input is:
P = 3VI(PF) where: P = electrical power input V = supply voltage
I = supply current
PF = power factor (Check PF ≈ 0.9).
Alternatively, the pump controller can display the electrical power supplied to the motor. This is
indicated as a percentage of maximum output power (2.2 kW). For example, a reading of 50% means
50 % of 2.2 kW = 1.1 kW.
35
Classification of Pumps
Some dimensionless parameters that are important in describing the performance of any pump are
listed below. The parameters relate the size D, head H(m), volume flow rate Q(m3/s), speed
ω(rad/sec), power P, gravitational acceleration and fluid density between similar machines and allow
machines to be analysed and classified.
22
3
.
.
D
HCCoeffHead
D
QCCoeffCapacity
H
Q
ω
ω
=
=
P
gHQEffOverall
D
PCCoeffPower p
ρη
ρω
=
=
.
.53
Another dimensionless term is often used in engineering applications to characterize different classes
of pump without reference to their size. This is known as the Specific Speed, Ns. Using the capacity
coefficient and the head coefficient, and rearranging them to eliminate D, gives
4/3
2/1
4/3
2/1
)(gH
QN
C
CS
H
Q ω==
NS may be plotted against η (overall efficiency) to indicate the relative performance characteristics of different type of pumps. For example, high-pressure, low flow rate centrifugal pumps operate at low
specific speed; propeller (axial flow) pumps operate at high specific speed.
(Note that if imperial units are used to calculate specific speed, the numerical value of the specific
speed will be different from those shown here. Many texts and data sheets use imperial units.
However, the trends are the same, regardless of the unit system used.)
36
Typical Characteristics and Problems with Pumps
Forward –curves, radial and backward-curved vanes all have their own general shape, as shown in
general by the following figure.
H
Q
Foreward Curved
Radial
Backward Curved
Problems can arise if the pump (head or pressure) curve has a peak value above the shut-off value – ie.
a rising-falling characteristic curve. For example, if the system curve intersects machine
characteristics at two or more points, there are two or more possible operating points. This can lead to
oscillation, or “surging”, between the two conditions. This is highly undesirable.
H
Q
Pump characteristic
curve
System
curve
This subject is discussed further in the Thermo-Fluids 2 (Fluid Mechanics) notes on (1) the matching
of pumps to pipe systems, and on (2) turbomachinery.
37
Laboratory
Your task in this laboratory is to obtain the performance characteristics of a modified Davey 6210,
close-coupled, 3-phase water transfer pump. The impeller that is fitted to this pump may be of
forward-curved, radial or backward-curved design. The pump is of a type known as a “turbine pump
with concentric casing” and contains vanes to diffuse the flow and convert the kinetic energy to
pressure head. This performs a similar function to the volute that is found in most commercial pumps.
Impeller Data
The following data are a close approximation to the actual impeller design.
Impeller inner diameter = 45 mm
Inlet flow angle = 0˚ (ie. radial flow at inlet)
Inlet width b1 = 11 mm
Impeller outer diameter = 160 mm
Exit blade angle = 19.1
Outlet width b2 = 3.8 mm (corrected for blade blockage)
Procedure:
1. Sketch and label a disassembled pump similar in design to the pump you will test (Davey 3-Phase
Pump).
2. Sketch the pipe system, noting the valves, bends, pump and flow meter, etc.
3. Check that the pump flow circuit is connected correctly and that there are no obvious water leaks.
4. Ensure that the isolation valve (lower) and flow control valve (upper) are both fully open.
5. Switch on the pump controller and set the frequency to zero.
6. Enable the pump rotation by pressing “RUN” on the controller, and slowly increase the pump speed
to the desired value.
7. Measure the pump flow rate, controller voltage, % output power and pump head for a range of
control valve settings. Six or more settings from wide-open to shut-off are needed to determine the
performance curve. The demonstrator will show you how to make the measurements.
8. Estimate the error associated with each measurement device.
Note that the rotational speed of the motor is not measured; only the frequency of the input power.
Here we assume that the slip between the input power and the motor frequency is approximately 5% at
all speeds. Hence, the actual frequency of the pump will be approximately 5% less than the frequency
indicated on the controller.
38
Report:
A short report is required. The report should be typed and all figures should be presented neatly and to
an engineering standard (neat hand drawn diagrams are fine).
The report should address the following instructions.
1. Describe the apparatus (including diagrams).
2. Summarize the Euler pump theory and the many sources of energy loss that may occur.
3. From the data provided, develop an expression for the theoretical Euler Head versus flow rate (in
litres/minute) for the original pump impeller.
4. Plot the overall head of the pump system versus flow rate in litres/minute for the chosen frequency.
Plot on the same axes the theoretical Euler Head versus flow rate. Plot also the manufacturer’s data
and any other data provided by the demonstrator for other impellers A and B.
5. Compare the head performance curves for your impeller with the data for the manufacturer’s
impeller and impellers A and B provided in the handout. Does the impeller within the pump have
forward-curved, radial or backward-curved blades? Explain the reasoning supporting this conclusion.
6. How well do the Euler Head curve and the measured curves match? If the curves do not match,
explain why this occurs. The answers to item 9 above may provide some clues.
7. Which impeller (forward, backwards or radial) is most likely to suffer from surge?
8. For your measured data, calculate (estimate) and plot the overall power input to the pump system
versus flow rate in litres/minute.
9. For your measured data, determine and plot the overall efficiency of the pump system versus flow
rate in litres/minute.
10. For your measured data, determine the best-efficiency point and shut-off head.
11. Determine the Head Coefficient, Capacity Coefficient and Specific Speed of the pump at the
maximum efficiency point found from item 9 above. Locate this point on the η versus Ns plot provided and classify the pump. If the point does not fall close to the given graph, estimate the
classification of the pump as best you can.
12. From your estimations of the errors associated with each measurement device, estimate the overall
error in your head versus flow rate curve.
13. Optional: Comment on the practical. This will not affect your mark and will help us to make the
lab classes more enjoyable and efficient.
Please note: the theory provided in this document is a brief summary of the theory available in the Thermo-Fluids I (Fluid Mechanics) and Thermo-Fluids 2 (Fluid Mechanics) notes and the course text book. The theory provided in this document is not sufficient for you to understand this subject fully. It is your responsibility to revise your notes and the course text book prior to the laboratory session.
39
Pump Curves for Davey 3-Phase Pumps
Impeller A
Q (l/min) H (m)
0 29
50 29.5
100 28.5
150 27
200 21
250 8
Impeller B
Q (l/min) H (m)
0 32
50 32
100 31.5
150 30
200 27.5
250 23
300 17
40
41
LAB 2:
42
43
44
45
46
47
48
49
E, I, A, ρ
x=L
x=0 x
LAB 3: VIBRATION BEHAVIOUR OF A CANTILEVER BEAM
The University of Adelaide
School of Mechanical Engineering
Level III Laboratories
Introduction It is important for engineers to gain some insight into the basic vibratory behaviour of diverse structural
components which may be encountered during the design and analysis of stationary structures and/or moving
machines. In any vibration problem, there exists a wide range of possibilities for the different structural
systems from which a vibration problem may originate. However in many cases, the vibration behaviour of
these systems can be simplified and expressed in terms of much simpler sub-systems, often in terms of the
motions of a simple beam system.
For the case considered here, the vibration characteristics due to the resonance behaviour of a simple
cantilever beam are investigated. This simple system consists of a uniform beam which is fixed in motion at
one end and has free movement at the other. The purpose of this laboratory class is to investigate the
vibratory behaviour of this simple system, understand its resonant modal behaviour and the procedures
involved with determining this experimentally and theoretically.
Aims
1. To analyse the nature of the lateral vibrations of a simple cantilever beam system.
2. To determine the resonant modal properties of a cantilever beam system.
Background Theory
Part 1
The vibratory motion of a cantilever beam represents a relatively simple one-dimensional system and can be
easily solved theoretically. The primary task of this section is to outline the theoretical procedure that is
required to derive the characteristic frequency equation. From this equation, the resonance frequencies for
the different modes of vibration in the beam can be determined. The system modelled for this purpose
consists of the lateral vibration of a uniform cantilever beam (fixed at one end and free at the other), with
constant properties E, A, I and ρ (see figure below).
50
The partial differential equation defining the motion of an arbitrary beam is
02
2
4
4
=∂
∂+
∂
∂
t
uA
x
uEI ρ (1)
Now, by the method of separation of variables, a formal solution to this beam equation can be written in the
general form
)()(),( tqxtxu φ= (2)
By assuming ttq sin)( ω= , Equation (2) can be rewritten as
txtxu sin)(),( ωφ= (3)
Differentiating Equation (3), four times, w.r.t x gives
txx
u sin
4
4
4
4
ωφ
∂
∂=
∂
∂ (4)
and, differentiating Equation (3), two times, w.r.t t gives
tt
u sin2
2
2
ωφω−=∂
∂ (5)
Substituting Equation (4 & 5), Equation (1) can be re-arranged in the form
04
4
4
=−∂
∂φλ
φx
(6)
where
EI
A 24 ωρλ = (7)
It can be shown from the theory of linear differential equations that the general solution to Equation (6) can
be written as
xCxCxCxCx λλλλφ coshsinhcossin)( 4321 +++= (8)
The boundary conditions at the fixed end of the beam require that the deflection at the point x=0 is zero, that
is
0),0( =tu (9)
and the slope of the beam at x=0 is zero, that is
0),0( =∂
∂t
x
u (10)
51
The boundary conditions at the free end of the beam (x=L) require that the momentum is zero, that is
02
2
=∂
∂
x
uEI (11)
And the shear force at the free end (x=L) is zero, that is
03
3
=∂
∂
x
uEI (12)
Note: For the case where an additional mass, M, is attached to the free end of the cantilever beam, the fourth
boundary condition (Equation (12)) is modified to
2
2
3
3
t
uM
x
uEI
∂
∂=
∂
∂ (13)
Now solving Equation (9) and Equation (10) respectively yields the following conditions:
042 =+CC (14)
and
031 =+CC (15)
Now, applying the conditions in Equations (11,12) and Equations (14,15) yields:
0)cosh(cos)sinh(sin 21 =+++ CLLCLL λλλλ (16)
0)sinh(sin)cosh(cos 21 =−++− CLLCLL λλλλ (17)
Therefore, the non-trivial solutions for C1 and C2 require that the determinant of their coefficients be zero,
that is
0)sinh(sin)coshcos(
)cosh(cos)sinh(sin=
−−−
++
LLLL
LLLL
λλλλ
λλλλ (18)
Expanding this determinant yields the frequency equation
01coshcos =+LL λλ (19)
The values of λL which satisfy this equation for the first four modes are given in the following table:
Mode λλλλL
1 1.875104
2 4.694091
3 7.854757
4 10.995541
52
Therefore, using the following properties for the cantilever beam,
Property Value
Length, L 0.388m
Height, h 0.003m
Width, b 0.02m
Young’s Modulus, E 68.97GPa
Density, ρ 2700kg/m3
Moment of Inertia, I (bh3)/12
Frequency, ω 2πf
the first four resonance frequencies for the cantilever beam system used in this experiment can be evaluated
analytically.
Part 2
A cantilever beam with a mass, M, mounted to the free end can be approximated by a single degree-of-
freedom mass-spring system as follows
M – mass mounted to the end of the beam
m – the total mass of the beam
The equivalent mass of the end-loaded cantilever beam system is
mMMeq 23.0+= (20)
The spring constant for the end-loaded cantilever beam system is
3
3
L
EIkeq = (21)
The fundamental frequency for the system is found from the expression
eq
eq
M
k=1ω (22)
Now, to find the mass when the fundamental frequency is found from experiment (assume that the
spring has no mass)
mk
Meq
23.02
1
−=ω
(23)
E, I, A, ρ
x=L
x=0 x
M
53
Experimental setup
• The cantilever beam is driven using a piezoelectric crystal. (Note: the crystal should be driven using
a sine wave input; the maximum input voltage should not be more than 10 volt peak to peak)
• Acceleration, at various positions along the length of the beam, is measured using an accelerometer
(Note: use 1volt = 3.924 m/s2 to convert output voltage to acceleration)
• Acceleration divided by the square of the resonance frequency gives displacement of the beam.
Procedure
Please not that the questions highlighted in italics are not to be solved during the lab session.
1. Using the theory for determining the resonance frequencies for a cantilever beam, calculate the beam’s
first four theoretical resonance frequencies.
2. Make connections as shown in the experimental setup. At this moment do not connect the signal
generator output to the control box input. First, generate a 10 Hertz, 6 volt peak-peak sine wave signal
using the signal generator and test the signal on the oscilloscope.
3. Now, connect the output of the signal generator to the input of the control box. Adjust the frequency of
excitation of the beam using the signal generator. Note how the end displacement of the beam varies
with frequency.
4. Using the output (at the free end of the beam) from the accelerometer (displayed on the oscilloscope),
find the first resonance frequency of the beam experimentally. In few words explain how the resonance
frequency was determined experimentally.
5. Compare the theoretically and experimentally determined resonance frequency. Suggest reasons for any
differences.
Signal
Generator
Control Box
4 Channel
Oscilloscope
Cantilever beam test rig
Cantilever beam Input signal Control signal
Measured signal
Measured
signal Accelerometer
54
6. Record the output of the accelerometer (for the first resonance frequency) at various positions along the
length of the beam. Using the output from the accelerometer, determine the displacement of the beam
along its length. Using this information, plot the mode shape for the first mode. Compare this with the
theoretical mode shape for the first mode.
7. Add a 15.55 gram test mass (50 cent coin) to the end of the beam. Measure the first resonance frequency
of the beam with the mass in place. Comment on the effect of adding mass to the end of a cantilever
beam. Suggest how this might be used to solve a practical vibration problem.
8. Using the theory (outlined in this handout) for determining the resonant frequencies of a cantilever
beam, show that the frequency equation for the case of an added mass M, at x=L is:
[ ] [ ] 0coshsinsinhcoscoshcos1 23 =−++ LLLLMLLEI λλλλωλλλ (24)
{Hint: redo the problem using the boundary condition defined in Equation (13)}.
9. Using the derived frequency equation (Equation (24)), calculate the mass added to the beam using the
first resonance frequency that you measured.
10. Using the theory outlined in Part 2 (background theory) calculate the added mass using the equivalent spring-mass analogy. Comment on how the mass calculated using these methods compares with the
actual mass of 15.55 gram.
11. Generate a 400 Hertz, 200 mili-volt peak-peak, sine wave signal using the signal generator and test the signal on the oscilloscope. Now, connect the output of the signal generator to the input of the control
box. Using the output (at the free end of the beam) from the accelerometer (displayed on the
oscilloscope), find the fourth resonance frequency of the beam experimentally. Record the four
accelerometer outputs, and using the concept of nodes, justify that the fourth mode has been excited.
12. Would it be a good idea to place actuators at node location? Explain.
13. IF TIME PERMITS: Find the second and the third resonance frequency of the beam experimentally. To do this drive the beam using a 1.5 volts peak to peak sine wave input.
Individual Report
The individual report for this laboratory should be written as a technical document. It should be written in
third person. You must convey all the relevant information in a clear and concise manner.
Executive Summary
Write a short summary about why the practical was undertaken and what was done.
Aim
Define the aims of the investigation.
Background
Write a short literature survey on modes and nodes. (Provide references wherever necessary)
Provide a short description on piezo crystal and accelerometer.
Experiment
Draw a schematic diagram of the experiment.
Explain, in detail, the experimental setup.
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Results / Discussion
Answer Questions 1-12. Discuss any other findings that YOU believe are relevant.
Conclusion
Conclude on the results and discussions of your report. Ensure that the conclusion address the aims
that you have stated.
Comments
This will not be marked and will not bias your report grade. You can comment on anything related to
this practical, good or bad.
NOTE:
• Do not reiterate, paraphrase or copy anything out of the practical notes. You will not get any marks
for copying out of the notes.
• Include, in the report, a quantification of the effort put in (during the lab and while writing the
report) by each member of the group. Grades will be given based on this quantification. Equal grades
will be assigned if no quantification is provided.
Reference
Tse, F.S., Morse, I. E. and Hinkle, R. T. “Mechanical vibrations: theory and applications, 2nd edition” Allyn
and Bacon (1978), pp 262-265, 274, 280.
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MECH ENG 3104 and MECH ENG 7073: Space Vehicle Design:
LAB 4: Micro-Gravity Laboratory
1 Aims of the Experiment
The aim of this experiment is to increase the knowledge of microgravity by simulating a 0-g
environment using a drop tower facility. A range of experiments applied in the facility will
develop a deeper understanding of basic science and engineering fundamentals in a
microgravity environment.
2 Requirements
Students are required to do the following in order to fulfill the requirements of this
laboratory:
1. Read the following text carefully and familiarize yourself with the experimental
procedure, as well as the safety guidelines.
2. Answer a short quiz at the beginning of the lab.
3. Conduct the experiment following the procedure given below, and record all
predictions and observations in your lab workbook.
4. Submit a report that meets the requirements stipulated in Section 8
5. Submit a copy of your report to Turn-it-in
NOTE: All students are required to bring an external storage device (such as a USB flash
drive) to the laboratory in order to obtain a copy of the acquired experimental data.
3 Mark Allocation
Unless otherwise specified by the supervisor/demonstrator, the assessment for the
microgravity laboratory is as follows:
Pre-lab Quiz = 10%
Participation = 10%
Lab workbook = 20%
Report = 60% (further details in Section 8)
Note: Participation marks are NOT awarded for attendance, but rather for how well students
participate and function as a group.
4 Background Information
As well as reading through and understanding this laboratory procedure, prior to attending
your laboratory session, you are also required to conduct your own background research into
microgravity, especially focussing upon:
- definition of microgravity
- gravity/microgravity effects
- methods of creating microgravity
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- benefits of microgravity research
The following list of references (live as of 5/07/11) should get you started:
http://virtualastronaut.tietronix.com/
http://www.nasa.gov/centers/marshall/news/background/facts/microgravity.html http://en.wikipedia.org/wiki/Micro-g_environment
http://www.spaceflight.esa.int/impress/text/education/Microgravity/
5 Apparatus
The drop tower facility consists of three parts: the drop tower frame, the drop chamber, and
the experimental attachments.
1 Frame
The frame of the drop tower facility is slightly more than two meters tall to enable a free fall
distance of approximately 2m. The frame can be disassembled and stored within a casing for
transportation. The frame is equipped with a rope and set of pulleys which are used to hoist
the drop chamber to the top of the tower. At the end of the rope is a release mechanism which
connects to the drop chamber. This mechanism includes a magnet that functions as a trigger
when the chamber is released. The release mechanism consists of a brake lever and cable
arrangement.
2 Drop Chamber
The drop chamber is fitted with a high-speed movie camera, an accelerometer and a time
display. All electronic equipment runs off a rechargeable battery, which is located within the
casing on the drop chamber. Data is collected on an SD card in the camera. The camera must
be in “Super Slow Motion Movie” video mode.
3 Experimental Attachments
There are five small experiments designed to demonstrate the microgravity phenomena:
- Scales
- Magnet
- Capillary action
- Surface tension
- Convection
Each experimental attachment is fixed onto its own experiment plate and is easily
interchanged within the chamber. The experiments slide into the base of the drop chamber
and are held in place with a securing pin. A separate magnet is also provided for the
calibration step of the procedure.
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6 Experimental Procedure
1 Safety
The apparatus is not to be used without a supervisor present.
Only one person is to hoist and release the drop chamber at any time.
Be aware of your surroundings and what you are doing at all times to prevent injury or
damage to expensive equipment.
Before any work is done around the apparatus check the following:
a) ensure the drop chamber is NOT at its top position,
b) ensure the release mechanism (held by the rope) is down inside the case,
c) ensure the Perspex front cover is securely fixed to the frame and case, and
d) ensure there is adequate padding in the bottom of the case.
2 Accelerometer calibration
Firstly the accelerometer will be calibrated for 1g: this is done by placing the chamber such
that the connection and release mechanism is on the top, on a flat level surface. Activate the
recording system by using the separate magnet on the Hall effect sensor. Allow the system to
stand for 5 seconds. Remove the SD card and copy the .CSV file to the computer with the name
'callibration1g'. Then rotate the drop chamber 90 degrees about a horizontal axis, such that it
is resting on its side. Again activate the recording system using the separate magnet and allow
the system to stand for 5 seconds. Again remove the SD card, copy and rename the .CSV file to
'callibration0g'. Together these two files allow for calibration of the accelerometer and hence
meaningful interpretation of the other experimental results.
3 Procedure
1. Insert the required experimental attachment and make sure it is securely in
position. Adjust the camera angle and zoom.
2. Sketch and describe the experiment in your workbook, including as much detail as
possible.
3. Predict what will happen when the experiment experiences microgravity, and
record your prediction in your notebook.
4. Before continuing, check:
a) everyone is clear of the facility
b) the inside of the case is clear of obstructions
c) sufficient cushioning material is an the case
d) Perspex sheet is in place
e) the camera is in 10s self-timer mode
IF ANY OF THE CHECKS ARE NEGATIVE, DO NOT CONTINUE. FIX THE
PROBLEM AND START AGAIN.
5. Connect the release mechanism to the drop chamber. Raise the chamber as high as
practicable, taking care that the release cable will be clear of the chamber's path,
while still ensuring you can reach the camera.
6. Push the shutter button of the camera.
7. Bring the chamber to an aligned position between the two top rails by pulling the
rope tight, again taking care of the release cable orientation.
8. Once the camera starts recording, with the release cable clear of the chamber,
release the chamber with the bicycle brake on the left hand side of the drop tower.
9. Carefully lift the chamber out of the case and push the camera shutter button to
stop recording as well as remove the SD card.
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10. Slowly use the rope to lower the release mechanism to the inside of the case.
11. Connect USB from camera to PC to copy the movie data. Insert SD card into PC, copy
the .CSV file to the PC, and rename appropriately.
7 Data Analysis
The camera stores 240 frames per second and the LED based time display counts up every
10ms. Acceleration data is collected from 500ms before to 3.0s after trigger. The first row of
data in the spreadsheet is time from trigger in 10ms increments (-50 = 500ms before release)
and the second row is raw acceleration data (use the calibration data).
You will need to create a graph showing acceleration over time for each experiment, and
interpret the features of the graph in relation to the physical events happening during the
experiment. Calculate the average duration and quality of microgravity achieved for each
experiment, remembering that ‘quality’ refers to both the magnitude and fluctuations of
acceleration during microgravity. Verify the drop time of the chamber by calculating it from
theory.
8 Individual Report
Unless otherwise specified by the supervisor/demonstrator, laboratory reports are due at
5pm, 2 weeks from the day of the practical.
Title Page - 1%
Aim – Must be written in your own words - 2%
Background – your own research as previously described - 11%
Equipment – include hand-drawn, clearly labeled sketches and all necessary details - 10%
Procedure – in sufficient detail to duplicate the experiments - 4%
Results and Analysis– for each experiment, include your predictions, a description and an
image of the experiment in microgravity, an analysis of the acceleration as described above,
and a discussion of all possible sources of error. - 35%
Discussion - answering the questions detailed in Section 9 - 30%
Conclusion - 5%
References - 2%
Note: Do not replicate, paraphrase or otherwise copy anything out of the practical notes, the
internet, or any other source. You will NOT be awarded any marks for copied material.
9 Questions
1) Explain what is meant by the term quality of microgravity and why zero gravity isn't
achieved in the experiment. - Suggested length 1 paragraph or less – Question grade
breakdown (of overall Report) 2.5%
2) Briefly explain why calibration of the accelerometer was necessary, and what it achieved. -
Suggested length 1 paragraph or less – Question grade breakdown (of overall Report) 2.5%
3) For each of the following items Explain whether or not they would function properly in a
microgravity environment such as the International Space Station, and if they wouldn't,
propose and explain a suitable alternative; pen, speakers, spirit level, scales, spray-can,
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drinking cup. - Suggested length 1 paragraph per item – Question grade breakdown (of overall
Report) 10%
4) Describe all of the sensor and actuator systems used in this experiment, including
inputs/outputs as well as identifying the principle/effect by which they function. - Suggested
length 2 lines per system – Question grade breakdown (of overall Report) 7.5%
5) Propose an additional phenomena/system to investigate in this microgravity lab. Include a
sketch of the system labeling its components, an explanation of its differing performance in
normal and microgravity environments, as well as a description of any sensors/actuators
required. - No specific suggested length, should be detailed but concise – Question grade
breakdown (of overall Report) 7.5%
