AOE3054 - Experiments Overview
Experiments Overview
A. Borgoltz and W. J. Devenport
Last Modified 26 August 2024
The purpose of the experiments in AOE 3054 is to give you hands on experience in organizing, conducting, and documenting experimental tests. You will get to see in real life some of the phenomena you only saw in theory in previous classes. You will get hands on experience of experimental techniques and equipment typical of aerospace and ocean engineering applications (as well as learning about other techniques in the classes and online lectures). Above all, you will be encouraged to think independently about the experiments you are given and the equipment you are using, considering both their capabilities and flaws. None of the experiments have required procedures or pre-set measurement objectives (except for experiment 5, and there are good reasons here). It is up to you to decide on what they will be. In addition, none of the experiments have 'expected results'. You are expected to open mindedly and objectively assess your own results, their limitations, and what they mean. Your results are unique and always have value as new and independent observations.
You are expected to keep comprehensive documentation of each experiment you perform in the form of a logbook. A logbook is like a detailed diary of your team's preparation for, and activity during, an experiment. All logbooks are kept in MS Excel. Logbooks are described in detail in appendix 1. You will be asked to write full reports on three selected experiments. Reports are also described in appendix 1, and report writing will be covered in class. You will have a chance to revise each report after you receive comments back from your instructor.
Lab Organization and Preparation
Experiments are held once every two weeks (except for experiment 6 which is done as part of instrumentation lab) and are performed in teams of 2 or 3 students. All experiments assume that you have mastered the material in the 'Basic Concepts in Experiments' chapter of the lab manual and the online lectures (in the Pages section of your CANVAS course website) on "Statistical Data Analysis" and "Estimating Experimental Error". In particular you are expected to be comfortable with the concepts of uncertainty analysis, and be ready to make formal uncertainty estimates (a.k.a. error estimates) for all the measurements you make, and results you infer from them. All experiments assume you are familiar with MS Excel and how to generate a logbook.
When you have an experiment scheduled, your homework on that week will be to prepare for it. To prepare you should:
(a) View the relevant online lecture. Background material for experiments 1, 2, and 3 is covered in the three online classes "Flow Visualization (Ex 1)", "Measuring Static Displacement and Deformation in Structures (Ex 2)", and "Measuring Velocity and Pressure in Fluid Flows (Ex 3)". These classes provide a broad overview of the technology in each of these areas, some of which you then get to use in each experiment.
(b) Carefully read the relevant chapter of the manual. It is important to be familiar with the descriptions of the measurement techniques and experimental set up, as well as any theoretical or descriptive background. Experiment chapters also include a photographic equipment inventory.
(c) Meet with the other members of your team and prepare a preliminary logbook. Your team members will be listed on your individual schedule handed out during the introductory lab period. Together, you will need to decide on goals (try to develop at least one goal not in the manual), on what measurements will be made, how tasks will be assigned and what uncertainties will need to be estimated. This information should be recorded on the preparation page of a new logbook, generated using the logbook template (note that the template also includes many suggestions for preparation). Your team's homework grade is assessed on the contents of this preparation page. You must email your instructor a copy of this logbook before coming to lab. Note that you may be able to visit the lab before your test to check on equipment, if you would find that helpful. Open times for Goodwin 140 will be posted on the course home page.
At the end of the experiment the team will need to complete the logbook and submit it to the instructor. The last few minutes of lab are a good time to identify the team you will be working with on your next experiment, and maybe look over the apparatus you will be using.
For those experiments on which you will be writing reports (the first, third and fifth experiments you do) the end of the lab period is a good time to check that everybody has everything they need. The following suggestions may be helpful.
- Look over the 'Recommended Report Format' section of the manual chapter. Do you have a good sense of what the objectives in your report will be, how you will describe what the various results mean, what the report conclusions are likely to be? There is no requirement that everybody in the team have the same objectives/conclusions, but it is critical that the team discuss this before leaving the lab, so that everyone is as well informed as possible. It is good to exchange ideas as a team about how you are going to write the report - this will save you a lot of time later.
- Has the team discussed how the data could/should be further (a) analyzed and (b) plotted, so as to make the most sense? Should the velocities/pressures/distances/strains be normalized? Plotted against what? On the vertical or horizontal axis? With error bars? What errors? If you are not sure about some data (why it was taken, how it should be plotted) it is your responsibility to initiate a team discussion (and logbook entry?) on this issue before everybody leaves the lab.
- Have you got all the information in the logbook you are going to need to describe all the apparatus, instrumentation, methods, coordinate systems, materials, etc.? Does anyone in the team have ideas for items for which model no. info, dimensions, photos are missing and need to be added to the logbook? Are there any obvious items not in the logbook (e.g. this measurement/tunnel/probe was lousy/great - just remember to include specifically why)? Have someone in the team skim the manual chapter for missed items/ideas.
- Has the team discussed how good/bad/useful the various pieces of data you have are? You will be expected to provide error/uncertainty estimates along with all the results presented in your report. Have you discussed in the team how large these errors might be? Are they calculated (or is the information needed to calculate them) in the logbook? Can anybody think of any further error sources/confounding factors? Is there consensus over what data is most reliable? Least reliable? Those factors in the experiment that most limit the applicability/validity of your conclusions?
Instructions for the Introductory Lab
To introduce you to the experiments part of this course, an introductory lab will be held at the start of the semester. Prepare for this lab period by reading the Introduction section of the course manual, this (overview) section and appendix 1 describing logbooks and lab reports. Look particularly at the logbooks. Download and check out the logbook template and sample logbook. You will need to bring to lab:
- Your laptop
- A digital copy of the logbook template can be found in Appendix 1.
Your lab will be held in Goodwin 140 which is in the ground floor of Goodwin Hall where the open jet wind tunnel is sited. The best way to get there from Randolph Hall is to take the stairs between Whittemore and Durham Hall, walk across the Perry Street Parking Lot and enter Goodwin Hall from the main entrance. Once you enter the main hall where the Rolls Royce aircraft engine is suspended, take a right before the stairs, and Goodwin 140 is the first lab on your left.
The meeting will include the following.
- First you will meet your teaching assistant for the lab experiments. (You will meet your Instrumentation Lab instructor at the first Instrumentation Lab meeting). Your TA coordinates the lab experiment periods and will grade your experiment logbooks and lab reports. They serve as a primary point of contact for you. Make sure you record their information.
- You will get an individualized schedule (on paper) that will show when you are doing each experiment and instrumentation lab period and with whom. Make sure you understand the sheet. You will find that for each lab you are working in a team of 2 or 3 students. Team assignments are different most weeks.
- You, and all the other student members of the group, will introduce yourselves so you can recognize those people you will be working with on each experiment. Everyone should confirm that their contact information (email) on the individual schedules is correct. This contact info is critical since it will allow students performing the same experiment at the same time to communicate in advance to prepare for that experiment.
- Your TA will explain how the group labs work, how it is the students responsibility to plan and perform the experiment, how experiments are expected to run for the complete lab period. Make sure you understand. Now is the time to ask questions if there is anything you don't understand. They will explain what preparation is expected for a lab (a preparation logbook) and how it is submitted (through CANVAS prior to the lab). They will also explain what a logbook is, how and when it is submitted (also through CANVAS at the end of lab), how it is graded and how comments are returned to you. Logbooks, including preparation, earn team grades i.e. all the members of a team in attendance for the same experiment get the same grade.
- You will learn about computer use in the lab. Students are expected to use their own laptop computers in lab. This is the time to let your TA know if you foresee any difficulties. You will need your laptop to write your logbook, download photos from the digital cameras (you are welcome to use your own digital cameras or camera phones as well) and, in Instrumentation Lab, take computerized measurements.
- You will get to see how to use the equipment in the lab that is used for experiments 1-4. This is your chance to get a really good look at things without the pressure of an experiment to complete. You are expected to cast an objective and critical eye on the equipment. You will have to objectively judge (or guesstimate) its accuracy when you do these experiments.
- Once you have been introduced to all the equipment you
should meet with the team members you will be working with during next week's
experiment (check your schedule to see who they are and go meet them next to
that setup). Along with them you should:
- Try out all the hardware for the experiment
- Try out your laptop in the lab. Can you get a wireless connection in the lab? If not let your TA know.
- Open the logbook template in your computer and start a logbook preparation.
- Try out the digital camera.
- Practice getting pictures from the camera into your logbook. To avoid huge files use the camera on its lowest resolution. Also, save the photos from the camera on your computer and then use Insert>Picture in Excel, rather than importing them directly. Learn to use the 'Compress Pictures' feature in Excel - on the Picture toolbar (it works in Word too).
- Try using the USB jump drive to transfer the logbook to the computers of other team members if needed .
- Try out for yourself all the equipment in your experiment.
- Start your preparation for the experiment as suggested in the relevant section of the course manual.