Lift and drag forces experienced on flow around objects in our large wind tunnel is the subject of this Lab. Background on flow around various objects can be found in the lab documents section below. Before you begin any analysis, watch the short intro video on the google drive for this lab.
Use the report template provided on canvas. The results section should have four parts. You decide how to present your data. Your results and discussion should include at least the following:
- Cylinder – Determine the drag force force on the cylinder (subtracting out the drag on the support rod), show how the drag force changes with wind speed, find the drag coefficient at various Reynolds numbers. Plot and compare to published results.
- Sphere – Similar to cylinder.
- Airfoil angle of attack. Create a plot that characterizes the effect of angle of attack on lift and drag coefficients. Do you notice stall? The photos and data are numbered so that you can tell which data corresponds to which photo. You must determine the angle of attack from each photo. Use your creativity and make sure to explain how you determined the angles in the experimental setup and procedure section.
Important Data:
Cylinder: diameter 2.575 inches, length 18.00 inches.
Sphere: diameter 4.0925 inches
Airfoil: chord 5.00 inches, length 18.20 inches.
Airfoil-pressure-Lift.pdf” href=”https://csus.instructure.com/courses/81264/files/11242565/download?verifier=ChZZCc4KkjG4hK0shP6lGfNCGB03X0xuPO96PvHR&wrap=1″ data-api-endpoint=”https://csus.instructure.com/api/v1/courses/81264/files/11242565″ data-api-returntype=”File”>
Theoretical Background Info;
This background doc uses pressure measurements in the flow over cylinder to calculate CL and CD, which you should be familiar with it. Instead, In our lab of airfoil testing, we use direct drag and lift measurements with data acquisition system to calculate CL and CD.
Experiments
Dimensions of the Model;
Cylinder; Diameter=65.37 mm, Length= 18 inches
Sphere, Diameter=125.12 mm
Support Rod, Diameter=12.83 mm, Height=6.5 inches
Airfoil Cord= 5 inches Span=18.2 inches, Thickness=1 inches, which is similar to NACA0020(00 means no camber, 20 means 20% thickness to cord)
At the windtunnel room, the wind speeds and drags, and lifts are collected from the screen on the data acquisition computer.
Measurement Complete Settings
Strutt, Sphere, Cylinder, Airfoil(AoA= Approximate -5, 0, 5, 10, 12, 13, 14, 15, 16, 17, 18, 20, 22)
The Drag and Lift data were zeroed already and corrected for the strutt drag at different speeds.
For Air Foil, Plot the graphs of
Lift Coefficients(CL) vs Angle of Attack and Cd vs. Angle of attack (40 Hz )
and compare them with the graphs of already known data.
Discussion about the graphs from our data.
For example is given as follows;
In the following xl file,
AirfoilRawData-forStudents.xlsx
The Raw-Data tab, I have gathered and organized for the Data for Report area with green highlight for 30 Hz.
On the left hand side to the green highlighted area, I made the result table for 35 Hz for your info.
Students only do the 40 Hz data for report;
I expect that students complete the table and generate graphs of AOA vs CL and AOA vs CD at 40 Hz and compare them with NACA0015 just as in the tap of Airfoil and discuss about how the graphs are compared.
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