MECH3410 Lab Report

MECH3410 – Fluid Mechanics
Experiment 3 – Measurement of Lift and Drag on an Aerofoil
Introduction
The mechanics regarding the streamline and fluid flow around an aerofoil is significant in various applications
that are frequently seen in today’s technology. With the advantage of wind tunnel technologies, we can
further analyse the aerodynamic forces for a scale model and later on be applied to a full scaled design. With
this experiment, we hope to gain a better understanding of the surface pressures acting on complex shapes
caused by the fluid. Similarly, concepts such as separation, boundary layer growth and stagnation points are to
be investigated and analysed.
Aims
This experiment aims to investigate the effects of numerous air speeds and angle of attack on the lift and drag
forces of an aerofoil, thus justifying the concept behind the pressure distribution over the surface of a two-
dimensional aerofoil. Certain objectives for the experiment include:
 Successfully measuring all pressure quantities;

 Determine the angle of attack that causes the aerofoil to stall;
 And, analysing the performance of the aerofoil under substantial fan speeds
Experimental Equipment
1. Low speed wind tunnel
2. CLARK Y 14% aerofoil
Experimental Procedure
1. The demonstrator will first discuss the general features of the wind tunnel and its operating
procedure.
2. By eye, set the aerofoil to zero angle of attack.
3. If available, insert the Pitot-static tube and locate the tip of the probe on the tunnel centreline.
4. In steps of 100 RPM increase the fan speed and record the pressures from the differential pressure
transducer and the pitot tube. Stop when pressure reaches 500 Pa Use the formulae developed in
your pre-work to create a chart of fan speed vs velocity.
5. Run the tunnel to a stable speed of 10 m s−1
6. Set the wing to zero angle of attack and confirm that air speed is correct. You may have to adjust fan
speed to account for blockage created by the wing.
7. Record pressure readings for all the pressure tappings.
8. Plot a line of pressure vs chord position on the provided chart.
9. Repeat steps 6. to 8. at the following angles of attack: α = 0 deg, 10 deg, 15 deg.
10. Find and record the angle of attack αs at which stall occurs. A good indicator are the tufts attached to
the wing suction side.
11. Repeat steps 5. to 10. at the following speeds 20 m s−1 , maximum attainable. During the process,
check repeatability by returning to at least one setting and taking a second set of readings. Time
permitting take extra readings at α = 5◦
12. If available introduce the smoke rake just upstream of the wing. Observe and sketch the flow patterns
at various angles of attack, including at stall. NOTE: Anyone with respiratory sensitivity to the smoke
should inform the demonstrator and leave the laboratory.
13. (Optional) Determine the sensitivity of αs to U. (Choose values of speed, U that you think are
appropriate. Feel free to experiment carefully but do not exceed the maximum pressure difference of
500 Pa).
Results
To calculate the fluid velocity associated with a desired fan speed desired, the differential pressure transducer
is measured from the machine and equation 10 was used. The equation was modified to look like this:
1 2
∆𝑃𝑝 = 𝜌𝑈 − (10)
2
This equation was rearranged to make U (Velocity) the subject:
2∆𝑃𝑝
𝑈= √ − (10𝑏)
𝜌
The velocities acquired from the fan speed increments are shown in Table 1.
Table 1: Pressure and Velocity output with changing RPM
Fan Speed (rpm) Differential Pressure Fluid Velocity (m/s)

Transducer (Pa)
200 10 4.040610178
300 28 6.761234038
400 52 9.214008855
500 85.5 11.81489893
600 122 14.11324461
FAN SPEED VS VELOCITY
700
600 y = 39.622x + 34.159

R² = 0.9985
500
Fan Speed (RPM)
400
300
200
100
0
0 2 4 6 8 10 12 14 16
Velocity (m/s)
To run the wind tunnel at 10 m/s equation 10b could be used. Using the fan speed and velocity trendline from
the graph shown in Figure #, a linear equation was established to predict the fan speed with a given velocity
(i.e. 10 m/s). Doing this yields the fan speeds indicated in Tables # and # below.
Pressure maintained at 62 Pa at 10 m/s

Fan Speed (rpm) 432 473 489 452
Angle 0 10 15
Pressure readings
1 0.05 4 0.15 0.05
2 0.3 4 0.6 0.55
3 0.45 2.5 0.5 0.5
4 0.5 3.5 0.5 0.45
5 0.45 4 0.5 0.45
6 0.4 4.5 0.5 0.45
7 0.4 4.5 0.5 0.45
8 0.4 4.5 0.5 0.45
9 0.4 4.5 0.5 0.45
10 0.4 4 0.5 0.45
11 0.4 4.5 0.15 0.15
12 0.35 4.5 0.2 0.25
13 3 4 0.25 0.3
14 3 4 0.25 0.3
15 2.5 4 0.2 0.3
16 2.5 4 0.2 0.3
17 2.5 4 0.25 0.35
18 2.5 4 0.25 0.35
19 2 4 0.3 0.45
Pressure maintained at 258 Pa at 20 m/s

Fan Speed (rpm) 829 915 983
Angle 0 10 15
Pressure readings
1 0 1.6 0
2 1.5 4.2 0
3 2.1 4 0
4 2.4 3.6 0
5 2.2 3.4 0
6 2.1 2.5 0
7 2 2.8 0
8 1.9 2 0
9 1.9 1.7 0
10 1.4 1.4 0
11 1.5 0.3 0
12 1.4 0.4 0
13 1.3 0.6 0
14 1.2 0.7 0
15 1.1 0.7 0
16 1.1 0.8 0
17 1.1 0.8 0
18 1 0.9 0
19 1 0.9 0
Discussion
Conclusion

MECH3410 Lab Report

Uploaded by

Copyright:

Available Formats

MECH3410 Lab Report

Uploaded by

Document Information

Original Description:

Original Title

Copyright

Available Formats

Share this document

Share or Embed Document

Sharing Options

Did you find this document useful?

Is this content inappropriate?

Copyright:

Available Formats

MECH3410 Lab Report

Uploaded by

Copyright:

Available Formats

MECH3410 – Fluid Mechanics

Experiment 3 – Measurement of Lift and Drag on an Aerofoil

 Successfully measuring all pressure quantities;

This equation was rearranged to make U (Velocity) the subject:

Table 1: Pressure and Velocity output with changing RPM

Fan Speed (rpm) Differential Pressure Fluid Velocity (m/s)

600 y = 39.622x + 34.159

Pressure maintained at 62 Pa at 10 m/s

Pressure maintained at 258 Pa at 20 m/s

You might also like