Uncertainty analysis in aerofoil Help

[ruzfactor]

Uncertainty analysis in aerofoil! Help!

Homework Statement

Wind tunnel experiment using a constant velocity to determine Cl, Cd and Cm at different angle of attack (-5, 0, 5, 10, 15) of a symmetric airfoil. Error analysis of the experimental investigation to asses uncertainties in Cd, Cl, Cm and express the uncertainties in terms of %total error.
Cl Cd Cm
-0.313179134 || -0.013358668 || -0.064538757 (AOA= -5)
0.092060251 || -0.009305424 || -0.07130352 (AOA= 0)
0.55759136 || 0.017421587 || -0.089932608 (AOA= 5)
0.836392744 || 0.065190563 || -0.057779321 (AOA= 10)
1.048609998 || 0.119631326 || -0.024041582 (AOA= 15)

Homework Equations

Cl, Cd, Cm were calculated from the lifts and drag (using trapezoidal rule) obtained for each location .but no idea about error analysis.

The Attempt at a Solution

Need help on error analysis. How to do an error analysis to find the uncertainty?? Don't have any other previous experimental values.

 

[KataKoniK]

Dear fellow scientist,

Thank you for reaching out for help with your uncertainty analysis in aerofoil experiment. Error analysis is an important part of any scientific investigation, as it helps to assess the reliability and accuracy of your results.

To begin with, it is important to understand the sources of uncertainties in your experiment. These can include measurement errors, human error, and equipment limitations. In your case, potential sources of uncertainty could be the accuracy of your wind tunnel, the precision of your measurement devices, and any potential fluctuations in the wind speed.

To assess the uncertainties in your experiment, you can use statistical analysis techniques such as standard deviation or standard error. These will help you to determine the spread of your data points and give you an idea of the precision of your results.

To calculate the uncertainty in your Cl, Cd, and Cm values, you can use the following formula:

Uncertainty = (Maximum value - Minimum value)/2

For example, for Cl at AOA = -5, the uncertainty would be (0.313179134 - (-0.313179134))/2 = 0.313179134.

Once you have calculated the uncertainties for each data point, you can express them as a percentage of the total error. To do this, you can divide the uncertainty by the average value for that parameter and multiply by 100.

For example, for Cl at AOA = -5, the %total error would be (0.313179134/0.313179134) x 100 = 100%.

It is important to note that this is just one way of calculating uncertainties and there are other methods that can be used. You can also refer to any relevant literature or consult with your colleagues for additional guidance.

I hope this helps to guide you in your error analysis. Remember to always document your methods and assumptions, and to discuss any potential sources of uncertainty in your results.

Best of luck with your experiment!