Force Distribution in Wind Tunnel Experiments

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SUMMARY

This discussion centers on the relevance of plotting force distributions in wind tunnel experiments when pressure distributions are already available. The participant is conducting experiments for their final year engineering project and has calculated the Pressure Coefficient (Cp) using the formula Cp = (p - po)/(0.5ρV²). They express skepticism about the necessity of force distribution plots, suggesting that since Cp represents force per unit area, it may be redundant. The conversation highlights the importance of understanding dynamic versus static pressure and the potential impact of turbulence on force measurements.

PREREQUISITES
  • Understanding of wind tunnel testing principles
  • Familiarity with Pressure Coefficient calculations
  • Knowledge of dynamic and static pressure concepts
  • Basic principles of fluid dynamics
NEXT STEPS
  • Explore the relationship between pressure distributions and force distributions in fluid dynamics
  • Research methods for measuring dynamic pressure in wind tunnel experiments
  • Investigate the effects of turbulence on force measurements and data interpretation
  • Learn about contour plotting techniques for visualizing pressure and force distributions
USEFUL FOR

Engineering students, researchers in fluid dynamics, and professionals involved in wind tunnel testing and analysis will benefit from this discussion.

leakeg
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Hi physics peoples,

[for the tl;dr peeps: is there any point plotting a force distribution when I already have a pressure distribution, aren't they essentially the same thing?]

I've been doing wind tunnel experiments on structures for my final year engineering project, my supervisor (who I have a feeling knows less about the topic than me, which isn't much) has asked me to come up with contour plots for the forces on a model, and I'm wondering how to go about it, and if it is even possible.

What I have at the moment is a bunch of pressure values at various locations and from this contour plots of the Pressure Coefficient, Cp = (p - po)/(0.5ρV2) - it seems trivial to convert these values to forces for some corresponding area - simply multiply Cp by 0.5ρV2L2 - but this will be a force value for a specific area, and seems pointless to plot this when we already have the Cp values with are a dimensionless representation of pressure - a force per unit area.

Any thoughts are appreciated... from what I can tell "plotting the force distribution" seems like a fairly pointless exercise when I already have the pressure distribution, but I'm keen to hear some opinions.

Thanks in advance for any help!
 
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Well the big question is how complicated your wind tunnel experiments are.

Do you differentiate between dynamic pressure and static pressure? If you have turbulence are there forces, that cannot be represented by an average pressure, like short bursts that would get averaged out? Can you say something about the stresses and torque inside your model?

Maybe answering some of this stuff can give you some ideas what you could present to your boss. Maybe not.
 
Thanks for the reply.

The model is very basic, just a wooden shell.
Dynamic pressure was not measured as the hardware we used does not take high frequency measurements. So it is all averages.

Also not boss haha! It's for uni, my supervisor is what we call our allocated professor.
 

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