# Force Distribution in Wind Tunnel Experiments

• leakeg
In summary, the person is conducting wind tunnel experiments for their final year engineering project and has been asked by their supervisor to create contour plots for forces on a model. They have a pressure distribution and are wondering if it is necessary to plot a force distribution since they already have the pressure distribution. The person also discusses the possibility of converting the pressure values to forces, but questions the usefulness of plotting this information. They are looking for opinions on whether plotting the force distribution is necessary or not. Additionally, they mention that their experiments are basic and only measure average pressure, not dynamic pressure or turbulence. They clarify that their supervisor is their assigned professor for their university project.
leakeg
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!

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.

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.

## 1. What is force distribution in wind tunnel experiments?

Force distribution in wind tunnel experiments refers to the measurement and analysis of the forces acting on a model or object placed in a wind tunnel. These forces include lift, drag, and side forces, and their distribution across the surface of the model is important for understanding the aerodynamic performance of the object.

## 2. How is force distribution measured in a wind tunnel experiment?

Force distribution is typically measured using load cells or strain gauges attached to the model in the wind tunnel. These sensors measure the forces acting on the model and provide data on the magnitude and direction of these forces. This data can then be analyzed to determine the overall force distribution.

## 3. What factors can affect force distribution in wind tunnel experiments?

Force distribution in wind tunnel experiments can be affected by a variety of factors, including the shape and size of the model, the speed and direction of the wind, and the surface roughness of the model. Other factors such as air density, turbulence, and test section geometry can also influence the force distribution.

## 4. Why is force distribution important in wind tunnel experiments?

Understanding force distribution is crucial in wind tunnel experiments because it provides valuable information about the aerodynamic performance of a model. By analyzing the force distribution, researchers can identify areas of high and low pressure, determine lift and drag coefficients, and make improvements to the design and performance of the object being tested.

## 5. How is force distribution used in real-world applications?

Force distribution data obtained from wind tunnel experiments is used in a variety of real-world applications, including aircraft design, vehicle aerodynamics, and building design. By understanding the force distribution on a model in a wind tunnel, engineers can make informed decisions about the design and performance of these objects, leading to more efficient and effective designs in the real world.

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