Aerodynamics of a ball/sphere

In summary: I'm thinking maybe I could use the Reynolds number and drag coefficient to calculate how the velocity and cross-sectional area of the ball affect its motion.
  • #1
daniscp
5
0
I have to do an investigation about the Aerodynamics of a ball/sphere and I have to look at how changing the velocity and the cross-sectional area of the ball affects it's motion.

I'm planning to build a wind tunnel out of cardboard and put a fan in it to generate the velocity wanted...I've got sponge spheres but not entirely sure they are the most appropriate

Any advices to this investigation would be welcome! Thanks

What equations are involved in this?
 
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  • #2
Does your "investigation" have to be an experimental setup? The reason I ask is because you can pretty easily calculate the Reynold's number and drag coefficient of a sphere. By looking at how the ball's diameter and the stream's velocity are used in those calculations, you can see which parameters have the biggest effects on the ball's overall calculated drag. Heck you could even make some nice graphs that compare sphere diameter and wind speed as the independent variables to show exactly how they compare.

Building a home-made wind tunnel could be problematic as you would need to make sure the air stream flowing over the ball is uniform in velocity and hopefully not too turbulent... plus you would need a very sensitive force gauge to measure the drag on the sphere since the drag will probably be very, very small. It seems to me you would have to account for a lot more variables than if you just solved the problem analytically.
 
  • #3
Sponge is not going to be a good choice for a model material. The biggest thing is that the sponge will deflect and change shape as the flow increases thus introducing even more error into your set up. Make the model out of something solid with a smooth surface, unless you also want to look at surface roughness effects.

The other thing you need to look at is what data you will get from a wind tunnel. I say this because your original purpose is to study the effects on its motion. What data do you hope to get from the tunnel? How will you relate those things to a sphere's overall motion? You'll get some drag data, but how are you going to use that data?
 
  • #4
Mech_Engineer said:
Does your "investigation" have to be an experimental setup? The reason I ask is because you can pretty easily calculate the Reynold's number and drag coefficient of a sphere. By looking at how the ball's diameter and the stream's velocity are used in those calculations, you can see which parameters have the biggest effects on the ball's overall calculated drag. Heck you could even make some nice graphs that compare sphere diameter and wind speed as the independent variables to show exactly how they compare.

Building a home-made wind tunnel could be problematic as you would need to make sure the air stream flowing over the ball is uniform in velocity and hopefully not too turbulent... plus you would need a very sensitive force gauge to measure the drag on the sphere since the drag will probably be very, very small. It seems to me you would have to account for a lot more variables than if you just solved the problem analytically.

Yes it does have to be an experimental setup unfortunatelY!
 
  • #5
FredGarvin said:
Sponge is not going to be a good choice for a model material. The biggest thing is that the sponge will deflect and change shape as the flow increases thus introducing even more error into your set up. Make the model out of something solid with a smooth surface, unless you also want to look at surface roughness effects.

The other thing you need to look at is what data you will get from a wind tunnel. I say this because your original purpose is to study the effects on its motion. What data do you hope to get from the tunnel? How will you relate those things to a sphere's overall motion? You'll get some drag data, but how are you going to use that data?

Yeah maybe your right sponge is not so good...

"What data do you hope to get from the tunnel? How will you relate those things to a sphere's overall motion? You'll get some drag data, but how are you going to use that data?"

That is my problem since I'm not entirely sure how to get some data relevant to my investigation
 

1. What is aerodynamics?

Aerodynamics is the study of how gases, such as air, interact with objects as they move through them. It involves the analysis of forces, such as lift and drag, that act on an object as it moves through a fluid, and how these forces affect the object's motion.

2. How does the shape of a ball/sphere affect its aerodynamics?

The shape of a ball or sphere greatly affects its aerodynamics. A smooth, rounded shape allows air to flow smoothly around the object, reducing drag and increasing stability. On the other hand, a ball with a rough or irregular surface will create more turbulence, increasing drag and reducing stability.

3. What is the difference between laminar and turbulent flow in relation to the aerodynamics of a ball/sphere?

Laminar flow refers to smooth, orderly air flow around an object, while turbulent flow is characterized by chaotic, irregular air flow. A smooth, round ball will experience laminar flow, resulting in less drag and more stable flight. A rough or irregular ball will experience turbulent flow, increasing drag and decreasing stability.

4. How does the speed of a ball/sphere affect its aerodynamics?

The speed of a ball or sphere greatly affects its aerodynamics. As the speed increases, the air flow around the ball becomes more turbulent, resulting in increased drag and decreased stability. This is why objects such as golf balls have dimples on their surface - to reduce turbulence and improve aerodynamics at high speeds.

5. How does air density affect the aerodynamics of a ball/sphere?

Air density is a major factor in the aerodynamics of a ball or sphere. As air density increases, the air becomes thicker and more resistant, resulting in increased drag and decreased stability. This is why balls will travel further in lower density environments, such as at higher altitudes or in thinner atmospheres.

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