Airflow calculations for levitating a foam golf ball

[BAB]

TL;DR

Foam ball levitate

Im trying to find someone or a company who can do some calculations for me. I started with a fluid dynamics modeling company and they felt I would need a physics calculation.
I need to a foam golf ball to be picked up by a column of air and held in place at aprox 10” until it is knocked off the column then picked back up and again levitated at aprox 10”.
I need to know what the fan requirements would be.
The foam ball is 42.6-41.9 mm and 8.5-11 gm in weight.

 

[Baluncore]

Welcome to PF.

That is a complex system and will be difficult to design numerically from first principles. I think you will get a better estimate by experimenting with a real system.

The jet of air that will support the ball will have a flow rate and an exit diameter. The flow of the jet, turbulent or laminar, will be important, as will a glossy or mat surface on the ball. If the jet is to be increased, from zero flow, to a set flow, to lift the ball, then the ball must be stable on the jet throughout the process of increasing the flow.

The demonstration is usually done with a ping pong ball.
The ball sticks to the jet because of the Coanda effect.
https://en.wikipedia.org/wiki/Coandă_effect

 

[BAB]

Welcome to PF.

That is a complex system and will be difficult to design numerically from first principles. I think you will get a better estimate by experimenting with a real system.

The jet of air that will support the ball will have a flow rate and an exit diameter. The flow of the jet, turbulent or laminar, will be important, as will a glossy or mat surface on the ball. If the jet is to be increased, from zero flow, to a set flow, to lift the ball, then the ball must be stable on the jet throughout the process of increasing the flow.

The demonstration is usually done with a ping pong ball.
The ball sticks to the jet because of the Coanda effect.
https://en.wikipedia.org/wiki/Coandă_effect

Thank you for the reply. I built this using a shop vac, obviously overkill, when I turned the shop vac on the first time it was so powerful it shot the ball several feet into the air. I was using pvc pipe so I put several vents in before I got the air flow low enough to perform as I needed.

I did buy a fan and motor initally, a squirrel cage type blower and it did not develop enough pressure? because when I tried a double blower of the same squirrel cage type it resulted in the same amount of lift.

The problem is I have no aproximation of the starting point. Motor/fan combos are expensive.

So how would I go about finding out the infomation I need? If I bought a motor fan combo and lets say it was too much. I could put that on a variable frequency drive but how would I arrive at the specs I need for the fan and motor without a vfd?
What I need is a person who can work with me to ovtain the info I need.

Thanks
Brian

 

[BAB]

Thank you for the reply. I built this using a shop vac, obviously overkill, when I turned the shop vac on the first time it was so powerful it shot the ball several feet into the air. I was using pvc pipe so I put several vents in before I got the air flow low enough to perform as I needed.
I did buy a fan and motor initally, a squirrel cage type blower and it did not develop enough pressure? because when I tried a double blower of the same squirrel cage type it resulted in the same amount of lift.
The problem is I have no aproximation of the starting point. Motor/fan combos are expensive.
So how would I go about finding out the infomation I need? If I bought a motor fan combo and lets say it was too much. I could put that on a variable frequency drive but how would I arrive at the specs I need for the fan and motor without a vfd?
What I need is a person who can work with me to ovtain the info I need.
Thanks
Brian

And to be clear Im not wanting this for free.

 

[Baluncore]

I did buy a fan and motor initally, a squirrel cage type blower and it did not develop enough pressure? because when I tried a double blower of the same squirrel cage type it resulted in the same amount of lift.

The problem is I have no aproximation of the starting point. Motor/fan combos are expensive.

The experiment is usually done with a borrowed hair drier (cold), and a ping pong ball. Try a hair drier with a foam ball.

You need to change the diameter of the air jet, to match the pressure and flow rate of the blower. Find out if a straw, a tube, or a funnel, works better than a simple hole in a flat sheet.

You have not fully specified the environment or constraints on the solution. You will need to verify any numerical solution by experiment. Now is the time to experiment, not to buy a solution. A physicist, capable of solving the problem without experiment, will cost you several hair-driers or blowers per hour.

 

[BAB]

The experiment is usually done with a borrowed hair drier (cold), and a ping pong ball. Try a hair drier with a foam ball.

You need to change the diameter of the air jet, to match the pressure and flow rate of the blower. Find out if a straw, a tube, or a funnel, works better than a simple hole in a flat sheet.

You have not fully specified the environment or constraints on the solution. You will need to verify any numerical solution by experiment. Now is the time to experiment, not to buy a solution. A physicist, capable of solving the problem without experiment, will cost you several hair-driers or blowers per hour.

I will proceed as you suggested. Thank you for the input.
Brian

 

[BvU]

The foam ball is 42.6-41.9 mm and 8.5-11 gm in weight

So size is approximately that of a ping-pong ball but weight is 3 to four times higher.
Calculations (I get 15 m/s for your balls ) aren't very useful, but at least give an order of magnitude.

I distinctly remember having fun with a home vacuum cleaner and ping pong ball sixty years ago and would have started experimenting (as @Baluncore so rightly suggested) but unfortunately only have a vac and no balls at hand.

'Foam' rings alarm bells (can't underpin or specify why...).

Is the application something like an aid for practicing softball ?

$\$

 

[BAB]

So size is approximately that of a ping-pong ball but weight is 3 to four times higher.
Calculations (I get 15 m/s for your balls ) aren't very useful, but at least give an order of magnitude.

I distinctly remember having fun with a home vacuum cleaner and ping pong ball sixty years ago and would have started experimenting (as @Baluncore so rightly suggested) but unfortunately only have a vac and no balls at hand.

'Foam' rings alarm bells (can't underpin or specify why...).

Is the application something like an aid for practicing softball ?

$\$

I work for a company that provides solutions for underserved markets. It will eventually go to market so thats all I can really say.