Airflow calculations for levitating a foam golf ball

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    Airflow Fan Physics
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Discussion Overview

The discussion revolves around the calculations and requirements for levitating a foam golf ball using a column of air. Participants explore the complexities of fluid dynamics, fan specifications, and experimental approaches to achieve stable levitation at approximately 10 inches. The conversation includes practical experimentation and theoretical considerations.

Discussion Character

  • Exploratory
  • Technical explanation
  • Experimental/applied
  • Debate/contested

Main Points Raised

  • One participant seeks assistance in calculating the fan requirements needed to levitate a foam golf ball, which weighs between 8.5-11 grams and has a diameter of 42.6-41.9 mm.
  • Another participant suggests that designing the system numerically from first principles may be complex and recommends experimenting with a real system instead.
  • Concerns are raised about the stability of the ball on the air jet as the flow increases, and the importance of the jet's flow rate and exit diameter is emphasized.
  • Participants mention the Coanda effect as a principle that could help in keeping the ball levitated.
  • One participant shares their experience using a shop vac, noting that it provided too much lift initially, and discusses the challenges faced with a squirrel cage blower that did not generate sufficient pressure.
  • Suggestions are made to experiment with different air jet configurations, such as using a straw or funnel, to optimize the air flow for lifting the ball.
  • Another participant points out that the foam ball's weight is significantly higher than that of a ping pong ball, which may affect the calculations and required air speed for levitation.
  • There is a mention of a potential application for the foam ball, although details remain vague.

Areas of Agreement / Disagreement

Participants generally agree on the need for experimental validation of any theoretical calculations. However, there is no consensus on the specific fan and motor specifications required, and multiple approaches to the problem are discussed without resolution.

Contextual Notes

Participants note that the environment and constraints of the levitation system have not been fully specified, which may impact the effectiveness of proposed solutions. The discussion highlights the need for practical experimentation to verify any numerical solutions.

Who May Find This Useful

This discussion may be of interest to individuals involved in fluid dynamics, experimental physics, engineering design, or those looking to explore practical applications of airflow in levitation systems.

BAB
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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.
 
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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
 
Baluncore said:
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
 
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BAB said:
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.
 
BAB said:
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.
 
Baluncore said:
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
 
BAB said:
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 :smile:) 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 ?

##\ ##
 
BvU said:
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 :smile:) 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.
 
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