Adding a shape to make a disc spin?

[Bill McGrath]

• I'm basically familiar with wings and lift. I've run into an issue with a sculpture I'm making. I have constructed a 48" disc of 1/16" perforated steel framed in a 1/4" thick by 1 1/4" steel rim. I want to attach bearings to opposite sides of the rim and allow it to spin in the wind, but I sense that, without some additional shape to opposite sides at "opposite" locations, it wouldn't spin very well as oncoming wind would hit both sides of the disc equally, thus either preventing it from spinning or creating a stuttering. I'd prefer to add as little as possible so that it retains the basic flat circle shape. I thought of a 12" wing shaped piece but if i understand rightly, it would be shuting highrprssure air directly into the steel disc which just would cause some kind of turmoil. Can anyone point me to a source or idea for an add-on "wind catcher director" thingy? Thanks so much.

 

[berkeman]

• I'm basically familiar with wings and lift. I've run into an issue with a sculpture I'm making. I have constructed a 48" disc of 1/16" perforated steel framed in a 1/4" thick by 1 1/4" steel rim. I want to attach bearings to opposite sides of the rim and allow it to spin in the wind, but I sense that, without some additional shape to opposite sides at "opposite" locations, it wouldn't spin very well as oncoming wind would hit both sides of the disc equally, thus either preventing it from spinning or creating a stuttering. I'd prefer to add as little as possible so that it retains the basic flat circle shape. I thought of a 12" wing shaped piece but if i understand rightly, it would be shuting highrprssure air directly into the steel disc which just would cause some kind of turmoil. Can anyone point me to a source or idea for an add-on "wind catcher director" thingy? Thanks so much.

Welcome to the PF.

Is the disc vertical? Is it free to gimbal so that the wind flows along both of its flat sides, as opposed to hitting one side head-on?

If the disc is horizontal, does the center of the disc sag a bit?

Can you just drive the rotation of the disc at the bearings, rather than using the wind directly? You could have a separate windmill arrangement to get the energy from the wind to give you the rotational torques at the bearings, for example...

http://cdn4.explainthatstuff.com/darrieus-vertical-wind-turbine.jpg

 

[Bill McGrath]

Welcome to the PF.

Is the disc vertical? Is it free to gimbal so that the wind flows along both of its flat sides, as opposed to hitting one side head-on?

If the disc is horizontal, does the center of the disc sag a bit?

Can you just drive the rotation of the disc at the bearings, rather than using the wind directly? You could have a separate windmill arrangement to get the energy from the wind to give you the rotational torques at the bearings, for example...

http://cdn4.explainthatstuff.com/darrieus-vertical-wind-turbine.jpg
View attachment 203869

Thanks for replying. yes it's vertical, so no day. I want to keep it simple so no other propellant or windmill-like tails to steer into wind. I think I'll experiment with a model. again.

 

[Bill McGrath]

Welcome to the PF.

Is the disc vertical? Is it free to gimbal so that the wind flows along both of its flat sides, as opposed to hitting one side head-on?

If the disc is horizontal, does the center of the disc sag a bit?

Can you just drive the rotation of the disc at the bearings, rather than using the wind directly? You could have a separate windmill arrangement to get the energy from the wind to give you the rotational torques at the bearings, for example...

http://cdn4.explainthatstuff.com/darrieus-vertical-wind-turbine.jpg
View attachment 203869

Or I could copy the blades as shown in your posted photo and insert my disc in the middle.

 

[berkeman]

Or I could copy the blades as shown in your posted photo and insert my disc in the middle.

Yes, that could be very nice. I've always wondered about wind turbines with designs like that. I have no intuitive idea how they work.

 

[berkeman]

BTW -- Very nice gallery of your work at your website, Bill. From your profile page:

https://www.billmcgrathsculpture.com/what-i-make-of-what-i-see