A vertical windmill is one that rotates along a vertical axis. The two types are lift and drag. The drag type is exemplified by two cones connected on a vertical axis free to rotate, common on ornamental wind vanes and wind speed indicators. The lift type use the principles of airfoils. They generate lift when neither perfectly perpendicular nor perfectly parallel to the wind direction.

A lift type windmill suffers fatigue, vibration, and noise due to the lift component alternately pulling and not pulling as the windmill rotates. Various solutions have been tried, such as extending the vanes into a helix shape.

Part of the cause of this fatigue and noise is wind separating from the lift surface at high angles of attack. This is an inevitable phenomenon when you're rotating a wing through 360 degrees. But wind cohesion can be improved. If the stall angle is raised there will be less fatigue as the range of directions the vanes are pulled in is reduced.

Furthermore increasing angle of attack before a stall will increase lift as the airfoil pulls over a wider range of motion.

Golf ball dimples aren't used on aircraft wings because the additional drag makes it not worth it. But for windmill airfoils drag doesn't matter nearly as much.

So the idea is to put golf ball dimples on the surfaces of lift type vertical windmill blades thereby maintaining laminar flow over a wider range of motion.
-- Voice, May 15 2021

vertical windmill https://granitegeek...is-wind-turbine.jpg
[Voice, May 15 2021]

Stall at high angle of attack https://youtu.be/6UlsArvbTeo?t=68
[Voice, May 15 2021]

Dimples on golf balls maintain laminar flow https://www.researc...es-on-golf-ball.png
[Voice, May 15 2021]

Is this a technology for water turbines (as per. category)?

Is this a technology for wind turbines?

Is this a technology for golf balls?

Or is this a secret code?
-- pocmloc, May 15 2021


I think maybe [Voice] was trying to remember the word ‘helicopter’ when writing “horizontal lift windmill”. So, this is a helicopter covered in the same kind of dimples as a golf ball, presumably for the same clever aerodynamic reasons. Not a bad idea at all.
-- hippo, May 15 2021


Ah, [Voice] has rewritten it since my earlier annotation...
-- hippo, May 15 2021


If you know what direction the helicopter blades or windmill blades are going to rotate then perhaps a golf ball hemisphere dimple could be replaced with an oval tailed dimple to maximize laminar flow. genetic algorithms could be used to make the best oval dimple shape.

Also, considering the way helicopter blade rotation speed causes the perimeter to rotate faster (through more air) dimples could be adjusted for the length -at- position of the windmill or helicopter blade, so say more ovoid dimples at the distal part and more hemispherical dimples at the near-rotor area.

Dimples at rotating blades could also have application to better water propeller design, as well as better turbine (like gas turbine) energy generation. Thanks [Voice].
-- beanangel, May 16 2021


With modern 3D manufacturing and AI algorithms, dimples don't have to be uniform and can vary across surface. Even become holes.
-- wjt, May 16 2021


[wjt] //holes//

I think I read about doing something like an air hockey table to airplane wings to decrease turbulence and drag. All of the numerous applications of [Voice]' idea (turbines, propellers, helicopters, windmills) could possibly have pressurized air/water/working fluid flowing out of holes to decrease drag.
-- beanangel, May 16 2021


[bean] I think the air is sucked into the holes, so as to keep the flow close to the surface and stop it separating
-- pocmloc, May 16 2021


Finding the right ratio of dimples (or better) could be done with software, and might obviate dimples replacing them with something like a streamlined hexagonal plane tiling with mushrooms that dip down to U shapes (golf ball dimples but better) to maximize laminar flow. A wing or turbine blade covered with microripples.

Noting microripples I am reminded of a corduroy surface wing or windmill that has all laminar flow, does the heightened surface of the corduroy (microripples) cause greater lift for a wing or turbine at the actual area of the wing?

Undersurface channels between golf ball dimples (or better) could connect golf ball dimples (or better) together and make customized pressure profiles on wing/turbine surface; one use is reintroducing laminar flow to a turbulent area rearward on the wing/turbine. Drones could wash the fussy little channels.

Now imagine it is the year 2040 and peltier effect modules and MEMs refrigerators are 10-20 times better. Select spots at the wing/turbine blade could be heated and cooled to supercling the boundary layer or produce controlled, directed turbulence. refrigerated-spot wings could have more lift from having a wider latitude of possible shapes that conserve the boundary layer like high lift high humps possible from the reduction in turbulent flow.

Ships of course could have dimples (or better) that are hydrodynamic.

[Voice] One improvement to wind generator blades is making them longer right on-site with additive manufacturing/3D printing. The largest base size of blade that can be transported is installed, and then drones deposit and make extensions to the blade, perhaps doubling its length. I read the longer wind turbine blades are the more energy they harvest. Efficiency might go up as well.
-- beanangel, May 16 2021



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