Random Aerodynamic Oddity of the Day Thread

[Bicycle Bob]

Originally Posted by freebeard

Not getting that at all. The rotor is wired like a bicycle wheel?

No, more like the wing of a Beaver or Cub - one strut per blade. On a turbine, it would only be in tension, so it could be even thinner. The hub would be extended into the wind to support the cable inner ends.

[freebeard]

Part of the claim is a 'highly advanced blade'.

I estimate 88 blades. The whole unit is the width of an RV door.

I'm suggesting positioning it on the top of a dome to supercharge it. A 1kW unit might be appropriate for a 20ft dome. A 60ft dome (not that large) could probably support a 5-10kW unit.

[jakobnev]

Turbine connected to a multimeter measuring amps being generated.

It is my highly personal opinion that these guys are just trying to scam investment money from people who are ignorant of physics.

[Bicycle Bob]

Originally Posted by jakobnev

It is my highly personal opinion that these guys are just trying to scam investment money from people who are ignorant of physics.

It could also be that they understand some physics, but are blind to economics. It isn't hard to get fixated on souping up a turbine, and lose track of comparative economics. It is hard for me to change gears and not worry about the free wind I let pass the same way I squeeze fuel.

People who attach wind turbines to their houses quickly tire of the vibration.

A wind turbine can be very efficient with just one blade. We use three for gyroscopic and balance reasons. You can visualize a cylinder of air going through a wind turbine being cut into spirals by the blade(s). The more blades, the thinner the slices per revolution. Thin slices don't pack much momentum. We built bi-planes because they are structurally efficient, but adding a third wing, to take a third slice, didn't improve the structure and increased the interference between the wings.

[freebeard]

People who attach wind turbines to their houses quickly tire of the vibration.

Depends on how you do it. Bracket a mast to a flat wall and it turns into a drumhead.

A vertical axis windmill at the summit of an hemisphere would vibrate in the plane of the structure instead of at right angles to it.

Then follow Julian Edgar's instruction on Tuned Mass Dampers.

[cRiPpLe_rOoStEr]

I'm still not so used to the absence of a "traditional" grille (or some ornament resembling it) in the Tesla Model 3, so it might qualify as an aerodynamic oddity.



That vent on the hood of the Jaguar I-Pace is still something quite unusual.

[RedDevil]

The 'grill' of the Model 3 is where the stagnation point is; the ideal shape might be a rounded nose, but you can flatten the area at minimal cost because the stagnant air bubble diverts the air around the area just as well.

Jaguar wanted a grille and a raised hood, but allows the air to escape through the vent again, so it roughly follows the same trajectory as the air that flows over the Model 3's hood.
Under the hood the I-Pace is not unlike the Model 3, literally.

But it still comes at a cost of increased air resistance. The I-Pace has a Cd of 0.29 while the Model 3 manages 0.23.
Jaguar effectively de-ranged the I-Pace.

[cRiPpLe_rOoStEr]

Originally Posted by RedDevil

The 'grill' of the Model 3 is where the stagnation point is; the ideal shape might be a rounded nose, but you can flatten the area at minimal cost because the stagnant air bubble diverts the air around the area just as well.

Even though it's not totally rounded, it's still quite curvy enough to not do much harm to the aerodynamics.

[kach22i]

Is it Photoshop?

2020 New Random Pics - Page 174 - Pelican Parts Forums

[kach22i]

https://www.pinterest.com/pin/188729040621835034/


EDIT:

https://www.youtube.com/watch?v=zF70Diz0mFk