Air Curtain

[Xist]

I am curious what they consider to be aerodynamic wheels.

[Madact]

Originally Posted by freebeard

I found this thread through Google Images!
I think this should be high-velocity. Otherwise a good summation of the concept, a variation on the Coanda nozzle.

I believe it's a bit of both... high pressure at the inlet where air is piling up at the edge of the air dam, which narrows to produce high velocity. I got a close look at a parked BMW a while back and while the intake looked to be about 3cm by 10cm as per the text, the outlet looked to be in the region of 1-1.5cm wide (as they say, "discharged through a very narrow opening at high speed"), so it narrows down quite a bit. High pressure at the intake, high velocity at the outlet.

On a side note, seeing it in the flesh I was surprised how little of the front edge of the tyre it 'covered', despite knowing that only the middle section of the tyre had the air curtain - the tyres in question were 225/45 R18, so about 66cm high.

[freebeard]

http://www.carmagazine.co.uk/spy-shots/mercedes-benz/mercedes-signs-off-four-electric-tesla-fighters/


The M-B design would translate well onto a Superbeetle front fascia. I've got a 'towelrack' bumper over-rider from the older style bumper that I want to hang upside down under the [higher] newer style front bumper. I don't want to drill mounting holes in the brand new bumper, so I'm still trying to figure that out. But it will have the center open section and plates clipped to the fender edge. It would also be a foundation for a front partial belly pan.

[aerohead]

Originally Posted by curv872

Stated in post #7, a reduction cd of .01

Is that 0.01%,or Delta-Cd -0.01 ? I'm confused from #7 (permalink)

[aerohead]

Originally Posted by freebeard

I found this thread through Google Images!



I think this should be high-velocity. Otherwise a good summation of the concept, a variation on the Coanda nozzle.

kach22i -- Your link gets 403:Forbidden. I think I found it at Access forbidden!

To move things along, here's an interesting article that ties BMW's research to a museum about the Graf Zepplin:
BMW EfficientDynamics

*The 3rd-gen X5 is reported at Cd 0.31
*The graphic shows that the wheelhouses and wheels are responsible for 30% of the total aerodynamic drag.
*That would be 0.093.
*Leaving 0.217 for the body in ground proximity.
*This is the most valuable info. I've seen in years!
-----------------------------------------------------------------------
*When Morelli added wheelhouses and wheels to the CNR 'banana' car,the Cd leaped,from Cd 0.161,to Cd 0.35,a 0.189 increase,217%.
*A.Cogotti (of Pininfarina's wind tunnel) saw a drag increase,from Cd 0.073,to Cd 0.157 when he added wheelhouses and wheels to his experimental body.A 215% drag increase.
The wheelhouses alone raised drag by 163%.

--------------------------------------------------------------------------
*The lower the drag of the basic body itself,the more important the wheel drag becomes

just like Hucho publishes.

[freebeard]

*This is the most valuable info. I've seen in years!

And it's only Tuesday!

Posted by kach22i in the Interesting Cars thread:



Apparently they recognize the problem but I don't see how anyone could expect that to perform in real life.

[mcrews]

Originally Posted by euromodder

Not every side-mounted airscoop develops into an air curtain.

THIS!
"Back in the day", front ducts were for cooling the brakes.

[aerohead]

Originally Posted by freebeard

And it's only Tuesday!

Posted by kach22i in the Interesting Cars thread:



Apparently they recognize the problem but I don't see how anyone could expect that to perform in real life.

It reminds me of what I think was an Audi concept in 'Minority Report'.
I don't know how you could survive a bump or pothole,or turn the wheels.

[freebeard]

There's one thing I can see working. Each pontoon fender has a part line with the flamboyant rocker panel. If it consisted of a cycle fender and a rigid mount with a pliable but rigid fill panel some limited wheel travel/steering could be absorbed by the fender.

Ross Lovegrove would be the guy to design it.

http://www.dezeen.com/2015/04/14/ross-lovegrove-design-schools-way-behind-need-embrace-digital-milan-2015/

I was looking for a picture of the underside on a chair seat that he did, this will have to do.

[hat_man]

Not that I would even know how to implement something like this, but I do like to learn as much as I can. After reading the last 10 pages it seems like these air curtains work by moving air from the higher pressure area in from of the vehicle (bumper area) through slots, and increasing it's velocity by narrowing the slots into slits before expelling the air across the face of the front wheels. This in turn either helps fill the cavity of the front wheel well causing a "boundary" so that the air moving around the vehicle doesn't get "scrambled" causing drag? Or the air coming through the slits is of a greater velocity (pressure?) than the air moving around the corner (bumper) creating this "curtain", again keeping the attached air from getting "scrambled"?

I am assuming these slits have their opening in the wheel well somewhere near the vertical mid-line of the tire or are they closer to the outer edge of the tire?

I know the "particulars" of this are way above my head, but man I do love to learn.