Air Curtain

[Cd]

I wonder what these guys were thinking ? Is that supposed to be air curtains or a parachute ?
At least they removed the mirrors.

[mcrews]

Originally Posted by botsapper

The BMW air curtain is a very subtle corner canard as compared to very extravagant front corner versions from the Japanese racing aftermarket. These external examples are corner box canard/splitters. Note the horizontal winglets are angled flat, collecting front air pressure flow and narrowing it down just before the well opening, probably with similar hopeful results.
http://www.gtrblog.com/wp-content/up...02-540x405.jpg
Other concept cars with these devices.
http://theblogaboutcars.com/wp-conte...citroen-GT.jpg

this thread has seemed to drift (no pun intended) on and off the specific topic of the 'curtain' as a shield.

I started back at the beginning and reread the posts.
While botsappers pictures were cool, I realized that the point was off base.

THE idea of the canard is (when placed at the 40-60degree angle) is to increase the downward air presure on the front corner, forcing the front tire down harder . Catching the air that would whip around higher than the splitter.
The splitter, of course is also increasing the downward presure on the front end.

also, as the first pictures show of the air flow (& the front slots), the air being captured for the 'curtain' is ONLY the air that is caught in the thin slot that then slides along the INSIDE wall of the fender (flat) to then exit uot the slot toward the tire.

I am sure that there is a relationship with how far uot/in the side of the tire is at in relation to the edge of the fender. I would imasgine that IF the tire was 10mm farther uot, the entire concept of 'curtaining' would fall apart.

As this thread has develped, my thoughts are this.
1. There was a point where the BMW automobile looked VERY dull from the front.
2. obvioulsy driven by windtunnel design.
3. WT/airflow was also leading to flat wheel designs or flat wheel covers.
4. I think that either by accident (think 3M sticky pad glue) or by thinking outside the box, someone discovered this concept 'the air curtain'
5. It allowed them to have a very aggrssive front look, with slots and opening, allowed them to have agressive looking wheel designs that weren't 'areo/eco flat'.
6. Gave some very minimal gain in cd while giving the larger advantages listed above.

reminds me a lillte bit of engine design thru the early 80's in the US. all the bolt-on epa stuff looked like crap hanging all over the engine, with no rhyme or reason as to why it was there.
In 1984, the totally redesigned Chevy Corvette had re-thought every part on the engine and created an engine that actually was pleasant to look at.

[mcrews]

Originally Posted by Cd

anybody notice the rear spoiler on this car??????

A proffesional version of any of a dozen coroplast spoiler on cars on this forum!!!!!

[mcrews]

http://www.youtube.com/watch?v=3dMQ3IqJqkk

Ist gem prius.
at 18 seconds, the aftermarket wraparound front bumber is set up for air curtains. just cant see the source of the air stream from the front.

[Otto]

Originally Posted by mcrews

Ist gem prius.
at 18 seconds, the aftermarket wraparound front bumber is set up for air curtains. just cant see the source of the air stream from the front.

Looks like possibly variable geometry air curtain slot, like a Fowler flap on an aircraft wing.

What about the triangular pieces at the base of the windshield? To prevent or channel laminar bubble? Prevent buffeting and noise on the windshield?

Were those small splitters at the front lower sides of the nose air dam?

[mcrews]

front splitters....red.....no I think it was just the red decal

on first look I thought the windshield ting was gauge pods on the dash.
Very interesting.
Bet that front windshied has a nice coat of the rainshield stuff. btw...I use that stuff and it works. esppecially if your doing above 45mph

all i can think on the curtains is they are tunnelling the air from the center opening with ducting.....

[mcrews]

Originally Posted by Cd

I wonder what these guys were thinking ? Is that supposed to be air curtains or a parachute ?
[/IMG]

typically body kits go one of a couple of ways.
1. overaccent the exisitng lines to create over-functional openings
2. create extra body lines and openings.....much messier(in my opiniun.)

I think they went with #1

[kach22i]

Earlier in this thread I mentioned a NASA fan blade which is vented, and blows air over certain areas to reduce sound (turbulence).

Here is the link:
Engineering and Fabrication Techniques for Low-Noise-Research Fan Blades

[Madact]

Found some extra links on the BMW version
BMW Drops the Goods on the 2011 1-Series M Coupe (With Photos!) | The Smoking Tire
BMW EfficientDynamics
BMW EfficientDynamics : Aerodynamics

From the first link:

Air Curtains.
Consistency between form and function is crucial to engineers at BMW M, who seek perfect balance of various aerodynamic factors in the wind tunnel. As a result, the 1 Series M Coupe has been equipped with BMW’s latest aerodynamic innovation. Air curtains, used here for the first time in a BMW production vehicle, improve air flow around the wheel arches with the benefit of significantly reduced turbulence.
This innovative aerodynamic feature consists of openings in the outer section of the lower front fascia that route high-pressure air through ducts at each front corner. The ducts are approximately 10 x 3 centimeters wide and are designed to channel air to openings at the front of each wheel arch, where it is discharged through a very narrow opening at high speed. The escaping air stream covers the side of the front wheels like a curtain, thereby reducing aerodynamically unfavorable turbulence around the rotating wheels.
This feature has a key role to play in the development of future aerodynamic innovations. An example of the air curtain principle was first presented in the concept study BMW Vision EfficientDynamics at the International Motor Show (IAA) in Frankfurt in 2009, and the developers of the BMW 1 Series M Coupe took on the pioneering task of applying this element to a production vehicle. To do so, they utilized the unique capabilities of the new full-scale “rolling road” Aerolab wind tunnel at the BMW Group’s new Aerodynamic Testing Center.

This gives a few nice details, in particular:
* The intake size in this case is only ~ 30 square cm, which is tiny by "ricer scoop" standards.
* They're using the venturi effect to accelerate the air to produce the air curtain, which makes sense.

An air curtain is a well-established phenomenon. Lateral forces have a smaller effect on the *direction* of a faster air stream than if it were moving slower - the fast moving air creates a 'virtual surface' which reduces cross-flow.

As noted previously in this thread, the BMW implementation only seems to cover the centre section of the tyre - perhaps this is because that's where the edge of the tyre is perpendicular to the airflow? One could speculate that the BMW engineers found that creating an air curtain over the whole height of the wheelhouse required too large a scoop, and chose the height with the best tradeoff between scoop drag and air curtain effect...

[freebeard]

I found this thread through Google Images!

This innovative aerodynamic feature consists of openings in the outer section of the lower front fascia that route high-pressure air through ducts at each front corner. The ducts are approximately 10 x 3 centimeters wide and are designed to channel air to openings at the front of each wheel arch, where it is discharged through a very narrow opening at high speed. The escaping air stream covers the side of the front wheels like a curtain, thereby reducing aerodynamically unfavorable turbulence around the rotating wheels.

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