What about turning vanes?

[wibiwo]

Does anyone have any ideas about turning vanes? By that I mean spoiler-like devices to point air into low pressure areas, like the tail of the car, or the rear window. The only automotive use I've seen is on open wheel race cars. "Barge boards" are used to direct air into the area behind the tires. In HVAC turning vanes are used in ducts to smooth flow around bends, lessening pressure drop, noise, and energy needed to push the air. Seems like it might help on wagons etc. Maybe even combined with a Kamm-back?

[FastPlastic]

I've seen a few on cars here and there. Mostly to keep the back window clean. Problem is in a stationary home heating system the turning vane just puts pressure on it's mount as the air pushes on it. Mounted to a car it would tend to induce drag as it pushes through the air. Now weather or not the improved flow cancels out the induced drag probably depends on the arrangement. I'm guessing it would probably be more useful if it reattached flow somewhere up front.

An example of a pickup turning vane

[aerohead]

I'm not current on this topic.In years past,experiments with turning vanes succeeded in moving air behind a bluff body,but the downside was that air would separate behind the vanes themselves,for a net overall drag increase.---------------------- In ductwork,vanes can create constant area flow around a corner,with virtually zero turbulence.I use them in my wind tunnel,they work great.------------------ When they're used to create an air curtain over a steep backlite to control back-soiling of the glass,it may be a conscious concession to higher drag for the sake of clear rearward vision.