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A-Pillar Aerodynamics

A-Pillar Aerodynamics

(OP)
I have noticed that cars are tending to have recessed windshields these days. The A-pillar is broader than previous habit. It appears that the A-pillar will guide air flow around and keep it attached. My question is this, does recessing the windshield by about 1 inch allow this to work?
I had formally believed you would need a slat to take the air flow off the windshield, turn it an lay it onto the side glass.

RE: A-Pillar Aerodynamics

I think you need to recalibrate your ruler. Just checking on a Mundano, the recess is of the order of 3mm beneath the surrounding sheet metal.

Quite how they manage to get the airflow to remain attached around the A pillar is not known to me, and is something that has only become common in the last 20 years.

Cheers

Greg Locock


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RE: A-Pillar Aerodynamics

(OP)
Greg, some are recessed as deep as an inch or more at the bottom, tapering to just shy of flush at the top. I don't know that the flow stays attached to the A-pillar all the way around. I know that you can make an A-pillar fairing that sticks up several inches and dams the windshield air forcing it to spill over the fairing and follow its surface around. I was skeptical that a small recess would do it. Nevertheless, the A-pillar treatment is different these days from years ago.
I also believe that a slat will do the job, but nobody uses one.

RE: A-Pillar Aerodynamics

Ah OK, yes I think I've seen that style. It may be acting as a splitter I suppose. Alternatively in days of yore people would deliberately 'trip' the airflow to 'energise' the boundary layer which helped it attach rather than separate. I use quotes as that was the terminology used but haven't heard an aero guy ever say the same sort of thing.

Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?

RE: A-Pillar Aerodynamics

(OP)
Greg, I looked up some info and found some discussion of A-pillars. It seems what they are doing is effective at reducing wind noise by as much as 10dB or more. The windshield is recessed, increasing the influence of the A-pillar shape. The A-pillar is broader and the flow stays attached farther around the curve, but far from all the way. The mirror is also critical for noise. Separating it a little farther out from the body helps. Look at this: http://www.srcosmos.gr/srcosmos/showpub.aspx?aa=14...

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