The Dreaded VG's again...
 

I have a question over vortex generators. I understand that they have very specific uses, and come with their own drag penalties, but I was wondering if they can be used to reduce certain problem areas of auto aerodynamics.

Looking at their use in Aircraft, they are predominantly used to keep flow attached to a wing with a high angle of attack, to lower stall speed of the wing.

Would it not make sense to install them in front of the front wheel arch/well? By installing one or more VG on the front bumper/wing, would this smooth airflow around the front wheels?

I have no means of testing or simulating this.

We did have this thread a while back, see second post on page two.

http://ecomodder.com/forum/showthrea...a-34854-2.html
http://www.mulsannescorner.com/AudiR...st2016-SC3.JPG

Ah missed that one - thanks.

Another tip that most environmentalists will scoff at, is to paint some used engine oil on the area you want to test for use with vortex generators. Then go drive down the highway for a few miles. The wind will leave a oil pattern on the vehicle showing you the air flow pattern. (works like a wind tunnel only with used oil) So you know where to place them, and how to angle them. Plus its easy to retest to get things perfect. I learned this from a friend who races airplanes.

http://longez.weebly.com/uploads/4/3...36581_orig.jpg

Great idea in general - thanks , :thumbup: but as my question was around wheels, I think I'll try to avoid using oil around them...

If you go to the link below CFD image showing wheel well air flow disruption.

http://ecomodder.com/forum/showthrea...s10-35043.html
http://i184.photobucket.com/albums/x...psgewe5pxk.jpg


The front wheels are way worse than the rear wheels as with most vehicles.

I think you are looking at a good problem to solve in other words.

Are there any general rules of thumb for the size of VGs?

I have also seen on Air craft VG's, they are often angled in a Zig-Zag pattern along the wings, rather than perpendicular to the leading edge. Does anyone know the thinking behind this?

What works to replace a front wheel skirt is an air curtain. They are used by BMW and Ford.

Latest aero on big trucks is skirting in the front fenderwell following same over the full course. About 1.5" deep. Covers most of air space. See Peterbilt 579 EPIQ aero pics.

That and full length skirting is what my pickup will eventually receive.

15° off the direction of flow (not travel) this will require testing before installing.
The top/tip must reach up above the boundary lair into free flow to be able to pull it were you want.
you tube link. Velox Motorsports FRS / BRZ Diffuser Flow Visualization Testing
This will be better than oil , easyer to clean up . They used" China Wight clay "and water.

Zig zag ... my theory is that they are trying to cause counter-rotating vortices. Instead of co-rotating vortices. I dont know witch is better , this may be application specific.
https://www.kseriesparts.com/graphic...PP-26001-2.jpg
As for use look at the Mitsubishi Evo, top of the back window VG's were used to reduce instability caused from separated air (due to the back glass angle and a trunk too short to allow for reattached boundary lair)
buffetting the back end reducing the safe top speed