Tuft Testing - "Vortekz" vortex generators on 2003 Jetta Rear Window

[Deezler]

Updates? none to be had, really. The 3-M adhesive tape these VG's come with rocks, they are still on super strong. They are still bending the airflow, but fuel economy benefit is still negligible.

This is definitely not the magic easy way to cut drag though. Focus on grill blocks, flat under-tray/underbody panels, and wheel covers, mirror deletes, etc.

[ac7ss]

But, do they keep the rear window cleaner?

[Otto]

Anybody tried vortex generators on a belly pan? Might get some downforce.

[Kyleyadon]

I started doing a little research on VGs after I started noticing them on a number of large trucks. Seems they are most useful in getting airflow to smooth out when crossing some kind of gap, like that between the back of a truck's cab and the front of it's trailer. But I did find an interesting video on the subject and some pictures that may help understand their effects and applications better. I think that I'll probably be adding some to my towcar. Just a matter of deciding the best type to try and the best place to put them. Since I go through an entire tank on a daily basis I should be able to provide a fair bit of practical use data on them.

https://www.youtube.com/watch?v=9Whd_KnsLKE

[freebeard]

All the Kyle Drives videos are good.

Have you thought about air dams and Coanda nozzles?

[ChopStix]

I have a pilot friend who races Long EZ airplanes. His advise on vortex generators was to paint used engine oil on the surface you would like to add them to. Then go drive on the highway for a few miles. The air washing over the oiled panel will define where the air flows, and thus where you need to put the generators to create separation for cleaner aero flow. It does work but its messy....

This is not his EZ, but one like his.

[Kyleyadon]

Originally Posted by freebeard

Have you thought about air dams and Coanda nozzles?

Not coanda nozzles, as they'll likely interfere with my towing equipment, but definitely considering air dams. I'm thinking of doing a trunk lid extension that will be something of a bonneville type flat spoiler and something of a partial boat tail, the VGs should help prevent the angle of the back glass from causing premature airflow separation, that way I'll get the most benefit out of the trunk lid extension.

[ChazInMT]

Ugh......VG's are borderline unicorn corral material. Airplane aerodynamics do not matter much for cars & trucks. Besides, by the very nature of flight, if you increase lift you increase drag....Think about that. If you came up with something that increased lift AND reduced drag you could have airplanes powered by 50 HP engines flying at 500MPH getting 60 MPG.

The only way to reduce aerodynamic drag is to change the shape of the vehicle, adding things that stick out increase drag. Any benefit from the vortices will only be a tiny bit better than the drag created, at best, and only in very rare circumstances.

[Kyleyadon]

That's a thought that's certainly worth considering. However in circumstances where changing the shape of the vehicle would be impractical, one takes their improvements where they can find them. A thousand minute gains can do the same as a single large gain, if one simply has the ability to see the big picture.

[aerohead]

Originally Posted by ChopStix

I have a pilot friend who races Long EZ airplanes. His advise on vortex generators was to paint used engine oil on the surface you would like to add them to. Then go drive on the highway for a few miles. The air washing over the oiled panel will define where the air flows, and thus where you need to put the generators to create separation for cleaner aero flow. It does work but its messy....

This is not his EZ, but one like his.

here,you can see Pininfarina doing this with the CNR car they developed between 1976 and '78

here,GM use lamp-black and kerosene to sort out their 1963 Sting Ray