Vortex generators

[Frank Lee]

Since the placebo effect is so rewarding, "yes".

[GhostWolfGT]

Originally Posted by ChazInMT

Please explain how a reduced stall speed equates to a lower drag?

On a plane VGs keep the air attached to the wing longer and put more air on the flaps to give it more control at slower speeds. Removing separation. On a car it should do the same thing of removing separation and giving a cleaner break at the back. I'm sure it is not a measurable boost to FE but they look cool. lol. (Not airtabs but the Evo style) Even so, just because a few people try something with no results is no reason others shouldn't try. Otherwise we'd all still be in the stone age.

I'm not arguing they in fact work. And I know from lurking here for years that this is beating a dead horse. And I'm very skeptical myself. But I'm still going to try.

[Eddie25]

i will leave this here. however i am not convinced yet GasPods - Saving Fuel with Roof Attachments | Tundra Headquarters Blog

[2000mc]

Gaspod vortex generators are so aerodynamic they'd barely do their supposed job anyway

[fbov]

Real science behind them...
Aerodynamics Research Revolutionizes Truck Design

Like any aeromod, you need a special case to see a big effect. Eddie's video shows a special case. Incremental beneficial aero effects are small, with large downsides when done poorly. On most modern cars, the latter generally dominates as factories have wind tunnels and real engineers; if VGs were aero-salvation, they'd be on the cars now.

Have fun,
Frank

[euromodder]

Originally Posted by Frank Lee

Feel free to be the first ecomodders to ever get any results with VGs.

He wouldn't be the first.
Darin tried them with some results - lots cleaner air over the rear window
I tried them (glider dimple tape) with some results - they quieted down A-pillar / mirror noise quite a bit and changed the airflow pattern over the side window.

The result however, was NOT fuel savings

[euromodder]

Originally Posted by ChazInMT

Nay.
1st Issue- The air is already turbulent on the skin of a car, you're only making it more turbulent.

And change the flow pattern while you're at it.

Driving in the rain showed me that VGs actually work.


Even glider dimple tape WAS working, I'm talking about 1 tot 2 mm high (1/25 to 1/12th of an inch) protrusions here ...

2nd Issue- The air in the first 2 inch layer of the car is only .05% of the air being moved about by your car.

But that layer dictates what the rest of the air is doing, and how smoothly it'll do so ...

In order to make a positive difference, the newly invigorated air would somehow have to not only overcome the drag it just produced, but it would have to somehow create less drag down stream. On any modern automobile, this simply isn't going to happen. Maybe some crap box from the 70's or 80's,

Yup.
That's why VGs were intended for square boxes: RVs, trailers, ... and the like.

4th Issue- Cars are not airplanes, they follow vastly different aerodynamic rules. Just the same......

Gliders operate in much the same speed range though - and they do use dimple or zig-zag tape (be it on aerodynamically cleaner designs)

Please explain how a reduced stall speed equates to a lower drag?

Beyond solving local airflow issues and buffeting, VGs are typically used to make the airflow remain attached to high-lift devices (flaps) on the rear of a wing
Essentially they "bend" the airflow.

And that's the useful feature on cars : make the air follow curves and angles where it'd normally detach from (causing high drag)

Or reduce lift under the nose

[HemiX2]

I've had Airtabs on the back of my Dodge Magnum and Jeep Grand Cherokee (just across the top) for years, but my main purpose is to keep the back window clean while driving on the highway. Works great for that, and as said, there are no FE gains, but that's OK with me.

[cyclopathic]

Originally Posted by ChazInMT

Nay.
1st Issue- The air is already turbulent on the skin of a car, you're only making it more turbulent.

2nd Issue- The air in the first 2 inch layer of the car is only .05% of the air being moved about by your car. There is a lot of air moving 10 feet on top and to each side of your car, and for hundreds of feet behind it. A .05% change in the air movement can not create a noticeable change in the drag.

3rd Issue- There is a certain amount of drag created by the "Vortex Generation" itself. In order to make a positive difference, the newly invigorated air would somehow have to not only overcome the drag it just produced, but it would have to somehow create less drag down stream. On any modern automobile, this simply isn't going to happen. Maybe some crap box from the 70's or 80's, but other than that, you'll only be shooting a squirt gun at the Hoover Dam and expecting it to improve it's performance.

4th Issue- Cars are not airplanes, they follow vastly different aerodynamic rules. Just the same......Please explain how a reduced stall speed equates to a lower drag? It is flim flam pseudoscientific jibberish designed to baffle and confuse. In fact, to generate more lift you must by definition create more drag.....think about it.....if by making more lift and LESS drag, you'd reach a point where a 400 foot wing span on a piper cub would be the ultimate flying machine with almost zero drag and the ability to lift hundreds of tons with a 95hp motor going 450 MPH getting 50 MPGs doing it. Yeah, that makes sense.

#4, VG had shown to reduce wing stall speeds from 60 to 45MPH, do you believe this is not applicable to cars?

#3 True that cars are much more aerodynamically optimized now, than they were back in 70s. Also true, VGs have drag by themselves. However they can be used to improve already existing aerodynamic features of the car.

For example placing VGs ~1'+ in front of hatchback/SUV/minivan roof spoiler increases speed of air stream at the edge of spoiler, and makes it more efficient in reducing trailing wake. I suspect placing them on the hood in front of windshield could be of benefit, but this needs to be looked in combination with wipers.

[cyclopathic]

Originally Posted by fbov

if VGs were aero-salvation, they'd be on the cars now.

They are on every Formula 1 car, aren't they?