diy vortex generators

[scifi]

I recently put on delta wing vortex generators on a 2005 scion xb with good results so far of course it is very square and flat sided. Ive been using a kiwi scanner to keep track my latest run is up from 29.3 mpg to 35.2 mpg even stopped by two places on the way home I always reset the kiwi and drive the same speed 60 miles per hour, 30 miles each way.

[euromodder]

Welcome to ecomodder !

Originally Posted by scifi

I recently put on delta wing vortex generators on a 2005 scion xb with good results so far of course it is very square and flat sided.

You're one of the first people on ecomodder to actually get good results with them.

Could you elaborate a bit on how many / where you put them on ?
(You'll need a few more posts before you can add links or pics in your posts though - anti-spam measure .
Leaving out the

http://www.

part and maybe split up an URL will help though )

Ive been using a kiwi scanner to keep track my latest run is up from 29.3 mpg to 35.2 mpg even stopped by two places on the way home I always reset the kiwi and drive the same speed 60 miles per hour, 30 miles each way.

What was the variation in mpg before putting on the vortex generators ?

Ideally, they should be tested in near-identical situations, under the same driving conditions (speed, distance, previous warm up, traffic density, ...)
That ain't always easy though.

[scifi]

I drive the same distance a day plus the same miles exactly 30 each way from my shop, there is each way a country road of 3 miles for warm up going 20 mph then 35 mpg each way then onto a highway, the speed limit posted is 65, I go 60 mpg each way no variance I do however get better milage to the shop than from w/o the vortex I get 31.8mpg to the shop and 29.3 back home. I live in the ozarks and theres a few hills, anyway with the vgs I got on the first try up from the shop 34.4 mpg of course I was sceptical this is the show me state you know, and I kept my notes in a book and used the Kiwi mpg meter on trip mpg and reset it each time so everything remains the same. well on my way to the shop I got 33.1 mpg I had to go to another shop to pick up something a 10 mile sidetrip, so on the return trip just last night I got 36.1 mpg went by the groceries store and them stopped for gas when I got home because of the stops I was at 35.2 mpg! Ill let you know shortly of any other results thanks again. Oh almost forgot I have 10 vgs on the back on the roof just before the spoiler [now I know why they call it a spoiler it screws up any airodynamics mine sits above the roof line so its more of a wind catcher, oem style of course] the center vgs are at 15 degrees as well as the next outer ones the next are at 10 degrees the next at 5 degrees and then 0 degrees

[euromodder]

That's quite promising

[seifrob]

there is another example - someone put AirTabs on Honda Fit (Airtabs on the Honda Fit), but still, there is lot of guesswork to put vortex generators right.

[Isaac Zackary]

I was thinking of doing this to my 1971 Beetle. From what I understand this can have the same effect as a golf ball. With a round smooth surface (like my Bug) the laminar flow detaches more forward creating a larger wake behind the vehicle and therefore more drag. A golf ball induces turbulent flow on the surface, which ironically holds down the laminar flow until further back creating a smaller wake and therefore less drag.

Vortex generators basically so the same thing as golf ball dimples. If placed before the point where laminar flow normally would separate from the vehicle's body, in theory they would hold the laminar flow into the vehicle further back and therefore create a smaller wake and less drag.

[freebeard]

Similar effect. Golf ball dimples are omnidirectional, air tabs are not.

Have you thought about the placement?

[Isaac Zackary]

Yes. On the roof near the rear about 6 inches from the rear window.

[ChazInMT]

Issac, there are 3 things very much flawed in your "If it works for the Golf Ball Imagine what it'll do to my car" logic.

1st A car is in ground effect, the golf ball is in free air. It makes a very significant difference.

2nd There is a property of a fluid to act differently to one size object vs another. The smaller the item in question the "Thicker" more viscous the fluid seems. The difference the golf ball feels in comparison to a car is not unlike the difference between water and corn syrup. So how the golf ball sized objects react to modifications is going to be different than how a car sized object will react.

3rd your drawing is a drawing and is an exaggerated illustration of how the air is reacting to the 1.7" diameter sphere, while there is a significant difference between smooth and dimpled, this drawing really blows it out of proportion.

Many pages in this forum and else ware in the world regarding the effects of dimples and VG's and even the oft quoted Mitsubishi only shows a modicum of improvement. The Evo involved a very particular set of circumstances and a whole crapload of highly trained engineers and sophisticated equipment to eek out a very slight gain.

I hope you have fun thinking about these things and I really hope it is a primer for you to really dig in to the fundamentals of aerodynamics so you gain a good understanding of what will work well and what will probably yield only a slight gain.

[ChazInMT]

Geez, I just scrolled up and saw the dates....ZomBIe THreAd....ARISE!!!!!

Urrrrrgh Brains!!!