Vortex Generators

Toyota wanted better MPG, and spent time in a wind tunnel to get it?

 

Didn't I read that vortex generators have also been used on some aircraft for noise reduction?

 

Vortex generator on Prius is generally use to divert air flow around the mirror mostly for wind noise the crease on the side of body is use to create a air flow channel reducing air turbulence/ low pressure Along the side of the car.

 

A vortex generator can also be used to promote clean separation of air flow from a surface. Air that just spills off the sides and roof of a car will cause drag inducing turbulence.

edit: just noticed a word choice that meant the opposite of what I meant.

 

The ones on my v seem to be working on airflow around the outside mirrors. US law does not allow cameras instead of mirrors, but it would help airflow.

 

A couple of years ago, I did some tuft testing with our 2003 Prius and found reverse flow behind the rear window:
Documenting NHW11 Prius rear window flow separation; testing AirTab vortex generators - Page 2 - Fuel Economy, Hypermiling, EcoModding News and Forum - EcoModder.com



So I tried some vortex generators and suppressed the reverse flow. But benchmarks did not show a measurable effect on MPG.

My experience and the literature suggests there are 'edge conditions' where vortex generators can make a measurable difference. But it is by no means a 'magic wand.' You have to test and confirm the effect.

Bob Wilson

 

I like the challenge, but lack the ability to measure to the degree required to isolate the effect of the generators. I have done some lightweight research and cannot find any solid evidence of measurable delta to MPG. Comes down to aestics

 

The one or two posters that have tried AirTabs on their trucks and boxy trailers may not have seen an measurable MPG improvement, but they were happy with the trailer's improved manners. A blog that did the same string test on a gen1 Prius and Insight also placed 4 just behind and underneath the Insight's front bumper claimed it improved the car's highway handling. The others actually worsened the cars drag by the string test. The ones by the Prius mirrors seem to be more about reducing noise than lowering drag in general.

VG can serve purposes beyond lowering drag.

 

Toyota seems to have some type of vortex generators on the majority of their cars and trucks. Looked at a 2015 Tundra and the tail lights had 2 as well as in the gap between the mirror and a-pillar.

 

I work at an aerospace company and we have a few engineers who told me that this could help, and could not do any harm. So I thought I would give it a go. I like the look.

 

Oh not against VGs but their use needs to carefully tested.

Did you do an A-B-A test?

• A - baseline the car without the change
• B - repeat baseline with the change
• A - repeat baseline without the change

This ensures the change has an effect and quantifies it. In my case, I used a 2003 Prius and found no measurable effect that exceeded the accuracy of the benchmarks. I could see it reduced the reverse flow behind the rear window but not enough to show up in the MPG.

Still, if it looks good, I understand 'bling' ... been married for too many years to express any esthetic beyond,"Looking good babe."

Bob Wilson

 

There are other techniques. I'd thought about a vacuum pump taking air from the front gap between the roof and hatch. But I suspect the 'low hanging fruit' are wheel well covers both front and rear. For now, moon-caps but what I've seen on the market, I would not touch.

Bob Wilson

 

Adds wind noise as down side?

Posted via the PriusChat mobile app.

 

No extra noise even with the moonroof open.