Go Back   EcoModder Forum > EcoModding > Aerodynamics
Register Now
 Register Now
 

Reply  Post New Thread
 
Submit Tools LinkBack Thread Tools
Old 03-05-2012, 11:52 AM   #1 (permalink)
Batman Junior
 
MetroMPG's Avatar
 
Join Date: Nov 2007
Location: 1000 Islands, Ontario, Canada
Posts: 22,274

Blackfly - '98 Geo Metro
Team Metro
Last 3: 70.09 mpg (US)

MPGiata - '90 Mazda Miata
90 day: 52.07 mpg (US)

Winter beater Metro - '00 Chevrolet Metro
90 day: 61.98 mpg (US)

Fancy Metro - '14 Mitsubishi Mirage top spec
90 day: 58.72 mpg (US)

Even Fancier Metro - '14 Mitsubishi Mirage top spec
90 day: 70.75 mpg (US)
Thanks: 3,810
Thanked 6,688 Times in 3,467 Posts
Factory / OEM vortex generators on trailing edge (side) of Toyota "Prius C / Aqua"

I just saw a review of the new Prius C hybrid in which it was stated that Toyota put vortex generators on the rear (side) of the car:

Quote:
These little winglets on the side of the tail light are meant to create less drag -- in effect creating little vortexes which let the car cut through the air in a much cleaner way.

These are actually made to make the car more aerodynamic.
Source: http://youtu.be/JH5CCN3FwLs (at about the 3:25 mark)






---

I can't comment on the credibility of what they reviewers say. It's just 2 guys reviewing a car. I presume they're repeating what a Toyota rep told them in the press briefing.

I tried to find a Toyota press release talking about this... and failed. (Maybe someone with better / more persistent digital ferreting skills can find something.)

It'd be good to have some official word on these things to help us noodle about their purpose/utility.

I figure this is somewhat significant because as far as I know, we haven't yet seen any credible evidence about the ability of VG's to directly affect the trailing wake of a vehicle in a way that's meant to improve efficiency.

(Versus ideas about stability or dust control on the rear glass as other claims that are sometimes made for placing VG's on the trailing edge.).

Attached Thumbnails
Click image for larger version

Name:	prius-c-vg.jpg
Views:	1926
Size:	33.4 KB
ID:	10417   Click image for larger version

Name:	prius-c-vg-2.jpg
Views:	1908
Size:	42.5 KB
ID:	10418  
__________________
Honda mods: Ecomodding my $800 Honda Fit 5-speed beater
Mitsu mods: Oops, I did it again! Bought another cheap, 3-cylinder Mirage. Mods in progress...
Ecodriving test: Manual vs. automatic transmission MPG showdown



EcoModder
has launched a forum for the efficient new Mitsubishi Mirage
www.MetroMPG.com - fuel efficiency info for Geo Metro owners
www.ForkenSwift.com - electric car conversion on a beer budget
  Reply With Quote
Alt Today
Popular topics

Other popular topics in this forum...

   
Old 03-05-2012, 01:05 PM   #2 (permalink)
Master EcoModder
 
Join Date: Jul 2008
Location: Private
Posts: 282
Thanks: 2
Thanked 73 Times in 47 Posts
Given the location, probably to specifically address turbulence from the side mirrors.
  Reply With Quote
Old 03-05-2012, 01:46 PM   #3 (permalink)
Batman Junior
 
MetroMPG's Avatar
 
Join Date: Nov 2007
Location: 1000 Islands, Ontario, Canada
Posts: 22,274

Blackfly - '98 Geo Metro
Team Metro
Last 3: 70.09 mpg (US)

MPGiata - '90 Mazda Miata
90 day: 52.07 mpg (US)

Winter beater Metro - '00 Chevrolet Metro
90 day: 61.98 mpg (US)

Fancy Metro - '14 Mitsubishi Mirage top spec
90 day: 58.72 mpg (US)

Even Fancier Metro - '14 Mitsubishi Mirage top spec
90 day: 70.75 mpg (US)
Thanks: 3,810
Thanked 6,688 Times in 3,467 Posts
I'm not aware of any type of VG that "cleans up" turbulence. (Meaning: if you place them in a turbulent flow, the results will be less downstream turbulence.)
__________________
Honda mods: Ecomodding my $800 Honda Fit 5-speed beater
Mitsu mods: Oops, I did it again! Bought another cheap, 3-cylinder Mirage. Mods in progress...
Ecodriving test: Manual vs. automatic transmission MPG showdown



EcoModder
has launched a forum for the efficient new Mitsubishi Mirage
www.MetroMPG.com - fuel efficiency info for Geo Metro owners
www.ForkenSwift.com - electric car conversion on a beer budget
  Reply With Quote
Old 03-05-2012, 02:37 PM   #4 (permalink)
Eco-ventor
 
jakobnev's Avatar
 
Join Date: Oct 2010
Location: sweden
Posts: 1,574

Princess - '92 Mazda MX-3 GS
House of Tudor
Team Mazda
90 day: 53.54 mpg (US)

Shirubāarō (*ω`*) - '05 Toyota Prius Executive
Team Toyota
90 day: 54.88 mpg (US)

Blue Thunder - '20 Hyundai IONIQ Trend PHEV
Team Hyundai
Plug-in Hybrids
Thanks: 68
Thanked 651 Times in 412 Posts
Send a message via MSN to jakobnev
Those don't look angled in the flow like VG's would be.

They look a bit like marketing and engineering had compromised on something that was intended to stabilize the flow.
__________________




2016: 128.75L for 1875.00km => 6.87L/100km (34.3MPG US)
2017: 209.14L for 4244.00km => 4.93L/100km (47.7MPG US)
  Reply With Quote
Old 03-05-2012, 02:54 PM   #5 (permalink)
Batman Junior
 
MetroMPG's Avatar
 
Join Date: Nov 2007
Location: 1000 Islands, Ontario, Canada
Posts: 22,274

Blackfly - '98 Geo Metro
Team Metro
Last 3: 70.09 mpg (US)

MPGiata - '90 Mazda Miata
90 day: 52.07 mpg (US)

Winter beater Metro - '00 Chevrolet Metro
90 day: 61.98 mpg (US)

Fancy Metro - '14 Mitsubishi Mirage top spec
90 day: 58.72 mpg (US)

Even Fancier Metro - '14 Mitsubishi Mirage top spec
90 day: 70.75 mpg (US)
Thanks: 3,810
Thanked 6,688 Times in 3,467 Posts
jacob - I wondered the same thing (about flow direction). But from the wind tunnel & tuft tests I've seen, local flow isn't always going quite in the direction we would expect!

So I'm waiting to see what Toyota says about these things.
__________________
Honda mods: Ecomodding my $800 Honda Fit 5-speed beater
Mitsu mods: Oops, I did it again! Bought another cheap, 3-cylinder Mirage. Mods in progress...
Ecodriving test: Manual vs. automatic transmission MPG showdown



EcoModder
has launched a forum for the efficient new Mitsubishi Mirage
www.MetroMPG.com - fuel efficiency info for Geo Metro owners
www.ForkenSwift.com - electric car conversion on a beer budget
  Reply With Quote
Old 03-05-2012, 03:12 PM   #6 (permalink)
A Legend in his Own Mind
 
Ken Fry's Avatar
 
Join Date: Dec 2011
Location: Atlanta
Posts: 281
Thanks: 52
Thanked 90 Times in 53 Posts
Quote:
Originally Posted by jakobnev View Post
Those don't look angled in the flow like VG's would be.

They look a bit like marketing and engineering had compromised on something that was intended to stabilize the flow.
... with very strong input from marketing.

The angle may be getting almost close to VG, because the flow there is downward, (i.e., roughly parallel to the roof line) so their angle of attack might be 5-10 degrees.

Mercedes used to advertise their tailights that cleaned themselves aerodynamically. But then they dropped the design with the next styling change. Hmmm. "We were only kidding... made a great story though, didn't it?"

I have "vortex generators" on the top of my proof concept prototype -- they look like little wings. They are actually the supports for the canopy when it is flipped open. They are streamlined mainly for fun, and as a conversation starter.

The other issue is that vortex generators are intended to energize flow over the surface of a vehicle (typically one that flies). Putting them at the very back of a vehicle makes no sense at all. The energy you have put into creating these supposed vorticies would be entirely lost.

Fins on late 50's cars had no real function at all, as proven by their elimination in the early 60's. But the manufacturer's (especially Chrysler) advertised them as stabilizing devices, rather than as the space-age-looking styling gimmicks that they were. They were positively huge as compared to these tiny bumps on the Prius taillights.

(Chevy: 1956: rounded fin sprouting; 1957: real fin; 58: no fin at all. 59: fin flopped over on it side; 60: flopped over fin with a corner. 61 fins gone for good, never to return.)

Last edited by Ken Fry; 03-06-2012 at 10:48 AM..
  Reply With Quote
Old 03-05-2012, 03:48 PM   #7 (permalink)
Master EcoModder
 
Join Date: Jul 2008
Location: Private
Posts: 282
Thanks: 2
Thanked 73 Times in 47 Posts
Using my "better / more persistent digital ferreting skills", I found this from a Toyota Media Preview.

From Scribd: 12Prius c Technical Presentation v3 2

2012 Toyota Prius c
Media Preview
La Jolla ● January 2012

Page 18, Slide 41:

3. Aerodynamic features

a. Aero stabilizing fins are installed on the side face of the rear combination lamp and at the base of the outer mirror

1) Initiates aero vortices that accelerate airflow along body side
2) Reduces weak boundary layer airflow near body and draws the main airflow closer to the body
3) Increases vehicle stability
4) Effective over 25 mph

b. Under body covers improve airflow

1) Smooth under body airflow
2) Vortex generators accelerate airflow

c. Lightweight aluminum wheels and wheel covers are designed with aerodynamic performance in mind

d. 0.28 Coefficient of drag
  Reply With Quote
The Following 3 Users Say Thank You to moorecomp For This Useful Post:
aerohead (03-05-2012), Cd (03-05-2012), MetroMPG (03-05-2012)
Old 03-05-2012, 04:35 PM   #8 (permalink)
Batman Junior
 
MetroMPG's Avatar
 
Join Date: Nov 2007
Location: 1000 Islands, Ontario, Canada
Posts: 22,274

Blackfly - '98 Geo Metro
Team Metro
Last 3: 70.09 mpg (US)

MPGiata - '90 Mazda Miata
90 day: 52.07 mpg (US)

Winter beater Metro - '00 Chevrolet Metro
90 day: 61.98 mpg (US)

Fancy Metro - '14 Mitsubishi Mirage top spec
90 day: 58.72 mpg (US)

Even Fancier Metro - '14 Mitsubishi Mirage top spec
90 day: 70.75 mpg (US)
Thanks: 3,810
Thanked 6,688 Times in 3,467 Posts
moorecomp, you da ferret!

I'm not sure they're claiming any drag reduction with those side VG's... "Increases vehicle stability" seems to be the claim. (That happens to be a common testimonial of AirTab users.)

Point b2 sounds like they've got VG's underneath the car as well.

Still skeptical.
__________________
Honda mods: Ecomodding my $800 Honda Fit 5-speed beater
Mitsu mods: Oops, I did it again! Bought another cheap, 3-cylinder Mirage. Mods in progress...
Ecodriving test: Manual vs. automatic transmission MPG showdown



EcoModder
has launched a forum for the efficient new Mitsubishi Mirage
www.MetroMPG.com - fuel efficiency info for Geo Metro owners
www.ForkenSwift.com - electric car conversion on a beer budget
  Reply With Quote
Old 03-05-2012, 04:52 PM   #9 (permalink)
Efficiency Aficionado
 
CigaR007's Avatar
 
Join Date: Jul 2010
Location: Canada
Posts: 645

GreenTurtle (Retired) - '01 Toyota Echo Sedan
90 day: 44.85 mpg (US)

Zulu - '14 Honda CR-Z
90 day: 47.95 mpg (US)
Thanks: 141
Thanked 178 Times in 119 Posts
a Cd of 0.28 is impressive for such a short car, provided that such figure is real.
  Reply With Quote
Old 03-06-2012, 01:05 AM   #10 (permalink)
Master EcoModder
 
Join Date: Jul 2008
Location: Private
Posts: 282
Thanks: 2
Thanked 73 Times in 47 Posts
You can watch the entire presentation here.


  Reply With Quote
The Following 3 Users Say Thank You to moorecomp For This Useful Post:
aerohead (03-07-2012), Cd (07-09-2012), Ryland (03-06-2012)
Reply  Post New Thread


Thread Tools




Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2021, vBulletin Solutions Inc.
Content Relevant URLs by vBSEO 3.5.2
All content copyright EcoModder.com