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

Reply  Post New Thread
 
Submit Tools LinkBack Thread Tools
Old 12-26-2012, 09:57 AM   #1 (permalink)
Not Ordinary Engineering
 
Join Date: May 2011
Location: Alabama
Posts: 57
Thanks: 9
Thanked 27 Times in 14 Posts
Prius Aerodynamics tuft test vids (no rain on rear glass = flow separation?)

***Can you believe I mispelled Prius in the title? LOL Sorry.***

Hey all,

I picked up a 2012 Prius two months ago. I studied aerospace engineering in college and understand the purpose of the Kamm-tail as an effective yet shorter tail for production vehicles...

However, I've been driving the vehicle and paying some attention to the rear glass and have noticed two things:

1. The flat rear glass (the vertical piece) has dust collection on it meaning there is some recirculation.

2. The kamm-tail glass remains dry when driving in the rain. I understand the angles and relative forward motion of the vehicle makes it impossible for rain to impact the rear glass but there are no streams pouring down it either indicating there is no attached flow.

I have not completed a tuft test, though I'm debating that effort.

Do we have any experts who have tackled this yet? Are there any manufacturers who tackle this? If not, I might.

Thanks guys!

Ryan


Last edited by ryannoe; 12-26-2012 at 10:10 AM..
  Reply With Quote
Alt Today
Popular topics

Other popular topics in this forum...

   
Old 12-26-2012, 12:44 PM   #2 (permalink)
Batman Junior
 
MetroMPG's Avatar
 
Join Date: Nov 2007
Location: 1000 Islands, Ontario, Canada
Posts: 22,513

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

MPGiata - '90 Mazda Miata
90 day: 52.71 mpg (US)

Even Fancier Metro - '14 Mitsubishi Mirage top spec
90 day: 70.75 mpg (US)

Appliance car - '14 Mitsubishi Mirage ES (base)
90 day: 60.16 mpg (US)
Thanks: 4,058
Thanked 6,957 Times in 3,602 Posts
Fixed your title.

There is definitely attached flow on the Prius' rear glass.

Your tuft test would bear this out. Please make a video if you do - it's not much effort at all.

EG: see this tuft test of the rear glass of a 1st generation Honda Insight (showing attached flow):



From: http://ecomodder.com/forum/showthrea...ght-19299.html

Perhaps the reason you're not seeing rain streaming down the rear glass is because streams on the roof can't transition to the hatchback owing to the gap (gutter) between them.
__________________
Project MPGiata! Mods for getting 50+ MPG from a 1990 Miata
Honda mods: Ecomodding my $800 Honda Fit 5-speed beater
Mitsu mods: 70 MPG in my ecomodded, dirt cheap, 3-cylinder Mirage.
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 12-26-2012, 01:07 PM   #3 (permalink)
Master EcoModder
 
AeroModder's Avatar
 
Join Date: Jan 2010
Location: Oregon
Posts: 471

Tank - '96 Ford Aspire 4 door
Team Ford
90 day: 46.75 mpg (US)
Thanks: 15
Thanked 65 Times in 48 Posts
+1 on the gap between the roof and the hatch being the culprit. Put a strip of tape over it to seal it and you should see the rain stream down the glass.
__________________
In Reason we Trust
  Reply With Quote
Old 12-26-2012, 01:44 PM   #4 (permalink)
Not Ordinary Engineering
 
Join Date: May 2011
Location: Alabama
Posts: 57
Thanks: 9
Thanked 27 Times in 14 Posts
Ok cool. Great catch! I youtube'd "Tuft Prius" and watched some short clips and the tuft on the rear wiper looks to have a nice angle to it. I think you're right.

BTW, how did you change the thread title? I couldn't find that option.
  Reply With Quote
Old 12-26-2012, 01:57 PM   #5 (permalink)
Batman Junior
 
MetroMPG's Avatar
 
Join Date: Nov 2007
Location: 1000 Islands, Ontario, Canada
Posts: 22,513

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

MPGiata - '90 Mazda Miata
90 day: 52.71 mpg (US)

Even Fancier Metro - '14 Mitsubishi Mirage top spec
90 day: 70.75 mpg (US)

Appliance car - '14 Mitsubishi Mirage ES (base)
90 day: 60.16 mpg (US)
Thanks: 4,058
Thanked 6,957 Times in 3,602 Posts
Edit > Go Advanced (preview screen)

----

I can find 3 tuft videos for Prius on Youtube. Not your generation of Prius, and not the best view of the rear glass. Here's one:

__________________
Project MPGiata! Mods for getting 50+ MPG from a 1990 Miata
Honda mods: Ecomodding my $800 Honda Fit 5-speed beater
Mitsu mods: 70 MPG in my ecomodded, dirt cheap, 3-cylinder Mirage.
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 12-26-2012, 02:16 PM   #6 (permalink)
Not Ordinary Engineering
 
Join Date: May 2011
Location: Alabama
Posts: 57
Thanks: 9
Thanked 27 Times in 14 Posts
That's the same Prius I watched... he has a few videos similar to that one. If you look closely, he has a few tuft (tufts?) on the rear wiper, the last looks like it is pointing in the right direction without too much turbulence.
  Reply With Quote
Old 12-26-2012, 02:40 PM   #7 (permalink)
Master EcoModder
 
Join Date: Sep 2009
Posts: 5,927
Thanks: 877
Thanked 2,024 Times in 1,304 Posts
I used rain-x on my Insight and the rear glass never had a rain drop that sat on it when I was moving at any decent speed. Not sure if you have rain-x on the glass but it could definitely make a difference.

regards
Mech
  Reply With Quote
Old 12-27-2012, 02:41 PM   #8 (permalink)
Not Ordinary Engineering
 
Join Date: May 2011
Location: Alabama
Posts: 57
Thanks: 9
Thanked 27 Times in 14 Posts
Completed a trial tuft test yesterday in some high wind on a 2010 Honda Civic. I was astonished by the difference the crosswind makes on the vehicle. I wouldn't have thought the shear on the passenger windows would be as much as it was.

I plan on completing the "initial look" 2012 Prius tuft test this afternoon. Any recommendations from some experience before I start?

I have a GoPro cam to record from a secondary vehicle.
The yarn is bright red and nicely visible and is held by some tacky masking tape (so I don't damage the paint).

I'll make sure to post results and discussion after reviewing the video.

So... Suggestions? and anything you want to see in particular?

-Ryan
  Reply With Quote
Old 12-27-2012, 02:53 PM   #9 (permalink)
Batman Junior
 
MetroMPG's Avatar
 
Join Date: Nov 2007
Location: 1000 Islands, Ontario, Canada
Posts: 22,513

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

MPGiata - '90 Mazda Miata
90 day: 52.71 mpg (US)

Even Fancier Metro - '14 Mitsubishi Mirage top spec
90 day: 70.75 mpg (US)

Appliance car - '14 Mitsubishi Mirage ES (base)
90 day: 60.16 mpg (US)
Thanks: 4,058
Thanked 6,957 Times in 3,602 Posts
One bit of advice: you don't necessarily have to drive fast to test airflow. The air behaves pretty much the same at 30 mph as it does at 70 mph. That may make it easier to find a suitable road to do this.

Have fun! Sounds like you're going beyond a simple examination of the rear glass (which you could have done on your own using just the Prius with the camera inside).
__________________
Project MPGiata! Mods for getting 50+ MPG from a 1990 Miata
Honda mods: Ecomodding my $800 Honda Fit 5-speed beater
Mitsu mods: 70 MPG in my ecomodded, dirt cheap, 3-cylinder Mirage.
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 12-27-2012, 03:26 PM   #10 (permalink)
Not Ordinary Engineering
 
Join Date: May 2011
Location: Alabama
Posts: 57
Thanks: 9
Thanked 27 Times in 14 Posts
Quote:
Originally Posted by MetroMPG View Post
One bit of advice: you don't necessarily have to drive fast to test airflow. The air behaves pretty much the same at 30 mph as it does at 70 mph. That may make it easier to find a suitable road to do this.
I would suspect the separation point move closer to the roof apex the faster I go... but more than likely, I'll drive around 50 mph.

  Reply With Quote
Reply  Post New Thread


Thread Tools




Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
Content Relevant URLs by vBSEO 3.5.2
All content copyright EcoModder.com