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


Reply  Post New Thread
 
Submit Tools LinkBack Thread Tools
Old 12-30-2018, 09:57 PM   #1 (permalink)
EcoModding Lurker
 
Join Date: Dec 2018
Location: USA,NJ
Posts: 8
Thanks: 4
Thanked 1 Time in 1 Post
Yaris hatchback grill block aerodynamics

Hello everyone! I've found cool areodynamic simulation of my car but can't post link yet. You can find it on youtube just type yaris totalsim. Air flow over top grill is good and bottom one is bad. I've tried block top grill at winter time and radiator fan was running more often at traffic idling and battery life decreased much quicker. When I cover whole bottom grill transmission warmed up much quicker and less wind noise on highway, radiator fan was running more often as well at idle. Is it better to block whole or partial top or bottom grill in my Toyota Yaris Hatchback at winter time?

  Reply With Quote
Alt Today
Popular topics

Other popular topics in this forum...

   
Old 12-31-2018, 12:28 AM   #2 (permalink)
Tyrant-at-large
 
Vman455's Avatar
 
Join Date: Feb 2012
Location: Champaign, IL
Posts: 1,194

Little Red - retired - '05 Honda Civic EX
90 day: 49.03 mpg (US)

Pope Pious the Prius - '13 Toyota Prius Two
Team Toyota
90 day: 46.89 mpg (US)
Thanks: 113
Thanked 986 Times in 507 Posts
I wouldn't say airflow over the top grill is "good" vs. "bad" over the lower. Let me explain.

What we're seeing in the first part of that video is a map of the velocity of the particles close to the vehicle surface. The CFD model does not have open grill areas (no airflow through them); instead, those surfaces are closed in order to generate a velocity or pressure map (they're related) over an idealized solid surface.

The purple area on the lower grill illustrates the stagnation point, where the energy of the airflow is almost entirely converted to pressure (velocity near zero), while the green over the upper grill area shows higher velocity/lower pressure. You'll get more airflow through the radiator (by having a greater pressure differential in front of/behind it) by leaving the lower grill open, while blocking the upper grill won't affect radiator efficiency as much but should improve drag by giving the airflow there a surface to flow over.

Radiator efficiency can be further improved by building a sealed duct from the grill to the radiator and, if you're really ambitious, a duct behind as well--but usually there's no room to do that without moving or angling the radiator itself.
__________________

  Reply With Quote
The Following User Says Thank You to Vman455 For This Useful Post:
yarisbaby (12-31-2018)
Old 12-31-2018, 10:42 AM   #3 (permalink)
EcoModding Lurker
 
Join Date: Dec 2018
Location: USA,NJ
Posts: 8
Thanks: 4
Thanked 1 Time in 1 Post
Thank you for detailed explanation Vman455! Does building sealed radiator duct would require to cut vents in the hood to redirect incoming air out?
  Reply With Quote
Old 12-31-2018, 12:44 PM   #4 (permalink)
Tyrant-at-large
 
Vman455's Avatar
 
Join Date: Feb 2012
Location: Champaign, IL
Posts: 1,194

Little Red - retired - '05 Honda Civic EX
90 day: 49.03 mpg (US)

Pope Pious the Prius - '13 Toyota Prius Two
Team Toyota
90 day: 46.89 mpg (US)
Thanks: 113
Thanked 986 Times in 507 Posts
Well, that's certainly an option. You could also choose to vent to a wheel housing, under the car, or out the side behind the wheel arch. Manufacturers have used all of these approaches.

For example, the Dodge Viper vented engine bay air out the sides since its first generation:



The BMW i8 has a nicely ducted radiator with a hood outlet:



The 2019 Honda Insight vents one of its radiators (inverter cooling system, maybe?) to the driver's side wheel housing:

__________________

  Reply With Quote
The Following User Says Thank You to Vman455 For This Useful Post:
yarisbaby (12-31-2018)
Old 12-31-2018, 12:58 PM   #5 (permalink)
aero guerrilla
 
Piwoslaw's Avatar
 
Join Date: Oct 2008
Location: Warsaw, Poland
Posts: 3,541

Svietlana II - '13 Peugeot 308SW e-HDI 6sp
90 day: 58.1 mpg (US)
Thanks: 1,056
Thanked 625 Times in 393 Posts
Maybe you should investigate an openable grille block, like the one I had in my previous Peugeot:

Closed for faster warm up, open only above a certain temperature.
__________________
e·co·mod·ding: the art of turning vehicles into what they should be

What matters is where you're going, not how fast.

"... we humans tend to screw up everything that's good enough as it is...or everything that we're attracted to, we love to go and defile it." - Chris Cornell

Piwoslaw's Peugeot 307sw modding thread

  Reply With Quote
Old 12-31-2018, 03:44 PM   #6 (permalink)
EcoModding Lurker
 
Join Date: Dec 2018
Location: USA,NJ
Posts: 8
Thanks: 4
Thanked 1 Time in 1 Post
Quote:
Originally Posted by Vman455 View Post
Well, that's certainly an option. You could also choose to vent to a wheel housing, under the car, or out the side behind the wheel arch. Manufacturers have used all of these approaches.

For example, the Dodge Viper vented engine bay air out the sides since its first generation:



The BMW i8 has a nicely ducted radiator with a hood outlet:



The 2019 Honda Insight vents one of its radiators (inverter cooling system, maybe?) to the driver's side wheel housing:

Those are very nice solutions. I like one with wheel housing vent because is the easiest to do and hidden.
  Reply With Quote
Old 12-31-2018, 03:52 PM   #7 (permalink)
EcoModding Lurker
 
Join Date: Dec 2018
Location: USA,NJ
Posts: 8
Thanks: 4
Thanked 1 Time in 1 Post
Quote:
Originally Posted by Piwoslaw View Post
Maybe you should investigate an openable grille block, like the one I had in my previous Peugeot:
Closed for faster warm up, open only above a certain temperature.
Is your radiator fan running more often when you sit in traffic? Do you keep this set up whole year long?
  Reply With Quote
Old 12-31-2018, 04:23 PM   #8 (permalink)
aero guerrilla
 
Piwoslaw's Avatar
 
Join Date: Oct 2008
Location: Warsaw, Poland
Posts: 3,541

Svietlana II - '13 Peugeot 308SW e-HDI 6sp
90 day: 58.1 mpg (US)
Thanks: 1,056
Thanked 625 Times in 393 Posts
Quote:
Originally Posted by yarisbaby View Post
Is your radiator fan running more often when you sit in traffic? Do you keep this set up whole year long?
The pic is of the lower grille. It is on year round.

The upper grille gets blocked only for the winter. The block is set a few cm in front of the upper grille opening, so that it diverts direct airflow, but still allows air to be sucked in should the fan turn on.

I used the lower grille block permanently, and the upper block seasonally, for 8-9 years. A few times I took both down for maintenance, so I had an idea of what the "baseline" is. Compared to this baseline, closing the lower grille block improves warm up time, blocking the upper grille improves further. Opening the lower block noticeably lowers the coolant temperature. Knowing how my engine behaves, ie how load and air temp effect coolant temp, allowed me to open and close the grille block early enough to avoid overheating. Yes in traffic the fan would turn on, but I doubt that this happened very often.

On the other hand, I drove so efficiently that with both grilles unblocked the engine would be a bit cooler than it should.
__________________
e·co·mod·ding: the art of turning vehicles into what they should be

What matters is where you're going, not how fast.

"... we humans tend to screw up everything that's good enough as it is...or everything that we're attracted to, we love to go and defile it." - Chris Cornell

Piwoslaw's Peugeot 307sw modding thread

  Reply With Quote
Old 01-06-2019, 07:15 PM   #9 (permalink)
EcoModding Lurker
 
Join Date: Dec 2018
Location: USA,NJ
Posts: 8
Thanks: 4
Thanked 1 Time in 1 Post
I decided to block half top and to get still some air flow to battery and half bottom grill for quicker warm ups.

  Reply With Quote
Reply  Post New Thread


Tags
grill block, yaris aerodynamic

Thread Tools




Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2019, vBulletin Solutions Inc.
Content Relevant URLs by vBSEO 3.5.2
All content copyright EcoModder.com