Radiator Position - LMP - Options and efficiency.
StuartBJ - 20/4/08 at 02:12 PM
Hi Fella`s,
I thought I would ask the wealth of knowledge on here first, regarding rads.
I can`t seem to find much info on radiator positions, apart from, they have been mounted just about everywhere possible over time (nose cone, side
pods, engine bay, under the rear wing etc)
The current trend in f1 is to mount them at 45 degrees to the angle of flow at high pressure region just behind/to the side of the driver.
LMP/ Group-C etc have at times mounted them horizontal to the direction of flow (basically laid flat and exposed at the top of the side pods.
Obviously there is a trade off cooling efficeincy in favour of aerodynamics here.
The lotus 79 mounted them at the leading edge of the side pods, graphted in due to the venturi effect pods they were running.
What seems to be the best option here for a dIY LMP aerodynaics conscious build? I guess this is more of an experience based decision, so if you have
a thought, please feel free to share 
Best Regards
Stuart
Volvorsport - 20/4/08 at 02:17 PM
if you can pipe it , at the front , design the duct correctly you can add downforce .
placing them at 45 degrees at teh side has two advantages , the duct can be straight and you can reduce the frontal area .
if your close to a decent library , get a couple of books on loan , even SAE papers can be got out on inter library loans .
StuartBJ - 20/4/08 at 03:13 PM
Do you mean at the front in the nosecone or in the side pods? And I assume you mean using something like a naca duct, due to the increase in pressure
they create.
Volvorsport - 20/4/08 at 05:40 PM
duct doesnt have to be naca shaped , they werent designed with an exit in mind , just make sure the exit isnt a great deal larger than the inlet itll
help drive it through .
Doug68 - 21/4/08 at 12:27 AM
I'd say in LMP & F1 development essentially the radiators have ended up in the space left over from other aerodynamic design requirements.
The plain fact of the matter is the radiator can go anywhere providing its got a decently designed duct feeding air to it from a high pressure region
and it exits to a low pressure region.
Its not a car but the Britten bike really makes this beautifully obvious, the radiator lying flat under the seat, air is ducted the nose (the highest
pressure point on the bike) and exits into the low pressure region behind the engine. Because of the efficient ducting the radiator itself is tiny
compared to the what normally would be fitted to a engine of this size.
I had intended to do my radiator as per the Ferrari 333SP but fear of failure forced me back
to something more conservative. When I get my balls back I may revisit the idea.
StuartBJ - 21/4/08 at 10:32 AM
Cheers that made things a lot clearer. Have the rads at the front and expel the air through the front wheel lurves. I just so happen to have a sheet
of lurves nice one! That 333 is a lovely machine to boot
TheGecko - 21/4/08 at 01:47 PM
quote:
Originally posted by StuartBJ
Do you mean at the front in the nosecone or in the side pods? And I assume you mean using something like a naca duct, due to the increase in pressure
they create.
Just to correct the common mis-assumption here. The NACA duct is NOT a ram scoop. It was specifically developed to allow air to be drawn into a
streamlined body with minimal disturbance to the flow. On road cars they are almost never used in any way that actually takes advantage of their true
characteristics, even assuming that issues of high speed laminar flow applied to those vehicles in most cases. They have, unfortunately, become a
part of the "cosmetic performance" world, much like pylon mounted bi-planar wings with huge endplates mounted on the boot-lid of little
hatchbacks.
I'm putting my radiator at that front, tilted down with plenty of exit area behind and above it. All the air in the world coming in can't
do anything if it then can't get out again.
Best of luck,
Dominic
kb58 - 21/4/08 at 06:11 PM
Correct. Many installations have great inflow but the exit is completely forgotten about. If half the effort went into the exhaust side, radiators
could be quite small.
StuartBJ - 21/4/08 at 10:04 PM
Gecko, when you say tilted down, how far forward?? 45 degrees? 30 degrees?
what entry duct shape would you recommend?
Delinquent - 22/4/08 at 08:15 AM
quote:
Originally posted by StuartBJ
Gecko, when you say tilted down, how far forward?? 45 degrees? 30 degrees?
what entry duct shape would you recommend?
Have a look at the Ultima rad for inspiration - I reckon 30 degree's from horizontal would be about the max slope on it.
Have a look at this build blog for some further ideas...
http://www.ultima-gtr.org.uk/july.php
StuartBJ - 22/4/08 at 09:08 AM
Cheers, great pic!
Well I guess its time to mount the rads then
TheGecko - 22/4/08 at 01:18 PM
quote:
Originally posted by StuartBJ
Gecko, when you say tilted down, how far forward?? 45 degrees? 30 degrees?
what entry duct shape would you recommend?
The front bay of my car is still to be completed so the final installation angle will be a compromise based on nosecone size and radiator size.
I've been mocking up my nosecone shape in CAD (Cardboard Aided Design ) and, based on that, I think the rad will end up somewhere between 30
and 45 degrees from vertical.
As for duct shape - the biggest and most direct you can fit in your bodywork design I'm building to a classic clubman profile (pic below) and
that gives me a quite good rad opening right at the front. That model pic doesn't show it but there'll be exit vent/s on the top of the
nosecone/bonnet area, Caterham CSR style, as well as venting out through the suspension area.
Delinquent's pic of the Ultima also underscores the other important point - make sure all of the air that comes in is forced to go through
the radiator and not around it. It amazing how often this simple rule is forgotten.
Hope this is helpful - best of luck with your build.
Dominic
[Edited on 22/4/2008 by TheGecko]
tadltd - 24/4/08 at 07:48 AM
Elise radiator is completely horizontal...
Doug68 - 24/4/08 at 10:15 AM
quote:
Originally posted by tadltd
Elise radiator is completely horizontal...
I love it! I've had so many people tell me it won't work (laying it flat that it is) where plainly it can be made to work.
Is the Elise rad much different in size to that used by the same engine in different cars?
Fred W B - 24/4/08 at 12:02 PM
quote:
I've had so many people tell me it won't work
exactly - as long as it's in a duct with the local air pressure higher at the intake than at the outlet the air HAS to go through it
Cheers
Fred W B
Delinquent - 24/4/08 at 12:03 PM
quote:
Originally posted by Doug68
quote:
Originally posted by tadltd
Elise radiator is completely horizontal...
I love it! I've had so many people tell me it won't work (laying it flat that it is) where plainly it can be made to work.
Is the Elise rad much different in size to that used by the same engine in different cars?
The problem most people have is that they picture a flat radiator, with air flowing over the top and bottom of it. They forget to visalise the large
scoop and formed structure that forces the air to pass through the radiator, exactly as it would were it standing up!
ETA beaten to it by Fred again!
[Edited on 24/4/08 by Delinquent]
tadltd - 25/4/08 at 07:32 AM
quote:
Originally posted by Doug68
quote:
Originally posted by tadltd
Elise radiator is completely horizontal...
I love it! I've had so many people tell me it won't work (laying it flat that it is) where plainly it can be made to work.
Is the Elise rad much different in size to that used by the same engine in different cars?
The Elise rad isn't that much different in size to conventional radiators. It may be a little smaller based on the fact it has extended cooling
pipe runs, which will help dissipate heat.
The biggest problem is bleeding air from it; as I understand it there's a specific procedure for doing this, with around 3 or 4 bleed points in
the system. It's worth checking the SELOC forum for more info' on this.