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fud2468 12-15-2008 10:15 PM

Ducting air from grille to radiator
 
When doing a partial grille block, wouldn't it make sense to duct air directly from the grille opening to the radiator? Otherwise it would seem there's too much chance for turbulence enroute. A duct might allow a smaller opening in the grille to get the same amount of cooling effect.
Of course there'd still be turbulence for air passing through the radiator and into the engine compartment, but that's unavoidable.
Ray Mac

Daox 12-16-2008 08:11 AM

Ducting would be ideal. However, its a huge pain in the butt to make which is why I don't think I've seen actual ducting work done.

bikin' Ed 12-16-2008 08:43 AM

pics to follow
 
Ok, it'll be a little while before I get pics, this is still in the planning stage. On my '06 Dodge Dakota quad cab I have blocked the entire grille and removed the cooling fan from the engine.

Even as cold as it has been (30 F), I'm having trouble keeping the engine cool enough. (It has been the plan all along to install an electric cooling before spring.) I'm hoping to be able to use the two holes below the bumper to duct cool air thru the radiator.

I'll keep you posted.

i_am_socket 12-16-2008 09:48 AM

Once I build my adjustable grill block, I plan to duct it. Not really ideal to do it while it's still all just packing tape.

Tango Charlie 12-16-2008 12:01 PM

I don't know if you can call it 'ducting', but I boxed in the area between the lower grille opening and the radiator of my Vibe. You can see it in post #53 of my 'Vibe mods' thread. With the upper grille completely blocked, and the lower opening blocked roughly 90%, coolant temperature is never an issue. In fact, I think it's taking LONGER to warm up than before. I noticed this immediately after installing the radiator-bumper 'ducting', which was before winter hit hard and we still had comfortable ambient temps.

If your car has a similar gap between the grille and the radiator, I would highly recommend boxing it in or 'ducting' it. You can get away with a much smaller grille opening. Of course, keep an eye on the coolant temps, preferably with a Scangauge.

aerohead 12-16-2008 01:19 PM

huge pain
 
Quote:

Originally Posted by Daox (Post 78737)
Ducting would be ideal. However, its a huge pain in the butt to make which is why I don't think I've seen actual ducting work done.

I incorporated complete air-tight inlet ducting within the noses of the CRX,Dodge D-100,and T-100.I was afraid not to ,as I'm running the Chrysler/Korff/Horner dead minimums for inlet ram area.It wasn't that big a deal.

Daox 12-16-2008 02:11 PM

Do you have any pics of your setups? Materials used? Tips on construction?

aerohead 12-16-2008 03:37 PM

pics
 
Quote:

Originally Posted by Daox (Post 78806)
Do you have any pics of your setups? Materials used? Tips on construction?

Daox,the pictures I have are mostly Kodachrome slides and the window of opportunity to transfer these to prints or digital is something I need to investigate.When I did the projects I was obsessed with completion and didn't always do a photo-journal.----------------- The nose of the CRX was mocked-up with cardboard and masking-tape right on the car,then I glassed over that.After the layups were done,I soaked the whole nose in a farm and ranching type stock tank.The corrugated paper turned to mush and separated from the composite fiberglass.------------- I built "light" so if I ever had a collision in the front,the nose would disinegrate,and not take the radiator out with it.------------------------------------- The nose of the Dodge was done with cardboard patterns,tranferred to plywood,cedar,Masonite,and I also used a very light gauge of aluminum sheet to form the inside of the duct.Foam rubber was used to close gaps at the radiator bulkhead,again,very light construction to protect innards in a crash.--------------------- The nose of the T-100 is constructed much as a cedar canoe,with cedar bulkhead,stringers,and formers,all joined with screws and in some places angle-brackets.Toyota did a faily good job inside the grille,and the grille remains in place,with the wood superstructure and skins marrying up to it with labor-intensive tailoring of the wood.Luan Mahogany door-skin is used to close the whole thing in,with spar varnish polyurethane and 35-year latex caulk to seal and weatherize.The grille opening is the lid from a stainless-steel trashcan lid which resembles a NACA ( precurser to NASA ) Cowl,and it is joined to an ABS plastic surround,which actually mated to the trashcan.This setup is more like a "plenum" than a duct,as the inlet simply "blows" into an airtight chamber.I experienced one over-heat episode this last Thanksgiving holiday do to extremely slow speed in traffic up a steep mountain ascent.Otherwise,there's been no trouble at speeds up to 115-mph.The face of the bumper has been cut away on either side of the internal ogival valve to allow a straight shot for the air.I have not done photo-bucket yet but hope to soon,as I do have a few good close-ups of the T-100.P.S. the skin facets for the non-airtight portion of the nose is fashioned from PVC shower stall sheeting I got from Home Depot.The turn- signal and headlight covers are heat-gun-formed plexiglas held on with stainless screws,

basslover911 12-16-2008 06:20 PM

Yeah I plan on ducting mine since I only have a 6 by 12" hole in the bottom. It is probably the #1 thing you can do to lower coolant temps again if you are doing a grill block, more than running the fans more or anything.

Plus it just makes the "system" (car) MUCH more efficient. Oh, one more thing that I have noticed (with a grill block and will probably notice it more with the ducting) is how clean my engine bay has been... it looks pretty much BRAND NEW.

fanamingo 12-16-2008 11:53 PM

Quote:

Originally Posted by aerohead (Post 78791)
... I'm running the Chrysler/Korff/Horner dead minimums for inlet ram area.

Can you elaborate? My google searches have turned up empty.

ChrstphrR 12-17-2008 08:34 AM

Korff's Ideal
 
Quote:

Originally Posted by fanamingo (Post 78949)
Can you elaborate? My google searches have turned up empty.

I remember Korff's book ** that Aerohead keeps on bringing up, and conveniently, he scanned in a part where Korff made a diagram with a summary of the details of "ideal" sealed ductwork for a radiator.

http://ecomodder.com/forum/member-ae...ing-system.jpg
  • Inlet duct should be equal to the radiator height.
  • (inlet) entrance height need only be 1/6th of the radiator height IF duct length is equal to radiator height
  • Duct must be sealed airtight on both sides of radiator to hold pressure.
  • No air leaks between duct and radiator.

Note that aerohead said AREA, not height like the book's diagram mentions. More precisely, you should be figuring that ideal openings are 1/6th the AREA of the radiator behind.

Most cars have too short a nose to have the 1/6th radiator slit up front. Unless you're going to fab up a nose cone like basjoos' Aerocivic, that would mean you'd have to have a larger than 1/6th opening, because of that shorter space.

My car's the same as what trebuchet03 is modelling in his CFD thread, and I think that flow is typical for most cars:

http://ecomodder.com/forum/attachmen...1&d=1228931035

Just look at the front where trebuchet03 did more detailed modelling of the opening with the grill slats, the bumper, and how the air eddies and has to move around the irregular shape of the engine before exiting out. And note that he didn't (yet?) try modelling how the fans (two on this model of Jetta) will make the airflow even more turbulent in the bay.
  • The bumper splits the airflow to the radiator
  • The nose to radiator distance is FAR shorter than needed for Korff's Ideal Radiator Duct
  • No clean exit for airflow from the radiator
  • Fans and fan shrouds restrict and "dirty" the airflow after the radiator (but ARE necessary for additional airflow, like when you are travelling at low speeds after cruising on the highway for a length of time)

Here's a compromise idea: two inlet ducts - one fitting the upper half of the radiator, one fitting to the lower half. This reduces the area / height for each duct, which MIGHT allow for Korff's ideals of width/height/area to work.

Splitting an 18" tall radiator into two 9" halves would mean an ideal 9" depth for a duct. For your own car... you'll have to measure to see! :)


**
Walter P Korff's book: Designing Tomorrow's Cars: From Concept Step by Step to Detail Design (1980) ISBN: 9780960385003

Tango Charlie 12-17-2008 10:51 AM

Quote:

Originally Posted by aerohead (Post 78820)
...the pictures I have are mostly Kodachrome slides and the window of opportunity to transfer these to prints or digital is something I need to investigate...

A good camera store in your area can do that for you. In my area, we have Meijers stores (similar to Wal-Mart) that also provide this service.

aerohead 12-17-2008 12:33 PM

searches
 
Quote:

Originally Posted by fanamingo (Post 78949)
Can you elaborate? My google searches have turned up empty.

fanamingo,what ChrstphrR posted( Thank you very much!!!!!!!!) should illustrate the ducting tech..Chrysler Aerospace Division used this technology when developing the nose for the 1969 Dodge Daytona Charger,which swept the NASCAR field for,I think two years.------------ Both Korrff and Chrysler' work can be traced to Sighard F.Hoerner's "Aerodynamic Drag",translated into English in 1951.In the section on radiators,a series of cooling systems are depicted for I think,a Messerschmitt fighter,and the system with the lowest drag is a dead-ringer for what Korff depicts,and what Dodge built.The P-51 Mustang used a system like this,but with a scoop,which I believe is credited to Chrysler.Thrust generated by the air expanding across the heat exchangers was actually enough to cancel the 2% drag of the cooling system and even provide a little net thrust to the plane.Truly delicious engineering! If you can track these materials down,you'll be rewarded with some great reading.

Otto 12-17-2008 12:47 PM

NACA did a lot of good work on ducting in the 1940s, with optimal inlet and outlet geometry.

The cooling air needs a chance to slow down and regain pressure (higher pressure air absorbs more heat) before it goes through the radiator, so the smooth inlet widens to that point. Inlet vanes help to distribute the cooling air evenly across the radiator, rather than just bunching up at the middle. Then, after it goes through the radiator and draws off the heat, the cooling air needs to be re-introduced to the airstream in a smooth, non-turbulent way, preferably as parallel to ambient flow as possible.

Ideally, a good inlet geometry takes advantage of the stagnation point at the nose for intake, coupled with a low pressure outlet along the side of the body, where the fast-traveling slipstream sucks the cooing air out.

There is a synergy here, if done right. Think: fish gill on a tuna or other fast swimmer.

Christ 12-17-2008 12:58 PM

SO... since there is high pressure at the windshield, could you make ducting inside the hood's framework to duct that high pressure air back to the front of the radiator, then let it dissipate into the low-pressure area under the hood behind the radiator?

Low flow volume would be the only real concern there, I'd think. And it should be pretty easy to duct your hood, but with the negative volume area under the hood, due to the flow under the car pulling with no non-turbulent inlets, it should create enough flow to aid in cooling, no?

Just a thought.

aerohead 12-17-2008 01:15 PM

cowl area
 
Quote:

Originally Posted by Christ (Post 79017)
SO... since there is high pressure at the windshield, could you make ducting inside the hood's framework to duct that high pressure air back to the front of the radiator, then let it dissipate into the low-pressure area under the hood behind the radiator?

Low flow volume would be the only real concern there, I'd think. And it should be pretty easy to duct your hood, but with the negative volume area under the hood, due to the flow under the car pulling with no non-turbulent inlets, it should create enough flow to aid in cooling, no?

Just a thought.

While the pressure at the windshield cowl is relatively high,it is not as high as at the forward stagnation point of the car.NASCAR uses the cowl area for engine induction air,as when drafting,there's virtually no pressure against the front of the car and they'd be losing ram air,however,there is some pressure at the cowl.The pressurized cooling system offers a "buffer" against melt-down during drafting,and you may see team crews either adding or removing duct-tape from the "grille" to tailor engine temp during the race.Funny-Cars may have the bug-catcher for the blower protruding right through the windshield,however,they are usually elevated above the cowl deck.actually "lead" the windshield,and the scoop itself provides the stagnation.----------------- My opinion is that for aero optimization we should stick with the front of the car.

Otto 12-17-2008 01:18 PM

Quote:

Originally Posted by Christ (Post 79017)
SO... since there is high pressure at the windshield, could you make ducting inside the hood's framework to duct that high pressure air back to the front of the radiator, then let it dissipate into the low-pressure area under the hood behind the radiator?

Low flow volume would be the only real concern there, I'd think. And it should be pretty easy to duct your hood, but with the negative volume area under the hood, due to the flow under the car pulling with no non-turbulent inlets, it should create enough flow to aid in cooling, no?

Just a thought.

Better to go back to post #11 of this thread, and have another look at the colored picture showing highest pressure at the nose and lowest pressure at the roof and sides. Inlet at the highest pressure stagnation point at the nose, then good ducting, then outlet at the low pressure area along the sides around or behind the wheels. (The roof has wonderful low pressure, but ducting to that point would be too much trouble--go with the sides. Actually, ducting out through the fender wells and around the wheels would work pretty good, and also be handy to draw off engine heat.

Christ 12-17-2008 01:26 PM

Quote:

Originally Posted by Otto (Post 79024)
Better to go back to post #11 of this thread, and have another look at the colored picture showing highest pressure at the nose and lowest pressure at the roof and sides. Inlet at the highest pressure stagnation point at the nose, then good ducting, then outlet at the low pressure area along the sides around or behind the wheels. (The roof has wonderful low pressure, but ducting to that point would be too much trouble--go with the sides. Actually, ducting out through the fender wells and around the wheels would work pretty good, and also be handy to draw off engine heat.

I said nothing of a roof... and that post was meant for a car more like basjoos' Civic, where there probably isn't as much pressure build up at the nose, but likely still a nominal high pressure area at the base of the windshield.

Ducting air through the hood is not a new concept, the 1990 Z24 Cavalier uses hood ducting for induction from the ram scoops on the hood. (yes, they're functional)

What I had mentioned was to take the pressure from the high pressure area at the top of the hood/base of the windshield, and vent it through the hood, back to the radiator, which does not disrupt aero at all.

Also, in the case of basjoos' Civic, which obviously doesn't allow alot of air through the front to the radiator, the engine bay would be a significantly lower pressure area than even post 11's diagram shows, meaning that it would be OK to vent that windshield pressure to that area, and could possibly create a slightly different aero profile for the car.

The only downside, other than complexity, that I see to the whole thing, is that if there is no high pressure area in that "crook" where the windshield is angled, flow will have a higher tendency to attach there, and may actually hurt the aerodynamics of the car, by causing more drag.

Without seeing a diagram of this modeled, I couldn't tell for sure.

aerohead 12-17-2008 02:20 PM

ducting
 
Quote:

Originally Posted by Christ (Post 79026)
I said nothing of a roof... and that post was meant for a car more like basjoos' Civic, where there probably isn't as much pressure build up at the nose, but likely still a nominal high pressure area at the base of the windshield.

Ducting air through the hood is not a new concept, the 1990 Z24 Cavalier uses hood ducting for induction from the ram scoops on the hood. (yes, they're functional)

What I had mentioned was to take the pressure from the high pressure area at the top of the hood/base of the windshield, and vent it through the hood, back to the radiator, which does not disrupt aero at all.

Also, in the case of basjoos' Civic, which obviously doesn't allow alot of air through the front to the radiator, the engine bay would be a significantly lower pressure area than even post 11's diagram shows, meaning that it would be OK to vent that windshield pressure to that area, and could possibly create a slightly different aero profile for the car.

The only downside, other than complexity, that I see to the whole thing, is that if there is no high pressure area in that "crook" where the windshield is angled, flow will have a higher tendency to attach there, and may actually hurt the aerodynamics of the car, by causing more drag.

Without seeing a diagram of this modeled, I couldn't tell for sure.

If you pull that kind of volume of air from the windshield area you'll cause separation over the roof.If anything you want to eject air at this location.This is what Kamm did,and its what made his K-Car work.You'll never see a car with this and there is a critical reason for it.

Christ 12-17-2008 08:18 PM

That's what I was thinking, as the air would become attached at the windshield, and then detach at the windshield-roof bridge line.

Thank you for reinforcing my doubt on this one, though.

trebuchet03 12-18-2008 03:38 AM

Quote:

Originally Posted by fud2468 (Post 78684)
When doing a partial grille block, wouldn't it make sense to duct air directly from the grille opening to the radiator? Otherwise it would seem there's too much chance for turbulence enroute. A duct might allow a smaller opening in the grille to get the same amount of cooling effect.
Of course there'd still be turbulence for air passing through the radiator and into the engine compartment, but that's unavoidable.
Ray Mac

I did a quick scan of the thread and didn't see this addressed.

The worst possible thing you can do, from a heat transfer perspective, is to have laminar flow through a heat exchanger (such as a radiator). You want nice, slow, turbulent flow passing through that radiator.

why?
Turbulence increases heat transfer coefficients :thumbup:

Going to borrow this image
http://ecomodder.com/forum/member-ae...ing-system.jpg

Diffuser slows down flow - due to increasing cross section.... Length and lower velocity should help the fluid go turbulent faster... Tapering diffuser behind radiator should increase velocity to be reintroduced with external flow.

Turbulence is your friend - everyone give your turbulence a hug, we've been bashing it too much :p

Quote:

* The bumper splits the airflow to the radiator
* The nose to radiator distance is FAR shorter than needed for Korff's Ideal Radiator Duct
* No clean exit for airflow from the radiator
* Fans and fan shrouds restrict and "dirty" the airflow after the radiator (but ARE necessary for additional airflow, like when you are travelling at low speeds after cruising on the highway for a length of time)
1. Yep
2. Totally
3. Not at all - there's other bits in the engine bay to cause problems too (hoses, et. al.)
4. It's not in front of me, but I do recall Hucho's book talking about fan shrouds (as in the Jetta model) being a compromise. All air entering the grille should pass through the radiator and never travel around. The actual car has foam sealant between the plastic shroud and radiator :thumbup: Plus, shrouding a fan increases it's efficiency :thumbup::thumbup:


-------
If you're looking for aero gains in the cooling department.... I don't think you'll find what you're looking for - for anything short of a redesign. Keep in mind that the maximum aero gains will be less than the gains from completely blocking off your front grille(s). A function of limits, unfortunately.

If you can measure.... Attempt to measure the gains from blocking the grille. Then, decide if your time/money is worth gains less than what you measured. I'm willing to bet that your time/money are not worth it and better spent elsewhere for higher gains (*cough* - complete block; with adjustable slots for the worried - *cough*) :thumbup:

aerohead 12-19-2008 03:36 PM

Rich Taylor,Director of General Motors Truck Division, is the guru who advocated grille-blocking for the Popular Science team,modifying a pickup for better mpg.It's one of the few things he claimed would show up at the fuel pump.A photograph of the article can be found in the archives,under the Phil Knox aerodynamic photo albums.

lunarhighway 12-19-2008 05:11 PM

would it be worth it building an extraction ducts behind the radiator?

i've got quire some clearence but i don't think i could get an ideal hight length ratio as shown in the drawing above...


is there a similar ratio for the exit duct and is this ratio constant ?

like when the front duct length would be 1/2 of the radiator height would the ideal intake height be 1/3 of the rad height?

aerohead 12-20-2008 03:00 PM

extraction ducts
 
Quote:

Originally Posted by lunarhighway (Post 79441)
would it be worth it building an extraction ducts behind the radiator?

i've got quire some clearence but i don't think i could get an ideal hight length ratio as shown in the drawing above...


is there a similar ratio for the exit duct and is this ratio constant ?

like when the front duct length would be 1/2 of the radiator height would the ideal intake height be 1/3 of the rad height?

My short answer is no,I don't know.The person to ask would be Professor Alberto Morrelli in Italy.When he did the R&D for the CNR "banana-car" he used the Pininfarina windtunnel to determine extractor outlets,such that as the air left the radiator duct,it blended with the surrounding airstream at the same velocity so as not to trip the flow.I believe Morrelli published a paper on the project however I never tried for a copy.If anyone knew,he'd be the guy.The Rutan Brothers,at Scaled Composites,Mojave,California probably know.A letter or e-mail to them might lead to a reference.Sorry,I'm not much help.

lunarhighway 12-21-2008 03:57 AM

thanks anyway.

i'll continue my search for information.
time permitting i might rig up a carboard prototype, although the exit duct would probably call for a redesign of my undertray.

given the overall crudeness of the average cooling setup on a car perhaps a simple shroud could improve things already, but that's speculation and airflow is one of these things that can confuse the uninformed mind :)

cmroseberry 12-21-2008 10:19 AM

I have been thinking about putting together some cooling airflow guidelines, but I need to do more research. Currently, I am leaning towards recommending a race-car type configuration like the illustration from Korff whenever possible. From my experiments back in '88 - '90, I know that inlets with frontal area recover much more of the freestream total pressure (ram) than "bottom breathers"; inlets that project no frontal area and rely on an airdam. However, I do not know where the optimum trade-off is between ram-recovery, fan power, and overall vehicle drag is. I discovered the day before yesterday that Jack Williams and my former advisor, Walt Oler wrote an updated paper in 2002 - Cooling Inlet Aerodynamic Performance and System Resistance (sae 2002-01-0256). I ordered it in electronic form from sae.org for $14. I have not had time to fully 'digest' it, especially since the notation has changed from what I used. It does say that the pressure loss from the fan to the engine bay is fairly minor compared to the other loss mechanisms and its not that sensitive to the spacing between the fan and the engine block. Having not thought about very long, my guess is the geometry of the duct downstream of the heat exchanger is not that critical - its sure to be better than the crude practice of directing the airflow at the engine block which results in most of it being deflected down. My research does support that ducting the frontal inlet(s) to the heat exchangers should be done whenever possible. Apparently non-uniform flow to the heat exchangers detracts significantly from the cooling system performance - yet another reason to favor a race-car configuration. I also believe that the fin design of high effectiveness heat exchangers (dimples, waves, etc.) generates sufficient turbulence on the proper scale to promote good heat transfer. I would keep the flow upstream of the heat exchangers smooth and clean.

Otto 12-21-2008 12:32 PM

"...Having not thought about very long, my guess is the geometry of the duct downstream of the heat exchanger is not that critical - its sure to be better than the crude practice of directing the airflow at the engine block which results in most of it being deflected down..."


I disagree. NACA et al found that the ducting downstream from the heat exchanger and back into the slipstream is just as important as inlet design. In other words, inlet ducting is only half the job, which is not finished until efficient outlet ducting is in place. This is why NACA et al developed cowl flaps, etc..

lunarhighway 12-22-2008 02:30 AM

i think the main advantage of ducting is that one would have control of where and how post radiator air exits and how it merges with the existing flow around the vehicle.

who can really say what the air does when it exits the radiator? with so many subtle differences in engine bay layouts, and all the different pressures in and around it i think it's hard to come up with a generic picture. so in real world imperfect design i think it's better to have some sort of duct that guides the exit flow than nothing at all. the only danger i think is that a poorly designed duct (and very few existing cars will allow a mathematical correct duct to be retrofitted) might restrict airflow, especially at slow speeds when the airflow trough the radiator might not be so well defined, and hot air might remain trapped in the duct.

NeilBlanchard 12-22-2008 06:02 AM

Hi,

I think exhausting out of the back of the hood, into a low pressure zone, works better?

Christ 12-22-2008 01:43 PM

The hood-windshield area (cowl, herein) is a high pressure zone on just about every car I've ever seen in my life, hence the reason for cowl induction hoods.

Radiator relocation would net the best testing application result, so that one could avoid the constraints of an engine bay.

Alternatively, get one of the Fiero guys to test something.. they still have the rad in the front, already angled, and no engine to contend with.

NeilBlanchard 12-22-2008 08:10 PM

Hello,

The very front of the car (the grill and bumper) is a high pressure zone, and it deflects much of the air flow up and over much of the hood; making the hood a low(er) pressure zone than the front. On my xA, which has the hood sloped down, this is still the case. The upper half of the windshield is also high pressure; but the base of the windshield is a low(er) pressure zone, as well.

The reason I know this the case on my car anyway, is when there is loose (light and fluffy) snow around the windshield wipers, it stays put; unless there is a gust of wind from the side.

In any case, the back of the hood/base of the windshield is a lower pressure zone than under the car. There are other threads that quote aerodynamic reference books showing that intake down low on the front and the exhaust on the back of the hood is the most efficient way to move air through a front radiator.

lunarhighway 12-23-2008 02:21 AM

autospeed had a great article on bonnet vents.

however i'm inclined to think from their results and from the placements of functional vents on production cars half way the hood is a better place the pressure difference with the front is much greater there than just ahead of the windshield. the back of the windshield is generally the place where the interior cooling air INTAKES are.

perhaps raising the hood at the back might still work because of the sheer size of the resulting gap, but relative small extractors early on the hood can do the same thing

i_am_socket 12-23-2008 09:44 AM

If I had time, money, and a workspace I'd be working on a way to duct my rad. I mean, look at all this space:

http://i443.photobucket.com/albums/q...9978403462.jpg

If I could move the top supports out towards the front, I could angle it nicely to duct it out to the hood. Forget money, I just need time and a workspace. *sigh*

Otto 12-23-2008 12:58 PM

Coroplast would make some nice ducting material, applied with duct tape.

i_am_socket 12-23-2008 03:09 PM

Quote:

Coroplast would make some nice ducting material, applied with duct tape.
badum bum http://spidermouse.us/images/smilies/drummer.gif

lunarhighway 12-24-2008 02:10 AM

is that a concrete undertray? seems like any sort of ducting might include or double as one too :)

Tesla 09-10-2013 05:31 PM

Another article on Radiator ducts, is about aeroplanes, but principles are the same, thought it best to tag on this thread:
Contrails ! Radiator aerodynamics

Regarding adjustment of mass flow, thought this comment was relevant:
Quote:

In theory, it should be necessary to alter the intake opening at the same time as the exit.
In practice, it has been shown that once the intake cross section is 30 to 50% of the radiator block frontal area, the volume flow depends only on the exit area.
Hence the regulation by control of the exit area by means of cowl flaps, preserving the static pressure at the front face of the radiator.

mcrews 09-10-2013 05:43 PM

Quote:

Originally Posted by lunarhighway (Post 80150)
is that a concrete undertray? seems like any sort of ducting might include or double as one too :)

probably see a 10% improvement from concrete to maybe,.........oh I don't know..........


2x4s.........:rolleyes:

mcrews 09-10-2013 05:44 PM

:o sorry.......... :D


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