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Quotes from another source: Contrails ! Radiator aerodynamics
The radiator in a free stream http://contrails.free.fr/images/sml_radia_lignes.pngPhoto GTH It is often wrongly believed that a radiator or finned barrel directly exposed in a free airstream will achieve efficient cooling. Actually, less than one third of the air arriving in front of the radiator will effectively flow across the core. The rest will flow around the obstacle, not without violent turbulence. The efficiency is poor and the drag is prohibitive. It is the pressure difference between the two faces of the radiator core, which forces air to flow through it : the ΔP. Without this pressure difference, no flow through the core, no cooling. http://contrails.free.fr/images/sml_DeltaP_radia1.png Minimizing drag To minimize internal drag, we thus need a core with sufficient area (volume flow), an airstream considerably slower than the aircraft airspeed, and as high a Delta T as possible. There is thus some advantage in running the engine as hot as compatible with safe operating limitations. Diffuser http://contrails.free.fr/images/sml_Kuch_diffuser.pngDoc Küchemann & Weber It is the most important part of the duct. It comprises a diverging portion (not funnel shaped) in order to slow down the airflow without causing any separation. According to Bernoulli's law, slowing air with no separation raises the static pressure. The presence of the radiator aft of a well designed diffuser renders flow separation still less likely. The gain is twofold : the increased pressure facilitates the passage through the core, and this pressure on the diverging walls of the diffuser results in a forward force, opposing the drag of the core. |
someone molded a s13 grill on it before
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I like when engineer nerds fight.
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btw, pat is right and you're all powerbottom queers.
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Originally Posted by hustler
(Post 374504)
I like when engineer nerds fight.
I'm curious as to what everybody on the big-frontal-area bandwagon has to say about this information mazda/nissan and I have posted. Also still curious how you can have different pressures and the same pressure simultaneously. |
Originally Posted by patsmx5
(Post 374532)
:fawk:
I'm curious as to what everybody on the big-frontal-area bandwagon has to say about this information mazda/nissan and I have posted. Also still curious how you can have different pressures and the same pressure simultaneously. |
I suppose it doesn't help to point out that in Savington's case the issue was that he had an oil cooler up there that was getting little if any flow at all, hence the hole. Others like myself who have a large intercooler (same one as you have I think pat) might do something like this to get some flow to the top half of the intercooler. But as to the radiator, I concur that ducting is the most essential element to make the radiator work more efficiently.
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I would like to see someone use the air flow through the front of the car to help act as downforce as per my article, but that may only be applicable on mid-engine cars :td:
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Pat, great stuff. It's all relevant for our cars - without huge fuckoff FMICs in front of the radiators. Drop an FMIC and it slows the airflow considerably, heats the air considerably, and changes the game.
I did my hole because I added an oil cooler and I didn't want to stack another heat exchanger in the mouth of the car. |
Originally Posted by Savington
(Post 374758)
Pat, great stuff. It's all relevant for our cars - without huge fuckoff FMICs in front of the radiators. Drop an FMIC and it slows the airflow considerably, heats the air considerably, and changes the game.
I did my hole because I added an oil cooler and I didn't want to stack another heat exchanger in the mouth of the car. Suppose you seal the exit of the IC to the entrance of the radiator, like what I did. Air first goes through the condenser (we will assume A/C is off) and then through the IC where it rejects some amount of heat, causing the air to increase in temperature. PV= RT. Guess what happens when T goes up? So does pressure. It's plausible that the IC adding heat to the air is actually increasing the flow through the radiator, possibly to the point that it's higher flow rate than no IC at all.... ;) Granted the temperature of said air will be above ambient as it exits the IC and presumably the specific volume of air will be lower than if there was no IC in front. But the larger delta P means more air moving faster through the radiator which causes turbulence, which would improve the heat exchangers efficiency, somewhat offsetting the loss in efficiency due to the decrease in delta T. Point is it's not quite as cookie-cutter simple as people take it to be. |
Originally Posted by hustler
(Post 372673)
I don't think a fan can move enough air to cool an engine at speed. The hood bulges from pressure at high-speeds...which tells me that we should focus on getting the air out, rather than adding fans.
I'm going to try making a little cup into my shrouding for the first 1/4 of the fmic...maybe this shit will work. Next, the reason you see the hood bulge @ speed is partially based on Bernoulli's principle. Air flowing over a convex surface, like your hood, when @ speed has high ram pressure, but low static pressure. The air under the engine bay is moving slower than the air going over the top of the hood which has less ram pressure but more static pressure. This actually induces lift, just like on a winged aircraft. In the case of the hood though, it will bulge giving people the impression that there is high pressure under the engine bay. Take a look at a 90 some convertible Mustang or Camero when they're on the freeway (they have really poor convertible top bracing). With the top up @ 60+ mph, it bulges quite a bit. Would you suggest that the passenger compartment has high pressure? No, but is does have higher static pressure than the air going over the convex shape of the top. |
If you continue talking shit to me, like a ------, I'm going to hold this igniter hostage.
not yours: http://i1.ebayimg.com/05/i/001/30/85/df75_1.JPG |
Originally Posted by crashnscar
(Post 374108)
How can you determine what size restrictor to use? I'm up for trying just about anything (within reason and that makes sense) to get this motor to not overheat.
Originally Posted by crashnscar
(Post 374108)
And what is the pretty/functional comment about???
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Originally Posted by hustler
(Post 374899)
If you continue talking shit to me, like a ------, I'm going to hold this igniter hostage.
not yours: http://i1.ebayimg.com/05/i/001/30/85/df75_1.JPG |
ooops, thought you were savington...damn sig pic!
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All you pansys need to just vmount with giant radiators and ICs and you are set just like me.
Everyone else = ball lickers. |
Originally Posted by Splitime
(Post 375288)
All you pansys need to just vmount with giant radiators and ICs and you are set just like me.
Everyone else = ball lickers. |
Originally Posted by hustler
(Post 375280)
ooops, thought you were savington...damn sig pic!
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that's how one of my friends unplugs things... FTL
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Originally Posted by Savington
(Post 375307)
Why did you cut the other end of the plug out? :m-freak:
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