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At 17:29 10/04/2003, you wrote:
Posted for "kevin lane" <n3773@attbi.com>:
Tracy - explain the optimal radiator plumbing. I would think that the hottest water and the coolest air would cool best, but you indicate the opposite? kevin
Depends. If what you want is the fastest transfer of heat to air, then you're right.
But, if what you want is to transfer as much heat to each kg of air that goes through your radiator, then Tracy's way is best.
Tracy has argued that all your cooling air comes in at 200mph, then has to slow down to almost 0mph to go through the radiator, then accelerate back to 200mph again. All that work being done on the air costs you -- it's drag. So he says that you want to put the minimum amount of air through the radiator.
I don't know whether its significant or not, but a couple of secondary effects occur to me...
1. If the air at the radiator is compressed, it will be able to carry more heat away per cubic metre. So you want to maximise the air pressure at the radiator. But compressing air heats it.
2. Heating the air as it comes through the radiator will cause it to expand, and therefore produce thrust, which might be useful in accelerating the air back up to the 200mph exit speed. I vaguely recall that the P51's cooling system produced some thrust.
Frank.
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