|
|
Posted by Desoto61 on Friday, July 24, 2009 at 11:25:42 :
In Reply to: I've alwas wondered about fan locations.... posted by Chriscase on Thursday, July 23, 2009 at 13:19:27 :
Some of that depends on the fan design. A vacuum cleaner usually uses an impeller type design vice the bladed design of your average radiator fan.
I remember reading that a puller type was more efficient, which considering almost all new vehicles still use them, I assume to be true.
I think the concept is that the output side of the fan creates a "tube" of air roughly the size of the fan. However the input side of the fan creates a low pressure space which causes air to rush in to from all sides, so you create a larger "bubble" of air movement. If you add a schroud between the fan and the radiator you restrict the input to only air coming through the radiator.
So the amount of air your moving is roughly the same, but the area over which you are moving it is larger on the input side, which means more airflow over more surface area and better heat transfer.
Technically the reduction in pressure would slightly cool the air too, vice the compression caused by the fan causing the air to get hotter. Of course that's more an acedemic discussion than a measurable benefit but hey, I have to justify that college education some how! LOL