fan direction MAMBA MONSTER - RC-Monster Forums

**fan direction MAMBA MONSTER -** 09.29.2009, 04:07 AM

I have a doubt.
The fan (ESC) must be positioned that blows air upwards, or that blows air downward?

shaunjohnson · 09.29.2009, 04:10 AM

blows down i think.

Dafni · 09.29.2009, 04:20 AM

Definitely. Air gets blown down over the heatsink.

09.29.2009, 04:32 AM

i dont see how people think that sucking the air away from the heatsink can be better than blowing fresh air onto it... i have a mate who i constantly give shit to about that -lol-

BrianG · 09.29.2009, 10:08 AM

Quote:

Originally Posted by danhfvcsd

i dont see how people think that sucking the air away from the heatsink can be better than blowing fresh air onto it... i have a mate who i constantly give shit to about that -lol-

It really depends. If the heatsink is in a duct, pulling air across it can be equal or more effective than shoving air into it. When you blow into a heatsink, you get turbulence before it goes elsewhere. The idea is to get a flow of air across the fins. Of course, the exhaust method requires some type of duct to work effectively.

snellemin · 10:35 AM

Quote:

Originally Posted by BrianG

It really depends. If the heatsink is in a duct, pulling air across it can be equal or more effective than shoving air into it. When you blow into a heatsink, you get turbulence before it goes elsewhere. The idea is to get a flow of air across the fins. Of course, the exhaust method requires some type of duct to work effectively.

We do it both ways here at work depending on the chassis design of the PC's. Like Brian said, Ducts are involved either way for max cooling efficiency. With the ducts you can run the fan at a lower rpm and still have sufficient cooling. Another benefit is lower fan noise. But who really cares about that in a RC

Anyways, without a duct you always want to blow the air towards the heatsink.

Pdelcast · 09.29.2009, 01:58 PM

Yep -- the fan should blow INTO the heat sink. I love that people on here are savvy enough to answer these questions.

10.01.2009, 05:13 PM

According to the results from the test conducted at the link below, the mounted fan blowing air over the heatsink is more effective at cooling the heatsink than the same fan pulling air across it. The tester concludes that the turbulent airflow created by the fan blowing air over the heatsink allows more air molecules to contact the fins compared to the laminar flow of air being pulled across the heatsink where molecules in the center of the column of air don't have an opportunity to contact the fins.

http://www.halfgaar.net/fan-cooling-intake-or-exhaust

ticklechicken · 10.01.2009, 05:22 PM

That conclusion is wrong. It has nothing to do with laminar flow as I'm sure he's well above the Re=2300 threshold. It's a function of flow patterns. Take the shroud off of your radiator fan on your car, and you'll see a noticeable temp change. You don't have to reverse the flow direction.

shaunjohnson · 10.01.2009, 05:26 PM

Quote:

Originally Posted by danhfvcsd

i dont see how people think that sucking the air away from the heatsink can be better than blowing fresh air onto it... i have a mate who i constantly give shit to about that -lol-

hot air rises so he may have a point, but axial fans (even with a primitive duct like these hve) arnt that good at sucking

10.01.2009, 06:18 PM

Quote:

Originally Posted by ticklechicken

That conclusion is wrong. It has nothing to do with laminar flow as I'm sure he's well above the Re=2300 threshold. It's a function of flow patterns. Take the shroud off of your radiator fan on your car, and you'll see a noticeable temp change. You don't have to reverse the flow direction.

Good point, nothing in that test confirms the type of flow through that heatsink to confirm the conclusion.