0
$\begingroup$

I just recently got a blower/centrifugal fan to use for layer cooling on my 3D printer and I'm thinking about how I want to mount it.

My primary question is exactly as the question title says: does a fan's orientation with respect to gravity affect its flow rate or static pressure? In other words, if I have blower fan in open space and air enters it from above to be blown out the side, will it move more air or do so at a higher static pressure in that orientation than if I were to flip it upside down?

My intuition says that gravity pushing down into the fan from above would be allow slightly better (faster?) flow of air than having to lift the air from below the fan, but I haven't been able to find any information on it.

$\endgroup$
  • $\begingroup$ @JohnForkosh - But still! And the only thing I can think of for the practical application is generally, I should point the intake towards open air. Something tells me that my printer moving at a maximum of 0.125 m/s won't really benefit from being thrown into a wind tunnel. $\endgroup$ – William - Rem Mar 15 '17 at 13:58
  • $\begingroup$ How much air do you think will pass through the fan per second? And how far would you have to "lift" the air as it passes through the fan? $\endgroup$ – biziclop Mar 15 '17 at 13:58
  • $\begingroup$ @biziclop - My particular fan is a 24v 4020 blower fan rated for 6.8 CFM and won't have any ducting before it, so there's no way for me (as someone without the skill to model fluid dynamics) to know how far the air would have to move to get into the fan intake. I'm more curious about fans in general though. $\endgroup$ – William - Rem Mar 15 '17 at 14:06
  • $\begingroup$ @MikeDunlavey - Could you put that in an answer? This seems obvious in retrospect, but I wasn't thinking about the air vis a vis buoyancy. $\endgroup$ – William - Rem Mar 15 '17 at 20:34
  • $\begingroup$ @JohnForkosh - The goal is not to cool the nozzle, but to cool the extruded plastic immediately after it heats the nozzle. The sooner I can get it to make a glass transition, the less sag the resultant parts will show. This is sometimes known as a "layer cooling fan" or "part cooling fan". 3D printers also usually have an extruder fan attached to the heat brake that keeps the hotend from melting whatever it's attached to. $\endgroup$ – William - Rem Mar 16 '17 at 7:22
1
$\begingroup$

The only reason there could be for "lifting" the air is if it would "fall" if you didn't. That would only happen if it's colder than the surrounding air. (convection)

$\endgroup$
0
$\begingroup$

If a fan draws air from above then it cannot leave a vacuum behind, and same amount air from the ambient must be raised to take its place. So you don't get anything extra by pointing the inlet upward.

$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.