Making a stronger air flow using 2 fans

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Discussion Overview

The discussion revolves around optimizing airflow using multiple fans, specifically in the context of cooling a PC. Participants explore different configurations, speeds, and setups to achieve stronger or faster airflow, addressing both theoretical and practical considerations.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Experimental/applied

Main Points Raised

  • One participant suggests placing two fans side by side or one in front of the other to create stronger airflow, questioning the effectiveness of running them at the same speed.
  • Another participant argues that slowing down the second fan would act as a brake, reducing airflow, and proposes angling the blades of the second fan more steeply to enhance performance.
  • There is a suggestion that using both fans at the same speed with adjusted blade angles could work, but this may not be effective in an airtight enclosure.
  • One participant mentions the use of a 120mm PC case fan and expresses a desire to increase airflow by placing multiple fans next to each other.
  • Another contributor emphasizes that while adding a second fan can increase the force of air blown, it does not necessarily speed up cooling and suggests using a higher voltage supply for increased fan speed.
  • A participant notes that fans are more effective in parallel arrangements for increasing volume rather than velocity, which may be more relevant for cooling applications.
  • There is a mention of maintaining slightly positive pressure in the case to prevent dust ingress, indicating a broader understanding of airflow dynamics in PC cooling.
  • One participant raises a question about the temperature of the air from the fan and its impact on cooling, sharing an experience where cooling the incoming air improved overall temperatures in a cabinet setup.

Areas of Agreement / Disagreement

Participants express differing views on the effectiveness of fan configurations, speeds, and arrangements. There is no consensus on the best approach to achieve stronger airflow, with multiple competing ideas presented throughout the discussion.

Contextual Notes

Some limitations include assumptions about fan compatibility with different voltages, the impact of airflow direction, and the specific cooling needs of the PC case. The discussion also reflects varying levels of understanding regarding airflow dynamics and thermal management.

chrisalviola
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I want to know what setup is best to create a stronger or faster air flow.
I want to place 2 fans side by side you have a second fan on front of another. because I already tried running both fans at the same speed the result is the air flow or air current is not strong somehow there's a conflict in air rotation or something, so I want to know what is the best setup.

what about making the second fan spin slower? would that work?
 
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No, if you make the second fan turn slower it will act as a break and slow down the air flow. You might try having both fans turn at the same speed, but angle the blades on the second and much more steeply. Because the air coming into the second fan is already in motion, you can angle the blades so sharply that it would burn out the motor if the fan were trying to move air that started out stationary. I should, however, point out that this will not work within an airtight enclosure. At least fans inside of ducting? If so, then you will get your best results by placing the fans side-by-side. Also, are you trying to get faster airflow, or greater volume? For greater volume, leave the ducting as wide as the two fans in parallel. For faster wind speeds, use narrower ducting, but this will result in a decrease of overall volume, as it will increase resistance.
 
wow that sounds really complex, I am using this 120mm pc case fan
http://www.acoustiproducts.com/images/products/acoustifan_dustproof/afdp12025b_withaccessories_570x470.jpg

what I need to do is make a stronger air current inside my pc by placing 2 or 3 of this next to each other.
 
Last edited by a moderator:
LURCH said:
No, if you make the second fan turn slower it will act as a break and slow down the air flow.

Agreed.

LURCH said:
You might try having both fans turn at the same speed, but angle the blades on the second and much more steeply.

Isn't the same as saying the second should be faster?
 
chrisalviola said:
wow that sounds really complex, I am using this 120mm pc case fan
http://www.acoustiproducts.com/images/products/acoustifan_dustproof/afdp12025b_withaccessories_570x470.jpg

what I need to do is make a stronger air current inside my pc by placing 2 or 3 of this next to each other.
Believe me, I've tried this ;)

You need to actually speed up the fan (not 2 fans) physically, using for instance, a 24V supply (not all fans can take it and life span is reduced drastically).

Adding a second fan will increase the force the air is blown in, but it will NOT speed up anything (in terms of cooling).
 
Last edited by a moderator:
A fan that is not designed for it will not work efficiently in series. You are much better off arranging the fans in parallel. Your airflow will not have a higher velocity, but it will have a higher volume. For cooling a PC that is probably more important anyway.
 
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120mm is a pretty big case fan. For a while, I had one sitting on the side panel of my computer blowing directly onto the motherboard. AFAIK, you can't mount them anywhere else. And it doesn't matter anyway, because one pushes enough air that you won't get the interior of the case any cooler by adding more.

The general theory on case fans, though, is to have the case slightly positive in pressure so that you don't pull dust in through every little crack.
 
just a question

just a little question.
If the air from the fan does not cool the object enough. Is the air temperature too warm?
maybe the air needs to be cooled? sorry for this but when i used a cheap old air conditioner and on a cabinet where the outside temp was about 36-40 c. The heat from the power supplies increased the temps. I had 2 6 inch fans blowing into the cabinet but this was not enough for the whole cabinet. But by cooling the air going in reduced the entire cabinet tempuratures and all the electronics started working properly.
 

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