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6 votes
Accepted

Fan performance curve

The yellow curve corresponds to a fan that will provide mostly a set pressure differential, say, keeping fumes from escaping a tank through elsewhere than dedicated vents. If there is a circumstance ...
SF.'s user avatar
  • 6,105
5 votes

Why does the manual to my floor fan tell me to pull out the cord whenever it's not in use?

No good reason Probably the legal department decided it was a little safer to not have power to the device all the time. Practically, there is no reason to do this.
Tiger Guy's user avatar
  • 6,969
3 votes
Accepted

Why does my self-made air pump not blow air in the correct direction?

If your fan is throwing back air out the inlet, you have choked the fan with an exit hole that is too small. Note that what is actually happening is that part of the fan disc is pulling air into the ...
niels nielsen's user avatar
1 vote
Accepted

Why is the fan efficiency zero at high flow rate?

But even if there is no pressure rise across a fan, the fan does cause the flow to happen by transferring energy (or power) to the fluid. Don't assume that the flow in that graph is driven by the fan ...
TimWescott's user avatar
  • 2,682
1 vote

Why does a centrifugal fan work better than an axial fan for high pressure drop systems?

If a fan has a shroud, only axial motion contributes to flow through the fan. If the fan is missing a shroud, notice that the area as you move radially increases. This increase helps convert energy ...
Abel's user avatar
  • 1,352
1 vote

Multiple inline fans

With fluid-/aerodynamics, exact figures are often hard to state. E.g.: Your fan is rated for 100 cfm in absolutely ideal conditions, i.e. airflow without any obstructions. The fan in your chimney will ...
Chris_abc's user avatar
  • 799
1 vote

What is the purpose of springs in rotor's ventilator/fan

Seems that these springs abut to some part that sits on the motor shaft firmly, closer to motor. Then their purpose is to press fan wheel to the pulley which drives the belt while fan wheel fits on ...
Vladimir's user avatar
  • 295
1 vote

Increasing airflow of fan

Devices like this are ubiquitous in industry. To name a few: Venturi vacuum generator (https://www.smc.eu/en-eu/products/zh-a~138195~nav), propane torch/bunsen burner (where the gas flow induces air ...
RJDB's user avatar
  • 106
1 vote

Increasing airflow of fan

The bag trick only works because the momentum of the air you're blowing into the bag is "knocking" it open. The force of the wind spreading the plastic apart is what draws more air in to ...
Jack's user avatar
  • 11
1 vote
Accepted

Routing the flow from an axial "box" fan

Converging ducts have been constructed for years. Often an exercise to work out the angle needed for lowest losses, about 6 degrees iirc. Aslo an exercise to calculate the shortest joint lines ...
Solar Mike's user avatar
  • 15.9k
1 vote

How can a fan keep spinning normally but suddenly move very little air?

It is possible that it is stalling. If the vector angle of the flow it creates, called relative wind, with the rotating edge of blade becomes larger than 16 degrees it may stall. When you re start the ...
kamran's user avatar
  • 22.5k

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