I am currently working on a device that requires omnidirectional air currents (e.g. breezes/winds) to be directed downwards through a vertical tube. I think it would be a very similar design to a whirlybird, but the air would have to flow inwards rather than outwards.

Could this be achieved by create several curved blades and arranging them in a 360 degree pattern, and then maybe having a second fan in the tube itself? Would one-way valves also be required to ensure that air is flowing into the tube?

  • 2
    What's the purpose of this device? How will it be used? Are you re-purposing some existing device?
    – LShaver
    Oct 30, 2017 at 2:47
  • that requires omnidirectional to be directed downwards?? It looks like something is omitted. Please edit your question.
    – user2451
    Oct 30, 2017 at 10:50
  • The more fans and valves, the more air flow restrictions which cuts down on the amount of air that can be moved. This article, energycut.com.au/business/wp-content/uploads/2015/02/… which has a long load time, suggests that whirlybirds are no longer a good solution for roof cavity ventilation since electrically powered devices move more air and solar power is a good solution. A whirlybird uses the wind as the motive power to turn a set of fan blades so just reversing the blades would change the direction. Nov 2, 2017 at 13:23

1 Answer 1


Not with a whirlybird ventilator. The idea here is that it acts as a centrifugal fan. Air will always go from the centre to the outside.

To do what you want, you need to decouple the whirlybird from the ventilation. E.g. Put the whirlbird higher up, with only an axel coming down. This axel powers a fan in the duct. This can be directed either way.

A simpler way to get air in is with a wind scoop. There are various weathervane chimney caps on the market that pivot away from the wind. You would need to add a tail to make it pivot into the wind. For example:

enter image description here

Note: A chimney doesn't move all that much air. If the purpose of this is to replace air conditioning, you will need substantial channels. Wind scoops are a big part of design in hot climates with prevailing winds, but are typically feet across.

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