screw fan

Looks like a new design

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The idea: see main picture. That thing is supposed to create airflow when the smaller piece is set spinning.

Potential advantages to conventional fans with thin blades:
* extremely strong, close to being unbreakable
* better pressure performance (but lower airflow when unobstructed)
* to improve ultimate pressure - simply extend the thickness. No need for multistaging.

Is it a truly new design? I bet, someone has already invented something very similar, and probably even patented it. But I failed to find anything similar so far.

EDIT: of course, it's not new. Turns out it is called "Labyrinth pump".

The model was made in a special branch of FreeCAD, so it won't work in regular FreeCAD. It will open though, and modeling steps can still be viewed, and BRep shapes can be extracted. It will fail to be recomputed if you try changing the parameters.

To recompute it, you'll have to build my FreeCAD branch called DeepSOIC4, and install a third-party workbench named Lattice (not Lattice2).

The model is also available in:

STL format (rotor, stator)

STEP format (compound)

Since the model was made for a specific motor that I had, it is probably not very useful.

  • Not new, but not common

    DeepSOIC12/14/2015 at 17:03 0 comments

    Thanks to ppemawm user at FreeCAD forum, who pointed out that the design is known for ages. It is called "screw-type labyrinth seal" or "labyrinth pump". The internet is definitely not full of pictures of this design.

    See ppemawm's post here:

  • First impressions

    DeepSOIC12/14/2015 at 00:42 0 comments

    So I designed a first model, 3d-printed it, and hacked it around a motor of a conventional fan.

    And it works!

    First, I was very surprised that the rotor itself works like a fan, with no stator. The blowing is quite directional, closer to being axial than radial.

    Then, when I've put it all together, I did a rough comparison with a similarly sized fan (the one on the photo)

    * the amount of airflow feels comparable, the conventional fan is probably doing a bit better
    * the amount of noise is similar, but different whine frequencies (my one makes a higher-pitched whine
    * the suction of my fan is substantially better
    * my fan makes much more noise when blocked. And compared to conventional fan, which starts to spin faster when blocked, my one slows down instead.
    All in all, I think this crude attempt worked absolutely fantastic! It was just a quick test to see if it wound make airflow at all!

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DeepSOIC wrote 12/17/2015 at 01:03 point


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interstellarsurfer wrote 12/14/2015 at 02:31 point

Looks like a simplified single screw compressor. Possibly fairly useful, definitely off-patent.

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Brian wrote 12/14/2015 at 01:33 point

Your design should work quite well as an axial flow fluid pump. You would need a stronger motor of course, and the pressure won't be as high as you would get from a scroll compressor or gear pump, but it's design is well suited to low viscosity fluids. 

You could also create a novel linear actuator by allowing more space between the rotor and stator and using two or more spherical parts (imagine bearing balls) attached to a hollow cylinder. The spherical components then ride within the spaces between the blades, which would preferably have spherical spaces in between them. The stator would need straight linear depressions in it if the actuator arm is not to rotate. The angled stator is fine if it did not matter that the actuator rotates. Of course you would need a strong, slow, gear motor to rotate the rotor in this application.

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