3d-printed compressor turbine

[DeepSOIC]

Lately, I've been designing a jet-engine-style electric blower/compressor. Mainly I'm doing it for fun, but I have a potential application in mind (if it works well, I'll probably try it as a blower for a vacuum cryogenic trap heating device).

I already had started to print one version, but quickly realized was way too large (I would have died printing it, and the motor it was designed for is too weak), so I had to revise the design to reduce the size.
Here is how the model looks like now:

jetter v07.1.png (217.32 KiB) Viewed 9452 times

The model can be downloaded here (6.5 MB):
https://drive.google.com/file/d/0B9lBm- ... sp=sharing

Made with:
OS: Windows 8.1
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.16.4783 +1 (Git)
Branch: unlim_externals
Hash: e37a182c417fa3fe35ad3f7b15709e2f344cafd4
Python version: 2.7.8
Qt version: 4.8.6
Coin version: 4.0.0a
OCC version: 6.7.1

I have to admit that having sketch-to-sketch links is a very powerful thing. Without it, I don't think I would have made it that far. The model is incredibly parametric.

[DeepSOIC]

Couldn't get a good symmetric slicing with infill out of Slic3r, so ... I make the infill in FreeCAD

infill-modeling.png (142.58 KiB) Viewed 9410 times

[yorik]

Nice... we should try to have a way to do such infill patterns in FreeCAD at some point in time, I guess it'd be useful for the forthcoming Path module too...

[DeepSOIC]

Today was a 3d-printing day . And unlike me, my printer doesn't look tired of it.

jetter prints.jpg (117.43 KiB) Viewed 9348 times

[DeepSOIC]

Tested. Not exciting at all, unfortunately.
It does not create much pressure, and it is deafeningly loud!
A simple centrifugal turbine beats it very easily.

[robertr]

Interesting work. I am thinking about a similar project with a reversible vacuum/compression pump as the goal. I'm interested in a few details of your first attempt: What was the motor speed (rpm)? The blade inside diameter and outside diameter? How many stages? What pressure did you get? I'm hoping to get about 5 PSI vacuum and about 3 PSI pressure. I'm considering using a 7000 rpm brushed motor. Thanks

[DeepSOIC]

I didn't measure anything, but the max rotation speed I can get is about the same as you are up to (limited by my power supply). I didn't measure the pressure, but it is obviously negligible, less than 0.1 psi I think.

The sizes are in the model that I shared in the first post. It isn't the final design only in that it has no infill modelled in the rotor (I should have named it spindle, probably...). It has 5 stator vane disks and 4 rotor vane disks.

[DeepSOIC]

I have just made a dirty estimate of max rotation rate of this turbine. I calculated, what rate is required to explode the outer ring of rotor vane disks.
Assuming PLA tensile strength of 57 MPa, and ring diameter = 62 mm, the rotation rate of explosion of the ring is 66000 RPM (1100 Hz). I'm not 100% sure I've done the math right... and I'm quite sure this turbine will crash long before that speed (due to aerodynamic forces, imbalance, vane collapse), but it makes me consider trying to build a turbomolecular high vacuum pump .

[simpo]

An awesome looking project.

[DeepSOIC]

Work in progress: making a nozzle

jetter nozzle.png (131.29 KiB) Viewed 8238 times

Importantly, it is parametric In that:
* I can change sizes and height of the nozzle
* I can modify the turbine, it will adapt
* I can modify wall thickness, all at once (tailored for a specific extrusion width for 3d printing)
Changing the number of fins is tricky (an angle in one sketch must match 360/number_of_fins). But still very possible.

Doing that fin sweep was the most tricky part (took me more than an hour of head scratching before I invented a way to do it).