After a bit more work, it’s coming together. I need to talk to an axial compressor engineer at some point, this is my first multi-stage design.
This is a parametric design. It was generated entirely by python scripting and the Blender API.
I’m no engineer but I’ve been working with jet engines for 15 years and I can tell you at a glance you have zero compression occurring in that design. Merely changing the angle of each set of blades does nothing if the air volume at each stage is the same. In fact as you get more compression the angle of the blades will actually get closer to perallel to the axial direction. The volume of air at each disk needs to match the compression ratio of the disk before it or you lose all the compression you just accomplished by allowing it to expand.
But the fact you did that with python script is pretty badass.
Hey @Ryan_Hescock_Stanos , Engineer or not, I’m happy to discuss compressor design with anyone. I’ll take whatever peer review I can get. So awesome that you work on jet engines! What do they power?
Air compression is actually not the goal here but rather to increase the air velocity as much as possible. This may be different for a turbine powered engine which likely requires compressed air for the combustion process. You’d be able to educate me a bit about this I think.
I guess you can’t see very well from my render, but the cross-sectional area of the air passage is reducing progressively from stage to stage. This converts the pressure increase, caused by the work the blades are imparting onto the air, into air speed. From Bernoulli’s equation, as speed goes up, pressure goes down. I’m working under the assumption of incompressibility.
The blade geometry and their angles are defined based on a few things. Probably the most important one is the Degree of Reaction of each stage. I’ve chosen high degree of reaction, particularly for the last stages to ensure minimum swirl and maximum axial velocity at exit of the stator blades. The design blade speed and axial flow rates also have an effect on blade geometry.
Note how the blades have less camber and the (blue) stator blade angles are more aligned with the flow with each progressive stage. This is due to the increasing air velocity.
Pic of stator and rotor separated.
Okay I guess I misunderstood what design you were going for. I work on GE F404s you can find plenty of pics online I’m on my phone and can’t seem to paste a URL right now.
So is this going to be for an electric RC?
That’s the plan yup. I’ve never seen anyone do this, which has me a tad concerned. But 3D printing has just given me the ability to design and prototype them. Nothing ventured nothing gained.
What do you plan to print it on?
A modified Printrbot GoLarge, using HIPS as support material.
Well I look forward to seeing the first test run. Only seen one other guy on YouTube testing printed turbine blades but they were the larger fan type. You will have a lot less centrifugal force on the blade tips. Printing it vertically with really good dissolvable support will give the best results. Definitely want to consider printing and testing a single stage for strength.
Sweet, thanks for the interest. I’ve actually already produced a 64mm ducted fan which anyone can download, print and use. I’ve run it on that 500W 3700KV motor at max throttle on a 3S; I’m not sure how fast it was spinning. http://www.circuitgrove.com/products/64mm-ducted-fan-single-stage-axial-compressor
I’ll be doing proper performance testing when time allows.
Hey Andre. I just joined and still browsing through the posts. Your compressor is eye catching, but what is it for? (I used to work on gas turbine gen sets.)
Welcome. It’s to power an RC jet model. They idea is to get more thrust than a ducted fan of the same OD.
Hey @Ryan_Hescock_Stanos , your comment about stator blade angles had me revisiting my choice of reaction for the blades. A stage reaction of 0.5 has the rotor and stator doing an equal amount of work. I’m choosing high reactions which means the rotor does most of the work on the fluid, this is likely bad. Thanks for commenting on this, it has me modifying my design. This jet has outlet guide vanes to redirect the flow axially after the last stage’s stators which still has swirl: https://youtu.be/CXSi4GXUojo
@Andre_Roy Glad to hear my comments helped you. Like I said I’m no engineer, just been working with them for a long time and at first glance the setup did not look like it was going to do much of anything in the way of compressing air. You will definitely have to come back and let us know if you get it working and what kind of velocity increase you achieve.