Need help creating the a mini wind-tunnel to show how rotorblades work.

All_In

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Normally I would give this project to ME (Mechanical Engineering Students) But their classes have already started and we have 2 projects with them this year.
I might be able to submit it to the EE (Electrical Engineering) students at USD. Their classes won't start until the end of September
It does need electronic sensors for the rotors, and the lift and the airspeed at least. They may pick it up this semester. So better write it up now.
Then I can test whatever you guys want at any airspeed you wish. We could ship it to members for their use requesting only data and a video for our library.

What other sensors would we need.want?
  1. Airspeed.
  2. RRPM
  3. A scale to measure the lift actually created mounted on the base of the mast.
  4. mini-prerotator

The basic design.

Going to use the largest fan we can get for the size max size and reduce it with a venture to the output.
A smoke system with holes drilled in pipes as a smoke manifold
Laser-cut boxes of soda straws in half and then stack the boxes in front of the smoke manifolds and fan to create streams of laminar airflow filled with smoke.

This part is too easy.
 

XXavier

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In order to get really accurate data, the Reynolds number has to be compensated somehow. One way is to pressurize the entire system, but that's difficult and probably very expensive...
 

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In order to get really accurate data, the Reynolds number has to be compensated somehow. One way is to pressurize the entire system, but that's difficult and probably very expensive...
Thank you.
I'll have to have them research that.
NASA isn't/wasn't pressurized when I toured it, way back when.
Any idea's how they do it?
 

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I guess we could use 3 fans. One input for pressure and two on each end in a closed pressure loop with a vent to reduce pressure to what you want????
 

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In order to get really accurate data, the Reynolds number has to be compensated somehow. One way is to pressurize the entire system, but that's difficult and probably very expensive...
XXavier do you know the pressure required?
 

XXavier

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XXavier do you know the pressure required?
It depends on the scale factor. If the models are real-size, you don't need to pressurize, but if the models are 1/4 scale, for example, you need to use an air density four times the normal one, and that would mean, roughly, to pressurize at four times the normal atmospheric pressure...

Or that's what I remember having read concerning the need to pressurize in order to get accurate results... but perhaps that's a level of accuracy rarely needed in practice...
 

All_In

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It depends on the scale factor. If the models are real-size, you don't need to pressurize, but if the models are 1/4 scale, for example, you need to use an air density four times the normal one, and that would mean, roughly, to pressurize at four times the normal atmospheric pressure...

Or that's what I remember having read concerning the need to pressurize in order to get accurate results... but perhaps that's a level of accuracy rarely needed in practice...
Thanks so much. With the venturi, the size would be reduced to 3' mini blades. We would need 10 atmospheres, So that's out. Back to simple.


The main purpose is to create videos and gather data that will show how air actually is deflected. Specifically what angle is the deflection and for what distance. We adjust the cyclic through all positions and airspeed and watch the show. Also video blade flap/sailing.

We are not testing different blade designs so...
Why can't we just create the algorithms needed to do the math, to scale? All in the same MCU used for the sensors and data-logging.
Make a copy of the blades to a specific manufacturer's and check the data against reality until we have the algorithm matching reality.
 
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