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Can I design a horizontal cylindrical hollow turbine blade

  1. Mar 1, 2017 #1
    Hello everyone,

    I need the following but I am not sure if it is possible or not? I don’t have mechanical engineering background. Please advise me on feasibility of this project and any suggestion would be greatly appreciated.

    I am looking to design a horizontal cylindrical hollow turbine blade.
    I have attached a simple image of what I need. I need a hollow cylinder that has a layer on its inner wall (green layer) which will rotate clockwise (or anti clockwise) whenever water (or any liquid) flows through the cylinder. The picture showing it from the front angle. Imagine water coming towards you, through the inner tube. The green layer supposed to have some sort of blade assortment that will catch the water flow and will make it rotate.

    thanks
     

    Attached Files:

  2. jcsd
  3. Mar 1, 2017 #2

    Nidum

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    There are probably ways of doing this . We need to know a bit more about what you are trying to achieve before we can give useful answers .

    What does the device do ? How big is it ? How much water flow ?
     
  4. Mar 1, 2017 #3
    hi,
    my plan is to place a system like this, inside a water hose (with the diameter of roughly 3cm to 6cm). Then possibly use the rotation made in this way to generated a few mW of power. After design of this turbine blade, I plan to use it as some sort of rotating impeller with some magnets attached to it so that I can generate some power outside the hose (by placing some coils on the outer surface of the hose).
    To be honest I dont have any specific flow of water in mind, but for now you can expect typical flow rate of an ordinary garden hose.
    thanks
     
  5. Mar 1, 2017 #4

    etudiant

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    One suggestion would be to have this as hose attachment, that ensures that the product can be fitted to any garden hose, rather than needing to be specifically integrated into one specific hose.
    Another idea might be to have the turbine use a conventional impeller. While it lacks the elegance of your cylindrical turbine approach, it is much cheaper to make and more easily integrated with a small generator.
    There are lots of hose water driven mechanisms around, mostly to either roll the sprinkler over the area to be covered or meters to limit the amount of water to be sprayed. An electronic controller would surely be much more capable, but needs to justify the cost.
     
  6. Mar 1, 2017 #5
    I appreciate your suggestion. But I was looking for this kind of cylindrical impeller because in my project the main challenge is to reduce the resistance to the flow of water. I thought to go with this kind of design (rather than normal typical impeller) since this kind of impeller is not directly blocking the water flow path.
     
  7. Mar 1, 2017 #6

    JBA

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    If there is no flow interference through the impeller there is no force available to rotate it.
     
  8. Mar 1, 2017 #7

    etudiant

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    Exactly.
    There is no free lunch in engineering. The power jjoll seeks to extract must come from somewhere.
     
  9. Mar 3, 2017 #8
    One suggestion would be to shift to a slower rotational speed and use a very low angle of attack. A conventional turbine uses a high angle of attack which causes a significant change in flow extracting the maximum energy. It does however also create a restriction.
    Instead look at something like a "inverted windmill." High aspect ratio and very low angle of attack distorts the flow very little but also creates minimum resistance. You will however as previously stated also extract less energy.
     
  10. Mar 3, 2017 #9

    Baluncore

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    Flow meters operate so as to minimise obstruction of flow. Some operate as follows. First there is a set of fixed vanes that put a helical twist in the fluid flow lines. An X section magnetic rotor follows that twist. Because the X section is parallel with the tube there is no end thrust, but it rotates due to the helical flow. Magnets on the rotor transmit flow rate pulses to external sensors.

    Here is an example of a flowmeter that operates on that basis.
    http://www.ebay.com.au/itm/Water-Fl...034517?hash=item1c4aae80d5:g:XM8AAOSwq7JUEA4v

    You could use a system like that to extract some power from the flow. Instead of sensing magnetic pulses you generate current by using external windings about the rotating magnetic field.
     
  11. Mar 5, 2017 #10
    Yes, you are right but I am trying to minimize obstruction of flow as much as possible (not totally eliminate it) as Ketch22 and Baluncore suggested.
     
  12. Mar 5, 2017 #11

    anorlunda

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    I'm sure that you have studied conservation of energy, but your posts reveal that you don't really understand what it means.

    Using conservation of energy, you can see that power can not be extracted without disturbing the flow or pressure in the pipe. It is not necessary to study the details of the turbine to know this must be true. That it the beauty of conservation of energy in engineering. You can use it to eliminate impossible dead ends before analyzing the details.

    Expressed in different words. If you could generate electric power with zero change in pressure or flow in the pipe, where would the energy come from?

    .
     
  13. Mar 5, 2017 #12

    Baluncore

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    If you do not need much current you could use a magnetic field across the flow and extract current with electrodes perpendicular to the flow and field.
    https://en.wikipedia.org/wiki/Flow_measurement#Non-contact_electromagnetic_flow_meters

    Another way would be to place dissimilar metal electrodes in the flow and harvest ions from the water by cell potential. You might consider using an LTC3108 “ultralow voltage step-up converter” made by Linear Technology to raise the cell voltage.
     
  14. Mar 6, 2017 #13
    And I am sure you can read! and you saw my response to previous comment since you quoted it. I dont expect ZERO change in pressure or flow in the pipe. I would like to minimize it to just get enough energy, NOT totally eliminate it.
     
  15. Mar 6, 2017 #14
    thanks. some good ideas. I will think about them.
     
  16. Mar 6, 2017 #15
    Okay... so then just use a regular impeller or turbine that has a high pitch angle and offers low resistance to the water's flow. https://en.wikipedia.org/wiki/Turbine
     
  17. Mar 7, 2017 #16
    Look up a Vortex Trap... here you will see a device similar to what you are seeking... if not a turbine flow meter with magnetic pickup is more likely what you are trying to design? ormus_magnetic_vortex_trap.jpg
     
  18. Mar 8, 2017 #17
    I imagine it'll work, but only with very specific configurations that are probably not calculatable. Luckily, there is a way to solve super complex problems like that: a genetic algorithm, they have the benefit of coming up with really strange designs that work better than what we design.

    This guy evolved a wind turbine that defies any common sense in aerodynamics, but in simulations, outperformed calculated ones.
     
  19. Mar 9, 2017 #18
    very interesting video and method. thanks for sharing
     
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