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Turbine: Straight or Rotational airflow?

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  1. Jan 13, 2015 #1
    I'm working on a project now and I'd like to know which type of airflow would power a turbine faster/better straight or rotational?
    Or will rotational airflow even have any effect on the turbine...?

    P.S. When I say rotational airflow, I mean circular airflow that rotates in the same direction as the turbine.
     
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  3. Jan 13, 2015 #2

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  4. Jan 14, 2015 #3

    CWatters

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    Presumably what matter is that the air enters the turbine at the "correct" angle to suit the turbine blade pitch. So if the air was rotating the blade pitch might need to be changed? Not sure why/if it would improve performance.

    You aren't thinking about the difference between radial and axial turbines are you? Early jet turbines had radial flow compressors and I think it's well established that axial flow is more efficient.
     
  5. Jan 14, 2015 #4

    russ_watters

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    How would you measure the wind speed? The rotation would have additional energy in it.
     
  6. Jan 14, 2015 #5

    anorlunda

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    Look up Francis, Axial, and Pelton turbines for hydro power, Each is radically different than the other. Each is optimal for some range of the parameters.

    The same applies to air. The answer depends on the details.
     
  7. Feb 16, 2015 #6
    It takes energy to creat circular motion, cut the cord and linear motion will result.

    How would you get the ai to spin?
     
  8. Feb 16, 2015 #7

    QuantumPion

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    Are you asking about impulse vs reactive turbines?
     
  9. Mar 15, 2015 #8
    Go to bombuli.com for the true answer to wind power

    Rotation dimininishes original air flow power
     
  10. Mar 17, 2015 #9
    Yea, that 's what I was wondering, if the additional energy from the rotation would make any difference to a normal wind turbine
     
  11. Mar 17, 2015 #10
    Nah, I'm asking about rotational airflow being directed at a normal wind turbine, would it's rotational force generate from rotation from the wind turbine?
     
  12. Mar 17, 2015 #11
    I haven't exactly figured out how to yet, but would the rotational force rotate the wind turbine easier than a straight airflow?
     
  13. Mar 18, 2015 #12
    Study page 6 & 9 of the document momentum.pdf @ bombuli.com, it's ground breaking physics in wind power dynamics.

    Any structure interfacing with the wind to cause the rotational air flow will reduce the energy of the original air stream, thus less energy down stream.
    What you are describing is a turbocharger in reverse, Carnot Cycles won't alow this. without the power input, the entropy and thermodynamics always run down hill

    The impulse of original air is the strongest at the first point of interaction because the interaction itself takes energy out of the system by dissapative internal forces of colision prior to any energy transfer process.
     
  14. Mar 18, 2015 #13
    The larg horizontal turbines use aerodynamic lift that strongly depends on the angle of attack and the resulting vectors of motion. Any manipulation of the airstream changes this relationship, and it's alway down hill. Shrouding of any kind limits the potential energy, the bucket effect.
     
  15. Mar 19, 2015 #14
    Sir. If you were to feed a vortex of air flow to the surface of the blades in the direction of intended rotation (depending on angle of attack) yes, you would impart force against it causing rotation depending on system resistance of course. I'm not sure as to why you would want to go to the trouble of applying air flow in a circular motion to a blade to produce rotation however when straight air flow is far more common. Changing direction of motion consumes energy. With the possible exception of vortices. They are found throughout Nature and where ever Nature works it usually expresses total conservation of energy. I think it would be interesting to see what you are trying to accomplish here.
     
  16. Mar 21, 2015 #15
    I guess you're right, I carried out an experiment with this wind tunnel I built: image.jpg , powered by a desk fan: image.jpg . The anemometer I got, is this model: image.jpg with a propeller typed-blade. And is located in the blue cuboid casing between the 2 pyramids.

    So it works by using the desk fan, located at the red pyramid, to suck in air through the blue pyramid, and the wind speed will be increased due to the Venturi effect, by 10 times, and pass through the anemometer, where the wind speed, or in this case, rate of propeller rotation, will be measured.
    Thus to create a vortex/rotational/circular airflow, I made a "filter", by placing columns 45 degrees to the circular opening: image.jpg , to make this: image.jpg . When the air gets sucked in due to desk fan, in theory, the wind should be sucked in 45 degrees to the opening and thus creating rotational airflow(same clockwise motion as my anemometer's rotation to straight airflow).

    I did 2 experiments, 1 without the "filter": image.jpg , and the other, with. Here are my results
    After measuring the wind speed(km/h) every 30 seconds, for 5 times.
    The average wind speed of the experiment WITHOUT the filter, was: 14.48 km/h
    The average wind speed of the 2nd experiment WITH the clockwise filter, was: 13.2 km/h
    A 8.8% wind speed/performance drop...
    Is this due to the angle of attack thing you mentioned about?
     
  17. Mar 21, 2015 #16
    The larg horizontal turbines use aerodynamic lift that strongly depends on the angle of attack and the resulting vectors of motion. Any manipulation of the airstream changes this relationship, and it's alway down hill. Shrouding of any kind limits the potential energy, the bucket effect.
    I guess you're right, I carried out an experiment with this wind tunnel I built: https://physicsforums-bernhardtmediall.netdna-ssl.com/data/attachments/63/63801-87b7f3a5f83618e471314aa60073a5db.jpg [Broken] , powered by a desk fan:https://physicsforums-bernhardtmediall.netdna-ssl.com/data/attachments/63/63802-8eb3c548c8d1d3d9c24c88a46e71f050.jpg [Broken] . The anemometer I got, is this model: https://physicsforums-bernhardtmediall.netdna-ssl.com/data/attachments/63/63803-d9501a8fc0335f2ceb7eecd7a996a574.jpg [Broken] with a propeller typed-blade. And is located in the blue cuboid casing between the 2 pyramids.

    So it works by using the desk fan, located at the red pyramid, to suck in air through the blue pyramid, and the wind speed will be increased due to the Venturi effect, by 10 times, and pass through the anemometer, where the wind speed, or in this case, rate of propeller rotation, will be measured.
    Thus to create a vortex/rotational/circular airflow, I made a "filter", by placing columns 45 degrees to the circular opening:https://physicsforums-bernhardtmediall.netdna-ssl.com/data/attachments/63/63804-1f71128e0b16f14e4e18a1644adc9e0a.jpg [Broken] , to make this: https://physicsforums-bernhardtmediall.netdna-ssl.com/data/attachments/63/63805-8a66e32ad6252bbd7fe35d567839f5bb.jpg [Broken] . When the air gets sucked in due to desk fan, in theory, the wind should be sucked in 45 degrees to the opening and thus creating rotational airflow(same clockwise motion as my anemometer's rotation to straight airflow).

    I did 2 experiments, 1 without the "filter": https://physicsforums-bernhardtmediall.netdna-ssl.com/data/attachments/63/63804-1f71128e0b16f14e4e18a1644adc9e0a.jpg [Broken] , and the other, with. Here are my results
    After measuring the wind speed(km/h) every 30 seconds, for 5 times.
    The average wind speed of the experiment WITHOUT the filter, was: 14.48 km/h
    The average wind speed of the 2nd experiment WITH the clockwise filter, was: 13.2 km/h
    A 8.8% wind speed/performance drop...

    I honestly have no idea why this is happening
     
    Last edited by a moderator: May 7, 2017
  18. Mar 21, 2015 #17
    Steve, as far as I can tell Sir. You are One: placing restriction in the air flow with the 'filter'. Two: The way the vanes are placed, is cause for air flow direction change which causes turbulence. Turbulence 'eats' energy which will show as energy lost (velocity drop). Perhaps try placing vanes attached on the outer inside edge/mouth of your cone if you feel you must 'induce' a vortex. Better still, in that flow configuration, a vortex should form of it's own accord as is natural especially if you were to build your cones with a more shallow angle. Study the overall cone structure of say, a tornado. Very shallow around 10 or so degrees depending on your requirements. Always think smooth laminar.

    I am attempting to get a machine built designed to augment it's own propulsion using fluid, vortexes,cavitation and jetting as a self driving (at least augmenting) system in hope of at least putting a dent in that last 1% efficiency level we can't seem to overcome. Even with Kaplan generators.
     
    Last edited by a moderator: May 7, 2017
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