DIY axial flow pump, fractional hp motor, highest level of water through 6 inch diameter 30 ft pipe

Discussion in 'Hydrodynamics and Aerodynamics' started by Luke Frisbee, May 5, 2021.

  1. Luke Frisbee
    Joined: May 2021
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    Location: Indialantic FL

    Luke Frisbee Junior Member

    In the first segment of your post you've quantified (given numbers) to what you have sifted out by reading my posts. And you did a good job of that if i was looking for an answer based on a quantity.
    I am not.
    I am looking for a qualitative conclusion...
    I am not concerned if a .5hp propeller pump will pump 50,000 gph or 500,000 gph.

    Now this could be all in my head, but a simple structure using a propeller attached to an electric motor correctly placed in front of the end of a pipe with the fewest structural barriers so the MAXIMUM flow can be achieved would be a vast improvement to the available pumps.

    And... what I would like to come to understand which propeller would be best. And how to arrange the other parts to the system around the propeller to maximize its draw from the pipe.
    I am not looking to design a pump to meet a specific need. I am just trying to get close in understanding what are some of the crucial aspects in building a "zero head" high flow axial/propeller pump.
    Could we just focus on the propeller. as in how much water(energy) slips off the ends of the propeller, and how far should the propeller be placed away from or inside the pipe to be where MAXIMUM flow can be achieved...
    Forget about head, forget about the bends, forget about the texture inside the pipe. forget about any obstruction supporting the propeller. (I have played with simplified software years ago).
    Where should the propeller be placed in relation to the pipe opening in a "zero head" application.
    If you must consider a 3 inch maximum head later.

    Then I have the next inquiry...
     
    Last edited: May 6, 2021
  2. baeckmo
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    baeckmo Hydrodynamics

    Sorry, but there is no "zero-head" pumping anywhere. In the very moment you induce a movement into the fluid, there is a dynamic head. Again, the pump configuration suitable for a "low head-high flow" operation is depending on the specific requirements. And in order to build an efficient pump you just have to understand the basic facts.

    To your finishing question about impeller placement: you should place it at the beginning of the duct.
     
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  3. ondarvr
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    ondarvr Senior Member

    I don't have any information on your primary question, but I'm curious about a few things.

    In a prior life I built and installed computer controlled filtration systems for large water features at resorts, swimming pools, and large aquariums (think Sea World, Las Vegas resorts, and Olympic size pools). This was a long time ago when it was new technology.

    Elephants and hippos needed different systems than fish or people.

    What type of filtration are you using?
     
  4. Luke Frisbee
    Joined: May 2021
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    Luke Frisbee Junior Member

    I thought I made it clear that "zero head" was fictitious.
    I phrased the question as several other descriptors indicating I wanted the least possible loss on the receiving side. and I am trying to accomplish this by diminishing the the head by reducing the friction/turbulences on that side. By placement of the propeller and any physical encumbrances around even down to lengthening the shaft to distance the motor from being in the flow..or creating a "cone structure around the shaft if that will help even more (doubt that though).
    Thousands of thousands of articles have been written about losses due to piping. And impellers in centrifugal pumps have their own books.
    Axial flow pumps get close to propellers but they still do not focus on an application where the most water pulled through an opening at the least possible head is the goal when concerned with the wash created by the propeller and the encumbrances other than the piping on the receiving side.
    And getting closer here... careers have been made designing props for boats. Boat props DO get close because the prop itself is designed without any encumbrances (other than a rudder in some cases) near it.
    Well props for boats are not designed to be placed in front of a strictive hole (unless you consider jet ski props but then the whole piping dynamics on the receiving side and directional use of the water movement ....)
    So a boat prop, The task is JUST to get the water out of a six inch diameter hole at the end of a 30ft pipe with two 90 degree sweeps (But please just forget about the pipe crap (we can visit that latter if it is special. ), and a .5hp prop with an RPM of 3100+/-, using all the energy created by the prop, with very little to foul up the designed hydro-dynamics what should the prop be in terms of pitch, number of blades, and size and shape? And where should it be placed to maximize the capture of the energy/movement of the water?
    Those two aspects. That's it...some of you know props inside and out...at least you know what shape and size props in the six inch range move the most water at 3000rpm's?
    And others of you might be willing to share if I need to put an adapter on the six inch pipe to increase the exit hole to a greater size and use a larger prop of a certain size to get the greatest volume through the six inch pipe using a half-horsepower motor.
    (I can of course buy a different motor with a different rpm, but please stay with me here...)
     
  5. Luke Frisbee
    Joined: May 2021
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    Luke Frisbee Junior Member

    and ...
    Do not think I am do not feel uneasy about asking you for this information. I understand that time and knowledge are valuable, and to aks you to share both with me is difficult for me. but I am at a loss.
     
  6. Luke Frisbee
    Joined: May 2021
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    Location: Indialantic FL

    Luke Frisbee Junior Member

    and there it is...?
    I know no more about how boat props move water than when we all started. Which is at the core of my inquiry.
    Thank you for your time/.
     
  7. Dejay
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    Dejay Senior Newbie

  8. gonzo
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    gonzo Senior Member

    A boat propeller will be very inefficient compared to any common device used in pumps. As you said previously, there are books and books written about the subject. If your goal is to create new technology, cobbling together mismatching parts won't do it. You need to design something that doesn't yet exist.
     
  9. Luke Frisbee
    Joined: May 2021
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    Location: Indialantic FL

    Luke Frisbee Junior Member

  10. Luke Frisbee
    Joined: May 2021
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    Location: Indialantic FL

    Luke Frisbee Junior Member

    I appreciate your time, and the energy it took to post.
     
  11. baeckmo
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    baeckmo Hydrodynamics


    ….yeah, that’s about it for now. Fluid mechanics can not be intuitively treated. Your problem is a trivial one, popping up about thirteen times on a dozen, but it still requires relevant knowledge to be explained and solved. You got some good input from several forum members, but in your caesarian ignorance, you turned them down as “crap”. With your lack of knowledge on the subject, you simply don’t have the competence to pick what knowledge is needed for the purpose.

    So, there you are; asking for free help requires some behavioural decency; the real crap in this thread is your attitude.
     
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  12. Dejay
    Joined: Mar 2018
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    Dejay Senior Newbie

    I believe it should be possible since it's a pump with the least moving parts. You'd just need to build your own motor. Glue up your rotor and wind your stator. Machine or 3D print your own parts. You'd just have to learn how they work and how to calculate. Then combine that with the formula for fluid pumping and pressure and with charts for propeller design to tune all the aspects. Make a design tool in a spreadsheet.

    Then come back and share your build and tell us how you did it :)
     
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