kaplan propellor looking for

Discussion in 'Props' started by french44, Nov 18, 2011.

  1. french44
    Joined: Mar 2006
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    french44 Junior Member

    Hi ,

    I'm looking for open water test of KA4 series with and without kort. We have some trouble to have all the rpm on the engine and the calculation was carried out with b series so i want to check the difference beetween the 2 open water diagram .

    Thanks a lot
     
  2. jehardiman
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    jehardiman Senior Member

    Vol 2, Chpt 6, Sect 9 of the current edition of PNA has the coefficients for a Ka 4-70 in a 19A and 37 nozzle. Without a nozzel, a Ka is going to absorb much more torque than a similiar B series for the same thrust-rpm.
     
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  3. french44
    Joined: Mar 2006
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    french44 Junior Member

    kaplan

    Thanks, i know that the torque should be more than b serie but i need to prove to the guys this fact and for that i need chart for this propellor : D 0.9 m ; Step : 0.846 m; p/d= 0.94 and Ae/A0= 0.6 kaplan KA4-60 . i have the chart and even software for b serie. I'm in central africa river congo and it's not easy to have doc or post mail ( 3/4 week mini) so if someone have it it will be very sympathic to send me.

    Thanks a lot in advance
     
  4. FishStretcher
    Joined: Oct 2011
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    FishStretcher Junior Member

    Sorry to ask, but what is PNA? I want to look at this reference.
    Thanks!
     
  5. jehardiman
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    jehardiman Senior Member

    "PNA" is Principles of Naval Architecture, published by the Society of Naval Architects and Marine Engineers (SNAME), and is a main reference work for NA&ME. Pricey but worth it, but is assumes you have been trained as a NA&ME and can handle the math on your own. Go get a copy from the library/intra-library loan unless you want to join SNAME.
     
  6. johneck
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    johneck Senior Member

    There is also SNAME paper from 1981 titled "Sizing Segmental Section Commercially Available Propellers for Small Craft" by Blount and Hubble that has Fourier coefficiencts for the data. This makes it easy to turn the data into a spreadsheet calculation.
     
  7. FishStretcher
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    FishStretcher Junior Member

    I am a Mechanical Engineer working on boats, but not a Naval Architect. So I should be able to get about half the math :D Thanks for the tip!
     
  8. DCockey
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    DCockey Senior Member

    The reference appears to be to the 1988 edition of Principles of Naval Architecture which is now out of print and no longer available from SNAME. It has three volumes with Volume II covering Resistance, Propulsion and Vibration. Used copies are available online though the prices can be quite high.

    The "new" version of PNA is now a "series", each volume on a separate topic corresponding to a single chapter in the previous edition. So far only 6 volumes have been published, one of which is Principles of Naval Architecture: Propulsion. I don't have that one but have several others and in general they contain the theory but not the "practical" data and charts the Propulsion volume may not have propeller charts. http://www.sname.org/SNAME/Pubs/Books/
     
  9. Oscar Cherro
    Joined: Oct 2018
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    Location: Argentina

    Oscar Cherro New Member

    Hello all,

    I´m also looking for a KA propeller characteristics without a nozzle. I´m studying a towboat fitted with KA propellers and happens to be performing pretty poorly. One of the reasons might be this one, but I´d like to confirm it mathematically.

    Thanks in advance.

    Oscar
     
  10. johneck
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    johneck Senior Member

    I don't think that there is data available for the propeller without the nozzle. The KA series props were intended to be used in nozzles and the performance without the presence of the nozzle will be very poor. I would also be concerned about heavy cavitation and vibration.
     
  11. Oscar Cherro
    Joined: Oct 2018
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    Oscar Cherro New Member

    Yes, that´s exactly what I thought.

    I have verified the cavitation and is indeed high. Way above 10% as per Burrill criteria.

    The performance is indeed very poor due to many factors in this particular case. Propeller diameter is small, it doesnt have a nozzle (plays a big part for push boats), its fitted with a KA propeller operating without a nozzle, its cavitating and it also has too low a pitch for engine power.

    Having listed all those issues it has made it clear why it is performing poorly, even if I dont have the charts to show it mathematically. :)
     
  12. dileep kumar
    Joined: Jul 2019
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    dileep kumar New Member

    have you
    Have you got the geometry
     
  13. Javier Allende
    Joined: Dec 2019
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    Location: Buenos Aires

    Javier Allende New Member

    Hi!

    I'm also looking for this info.
    I know that Kaplan propellers are far more efficient with nozzle, but it's a fact that it's common to find push boats with KA prop. without nozzle.

    The Kt Kq curves for this proppellers have also de Ktn curve, that infires the thrust on nozzle. Would it be wrong to asume the thrust of the proppeller alone as the difference between T (from Kt) and Tn (from Ktn)?
    I know that the open water tests were made with the nozzle, but, why would they offer the curves of Ktn if they weren't the difference respect the without-nozzle tests?
     
  14. jehardiman
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    jehardiman Senior Member

    Javier
    Welcome to the forum.
    The action between a Kaplan propeller and nozzle are complementary to each other. Each by itself degrades efficiency. DO NOT CONFUSE MAXIMUM THRUST WITH MAXIMUM EFFICIENCY!

    Because Kaplan propellers have more blade span as r increases, they have more thrust (T) due to increased area acted on by v (r*omega) for a given alpha (sin J/v) at most r. However the increased span increases torque (Q) with r^2, meaning that efficiency (T*J/Q) DECREASES with increasing r. So Kaplan blades of similar size and RPM to B series produce more thrust and absorb much more torque and so are less efficient.

    Nozzles ALWAYS increase drag, requiring an increased T to compensate for a given J. However most nozzles optimized for Kaplan blades are increasing nozzles, i.e. they increase the velocity of J at the propeller disk. This has the function of increasing alpha for a given v, which increases both thrust and efficiency for a given torque for both Kaplan blades and B series . Therefore, because all vessels have both a propeller diameter and a delivered Q limit, fitting a Kaplan blade into a nozzle is a way to increase thrust for a given rpm and torque fitted when limited by r and J.

    A Kaplan propeller in an increasing nozzle provides more thrust with less loss of efficiency at a given J than other methods.
     

  15. Javier Allende
    Joined: Dec 2019
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    Location: Buenos Aires

    Javier Allende New Member


    First of all, thanks for your welcome and response,

    I am in a project in which I have to design a propeller for a pushboat without nozzle. How can I calculate Kaplan propellers without nozzle? I only found Kt Kq curves for different kaplans with Kort 19a.
     
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