What is the difference between impeller and propeller

Discussion in 'Surface Drives' started by Tracie Kaneshiro, Jul 1, 2020.

  1. Tracie Kaneshiro
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    Tracie Kaneshiro New Member

    An impeller is a rotating part of a centrifugal pump which transfers energy from the motor that drives the pump to the fluid pumped by accelerating the fluid outwards from the center of rotation.

    A propeller is a device with a rotating hub, that when rotated, performs an action that is similar to Archimedes' screw. It transforms rotational power into a linear thrust by acting upon a working fluid such as water.

    i think this the main diffrence between impeller and propeller
     
  2. gonzo
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    gonzo Senior Member

    There are several types of impellers. Most boat engine impellers are flexible and work as a displacement pump. At higher speeds, some are design to transition into a different mode as centrifugal pumps. Jet drives also use impellers and are not centrifugal pumps.

    That is not quite right. Propellers are rotating foils operating on a fluid that can be considered incompressible within limits. An Archimede's screw operates inside a pipe, which is a very different condition.
     
  3. TANSL
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    TANSL Senior Member

    In other words, the device carried by planes powered by the so-called (misnamed?) "propellers" are not propellers because the fluid in which they operate is compressible.

    .
     
  4. gonzo
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    gonzo Senior Member

    This is your usual nonsense. Please show any plane operating under water. :rolleyes:
     
  5. TANSL
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    TANSL Senior Member

    Now you have caught me, what a smart man you are! I can't find any examples of a submarine plane, I can only think of seaplanes that don't go under water but over water. But even those planes, which have what I call propellers, in fact, according to your theory, do not have propellers because that device that propels them does not work in an incompressible fluid (they are not rotating foils operating on a fluid that can be considered incompressible within limits). One always learn something new and I, fortunately, am still of learning age.
     
  6. hoytedow
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    hoytedow Carbon Based Life Form

    Boat propeller does operate in a mostly incompressible liquid fluid, whereas airplane propeller operates in a very compressible gaseous fluid. One assumes this thread was addressing the mechanics within the liquid fluid.
     
  7. hoytedow
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    hoytedow Carbon Based Life Form

    Welcome, Tracie.
     
  8. jehardiman
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    jehardiman Senior Member

    Welcome to the forums.
    Actually I think a much simpler way to state the difference is that a propeller is made to propel the vehicle and an impeller is made to pump the fluid through a guided passage. A Voith-Schneider is a propeller, as is a Kaplan propeller in a duct, but a pump jet has an impeller, as does a White-Gill thruster.
     
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  9. Mr Efficiency
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    Mr Efficiency Senior Member

    Then there is the "compeller", which in some cases, doubles as "the wife" ! :eek:
     
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  10. hoytedow
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    hoytedow Carbon Based Life Form

    Or, as I call her, SWMBO.


    She who must be obeyed. :confused:
     
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