Marine Propeller Resistance

  • Thread starter copria
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Main Question or Discussion Point

Is there a noticable diffence in torque required to spin a marine propeller at a constant rpm (say 2000rpm) when under a different water column? (5m vs 35m)
 

Answers and Replies

  • #2
mgb_phys
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Not much, water isn't very compressible.
ussually the problem is running them near the surface, the impact from air onto the surface of the water causes cavitation.
 
  • #3
russ_watters
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note, however, that cavitation is reduced with depth because of the pressure.
 
  • #4
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If I want to optimize the energy release from cavitation would it be better to have a shallow water column (producing larger amounts of cavitation) or a deep water column (larger force collapsing the cavitation bubble)?
or
Would both cases yield the same energy release?

assuming the propeller is at a constant speed
 
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russ_watters
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Energy release? What energy release?
 
  • #6
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thermal energy release
 
  • #7
russ_watters
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You mean you want to eliminate cavitation, right? Higher pressure reduces/eliminates cavitation, reducing energy/efficiency loss.
 
  • #8
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No, I want to create cavitation (like a cavitation water heater).

Sorry I did not specify earlier.
 

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