KISS Principle Marine Propulsion

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Discussion Overview

The discussion revolves around the application of the KISS (Keep It Simple, Stupid) principle in marine propulsion systems, particularly focusing on a permanent magnet motor design where the propeller acts as the rotor. Participants explore various concepts related to this design, including power generation and comparisons to other mechanical systems.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant shares a concept of a permanent magnet motor where the propeller is the rotor, suggesting it simplifies mechanical power transmission.
  • Another participant proposes a lightweight flying platform utilizing a closed-loop steam cycle for power generation, drawing parallels to the discussed marine propulsion system.
  • A comparison is made to washing machine pumps that use permanent magnets submerged in water, eliminating the need for watertight bearings.
  • Concerns are raised about noise, vibration, and cavitation in relation to the design, with questions about the implications of blade shape on cavitation issues.
  • One participant suggests that adding more vanes to the propeller could reduce RPM and, consequently, cavitation.

Areas of Agreement / Disagreement

Participants express various ideas and concerns, but there is no clear consensus on the effectiveness of the proposed designs or the implications of cavitation. Multiple competing views remain regarding the optimal design and functionality of the propulsion systems discussed.

Contextual Notes

Participants mention several assumptions about the mechanics of the proposed systems, such as the effectiveness of the permanent magnet motor and the design of the propeller blades, but these assumptions are not fully explored or resolved.

anorlunda
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I"m a big fan of the KISS principle in engineering. I'm also a boater. I just found something I wanted to share.



It is a permanent magnet motor in which the propeller itself is the rotor. The video hints that it works with simple reversals of polarity similar to a stepper motor.

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That eliminates nearly all of those troublesome intermediate devices and hull penetrations for mechanical power transmission, It is about as KISS as I can imagine for an electric drive.

Put one of those forward and another one aft, and you have a superbly maneuverable vessel.

How to generate the electric power on board is a separate question.
 

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anorlunda said:
I"m a big fan of the KISS principle in engineering. I'm also a boater. I just found something I wanted to share.How to generate the electric power on board is a separate question.

This is almost the exact concept in my mind when I made the comment in the Boeing Challenge thread, my thoughts are a very lite-weight flying platform (more complicated) where this is a perfect heat exchange opportunity. One has only to imagine a closed loop steam cycle within the blades and hub section. electric is generated at the outer ring and a resistance inside the blade tips makes high pressure steam that moves to the hub and provides torque to drive the blades, the bulk of the blade area serves to exchange heat that returns the spent steam to liquid and the cycle repeats.

ps. The mechanics would be similar to the workings of a bubble jet printer, just a much greater scale. Perhaps this might help build a mental picture of the basic workings.
 
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The pump in our washing machine works in a similar manner. There are permanent magnets on the rotor which is submerged in the water. Means there is no need for a water tight bearing which reduces chances of a leak.
 
Video text said:
... with reduced noise and vibration levels and hardly no cavitation.
Is that a double negative there?
What has cavitation got to do with it? Maybe the blades are so poorly shaped that they have problems with cavitation.
 
Baluncore said:
Is that a double negative there?
What has cavitation got to do with it? Maybe the blades are so poorly shaped that they have problems with cavitation.

I think if you add more vanes on the prop, you can reduce the RPM for the same power. At reduced RPM you have less cavitation.
 

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