Innovations in Waterjet Technology

[camglasgow]

Hello all, this is my first post in what looks like a great forum & community.

I’m a final year aeronautical engineering student at the University of Glasgow. My final year project is to propose and research design innovations for marine waterjet propulsion systems. So far I have looked into the viability of creating an electrically powered waterjet (to drive a cabin-cruiser type boat). The innovation part here is the integration of an electric motor in the waterjet duct so essentially it is a shaftless device, with the impeller ring acting as an armature.

I was wondering if anything similar to this had been done before, and if anybody could point me in the direction of any helpful resources for electric waterjets?

Thanks,
Chris

[JonathanCole]

I was thinking along these lines when I saw this new type of thruster.
http://www.yachting.nl/news.php?m=3&cod=33

[camglasgow]

This seems to be along the same lines as I was thinking. How does the impeller ring rotate here?

Cheers,
Chris.

[john zimmerlee]

Can these be driven by 12V 30 amp motors?
What's the smallest size?
Are controllers available?

John

[marshmat]

Would almost be tempted to wrap a permanent-magnet rotor around that impeller and place the whole thing inside a ring-shaped stator winding hooked up to one of Tritium's new WaveSculptor three-phase inverters... $$$$!
I doubt it's in production yet, but it's an interesting concept. Would be neat to see what the performance curves end up looking like.

[Guillermo]

Have a look at:
http://www.marinenorway.com/index.pl..._niv3=&grNavn=
http://www.brunvoll.no/Web/resources.nsf/0/0F5A219AA75C9EC4C1257083002E22F7/$FILE/Brunvoll_developes_RDT.pdf

[marshmat]

Quite an interesting little unit there, Guillermo. Intuitively, it does look like it should be more efficient than a conventional prop, since the stream is confined within the duct and cannot diffuse radially outwards like a conventional prop-wash does. I would hate to run aground with the thing, though!

[Guillermo]

Originally Posted by marshmat

...I would hate to run aground with the thing, though!

Well, the image is from a test boat and I think that for 'normal' uses we can locate the propeller in more or less the same place as they are now, only that we can avoid the rudder.
I find this idea very eye-catching because it's an hybrid among a pod and a nozzeled propeller such as those used for fishing trawlers, but with the advantage of the electric rim power transmision, so avoiding gear, shaft and hub.
Although in Brian Eiland's thread (http://boatdesign.net/forums/showthread.php?t=9432) Deering raised the concern about problems due to floating debris (ropes, logs and the like), I find it very interesting for fishing trawlers and tugs, if developers can come up to the powers needed. I have some doubts about the rim powering ability to handle let's say 4000 HP and keeping at the same time watertighteness (?).
It's going to be interesting to follow further developments.