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Rim Driven Propellers

Discussion in 'Technical Discussion' started by brian eiland, Nov 16, 2005.

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  1. brian eiland

    brian eiland Senior Member

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    I posted a similar subject matter to the diesel/electric subject thread just recently as I thought the two subjects were very related. But, it is not neccessarily so that the peripheral drive concept be only an electrically driven concept.

    So here I reference two older patents that addressed the peripheral drive subject without being electrically powered. Have a look here Peripheral Journal Propeller Drive

    And here for the Diesel Electric posting
  2. Codger

    Codger YF Wisdom Dept.

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    Peripheral Drives are called Ducted Fans when they are moving air instead of water. Substantial increases in efficiency in air. Flew a small aircraft once with that configuration, worked very well. Wonder if the same holds true in water. Any hydrodynamicists hanging around here?
  3. Arniev

    Arniev Senior Member

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  4. brian eiland

    brian eiland Senior Member

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    Ducted vs Peripheral Drive

    Kort nozzels are ducted marine propellers. These are very good for maximizing thrust of the enclosed prop on tugs, etc, but suffer from higher drag at higher boat speeds.

    Note that the peripheral drive is significantly different than a ducted fan(prop) unit in that the blades are attached at the perimeter wall rather than just 'in close proximity'.
  5. Codger

    Codger YF Wisdom Dept.

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    Thanks for pointing out the specifics.
    I wonder if there really is a propulsion system without downsides. :)
    Everything seems to be a compromise of one sort or another.
  6. YachtForums

    YachtForums Publisher/Admin

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    Hhmmm.... there might be. ;)

    This is a good thread and one of my favorite subjects, but I'm absolutely slammed. If it's OK, I'd to chime-in a little later. Addressing some server issues this week and way behind the 8-Ball on a bunch of projects.
  7. brian eiland

    brian eiland Senior Member

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    Rim Driven Propulsers

    I originally posted a notice of this 'exciting new EPS Thruster' award under the Diesel Electric Propulsion subject thread, but I thought it might do to cross-link the subject threads as this thruster (bow) technology might well lead to propulsion technology. I noticed also that the EPS subject was rather more difficult to find on their website so I've attached their PDF file (opps, file to large....you need to go to their site and go to "news", and click on "EPS Silent Thruster")

    From the latest issue of The Yacht Report there is a new product news release. "Voith told Project 2004 delegates last year of an impending sea trial experiment using VSPs (Voith Schneider Propellers) for roll stabilisation; the "VSR" concept. Although not currently available, the results must have been satisfactory as they will supply their first Platform Supply Vessel (PSV) with VS units to both propel and stabilise the 85m vessel. The stabilisation works under way and at anchor or rest. Ever technically innovative, Voith is also entering into a commercial cooperation with another innovator, AIR Fertigung-Technologie GmbH. AIR have sold composite automatically adaptive pitch Carbon Fibre propellers to the superyacht market, but will now offer electrically rim driven propulsors from 0.2 to 200 kW. These can be transverse or azimuthing thrusters, or main drive pods azimuthing or fixed. Their transverse thruster strongly resembles the Van der Velden EPS rim driven thruster. This is apparently not coincidence as Dirk Bucher of AIR told me that the two companies were until recently working together on that project."
    http://www.voithturbo.de
    http://www.air-composite.com

    I underlined that one phrase as it caught my attention that this technology might well morph into propulsion units after thrusters.

    Attached Files:

    Last edited: Mar 8, 2006
  8. brian eiland

    brian eiland Senior Member

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    Rim Driven Thruster & Propulsor

    Looks as though there are a few players in this technology, and Brunvoll appears as a front runner having done some considerable big scale prototyping and testing.

    Interestingly it appears as though the relatively new permanent magnet electric motor technology has driven this new interest in rim-drive propulsion. From Brunvoll," the development of RDT has been triggered by market demand for an increased number of ships where both the main propulsion units and the manouevering thrusters have electric motors with variable speed drives. In this context the RDT offers a number of advantages."

    So rim drive propulsion is advancing right along with the thruster development. Brunvoll has worked together with the company Norpropeller to test a novel drive system for variable speed electrically driven propellers. This system involves the use of variable speed permanent magnet generators and PM motors. The design implies that the prime mover, the diesel engine, can be run as in a traditional system, as if the engine was direct mechanically coupled to the propeller, but not requiring a reduction gear, nor a battery storage source.

    Brunvoll is planning to market the RDT for ships and larger craft, while Norpropeller will focus on the market for smaller craft

    Another player, AIR Fertigung-Technologie GmbH, that have sold composite automatically adaptive-pitch Carbon Fiber propellers to the superyacht market will now work to provide electrically rim driven propulsors from 0.2 to 200 kW.

    A more direct link to the Brunvoll PDF file

    Lets add some pictures of the Brunvoll test unit.

    Attached Files:

    Last edited: Mar 10, 2006
  9. Ben

    Ben Senior Member

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    Can anyone tell me the purpose of the special keel on the bottom of the test boat, and why it doesn't have a normal keel like in the top picture?
  10. nilo

    nilo Senior Member

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    i am not an expert on hull designs, but i believe they are trying to monitor the water flow into the propellor. this is very important in regards to the efficiency.
  11. Innomare

    Innomare Senior Member

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    Correct, the more your propeller is working in "open water", the better it is.

    One exception is the jet drive though, where the propeller (actually impeller) is so efficient because it hardly has any blade tip losses. I wonder when or if they'll come up with an electrically driven rimdrive waterjet propulsion. It seems like the best of both worlds to me. No shaft going into the waterjet, just a cable on the outside.

    Maybe I should take a patent on that...

    Oops, too late, it's already common knowledge now.:p

    Bruno
  12. brian eiland

    brian eiland Senior Member

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    Water Jet rim drive unit

    Old material here http://boatdesign.net/forums/attachment.php?attachmentid=4590&d=1132159037

    Don't you imagine this thruster image could just as well be a jet unit.

    Attached Files:

  13. Innomare

    Innomare Senior Member

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    Electrical waterjets

    You're right Brian, it's not novel. I also had a look and found two patents specifically for electrically driven waterjets:

    1. WATERJET PROPULSOR POWERED BY AN INTEGRAL CANNED ELECTRIC MOTOR
    http://v3.espacenet.com/textdoc?DB=EPODOC&IDX=CA2137607&F=0&QPN=CA2137607

    2. Waterjet with internal drive motor
    http://www.freshpatents.com/Waterje...t20050324ptan20050064769.php?type=description

    I have also seen they use electrical waterjets on remote controlled boat models. Remains the question: Why has it never been used on a large scale? Or has it?
    Maybe there's too much transfer losses in comparison with the direct drive. And not so much gain. The engines are pretty much where you'd want them when you use waterjet propulsion.

    Sorry if this takes us away from the original topic...

    Bruno
  14. brian eiland

    brian eiland Senior Member

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    AIR Fertigung unit

    --------------------------------------------------------------------------------

    I received a PDF document from this company just the other day, and it certainly looks as though they are persuing the smaller unit sizes we might utilize in yachting vessels verses commerical boats, 4-100kW.

    From the PDF, "The Inline Thruster, as a compact unit, can be installed subsequently at any time as a bow or stern thruster, or soon as main or auxilary drive"

    I noted from the PDF document you sent me previously, "the mounting of the rotor is realized by proven water lubricated floating bearings...".

    I did not detect any substantial indication on the drawings of proper thrust-load bearings?? These bearings are going to see much higher loads than the peripheral bearings.

    And in the case of a main or aux drive unit, as opposed to the thruster units, both of these bearings are going to experience more 'heated operation' as a result of the continuous rather than intermittent loading. Can you comment on these questions and/or offer any discussion of these bearing problems/details.

    Your 'floated box' solution to the servicing accessability looks very nice.

    Attached Files:

  15. brian eiland

    brian eiland Senior Member

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    Rolls-Royce, Rim Drive

    Does appear as though there is a LOT of interest in this technology

    Rolls-Royce introduces Rim Drive thruster technology

    15 November 2005


    Rim Drive thruster


    The first commercial application of a new type of Rolls-Royce tunnel thruster launches a technology which will have a major impact on marine propulsion in the future.

    Rim Drive is a tightly integrated system combining electrical, mechanical and hydrodynamic elements. The electrical motor takes the form of a thin ring. Its stator is incorporated in the tunnel and its rotor carries propeller blades that point inwards.

    The first application is on an offshore support vessel, in the form of a tunnel thruster type RT1600 rated at 800kW. In due course the power range of rim tunnel thrusters will be broadened, and the technology will be used in other types of propulsor. The electro-mechanical part of the technology will also be applicable to winches, steering systems and other Rolls-Royce products.

    This technology has been developed in Norway over a period of several years by Rolls-Royce in Ulsteinvik and Smartmotor in Trondheim working in close collaboration. A prototype unit has been subjected to function trials and long periods of endurance testing in Norway, and to detailed hydrodynamic evaluation in the cavitation tank at the Rolls-Royce hydrodynamic research centre in Sweden.

    Several features combine to provide advantages for the owner, as R&T Project Manager Gunnar Johnsen explains.

    "Water flow through the unit is unobstructed since there is no gearbox in the tunnel, nor are struts needed to support a hub. Propeller blades are attached to the rim, eliminating uncontrolled flow between blades and tunnel. The permanent magnet motor design is very efficient. Together these factors give a high total efficiency and reduced noise and vibration. Because more thrust is produced for a given power input, fuel consumption is reduced, and this saving can be substantial in applications such as offshore support vessels operating in dynamic positioning (DP) mode where thrusters may run for hundreds or thousands of hours a year. Fuel saving is not only a matter of money; the impact of the vessel on the environment is also reduced.

    "The Rim Thruster is designed to be mountable and dismountable under water, so that it can be removed for servicing if required without drydocking the vessel. We use water-lubricated bearings, eliminating propeller shaft seals and oil-filled gear housings.

    "The motor is an integral part of the unit in the tunnel, so the ship designer no longer has to find space for a bulky electric motor in a thruster room. The only parts of the thruster inside the hull are the cables connecting it to the frequency control supply cabinet. The cabinet is similar to that used with any frequency controlled electrically driven thruster, and its location is flexible."

    Olympic Shipping, based in Fosnavåg in Norway, has ordered the first RT1600 for their UT 712 CD anchor handler now under construction at Aker Yards Søviknes. This vessel will have twin CP propellers for main propulsion, and other thrusters to give the station keeping power needed to meet IMO DP2 dynamic positioning standard. The rim drive unit will be installed in the aft skeg acting as a stern side thruster.

    Helge Gjerde, President-Offshore Propulsion in Rolls-Royce said, "We are delighted that Olympic Shipping is fitting the new thruster type to their latest vessel. As equipment manufacturers we are dependent on forward thinking shipowners to bring new products and systems to market. Olympic's UT 712L is also the first to fit the newly developed Rolls-Royce DP2 dynamic positioning system, and also the equipment for making work on deck safer."

    Bjørn Kvalsund, operations director of Olympic Shipping, makes the point that, "Our background in fishing and offshore has shown us that good equipment is the key to success, and that investment in technology that increases efficiency pays off in the long term. We aim to provide our oil company customers with vessels suited to their present and future needs, not their past ones, and to offer fuel efficient vessels with low environmental impact. The safety and well-being of our crews is just as important, and equipment that produces less noise and vibration is a valuable contribution to this."

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  16. Kyfho

    Kyfho New Member

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    Rim thrusters.

    These rim thrusters are already in a size and power for integration into mainstream yachting circles. Canyon ROV utilise these on their Schilling Quest electric work class ROV. Alstrom bankrolled the development with their eye on future markets. There were initial teething issues, mainly to do with material/lubrication of the ring bearing and adjacent surfaces, and these have been resolved. Cost is the prohibiting factor at present for the general public. Now that the idea is out there and proven, development by competitors is sure to reduce the cost to a more attainable level.
    Regards,
    C.
  17. YachtForums

    YachtForums Publisher/Admin

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  18. brian eiland

    brian eiland Senior Member

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    Design of 100kW Permanent Magnet Thruster

    Haven't heard much on this subject in quite some time, so I thought I might look thru the internet to see what might be found.

    Found this PDF, Design of an Integrated 100kW Permanent Magnet Synchronous Machine in a Prototype Thruster for Ship
    "An alternative solution is a rim driven thruster where the shaft and gear has been removed. There are only propeller blades in the water path and only electric cables go through the hull. This improves the efficiency of the propeller, removes the gear and reduces vibration. In this paper the design of an integrated electric machine is presented together with results from the testing of the electric machine. Bearings, hydrodynamics and noise are not discussed"

    www.elkraft.ntnu.no/eno/Papers 2004/ICEM04-Krovel-Nilssen-Skaar-Lovli-Sandoy.pdf

    Can anyone add anything new?
  19. brian eiland

    brian eiland Senior Member

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    RimDrive view

    Extracted this view of a rim drive unit from a document recently sent to me

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  20. Kruse

    Kruse Member

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    nice

    I see a lot of potential in these systems:
    - The large diameter of the motor will produce a lot of torque.
    - Potential for max efficiency with the direct drive (no gearing or gearbox).
    - Minimal profile in water, the benefit of ducting (efficiency and build-in rudder function).
    - The rim-mounting of the blades (no center hub) should make them much less sensitive to damage.
    With somewhat flexible blades (less pressure on the blades in the center),
    they could survive chewing on fishing nets, logs, big fish, terrorist divers and pirates etc.;)

    The big question now is longevity, effectiveness, availability, and prize.

    Any risk of a galvanic corrosion problem on metal ships with the Carbon/plastic?

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