Rim Driven Propellers

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

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'.

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.

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.

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.

AIR Fertigung unit

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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.

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."

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?

RimDrive view

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