Rim Driven Propellers

Another Alternative

Abstract

Rim driven thrusters with structurally integrated brushless PM motors are now an established technology with an increasing range of applications. In these thrusters, the stator of the motor is housed within the thruster duct, and the rotor forms a ring around the tips of the propeller. Such high pole number motors tend to be very thin radialy, have very small length to diameter ratios, and have relatively large airgaps to accommodate corrosion protection layers on the surfaces of the rotor and stator. The relatively large diameter stator laminations of such machines tend therefore to have very thin back of core and narrow teeth, which make them expensive and difficult to manufacture. This paper proposes an alternative potentially lower cost motor topology featuring a slotless stator whose laminations are manufactured from a single strip of steel that is edge wound into a spiral (like a “slinky” and then fitted over the windings that are preformed on the outside surface of a non-conducting former. The former is also part of the sealed housing that protects the stator from corrosion in seawater. The paper discusses the design optimisation of such a motor using analytical and finite element analysis (FEA), describes a demonstrator motor and reports experimental and FEA results.

(had trouble posting rest of article with small file size allowed...will try later to decrease size of file)

Rolls Royce literature

Rolls Royce has posted a few new PDF documents

http://www.rolls-royce.com/marine/downloads/article/id9_rimdriven.pdf
http://www.rolls-royce.com/marine/downloads/propulsion/prop_broc.pdf

Rim-Drive Impeller for Jet Pump

You might have a look thru some of these jet pump discussions, and note in particular I suggested such a 'rim drive impeller'

http://www.yachtforums.com/forums/technical-discussion/4470-jet-drive-vs-prop-3.html

Tidal Flow Rim Drive Generator

Your magnetic turbine posting came to mine when I was looking for rim-drive propulsion concepts operated in reverse....as generators of electrical power in high tidal/current zones.

I ran across this interesting site:
Tidal Flow Generator
http://www.openhydro.com/home.html

Panamax super-ketch

To be installed on the new Panamax 'super-ketch'

"It’s not the only movable appendage below the waterline. Like an increasing number of new yachts, the Panamax ketch will take advantage of the advances in diesel electric power generation , in this case designed by MR Fertigung-Technologie GmbH, a German company based in Rostock. This allows the use of two retractable, electrically driven propellers developed by the award-winning Dutch company Van der Velden. By swinging or retracting the props into the hull the yacht's underbody will become perfectly flush when sailing, further enhancing -performance

Instead of using a conventional engine for propulsion, the Panamax will befitted with a number of generating sets (the likelihood is four) which, as Erik Wassen put it: “Will provide a power sharing opportunity with a priority system.”

In other words the generating sets will automatically deliver power to the numerous systems precisely when they want it and at sufficient levels, whether it be the hydraulic pumps for the big winch packages, domestic power to run the hotel systems or power for propulsion. Heavy battery banks are limited to emergency sets.

The generating system can devote all its energy to the retractable hubless props—the blades of the propellers are set on the inner surface of the circular units, which house the electric motors themselves instead of on a central hub."

...more
http://www.ybw.com/yw/blog/20070028174123blog_david_glenn.html

http://www.balticyachts.fi/documents/Pressrelease.pdf

Brunvoll News

RIM DRIVEN THRUSTERS
The development project of Rim Driven Thrusters continues. Design, production and testing of our prototype of 100 kW since 2003, has brought us
invaluable experience to use as we go further with our development. We also completed additional tests on this prototype in 2006.

The first of our larger units is scheduled to be delivered in 2007 for an offshore support vessel. This is an 810 kW tunnel thruster and is quite a departure from the first prototype.

To supplement experimental data for this type of design, adcanced design tools are applied. One of these is Computational Fluid Dynamics (CFD). This is a tool with direct integration with our 3D CAD/CAE tools and the flow calculations can include viscosity effects, turbulent flow and cavitation.