Exciting New EPS Thruster (& Propulsion)

[marshmat]

Personally I don't care for the volumn of water carried along in this 'waterbox'.

Agreed... any production model would have to have a retraction housing that is a fairly tight fit around the retracted drive. As drawn there, the housing holds about three tonnes of water when the drive is extended, a pretty significant load. The main reason is that the housing drawn is rectangular; by fitting the housing as tightly as possible around the retracted drive (circular where the prop comes up, and no excess water space around the strut) they could probably bring the entrapped water volume down by half.

[brian eiland]

I noted the use of 'magnetic levitation bearings' in the NASA air turbine unit.

In many cases magnetic levitation has often appeared as an unecessary complication to new products. Imagine the loads that the 'magnetic' thrust bearings would have to resist with the air-turbine.

So far I believe at least one of the rim-driven propulsers are utilizing ceramic bearings. Something I have yet to see in a actual use is the 'Near-Frictionless Carbon" bearing material developed in our national labs
http://www.anl.gov/Media_Center/News...ews050610.html
http://www.spacedaily.com/news/materials-02ze.html
http://www1.eere.energy.gov/vehicles...ess_carbon.pdf

[kach22i]

Originally Posted by brian eiland

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:
http://www.openhydro.com/home.html

Cool, so that's what the future looks like.

[brian eiland]

I extracted this new view of a rim drive unit from a document recently sent to me

[brian eiland]

...introduction to the paper

Structurally Integrated Slotless PM Brushless Motor with Spiral Wound Laminations for Marine Trusters

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.

[kach22i]

What's the best way to get juice to something like that?

[Guillermo]

I think there is an ample array of applications for rim thrusters, ranging from main propulsion to auxiliary thrusters, in all kind of vessels.
I'm interested in high powered ones for ships propulsion, specially for big trawling FV and tugs.
Cheers

[marshmat]

What's the best way to get juice to something like that?

Dilithium-crystal warp core, of course.
Actually I was thinking more along the lines of a solid-oxide fuel cell stack, would be a good match for a ship- they take a couple hours to get up to peak efficiency, but that peak efficiency is more than double that of a good diesel (60% versus 30 or so). SOFCs love a steady, constant load- like that of a ship's drivetrain- and the extra bulk compared to the PEMFC type used in fuel cell cars isn't an issue in a ship's engine room.

[kach22i]

Originally Posted by marshmat

Actually I was thinking more along the lines of a solid-oxide fuel cell stack

That just requires hydrogen and oxygen, right?

Are there any Fuel Cells which use Diesel fuel or E85?

I found this earlier today, cool.
http://history.nasa.gov/SP-4002/p1b.htm

Figure 12. The operating principle of the fuel cell designed by General Electric, adopted for use in the Gemini spacecraft. (McDonnell, "Project Gemini Familiarization Charts," June 5, 1962, unpaged.)

[marshmat]

Hydrogen and oxygen, yep. The latter's easy to get, the former's a royal pain in the butt to store though.
There are "direct-methanol" fuel cells, currently being developed for laptops and cellphones, which work directly off the simpler methanol (methyl alcohol). No larger versions that I know of can do so.
Heavier fuels such as diesel oil, at present, must first be converted into hydrogen and carbon dioxide, often by high-temperature steam. Although this defeats the zero-emissions advantage of the fuel cell, the CO2 released is reported to be somewhat less than produced by a combustion engine of comparable power, due to the fuel cell's substantially better overall efficiency and thus its lower fuel consumption. (The waste steam from the cracking process and the steam that is the exhaust of the fuel cell can be used to spin turbines, improving the overall system efficiency.)
I have heard of research into SOFCs that might be able to catalyze a liquid fuel into hydrogen internally, but I haven't seen a working model yet.

[kach22i]

Originally Posted by marshmat

There are "direct-methanol" fuel cells, currently being developed for laptops and cellphones, which work directly off the simpler methanol (methyl alcohol).

The "E" in E-85" is ethanol which is a type of alcohol, right?

http://en.wikipedia.org/wiki/E85

E85 is an alcohol fuel mixture that typically contains a mixture of up to 85% denatured fuel ethanol and gasoline or other hydrocarbon by volume.

Are there any Fuel Cells which use ethanol?

FYI: I started a simlar topic in a Physics Forum;
http://www.physicsforums.com/showthread.php?t=182242

[marshmat]

E-85 is 85% ethanol (ethyl alcohol, CH3CH2OH), and 15% gasoline. Ethanol is also, coincidentally, the intoxicating agent in beer and liquor, although the gasoline blend will not make you drunk- just really, really sick.
Methanol (methyl alcohol, CH3OH) is used as a fuel in race engines and, now, in small fuel cells. It is not drinkable (causes blindness).

[brian eiland]

Might I make a suggestion that the subject of alternative fuels be carried on at other 'fuel threads', or even on its own individual subject thread.

It is a BIG subject in its own right.

And there are lots of controverses about the subject of E85 that would drown out the subject at hand, 'rim drive propulsers'.

Thanks for your considerations, Brian

[brian eiland]

Rolls Royce has posted a few new PDF documents

http://www.rolls-royce.com/marine/do..._rimdriven.pdf
http://www.rolls-royce.com/marine/do.../prop_broc.pdf

[brian eiland]

Curtiss-Wright Electro-Mechanical Corporation
CW-EMD's unique motor technology has led to other product innovations. Our Integrated Motor Propulsor System integrates a number of advanced technologies, a unique canned induction motor, material selection and deployment flexibility. The development and qualification program for this rim driven propulsor was so successful that the prototype unit was used without any post-testing modification or refurbishment.

A similar product innovation utilizing our canned motor technology is the hazardous waste pump. This integral submerged canned motor/pump eliminated the need for externally supplied cooling and lubricating systems. The long-life, highly reliable design has dramatically contributed to life cycle cost savings in the transfer of hazardous wastes.
http://wxemd.com/about.shtml