While a tesla turbine might be interesting to try, this was similar to the dyson in that it used a venturi, just like the dyson fan does, to convert a high-velocity low-volume stream into a low-velocity high-volume stream. Doing this inside a venturi reduces the amount of energy spent creating turbulence. Using a venturi that introduces the high-velocity stream at the periphery rather than in the center removes a component on which weeds might snag.
As Eric said, this is just like a jet-pump used in wells.
--- In electricboats@yahoogroups.com, Arby bernt <arbybernt@...> wrote:
>
> Hi Tim,
> You might be thinking of a Tesla turbine, a blade-less stack of discs that uses laminar shear to accelerate fluids through a pump. I've built a couple using plans I found online. Unfortunately, they're about 40% efficient, pretty poor for propulsion. As the pumped material ideally has a near-zero velocity at the disc surface, they were used for de-watering mines when filtration was difficult. A Tesla turbine pump could pass stones without any wear on the rubber-coated "blades".
>
> Be Well,
> ArbyÂ
>
>
> ________________________________
> From: Eric <ewdysar@...>
> To: electricboats@yahoogroups.com
> Sent: Wednesday, February 8, 2012 1:11 PM
> Subject: [Electric Boats] Re: bladeless propulsion ?
>
>
> Â
> Hi Tim,
>
> I don't know any specifics about the jet drive that you're talking about, but the Dyson "fan" is a lot like a typical jet pump with an exotic nozzle.
>
> "Calling the Dyson Air Multiplier a fan with no blades is perhaps a touch misleading. There are blades in the fan -- you just can't see them. The pedestal hides the blades...." So it is really a ducted fan with the prop (impellor) in the base.
>
> I would very surprised to see objective test data that showed a water drive configured like that was more efficient than a regular prop drive at thrust values above 10 pounds or more. Though I could believe that it might work ok for a very low power trolling motor.
>
> Fair winds,
> Eric
> Marina del Rey, CA
>
> --- In electricboats@yahoogroups.com, "Tim" <haywardt@> wrote:
> >
> >
> > .... For shallow drive and in weeds I know of a patent on a small jet drive that was made for foldboats and canoes that worked like the Dyson blade-less fan. It was highly efficient and worked very well in shallow water and weeds. It might be worth resurrection.
> >
>
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