CPC B63H 1/16 (2013.01) | 30 Claims |
21. A watercraft propulsion unit, comprising:
a flow expander;
a vortex chamber body having an upstream end portion thereof attached to a downstream end portion of the flow expander;
a central tube within an interior space of the vortex chamber body; and
a plurality of flow diverting vanes within the interior space of the vortex chamber body, wherein the vortex chamber body, the central tube and adjacent ones of the flow diverting vanes jointly define a plurality of helical flow passages, and wherein each of the flow diverting vanes extends in a helical manner around a centerline longitudinal axis of the central tube from a first end portion thereof proximate the flow expander to a second end portion thereof proximate a downstream end face of the vortex chamber body.
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