| 摘要 |
<p>A marine propulsion unit (10) supported from a vessel (16) by a strut (12) contains an electric motor (18) within a housing (22) and a forward propeller (24) driven by the electric motor (18) andhaving a diameter larger than that of the housing (22). Hydrodyn amic vanes (44, 48) projecting from the surface of the housing (22) counteract tangential flow generated by the forward propeller (24). An aft section with a pair of counter-rotating blade rows (36) driven by the electric motor (18) is mounted at the rear of the housing (22) and including a shroud (42) surrounding the aft blade rows (36). The shroud (42) is spaced from the housing (22) so as to receive the boundary layer (32) of liquid passing along the surface of the housing (22) to inhibit cavitation and improve efficiency. Rearward portions (52) of the shroud (42) are movableto form a clamshell causing reversal of the flow of the liquid passing through the shroud (42).</p> |
