| 摘要 |
PCT No. PCT/AU92/00085 Sec. 371 Date Aug. 21, 1995 Sec. 102(e) Date Aug. 21, 1995 PCT Filed Feb. 27, 1992 PCT Pub. No. WO93/16915 PCT Pub. Date Sep. 2, 1993A tunnel jet propulsion unit (11) for marine craft, wherein the passing water mass in the tunnel is converged by decreasing the cross-section flow area of the tunnel. The unit (11) comprises an intake section (1); an impeller section comprising a cylindrical housing (31), a rotatable hub (34) and a plurality of a radially spaced impeller blades (36); a diffuser section comprising an inwardly tapered inside surface (39), a fixed hub (38) and a plurality of radially spaced diffuser blades (40); discharge section (D); a bearing between the hubs (34) and (38); and means for rotating the rotatable hub (34). Additional features include anti-balling by-pass valve (172) positioned upstream from the impeller (33) to relieve excessive water pressure on the hull if unit (11) handling capcity is exceeded and a trim adjusting machanism in the discharge section (D) for adjusting the height of the unit outlet (30) with respect to the water surface. Also a nozzle (21) having a variable outlet orifice can be used to fine tune performance.
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