CONTRA-ROTATING DUCTED IMPELLERS

摘要

A marine ducted impeller drive assembly (1) has a water inlet end (2) and a water outlet end (3) in an annulus between which are located two sets (15, 16) of impeller blades. The sets are rotated in respectively opposite directions by a single drive shaft (7) which is connected directly to rotate one blade set (15) in one direction, and is connected indirectly to drive the other blade set (16) in the reverse direction. Contra-rotation of the blade sets (15, 16) is achieved by gearing provided by double-ended pinions (21) driven from the shaft (7) through an external gear (23, 22) and driving the set of blades (16) through an internal gear (24, 25). Flow-straightening blades (18) straighten out whirling motion of the water discharged from the assembly and support a downstream part of the inner wall of the annulus.