HYDRAULIC JET PROPULSION APPARATUS FOR BOATS

摘要

A water jet propulsion unit comprising an intake section (1), a pump section (3) habing a pair of counter-rotating impellers (6, 7) mounted side by side on parallel driving shafts (8, 9) in separate cylindrical passages (22, 23) through the pump section (3) and a mixing discharge section (5) ending in a discharge nozzle (24). The mixing/discharge section (5) is adapted to converge the flows of water discharge from the impellers (6, 7) to neutralise non-axial flow components from one impeller (6) by means of non-axial flow components from the other impeller (7) to maximise axial flow out of the mixing/discharge section (5). The unit may be operated as a high mass/low pressure unit or low mass/high pressure unit.