Water jet propulsion unit for use in a jet boat

摘要

PCT No. PCT/NZ93/00095 Sec. 371 Date Jun. 8, 1995 Sec. 102(e) Date Jun. 8, 1995 PCT Filed Oct. 13, 1993 PCT Pub. No. WO94/08845 PCT Pub. Date Apr. 28, 1994A water jet propulsion unit intended for use in jet boats. The unit has an intake section, a pump section and a nozzle section. In the pump section there are two counter-rotating impellers on concentric counter-rotating shafts calibrated so that any radial flow created in the upstream impeller is converted into axial flow by the downstream impeller. In one embodiment the nozzle section has a throttled outlet to allow for a high mass/low pressure operation while maintaining pump priming. There are no support structures or stators downstream of the intake section in the preferred embodiment.