METHOD FOR SYSTEM FOR A WATER JET PROPULSION SYSTEM FOR A SHIP

摘要

This invention relates to a system and method of starting a water jet propulsion system for a ship, said propulsion system including a stator shell (1) adapted to be mounted to the hull and having a nozzle (4) ending in an outlet (5) with a cross-sectional outlet area (A), an impeller housing (6) attached to the stator shell (1) and having an upstream inlet (7), and an impeller rotatably mounted in the impeller housing (6) for receiving water from the inlet (7) and discharging it through the nozzle (4) of the stator shell (1) so as to create a water jet upon rotation of the impeller, said method including reducing the outlet area by partly closing the nozzle (4) during a start up phase of the water jet propulsion system, wherein there is provided a back flow hindering arrangement (8,9; 18), arranged to hinder air to enter into said impeller housing via said nozzle (4).