Sliding-blade water jet propulsion apparatus for watercraft

Abstract

A sliding-blade water jet propulsion apparatus has an oval-shaped chamber and a water channel extending generally tangential to the chamber with a cylindrical rotor rotatably mounted eccentrically in the chamber. The rotor has at least two rectangular blades slidably mounted in slots extending through the cylindrical rotor in mutually perpendicular relation and each blade is independently movable relative to the other in a radial direction. Each blade has a guide element extending from opposed sides and through the opposed end walls of the rotor which are slidably received in guide grooves in the chamber end walls. The guide elements traveling in the guide grooves cause the blades to extend and retract radially with their outer ends following the inner periphery of the chamber side wall and a portion of the water channel with a constant clearance. In one embodiment, the rotor is rotated by a working gas entering the chamber and upon expansion effectuating gas pressure on one side of the blades which causes water in the water channel to be expelled by the opposite side of the blade without substantial mixing of the gas with the water, and as the rotor rotates more water is drawn into the water channel. In another embodiment, the rotor is rotated by an external power source connected to the shaft of the rotor rather than by a working gas.