A propulsion device with outboard waterjet for high-speed marine vehicles, the propulsion device comprising:
- a nacelle comprising a housing with hydrodynamic shape, to be connected to exterior of a bottom of a ship in order to be immersed within a fluid in which said ship is intended to advance, wherein said housing is extended axially according to an extension direction (X) between a front end and a rear end, and is provided with a conveyance channel, which is extended along said extension direction (X) between an inlet section, arranged at said front end, and an opposite outlet section arranged at said rear end;
- a propeller arranged within the conveyance channel of said housing and actuatable in order to determine a propulsion in a specific advancement direction (V1) substantially transverse to the inlet section of said housing;
- wherein:
- said propeller comprises a pump actuatable for generating a flow of said fluid through said conveyance channel according to an outflow sense (VF) which goes from said inlet section to said outlet section;
- wherein said pump is provided with at least one impeller having a radius and a rotation axis (Y) parallel to the extension direction (X) of said housing;
- said nacelle comprises:
- a dynamic intake, which comprises a substantially axially-symmetric front section of said housing;
- wherein said front section is extended axially along said extension direction (X) between said inlet section and said pump, and has passage sections, transverse to said extension direction (X), increasing according to said outflow sense (VF), in a manner such to cause, in said dynamic intake, a slowing of local speed of said fluid and a pressure rise of said fluid;
- a discharge nozzle, which comprises a substantially axially-symmetric rear section of said housing;
- wherein said rear section is extended axially along said extension direction (X) between said pump and said outlet section, and has passage sections, transverse to said extension direction (X), decreasing in said outflow sense (VF), in a manner such to cause, in said discharge nozzle, an increase of the local speed of said fluid and a pressure decrease of said fluid, creating a propulsive thrust jet exiting from said outlet section;
- a central body comprising an intermediate section of said housing;
- wherein said intermediate section is extended along said extension direction (X) between said dynamic intake and said discharge nozzle, at its interior houses said pump and has passage sections, transverse to said extension direction (X), having constant area along said extension direction (X);
- wherein the front section of said dynamic intake has an inner surface which is connected to an external surface of the housing of said nacelle by means of a lip whose longitudinal profile has a convex rounded shape, said lip defining an edge of the inlet section of said nacelle;
- wherein said convex rounded shape of the lip determines a limited and circumscribed local narrowing of the passage sections starting from the inlet section of said nacelle;
- wherein said convex rounded shape of said lip has a curvature that decreases from said inlet section towards the inner surface of the front section of said dynamic intake;
- wherein the longitudinal profile of the inner surface of said front section has a curved concave shape, which extends from said lip to said intermediate section and is linked to said convex rounded shape of said lip in an inflection point which is placed upstream of said propeller;
- wherein the longitudinal profile of the external surface of said housing has, along said front section, a curved convex shape, which extends from said lip to said intermediate section and is smoothly linked with the convex rounded shape of said lip.