Pump jet with redirected exhaust gas through stator vane for drag reduction

A pump jet apparatus for a marine engine, comprising:

• a rotor assembly having an axis of rotation and comprising a rotor hub having a channel for receiving exhaust gas from the motor;
• a housing surrounding said rotor assembly and having an inlet and an outlet;
• an exhaust plenum positioned rearwardly of said rotor hub and inside said housing, and in flow communication with said channel in said rotor hub;
• a hollow member in flow communication with said exhaust plenum and having an exhaust outlet penetrating said housing;
• and
• a wall attached to said housing and overlying said exhaust outlet,
• wherein said wall and said housing define an opening which is in flow communication with said exhaust outlet, and said wall comprises a cylindrical skirt circumferentially surrounding a portion of said housing.

A pump jet apparatus for a marine engine, comprising:

• a rotor assembly having an axis of rotation and comprising a rotor hub having a channel for receiving exhaust gas from the motor;
• a housing surrounding said rotor assembly and having an inlet and an outlet;
• an exhaust plenum positioned rearwardly of said rotor hub and inside said housing, and in flow communication with said channel in said rotor hub;
• a hollow member in flow communication with said exhaust plenum and having an exhaust outlet penetrating said housing;
• and
• a wall attached to said housing and overlying said exhaust outlet,
• wherein said wall and said housing define an opening which is in flow communication with said exhaust outlet, and said wall comprises a conical skirt circumferentially surrounding a portion of said housing.

A pump jet apparatus for a marine engine, comprising:

• a rotor assembly having an axis of rotation and comprising a rotor hub having a channel for receiving exhaust gas from the motor;
• a rotor housing surrounding said rotor assembly and having an inlet and an outlet;
• a stator housing coupled to said rotor housing and having an inlet and an outlet, said inlet of said stator housing being in flow communication with said outlet of said rotor housing;
• an exhaust plenum positioned rearwardly of said rotor hub and inside said stator housing, and in flow communication with said channel in said rotor hub;
• first and second hollow members in flow communication with said exhaust plenum and having first and second exhaust outlets respectively, said first and second exhaust outlets penetrating said stator housing at first and second locations respectively;
• and
• first and second exhaust ducts attached to said stator housing and overlying said first and second exhaust outlets respectively,
• wherein said first and second exhaust ducts and said stator housing define first and second openings respectively which are in flow communication with said first and second exhaust outlets respectively, and each of said first and second exhaust ducts comprises a respective section of a cylindrical tube.

A pump jet apparatus for a marine engine, comprising:

• a rotor assembly having an axis of rotation and comprising a rotor hub having a channel for receiving exhaust gas from the motor;
• a rotor housing surrounding said rotor assembly and having an inlet and an outlet;
• a stator housing coupled to said rotor housing and having an inlet and an outlet, said inlet of said stator housing being in flow communication with said outlet of said rotor housing;
• an exhaust plenum positioned rearwardly of said rotor hub and inside said stator housing, and in flow communication with said channel in said rotor hub;
• first and second hollow members in flow communication with said exhaust plenum and having first and second exhaust outlets respectively, said first and second exhaust outlets penetrating said stator housing at first and second locations respectively;
• and
• an exhaust skirt attached to and surrounding a portion of said stator housing and overlying said first and second exhaust outlets respectively,
• wherein said exhaust skirt and said stator housing define an annular opening which is in flow communication with said first and second exhaust outlets.

A pump jet apparatus for a marine engine, comprising:

• a rotor assembly having an axis of rotation and comprising a rotor hub having a channel for receiving exhaust gas from the motor;
• a housing surrounding said rotor assembly and having an inlet and an outlet;
• an exhaust plenum positioned rearwardly of said rotor hub and inside said housing, and in flow communication with said channel in said rotor hub;
• a hollow member in flow communication with said exhaust plenum and having an exhaust outlet penetrating said housing;
• and
• means for redirecting exhaust gas exiting said exhaust outlet in a direction substantially parallel to said axis of rotation of said rotor assembly,
• wherein said redirecting means and said housing define an opening which is in flow communication with said exhaust outlet.

An apparatus for propelling a watercraft, comprising:

• a powerhead which produces exhaust gas;
• a powerhead exhaust channel in flow communication with said powerhead for receiving exhaust gas therefrom;
• a rotor assembly comprising a rotor hub having a hub exhaust channel in flow communication with said powerhead exhaust channel;
• a housing surrounding said rotor assembly and having an inlet and an outlet;
• an exhaust plenum positioned rearwardly of said rotor hub and inside said housing, and in flow communication with said channel in said rotor hub;
• a hollow member in flow communication with said exhaust plenum and having an exhaust outlet penetrating said housing;
• and
• means for redirecting exhaust gas exiting said exhaust outlet in a direction substantially parallel to said axis of rotation of said rotor assembly,
• wherein said redirecting means and said housing define an opening which is in flow communication with said exhaust outlet.