Bypass gas turbine fan employing a stub rotor stage and a main rotor stage

Claim 1

A gas turbine engine comprising a core engine having an intake and having compressor means, combustion chamber and turbine means in flow series; a fan upstream of said intake of said core engine and operatively driven by said core engine, said fan including at least one annular array of rotor blades defining a main rotor stage and a further annular array of rotor blades downstream of said main rotor stage and defining a stub rotor stage, said further annular array of rotor blades of said stub rotor stage having a smaller radial extent than said at least one annular array of rotor blades of said main rotor stage, said main rotor stage and said stub rotor stage each being adapted to compress air to form a main fan airflow and a stub stage airflow respectively; a first splitter ring extending around said stub rotor stage and defining an outer boundary of said stub stage airflow, said first splitter ring being arranged to divi-e said main airflow of said main rotor stage into a first portion passing about the exterior of the same and a second portion passing through said stub stage rotor; a second splitter ring defined by an upstream end of said intake of said core engine, said second splitter ring being arranged to divide said stub stage airflow into a first portion which enters said core engine through said intake and a second portion which joins said first portion of said main fan airflow; and inner and outer stub stage outlet guide vanes extending respectively inwardly from said second splitter ring and outwardly of said second splitter ring to said first splitter ring, said inner and outer stub stage outlet guide vanes being adapted to give different degrees of deflection to said first and second portions of stub stage airflow respectively.