Method for adapting the air flow of a turbine engine having a centrifugal compressor and diffuser for implementing same

Abstract

A method for maintaining efficiency and duty of a turbine engine compressor to reduce specific consumption, while guaranteeing a high enough pumping margin with partial load. The method adapts airflow to a variable demand for flow or mechanical or electric power in a centrifugal compressor of a turbine engine. The method includes diffusing the airflow through a first annular blade ring having variable pitch blades, radially bordered by a second annular blade ring having a same number of fixed pitch blades with an equivalent extension, guiding the radial extension diffusion by coupling the blades of the two blade rings. According to the method, each blade of the first blade ring is spun off-axis.

1 - 10 . (canceled) 
     
     
         11 . An adaptation method for air flow in a centrifugal compressor of a turbine engine, comprising:
 providing a diffusion of air through a first annular blade ring with variable pitch blades, radially bordered with a second annular blade ring having a same number of fixed pitch blades with an equivalent extension; and   guiding the diffusion in the radial direction by coupling the blades of the first and second blade rings, wherein each blade of the first blade ring is driven into rotation at a distance of the blade.   
     
     
         12 . The adaptation method according to  claim 11 , wherein the variable pitch radial diffusion on a centrifugal compressor is coupled with a variable pitch power turbine distribution, power distribution being either free with a downstream exchange or bound, either on an axial or centripetal way, with or without downstream exchange. 
     
     
         13 . A variable pitch turbine engine diffuser configured to implement the method according to  claim 11 , comprising:
 a first annular blade ring with variable pitch blades being radially bordered by a second annular blade ring with fixed pitch blades of an equivalent extension and a same number of blades, forming successive diffusion channels by coupling of the blades of the first and second blade rings in radial extensions,   wherein each blade of the first blade ring is driven by driving means configured to exert a proper rotation of the blade off-centered with respect to the rotation axis thereof.   
     
     
         14 . The diffuser according to  claim 13 , wherein each variable pitch blade extends between two facing cups and in a parallel and off-centered way with respect to a common axis of the cups coinciding with the rotation axis. 
     
     
         15 . The diffuser according to  claim 13 , wherein each blade is coupled with a driving rod that presents at least one orifice into which a lock pin is introduced for an adjustment washer for an axial position of the cups. 
     
     
         16 . The diffuser according to  claim 15 , wherein the rod is integral with a lever presenting a ball joint coupling housed within a cylindrical housing of a control crown configured to drive into rotation around the rotation axis, the lever configured to slide in the cylindrical housing. 
     
     
         17 . The diffuser according to  claim 16 , wherein the cylindrical housings present a depth being a function of a stroke of the levers, itself being a function of a predetermined rotation interval of the blades. 
     
     
         18 . The diffuser according to  claim 14 , wherein a leading edge of each variable pitch blade is close to peripheries of the cups, a distance from the blade to the rotation axis being higher than or equal to a mid-radius. 
     
     
         19 . The diffuser according to  claim 13 , wherein the fixed blades of the second blade ring present a thicker leading edge profile than one of the blades of the second blade ring. 
     
     
         20 . The diffuser according to  claim 13 , wherein pitch angles of the blades are between +12° and −5° corresponding to a collar section respectively to 50% and 120% with respect to a section corresponding to a nominal keying.