Spanwise split variable guide vane and related method

Abstract

Accordingly, in one aspect, the invention relates to a variable guide vane for an axial flow compressor comprising: a first radially outer vane section; and a second radially inner vane section; the first and second vane sections angularly adjustable relative to each other about a longitudinal radial axis of the vane.

1 . A variable guide vane for an axial flow compressor comprising:
 a first radially outer vane section; and   a second radially inner vane section; said first and second vane sections angularly adjustable relative to each other about a longitudinal radial axis of said vane.   
     
     
         2 . The variable guide vane of  claim 1  wherein said first and second vane sections interface along a horizontal split line substantially perpendicular to said longitudinal axis. 
     
     
         3 . The variable guide vane of  claim 2  wherein said horizontal split line is located about mid-way along a radial length dimension of said vane. 
     
     
         4 . The variable guide vane of  claim 1  wherein said first and second vane sections are secured to respective shafts lying, on said radial axis, each of said shafts being independently rotatable. 
     
     
         5 . The variable guide vane of  claim 4  wherein each of said shafts has a gear secured at a respective end thereof, engageable with a respective sync ring gear. 
     
     
         6 . The variable guide vane of  claim 1  wherein said first and second vane sections are mounted on a common shaft lying on said longitudinal axis, one of said vane sections fixed to said shaft, and the other of said vane sections rotatable relative to said shaft. 
     
     
         7 . The variable guide vane of  claim 1  wherein said first and second vane sections are mounted to respective shafts, each fixed to a gear at respective opposite ends of the guide vane. 
     
     
         8 . The variable guide vane of  claim 5  wherein said respective sync gears are each rotatable by a hydraulic actuator. 
     
     
         9 . A variable guide vane for an axial flow compressor comprising:
 a first radially outer vane section;   a second radially inner vane section; said first and second vane sections angularly adjustable relative to each other about a longitudinal radial axis of said vane; and   wherein said first and second vane sections are secured to respective shafts lying on said radial axis, each of said shafts being independently rotatable.   
     
     
         10 . The variable guide vane of  claim 9  wherein said first and second vane sections interface along a horizontal split line substantially perpendicular to said longitudinal axis. 
     
     
         11 . The variable guide vane of  claim 9  wherein said horizontal split line is located about mid-way along a radial length dimension of said vane. 
     
     
         12 . The variable guide vane of  claim 9  wherein said first and second vane sections are secured to respective shafts lying on said radial axis, each of said shafts being independently rotatable. 
     
     
         13 . A method of eliminating rotating stall aerodynamic excitation associated with axial flow turbine compressor inlet guide vanes comprising:
 (a) splitting each variable guide vane in a row of such inlet guide vanes to form a radially inner section and a radially outer section; and   (b) adjusting relative angular positions of said radially inner and radially outer sections relative to a direction of flow of air across said guide vanes.   
     
     
         14 . The method of  claim 13  wherein said radially inner and radially outer sections are adjusted by separate ring gears. 
     
     
         15 . The method of  claim 13  including selecting a radial length for each section based on computational fluid dynamics predictions. 
     
     
         16 . The method of  claim 13  comprising angularly offsetting said radially inner and radially outer sections during start-up and shut-down. 
     
     
         17 . The method of  claim 16  comprising reducing the angular offset between said radially inner and radially outer sections substantially to zero during normal full load operation.