Method of calibrating the air flow of a swirler of a gas turbine burner

Abstract

A method of calibrating a swirler for a burner of a turbine engine, the swirler having a plurality of vanes and a plurality of mixing channels between the vanes, wherein each mixing channel directs air from a radially outer end of the mixing channel to a radially inner end of the mixing channel, the method of calibrating the swirler including: determining a flow characteristic of the swirler, calculating the difference between the determined flow characteristic of the swirler and a predetermined flow characteristic of the swirler, and dependent on the difference, applying a calibration to the swirler to alter its flow characteristic, the calibration having a known influence on the flow characteristic such that the altered flow characteristic is within an acceptable tolerance of the predetermined flow characteristic.

1 . A method of calibrating a swirler for a burner of a turbine engine,
 the swirler comprising a plurality of vanes and a plurality of mixing channels between the vanes, wherein each mixing channel directs air from a radially outer end of the mixing channel to a radially inner end of the mixing channel,   the method of calibrating the swirler comprising:   determining a flow characteristic of the swirler,   calculating the difference between the determined flow characteristic of the swirler and a predetermined flow characteristic of the swirler, and dependent on the difference,   applying a calibration means to the swirler to alter its flow characteristic, the calibration means having a known influence on the flow characteristic such that the altered flow characteristic is within an acceptable tolerance of the predetermined flow characteristic.   
     
     
         2 . A method of calibrating a swirler as claimed in  claim 1 , further comprising:
 forming the swirler having a nominal flow characteristic which is greater than the desired flow characteristic.   
     
     
         3 . A method of calibrating a swirler as claimed in  claim 2   wherein the swirler has a nominal flow characteristic which is up to 3sigma greater than the desired flow characteristic.   
     
     
         4 . A method of calibrating a swirler as claimed in  claim 1 , further comprising:
 selecting the calibration means from a group of calibration means, each calibration means of the group having a different and known influence on the flow characteristic of the swirler.   
     
     
         5 . A method of calibrating a swirler as claimed in  claim 4   wherein the group of calibration means comprises a number of calibration means having known influences on the flow characteristics of the swirler of at least two of 0.5%, 1.0%, 1.5%, 2.0%, 2.5%, 3.0%, 3.5%, 4.0%.   
     
     
         6 . A method of calibrating a swirler as claimed in  claim 1   wherein the calibration means comprises a mesh ( 3 ,  6 ,  6 ′,  6 A,  6 B,  6 C,  6 D) having a lattice of wires,   wherein the method further comprises:   selecting any one or more of the spacing of the wires, the thickness and the shape of the wires to determine the known influence on the flow characteristics of swirler.   
     
     
         7 . A method of calibrating a swirler as claimed in  claim 1   wherein the calibration means comprises a plate having at least one cut-out   wherein the method further comprises:   selecting any one or more of the size and number of the cut-out to determine the known influence on the flow characteristics of swirler.   
     
     
         8 . A method of calibrating a swirler as claimed in  claim 1   wherein the calibration means is in the form of a ring,   the method further comprising:   applying the calibration means around the outer perimeter of the swirler.   
     
     
         9 . A method of calibrating a swirler as claimed in  claim 5   wherein the each mixing channel has a height,   the method further comprises:   selecting a height of the calibration means to cover at least a part of the height of the mixing channel to at least partly influence the flow characteristics of swirler.   
     
     
         10 . A method of calibrating a swirler as claimed in  claim 1   wherein the acceptable tolerance of the predetermined flow characteristic is 1 sigma.   
     
     
         11 . A method of calibrating a swirler as claimed in  claim 1   wherein the step of applying a calibration means comprises   applying the calibration means around an outer perimeter of the swirler vanes.   
     
     
         12 . A turbine engine having
 an array of combustors, each combustor having a swirler,   wherein the swirler comprises a plurality of vanes and a plurality of mixing channels between the vanes, wherein each mixing channel directs air from a radially outer end of the mixing channel to a radially inner end of the mixing channel, and   wherein at least one of the swirlers has been calibrated by:   determining a flow characteristic of the swirler,   calculating the difference between the determined flow characteristic of the swirler and a predetermined flow characteristic of the swirler, and dependent on the difference,   applying a calibration means to the swirler to alter its flow characteristic, the calibration means having a known influence on the flow characteristic such that the altered flow characteristic is within an acceptable tolerance of the predetermined flow characteristic.   
     
     
         13 . A turbine engine as claimed in  claim 12 ,
 wherein at least one of the swirlers comprises a calibration means.   
     
     
         14 . A turbine engine as claimed in  claim 13 ,
 wherein all of the swirlers comprise a calibration means.   
     
     
         15 . A turbine engine as claimed in  claim 12 ,
 wherein all the swirlers comprise a flow characteristic within the acceptable tolerance of the predetermined flow characteristic of 1 sigma.