Patent ID: 8113000

Claim:
A fuel supply system in a gas turbine engine, the fuel supply system comprising: a plurality of main fuel injectors surrounding a center pilot nozzle; and a plurality of pre-mixer assemblies, each pre-mixer assembly associated with a respective one of said main fuel injectors, said pre-mixer assemblies for effecting a mixing of air and fuel upstream from a main combustion zone in the gas turbine engine, each pre-mixer assembly comprising: a swirler assembly disposed about said respective main fuel injector, said swirler assembly including a forward end defining an air inlet and an opposed aft end; a pre-mixer transition member extending from said aft end of said swirler assembly toward the main combustion zone, said pre-mixer transition member including a forward end affixed to said aft end of said swirler assembly and an opposed aft end defining an outlet of said pre-mixer assembly to the main combustion zone, wherein said aft end of said pre-mixer transition member is spaced from a base plate such that a gap is formed between said aft end of said pre-mixer transition member and said base plate, said gap permitting a flow of purge air therethrough to effect an increase in a velocity of the air and fuel mixture exiting said pre-mixer assembly; wherein a plurality of apertures is formed in each of said swirler assembly and said pre-mixer transition member to allow additional purge air to flow therethrough, said additional purge air for effecting an increase in said velocity of the air and fuel mixture as the air and fuel mixture flows through said pre-mixer assembly proximate to a boundary layer of said pre-mixer assembly; and wherein said apertures formed in said pre-mixer transition member have a smaller diameter than a diameter of said apertures in said swirler assembly.