Gas fuel injector for wide range of calorific values

Claim 1

A combustion system for a gas turbine engine having air compressor means, combustion means and turbine means in a flow series, said combustion system being capable of use with gas fuels having a range of calorific values and comprising: a combustion chamber having a primary zone at an upstream end thereof; a gas fuel supply; a gas fuel duct communicating with said gas fuel supply and having an outlet; a gas fuel injector, said gas fuel injector including a swirler assembly having upstream and downstream ends and arranged to receive a flow of compressed air from said compressor means and a flow of gas fuel from said outlet of said gas duct, said swirler assembly including an outer housing having upstream and downstream ends, an inner hub concentric with and spaced from said outer housing, said hub having upstream and downstream ends, and a plurality of swirler vanes positioned between said outer housing and said inner hub, said vanes having outer upstream and downstream portions and inner upstream and downstream portions, said outer housing, said inner hub and said swirler vanes defining a plurality of passages of decreasing cross-sectional area in a direction of flow therethrough, said outlet of said gas fuel duct being greater in diameter than said upstream end of said hub and smaller in diameter than said upstream end of said housing and terminating between said upstream and downstream ends of said swirler assembly, said gas fuel duct, said hub and said inner upstream portion of said vanes forming gas fuel flow passages, and said gas fuel duct, said housing and said outer upstream portions of said vanes forming compressed air flow passages, and said housing, said hub and said downstream portions of said vanes forming flow passages for mixing gas fuel and air to cause an energy interchange therebetween whereby the gas fuel and air are moving at similar velocities.