Patent ID: 7263833

Claim:
A method of operating a gas turbine engine combustor comprising a variable geometry pre-mixing fuel injector and a combustor liner having dilution ports, the variable geometry pre-mixing fuel injector comprising an air inlet, a fuel inlet positioned downstream of said air inlet, a duct extending at least downstream of said fuel inlet to define a fuel and air pre-mixing zone that narrows to form an opening, means for varying the flow of fuel/air mix from the pre-mixing zone through the opening, the means for varying the flow of fuel/air mix from the pre-mixing zone comprising a centre body movable within duct walls to vary the flow of the fuel/air mix from the pre-mixing zone through the opening and movement of the centre body constricts the air inlet, the method comprising the steps of simultaneously: varying the flow of air through the dilution ports in the combustor liner into a dilution zone of the combustor, varying the flow of air into the air inlet of the variable geometry pre-mixing fuel injector, and varying the flow of fuel/air mix from the pre-mixing zone through the opening of the variable geometry pre-mixing fuel injector.