Fuel Staging in a Burner

A method for staging an operation at start up of a burner for a gas turbine engine combustor, comprising:

• providing a burner housing, the burner housing enclosing the burner and a pilot combustor;
• adding fuel mixed with air to the pilot combustor;
• igniting the mixture utilizing an igniter provided at an upstream end of the pilot combustor for initiating a lean flame inside the pilot combustor and for providing a flow of an unquenched concentration of radicals at non-equilibrium and heat to a downstream main combustion room;
• imparting a first swirl of fuel and air outside a first exit of the pilot combustor at an upstream end of an combustion room for creating and sustaining a main lean flame in the main combustion room;
• generating a second swirl of air and fuel from a second exit of a first lean premixing channel downstream of the first exit and from a third exit of a second lean premixing channel downstream of the second exit,
• wherein the burner includes axially opposed upstream and downstream end portions, and
• wherein the pilot combustor is located at an upstream end of the burner,
• wherein the pilot combustor is provided with fuel and air for burning fuel for a creation of the flow of radicals and heat from a pilot combustion zone directed downstream along a center line of the pilot combustor through a throat at an exit of the pilot combustor, and
• wherein the burner is further provided with the main combustion room defined by a plurality of quarl walls downstream of the exit of the pilot combustor for housing the main flame and a main recirculation zone for recirculating unburnt radicals.