US 5,402,634 AGranted

Fuel supply system for a staged combustor

AssigneeUnited Technologies Corporation

InventorRichard L. Marshall

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Abstract

A fuel supply system for a gas turbine engine having a multi-stage combustor provides responsiveness by blocking the drainage of fuel within the fuel lines during pilot only operation. In a particular embodiment, the fuel supply system includes a fuel source, a flow splitter valve, a main flow divider valve interconnected with a plurality of main fuel injectors, a pilot flow divider valve interconnected with a plurality of fuel injectors, and check valves disposed in the fuel lines connecting the main flow divider and the main fuel injectors. The check valves block the flow of fuel to the plurality of main fuel injectors during pilot only operation. A method of operating the fuel supply system includes built in hysteresis. The method includes the steps of switching from pilot to staged at a first thrust level TL.sub.1, and switching from staged to pilot at a second thrust level TL.sub.2 <TL.sub.1.

A fuel supply system for a gas turbine engine having a multi-stage combustor, the combustor including a pilot stage and a main stage, the combustor having a pilot operation characterized by combustion occurring in the pilot stage only and a staged operation characterized by combustion occurring in both the pilot stage and the main stage, the fuel supply system including:

means to generate control signals in response to thrust demands, the control signal including fuel flow requests and operation requests;
a fuel metering means in fluid communication with a source of fuel, the fuel metering means adapted to meter the fuel flow W.sub.f from a source of fuel in response to a fuel flow request;
splitter means including an fuel inlet, a pilot outlet, and a main outlet, the fuel inlet in fluid communication with the fuel metering means, the pilot outlet directing a pilot fuel flow W.sub.f,p to the pilot stage via a pilot fuel line, W.sub.f,p corresponding to at least a portion of the fuel entering the fuel inlet, the main outlet directing the remainder of the fuel flow W.sub.f,m to the main stage via a main fuel line, wherein the splitter means varies a ratio W.sub.f,p /W.sub.f in response to the operation request from the engine controller, the splitter means having a first operational condition characterized by W.sub.f,p /W.sub.f =1.0 and corresponding to pilot operation, and a second operational condition characterized by W.sub.f,p /W.sub.f <1.0 and corresponding to staged operation;
a pilot flow divider means including a fuel inlet and a plurality of fuel outlets, the fuel inlet being in fluid communication with the pilot fuel outlet;
a main flow divider means including a fuel inlet and a plurality of fuel outlets, the fuel inlet being in fluid communication with the main fuel outlet;
a plurality of pilot fuel nozzles, each of the pilot fuel nozzles in fluid communication with one of the pilot flow divider means outlets via a plurality of pilot nozzle lines;
a plurality of main fuel nozzles, each of the main fuel nozzles in fluid communication with one of the main flow divider means outlets via a plurality of main nozzle lines;
and
means to block fuel within the main fuel line and main nozzle lines from draining during pilot operation.

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Abstract

Claims9