Fuel flow divider and ecology system for a gas turbine engine fuel flow control system

A flow divider and ecology system for a gas turbine engine that includes a start nozzle manifold and a run nozzle manifold, the system comprising:

• a flow divider valve body including an inlet port, a start nozzle manifold outlet port, a run nozzle manifold outlet port, a start flow orifice disposed between the inlet port and the start nozzle manifold outlet port, and an inner surface that defines a flow divider valve chamber;
• a flow divider valve element disposed within the flow divider valve chamber and movable therein between a closed position and a plurality of open positions, the flow divider valve element including an inner surface, an outer surface, and a flow regulation port, the inner surface defining an internal channel, the flow regulation port extending through the flow divider valve element between the inner surface and the outer surface and providing fluid communication between the internal channel and the run nozzle manifold outlet port;
• an ecology valve body including a control pressure port, a burn flow pressure port, a run nozzle pressure port, and an inner surface that defines an ecology valve chamber, the burn flow pressure port in fluid communication with the internal channel of the flow divider valve element, the run nozzle pressure port in fluid communication with the run nozzle manifold outlet port;
• and
• an ecology valve element disposed within the ecology valve chamber and movable therein between a plurality of positions, the ecology valve element dividing the ecology valve chamber into a variable volume control chamber and a variable volume fuel reservoir, the variable volume control chamber in fluid communication with the control pressure port, the ecology valve element configured, in response to fuel pressure at the control pressure port, to selectively place the variable volume fuel reservoir in fluid communication with one of the burn flow pressure port and the run nozzle pressure port;
• wherein the flow divider valve element is configured such that:
• when the flow divider valve element is in the closed position, the inlet port is fluidly isolated from the start nozzle manifold outlet port, the run nozzle manifold outlet port, and the internal channel, and
• when fuel pressure at the inlet port is between a first predetermined pressure and a second predetermined pressure:
• the flow divider valve element is in one or more of the open positions and the inlet port is in fluid communication with (i) the start nozzle manifold outlet port via the start flow orifice and (ii) the run nozzle manifold outlet port via the internal flow channel and the flow regulation port, and
• fuel flow through the start flow nozzle manifold outlet port is substantially constant regardless of fuel flow into the inlet port.

A gas turbine engine fuel control system, comprising:

• a pump configured to selectively discharge fuel at a discharge pressure;
• a fuel metering valve coupled to receive the fuel discharged from the pump, the fuel metering valve including a variable area flow orifice through which at least a portion of the fuel is discharged at a fuel pressure;
• and
• a flow divider valve including an inlet port, a start nozzle manifold outlet port, and a run nozzle manifold outlet port, the inlet port coupled to at least selectively receive the fuel discharged from the fuel metering valve, the start nozzle manifold outlet port configured to couple to a start nozzle manifold in a gas turbine engine combustor, the run nozzle manifold outlet port configured to couple to a run nozzle manifold in the gas turbine engine combustor, the flow divider valve configured, whenever fuel pressure at the inlet port is between a first predetermined pressure and a second predetermined pressure, to supply the fuel to the start nozzle manifold outlet port at a substantially constant flow rate, and direct any fuel flow in excess of the substantially constant flow rate to the run nozzle manifold outlet port.