Combustion section supply system having fuel and water injection for a rotary machine

For a gas turbine engine having a combustion section which includes a plurality of fuel injectors and a fuel supply system in flow communication with a source of liquid fuel via a liquid fuel conduit and a source of water via a water supply conduit for supplying a combustible liquid to the fuel injectors at a first flow rate at a first operative condition of the engine and a second flow rate at a second operative condition of the engine, a fuel supply system which comprises:

• an auxiliary mixing system for each fuel injector which includes
• an auxiliary mixer at each fuel injector which is adapted to mix liquid fuel and water to form a combustible liquid, and,
• a first conduit which extends from the fuel injector to the auxiliary mixer in flow communication with the auxiliary mixer and with the fuel injector at a first point A, the conduit having a hydraulic diameter D.sub.h and a length which is less than fifty times the hydraulic diameter D.sub.h of the conduit;
• a main supply system which includes
• a main mixer which is adapted to mix liquid fuel and water to form a combustible liquid,
• a second conduit which extends from the main mixer to place the main mixer in flow communication with a source of liquid fuel via the fuel supply conduit,
• a third conduit which extends from the main mixer to place the main mixer in flow communication at a fourth point D with the source of water via the water supply conduit,
• a fourth conduit extending downstream from the main mixer which is adapted to place the main mixer in flow communication with a flow divider valve,
• a flow divider valve downstream of the main mixer which is in flow communication with the main mixer through the fourth conduit at a second point B,
• a plurality of fifth conduits extending at a third point C from the flow divider valve, each fifth conduit extending to an associated auxiliary mixer to place the auxiliary mixer in flow communication with the flow divider valve,
• an auxiliary water supply system which includes
• a sixth conduit in flow communication with the source of water at a fourth point D, the sixth conduit including a regulating valve downstream of the fourth point D which is in flow communication with the source of water and which is responsive to back pressure such that the regulating valve opens at the second operative condition of the engine,
• a water manifold in flow communication with the sixth conduit at a point E downstream of the regulating valve,
• a plurality of seventh conduits extending from the water manifold, each seventh conduit extending from the water manifold to an associated auxiliary mixer,
• means for supplying fuel and water to the supply system such that the water is supplied as a function of the flow rate of the fuel;
• wherein the volume of each first conduit is less than a predetermined amount to avoid blow out of the combustion chamber during transient operation from the second operative condition to the first operative condition;
• and
• wherein the volume of the main supply system from the flow divider valve via one fifth conduit and the auxiliary mixing system to the fuel injector is substantially equal to the volume from the flow divider valve to the fuel injectors of the other fifth conduits to ensure the combustible liquid arrives at each fuel injector at approximately the same time during start up of the axial flow rotary machine,
• wherein the pressure-flow distribution characteristic of the main supply system from the flow divider valve to the fuel injector provides for approximately equal flow to each fuel injector for the first flow rate during operative conditions of the engine that are less than the second flow rate, and
• wherein the pressure flow distribution characteristic of the auxiliary water supply system from the regulator valve to the fuel injector provides for approximately equal flow rates from the auxiliary supply system to each fuel injector at the second flow rate to ensure that equal amounts of additional water are provided to each fuel injector.