Fuel injector for a dual fuel turbine engine

摘要

A fuel injector (1) for a combustor of a gas turbine engine operable on first (G) and second (L) fluid fuels, in which fuel orifices (4a, 4b) for injecting the first fuel into the combustor are exposed to combustion products during operation of the engine on the second fuel. A downstream portion of a fuel manifold (3) is divided into a radially outer annular fuel supply passage (8) for supplying a radially outer set (4a) of the fuel orifices and a radially inner annular fuel supply passage (9) for supplying a radially inner set (4b) of the fuel orifices. There is also an annular air passage (11) for admission of compressed air into the combustor, this passage being defined between an external wall (13) of the fuel manifold and an outer shroud member (10) surrounding the fuel injector. Disposed upstream of the dividing wall (7) is a first set of air purge holes (14) provided in the external manifold wall (13) to permit fluid connection between the air passage (11) and the annular fuel manifold (3). A second set of air purge holes (15) is provided in the external manifold wall (13) downstream of the first set of purge holes (14) to permit direct fluid connection between the air passage (11) and the radially outer annular fuel supply passage (8). In this way, pressure in both the radially inner (9) and radially outer (8) annular fuel supply passages is maintained greater than that in the combustion zone (2) during operation of the engine on the second fuel, so preventing ingress of hot combustion products through both the radially inner and outer sets of fuel orifices.