Abstract: A system for minimising the formation of ice crystals in the fuel system pipework of a gas turbine engine. The system includes an ultrasonic transmitter located within a wall of a pipe in the fuel system through which fuel passes. The system also includes a controller that causes said ultrasonic transmitter to produce ultrasonic waves when the temperature of the fuel is sufficiently low for any water in the fuel to freeze, the ultrasonic waves being sufficient to break particles of ice contained in the fuel that passes through the pipe. A method of minimising the formation of ice crystals in the fuel system pipework of a gas turbine engine is also disclosed.

Abstract: A variable geometry combustor having a combustor liner that defines at least one dilution port in order to provide air to a dilution zone within the combustor. At least one valve is positioned adjacent the dilution port for controlling the flow of air through the dilution port wherein the valve is settable to maintain one of a plurality of different open configurations.

Abstract: A fuel injection apparatus (10) for a gas turbine engine (110) comprising a prefilmer (26), the prefilmer (26) comprises a body (50), the body (50) defines an axis (51), an annular surface (40) and a downstream edge (44), the prefilmer (26) arranged so that when working in operative association with the fuel injection apparatus (10) fuel impinges on the surface (40) and flows, by means of a passing airflow, to the downstream edge (44), from where the fuel is shed, characterized in that the fuel injector (10) further comprises a means for circumferentially varying the residence time of the fuel across the surface (40).

Abstract: A variable geometry pre-mixing fuel injector (50) for injecting a fuel/air mix in a downstream direction, comprising: an air inlet (60); a fuel inlet (58) positioned downstream of the air inlet (60); a duct (56) extending at least downstream of the fuel inlet (58) to define a fuel and air pre-mixing zone (62), that narrows to form an opening (64); and means for varying the flow of fuel/air mix from the pre-mixing zone (62) through the opening (64).

Abstract: A variable geometry pre-mixing fuel injector (50) for injecting a fuel/air mix in a downstream direction, comprising: an air inlet (60); a fuel inlet (58) positioned downstream of the air inlet (60); a duct (56) extending at least downstream of the fuel inlet (58) to define a fuel and air pre-mixing zone (62), that narrows to form an opening (64); and means for varying the flow of fuel/air mix from the pre-mixing zone (62) through the opening (64).

Abstract: A variable geometry pre-mixing fuel injector (50) for injecting a fuel/air mix in a downstream direction, comprising: an air inlet (60); a fuel inlet (58) positioned downstream of the air inlet (60); a duct (56) extending at least downstream of the fuel inlet (58) to define a fuel and air pre-mixing zone (62), that narrows to form an opening (64); and means for varying the flow of fuel/air mix from the pre-mixing zone (62) through the opening (64).

Abstract: A fuel injection apparatus (10) for a gas turbine engine (110) comprising a prefilmer (26), the prefilmer (26) comprises a body (50), the body (50) defines an axis (51), an annular surface (40) and a downstream edge (44), the prefilmer (26) arranged so that when working in operative association with the fuel injection apparatus (10) fuel impinges on the surface (40) and flows, by means of a passing airflow, to the downstream edge (44), from where the fuel is shed, characterised in that the fuel injector (10) further comprises a means for circumferentially varying the residence time of the fuel across the surface (40).

Abstract: A variable geometry combustor (15), comprising: a combustor liner (42) defining at least one dilution port (86) for providing air to a dilution zone (85) of the combustor; and at least one valve (90) positioned adjacent the dilution port (86) for controlling the flow of air through the dilution port (86), the valve (90) being settable to maintain one of a plurality of different open configurations.

Abstract: A variable geometry pre-mixing fuel injector (50) for injecting a fuel/air mix in a downstream direction, comprising: an air inlet (60); a fuel inlet (58) positioned downstream of the air inlet (60); a duct (56) extending at least downstream of the fuel inlet (58) to define a fuel and air pre-mixing zone (62), that narrows to form an opening (64); and means for varying the flow of fuel/air mix from the pre-mixing zone (62) through the opening (64).

Abstract: A fuel injection apparatus (10) for a gas turbine engine (110) comprising a prefilmer (26), the prefilmer (26) comprises a body (50), the body (50) defines an axis (51), an annular surface (40) and a downstream edge (44), the prefilmer (26) arranged so that when working in operative association with the fuel injection apparatus (10) fuel impinges on the surface (40) and flows, by means of a passing airflow, to the downstream edge (44), from where the fuel is shed, characterised in that the fuel injector (10) further comprises a means for circumferentially varying the residence time of the fuel across the surface (40).