Gas turbine engine power setting

#The present disclosure relates to a method of calibrating a gas turbine engine, a method of calibrating an engine core and a fan, and an apparatus for measuring the thrust generated by an engine core of a gas turbine engine.

#Gas turbine aircraft engines comprise a propulsive fan arranged downstream of an air intake. The fan is surrounded by a fan case, and typically generates two separate airflows. A first airflow is received by a core of the engine, and a second airflow is received in a bypass duct. The core comprises one or more compressors, a combustor, and one or more turbines. The bypass duct is defined around the core.

#In use, the core airflow is compressed by the compressors, mixed with fuel and combusted in the combustor. The combustion products are expanded through the turbine stages and exhausted through a core nozzle. The turbines drive the compressor stages and propulsive fan through one or more interconnecting shafts.

#Embodiments will now be described by way of example only, with reference to the Figures, in which:

#FIG. 1 is a sectional side view of a gas turbine engine;

#FIG. 2 is a close up sectional side view of an upstream portion of a gas turbine engine;

#FIG. 1 illustrates a gas turbine engine 10 having a principal rotational axis 9. The engine 10 comprises an air intake 12 and a propulsive fan 23 that generates two airflows: a core airflow A and a bypass airflow B. The gas turbine engine 10 comprises a core 11 that receives the core airflow A. The engine core 11 comprises, in axial flow series, a low pressure compressor 14, a high-pressure compressor 15, combustion equipment 16, a high-pressure turbine 17, a low pressure turbine 19 and a core exhaust nozzle 20. The nozzle 20 may be formed by a section of core housing attached to the downstream end 70 of the core air flow B. The fan 23 is attached to and driven by the low pressure turbine 19 via a shaft 26 and an epicyclic gearbox 30.

#The propulsive fan 23 includes a plurality of fan blades 25 extending radially outward from a hub 29 mounted on an output shaft of the gearbox 30. The radially outer tips of the fan blades 25 are surrounded by a fan casing 42, which extends downstream behind the fan 23. The fan casing 42 will be discussed in more detail below, in relation to FIGS. 4A and 4B. Behind the fan casing 42, in the axial flow direction (downstream), a nacelle 21 surrounds the engine core 11. The fan casing 42 and nacelle 21 define a bypass duct 22 and a bypass exhaust nozzle 18 around the engine core 11.

#The bypass airflow B flows through the bypass duct 22. At an upstream end of the bypass duct 22, adjacent an intake 31 of the bypass duct 22, and downstream of the fan 23, a plurality of outlet guide vanes 33 extend radially between the engine core 11 and the fan casing 42. The outlet guide vanes 33 reduce swirl and turbulence in the bypass airflow B, providing improved thrust.