Abstract: A nacelle for a turbofan gas turbine engine is provided. An inner wall of the nacelle defines an air intake which directs air into the fan section of the engine. The intake has, in flow series, an intake lip, a throat and a diffuser. The diffuser has, in flow series, first and second flow conditioning sections over both of which the flow cross-sectional area of the diffuser increases with increasing downstream distance from the throat. In addition, over the second section the nacelle inner wall lies substantially on a surface of an oblique circular cone having an apex which is offset from the centerline of the engine.

Abstract: A nacelle for a turbofan gas turbine engine is provided. An inner wall of the nacelle defines an air intake which directs air into the fan section of the engine. The intake has, in flow series, an intake lip, a throat and a diffuser. The diffuser has, in flow series, first and second flow conditioning sections over both of which the flow cross-sectional area of the diffuser increases with increasing downstream distance from the throat. In addition, over the second section the nacelle inner wall lies substantially on a surface of an oblique circular cone having an apex which is offset from the centreline of the engine.

Abstract: A gas turbine engine having a rotational axis, an intake and a compressed gas source; the intake includes a lining having a facing which defines an inlet surface and an array of holes; the array of holes includes at least a first set of holes and a second set of holes, the holes of the first set of holes are angled a relative to a radial line and the holes of the second set of holes are angled ? relative to the radial line; the angles ? and ? are different. An active flow control arrangement including a compressed gas supply pipe, a valve arrangement, a controller, a compressed gas distribution pipe may be provided. Compressed gas may be provided to prevent the formation of separation of a main gas flow through the intake and prevent or remove ice accretion.

Abstract: Varying the fan nozzle flow area in a gas turbine engine allows adjustment of the bypass flow for varying operational conditions such as cruise and take off. However, care must be taken with regard to variation in order not to introduce drag or operational susceptibility to failure. By provision of a deformable member having a contiguous surface, which is deformed laterally from a splitter such as a pylon variation in flow area is achieved. A deformable member will be secured through seals to ensure a smooth surface. Actuation may be through a shape memory alloy material or provision of mechanical actuators to cause deformation of the contiguous surface.

Abstract: Varying the fan nozzle flow area in a gas turbine engine allows adjustment of the bypass flow for varying operational conditions such as cruise and take off. However, care must be taken with regard to variation in order not to introduce drag or operational susceptibility to failure. By provision of a deformable member having a contiguous surface, which is deformed laterally from a splitter such as a pylori variation in flow area is achieved. A deformable member will be secured through seals to ensure a smooth surface. Actuation may be through a shape memory alloy material or provision of mechanical actuators to cause deformation of the contiguous surface.