Abstract: Problems can arise with regard to noise created by bleed valve arrangements in gas turbine engines. It is known to utilize pressure differential inducing elements such as pepper pots and perforated surfaces in order to attenuate noise from bleed valves. However, these arrangements tend to have a portion which expands such that the exit aperture into a bypass duct wall can significantly affect mechanical strength and operational performance. By providing internally created pepper pots or other pressure differential inducing elements within a path of an arrangement and a constriction to an exit noise attenuation is still achieved but with less detrimental effect with regard to bypass duct wall strength and aerodynamic losses altering operational performance.

Abstract: A bleed valve bleeds hot gases from a compressor into a bypass duct of a gas turbine engine. The valve comprises a diffuser having opposing walls and a divider located between the walls and which define at least two passages through which a bleed fluid flows and into a fluid flow through the bypass duct. The passages are angled towards each other to force the two gas flows together to form a high aspect ratio plume. This plume has a relatively large surface area that that improves mixing with the bypass flow to cool it and prevented otherwise hot bleed flows from impinging on heat sensitive components adjacent the bypass duct.

Abstract: A thermal control system for a turbine casing (2) mounted radially outwardly of and circumferentially surrounding blade tips of the turbine blades, the system comprising: one or more circumferential chamber walls (6), each disposed around the casing (2), each to form a circumferential flow chamber (7) radially outward of said surface of the turbine casing (2), each to form a circumferential gap (12) between the circumferential chamber wall (6) concerned and said surface of the turbine casing (2), and the one or more circumferential chamber walls (6) define at least one opening (9) on the radially inward side of the chamber (7) adjacent the surface of the turbine casing (2) such that a thermal fluid injected into the flow chamber (7) concerned may leak out through the circumferential gap (12) via the opening (9), and means to induce circumferential flow on the surface of the casing (2) bounded by the circumferential flow chamber (7) comprising one or more ducts (8) radially outwardly connected to the or each c

Abstract: A noise reduction device, for example for use in a bleed assembly of a gas turbine engine, comprises partitions having apertures which provide contractions and sudden expansions of flow passing through the device, turbulators being provided between the partitions to break up jets issuing from the Apertures. Breaking up the jets before impact with the partitions enables the partitions to be disposed closer together, so enabling adequate noise reduction to be achieved in a device of relatively small thickness.

Abstract: A thermal control system for a turbine casing (2) mounted radially outwardly of and circumferentially surrounding blade tips of the turbine blades, the system comprising: one or more circumferential chamber walls (6), each disposed around the casing (2), each to form a circumferential flow chamber (7) radially outward of said surface of the turbine casing (2), each to form a circumferential gap (12) between the circumferential chamber wall (6) concerned and said surface of the turbine casing (2), and the one or more circumferential chamber walls (6) define at least one opening (9) on the radially inward side of the chamber (7) adjacent the surface of the turbine casing (2) such that a thermal fluid injected into the flow chamber (7) concerned may leak out through the circumferential gap (12) via the opening (9), and means to induce circumferential flow on the surface of the casing (2) bounded by the circumferential flow chamber (7) comprising one or more ducts (8) radially outwardly connected to the or each c

Abstract: A noise reduction device 40, for example for use in a bleed assembly 30 of a gas turbine engine, comprises partitions 52, 56, 60 having apertures 64, 66, 68 which provide contractions and sudden expansions of flow passing through the device, turbulators 62 being provided between the partitions 52, 56, 60 to break up jets issuing from the apertures 64, 66, 68. Breaking up the jets before impact with the partitions 52, 56, 60 enables the partitions to be disposed closer together, so enabling adequate noise reduction to be achieved in a device of relatively small thickness.

Abstract: A noise reduction device 40, for example for use in a bleed assembly 30 of a gas turbine engine, comprises partitions 50, 52 forming cells 54 having apertures 56, 58, 60 which provide contractions and sudden expansions of flow passing through the device. The apertures 56, 58, 60 are disposed relative to each other so as to force the flow to change direction within the cells 54 to break up jets of gas issuing from the apertures 56, 58, 60. Webs 62, 64, 66 may be provided adjacent the apertures 56, 58, 60 to direct flow and to assist in generating turbulence.

Abstract: Problems can arise with regard to noise created by bleed valve arrangements (5, 25, 50, 70) in gas turbine engines (10). It is known to utilise pressure differential inducing elements (29, 59, 55) such as pepper pots and perforated surfaces in order to attenuate noise from bleed valves. However, these arrangements tend to have a portion which expands such that the exit aperture (27, 54) into a bypass duct wall (53) can significantly affect mechanical strength and operational performance. By providing internally created pepper pots (29, 59) or other pressure differential inducing elements within a path of an arrangement (25, 50, 70) and a constriction to an exit (27, 54) noise attenuation is still achieved but with less detrimental effect with regard to bypass duct wall strength and aerodynamic losses altering operational performance.

Abstract: A bleed valve bleeds hot gases from a compressor into a bypass duct of a gas turbine engine. The valve comprises a diffuser having opposing walls and a divider located between the walls and which define at least two passages through which a bleed fluid flows and into a fluid flow through the bypass duct. The passages are angled towards each other to force the two gas flows together to form a high aspect ratio plume. This plume has a relatively large surface area that that improves mixing with the bypass flow to cool it and prevented otherwise hot bleed flows from impinging on heat sensitive components adjacent the bypass duct.

Abstract: A bleed valve (30) for a gas turbine engine (10) comprises a diffuser (50), through which heated compressor bleed air flows (54) into a bypass duct (22) air stream (B), has a plurality of small holes (40). The plurality of holes (40) is divided into two or more arrays of holes (52p,q,r), each array of holes (52p,q,r) is angled (?) away from one another so that their respective bleed flows (54p,q,r) do not coalesce. This separation improves mixing with the air stream (B) and helps prevent hot bleed air damaging nacelle and other engine components.