Abstract: Gas turbine core engine located on an engine axis, fan bypass duct surrounding the core engine and terminating in a bypass exhaust nozzle, and a pylon fairing extending across the bypass duct at a given angular position enclosing a pylon for attaching the core engine to an aircraft airframe, the pylon fairing having a leading edge inside the duct at a position upstream of the bypass exhaust nozzle and a trailing edge downstream of the bypass exhaust nozzle. Bypass duct is notionally divided into first and second halves to either side of a plane at 90° to the given angular position and containing the engine axis such that the first half is opposite to the pylon fairing and the second half contains the pylon fairing, and such that at any given axial position the total flow area of the bypass duct is the combined flow areas of the two halves.

Abstract: Fan flutter attenuators are optimized so that they occupy the minimum area of the intake duct, and so can be accommodated more easily, without significantly compromising the area available for liners targeting community noise. In such circumstances resonators for flutter frequencies are typically associated with existing acoustic liner and take the form of chambers incorporating labyrinthine cores for absorption of acoustic frequency waves or utilize Helmholtz chambers with appropriate volumes and inlet pipe aperture configurations for tuning to desired flutter frequencies to be attenuated.

Abstract: A duct wall of a fan casing of a gas turbine engine comprises an intake section and a containment casing, which are interconnected by bolts at flanges. An acoustic flutter damper is provided between the flanges to reduce or eliminate flutter arising in blades of the fan at certain important operating conditions. The damper provides flexibility at the connection between the intake section and the containment casing so that, in the event of detachment of a blade or a bladed fragment, the resulting deflection wave in the containment casing can be accommodated by displacement and/or deformation of the acoustic flutter damper, reducing the risk that the bolts will shear to allow the intake section and the containment casing to become detached from each other. The acoustic flutter damper may comprise a circumferential array of separate segments.

Abstract: Fan flutter is a significant problem with regard to gas turbine engines and can lead to premature failure and unacceptability with respect to engine operation. Traditional acoustic liners for noise abatement are formed to reduce environment noise. Fan flutter frequencies are typically much lower than community noise targeted by traditional acoustic liners, and therefore require different approaches with respect to attenuation. By altering the acoustic propensities of the intake duct, it is possible to increase the safe operating envelope of the engine. The flutter attenuators according to this invention are optimised so that they occupy the minimum area of the intake duct, and so can be accommodated more easily (without significantly compromising the area available for liners targeting community noise, for example).

Abstract: A duct wall of a fan casing of a gas turbine engine comprises an intake section and a containment casing, which are interconnected by bolts at flanges. An acoustic flutter damper is provided between the flanges to reduce or eliminate flutter arising in blades of the fan at certain important operating conditions. The damper provides flexibility at the connection between the intake section and the containment casing so that, in the event of detachment of a blade or a bladed fragment, the resulting deflection wave in the containment casing can be accommodated by displacement and/or deformation of the acoustic flutter damper, reducing the risk that the bolts will shear to allow the intake section and the containment casing to become detached from each other. The acoustic flutter damper may comprise a circumferential array of separate segments.

Abstract: A gas turbine engine (10) comprises a fan rotor (26) having a plurality of fan blades (24) and an apparatus (34) for detecting an impact on the fan blades (24). The apparatus (34) comprises speed sensors (48,48B) arranged to measure the speed of rotation of the fan rotor (26) and the turbine rotor (58) and to produce speed signals. A processor unit (40) analyses the speed signals to determine the angle of twist between the ends of the fan rotor (26). The processor unit (40) is arranged to analyse the angle of twist to determine if the angle of twist of the fan rotor (40) oscillates by more than a predetermined level from an average level. The processor unit (40) is arranged to produce a signal indicative of an impact to at least one of the fan blades (24) if the angle of twist oscillates by more than the predetermined level and sends a signal to an indicator device (44,46).

Abstract: A gas turbine engine (10) comprises a fan rotor (26) having a plurality of fan blades (24) and an apparatus (34) for detecting damage to the fan blades (24). The apparatus (34) comprises a transducer (36) arranged to detect the pressure in the gas flow around the fan blades (34) and to produce a pressure signal. A speed sensor (48) is arranged to measure the speed of rotation of the fan rotor (26) and to produce a speed signal. A processor unit (40) analyses the pressure signal and the speed signal to detect changes in the amplitude of the pressure signal, which occur at multiples of the rotational frequency of the fan rotor (24). The changes indicate differences in pressure between the gas flow around a damaged fan blade (24) and the gas flow around the remainder of the fan blades (24). The processor unit (40) sends a signal indicative of damage to a fan blade (24), if the difference in pressure is above the predetermined level, to an indicator device (44, 46).

Abstract: A gas turbine engine (10) comprises a fan rotor (26) having a plurality of fan blades (24) and an apparatus (34) for detecting damage to the fan blades (24). The apparatus (34) comprises a transducer (36) arranged to detect the pressure in the gas flow around the fan blades (34) and to produce a pressure signal. A speed sensor (48) is arranged to measure the speed of rotation of the fan rotor (26) and to produce a speed signal. A processor unit (40) analyses the pressure signal and the speed signal to detect changes in the amplitude of the pressure signal, which occur at multiples of the rotational frequency of the fan rotor (24). The changes indicate differences in pressure between the gas flow around a damaged fan blade (24) and the gas flow around the remainder of the fan blades (24). The processor unit (40) sends a signal indicative of damage to a fan blade (24), if the difference in pressure is above the predetermined level, to an indicator device (44, 46).

Abstract: Apparatus for measuring contamination in a hot melt flow. The apparatus includes a flow cell tube adapted to pass the melt flow. Apparatus is provided for directing laser energy through the tube and the melt flow passing through the flow cell tube to a laser energy detector producing an electrical signal representative of the size of a contaminant in the flow melt. A heater is provided for heating the melt flow as such melt flow passes through the flow cell tube. The apparatus is adapted to measure contamination in a hot melt where the temperature of the melt must be maintained as the melt passes through the flow tube. The flow tube, laser, detector and heater are disposed within a housing. The housing has a cooling chamber. The detector is disposed in the cooling chamber to thermally isolate the detector from the heating of the flow.

Abstract: A sheet material for covering substrates comprising (a) a carrier layer comprising a polymer selected from polyesterethers, copolyesters and blends thereof, and (b) a tie layer bonded thereto, said tie layer being a low molecular weight polymer containing ethylene repeat units. The sheet material is provided with a decorative and/or protective coating, and preferably, a top coat.

Abstract: Disclosed are multilayered sheets or films which have excellent adhesion. The sheets or film comprise a layer of copolyesterether or copolyester bonded to a layer of polyolefin by means of a tie layer of a copolymer of ethylene and at least one other unsaturated monomer.