Abstract: An inlet duct for an auxiliary power unit comprises an inlet end, and extends to an outlet end. At least one splitter is positioned within the duct and between the inlet and the outlet end to sub-divide an interior of the duct into plural flow paths.

Abstract: An exhaust silencer assembly comprising a casing having an exhaust gas entrance opening, an exhaust gas exit opening, and a cooling air inlet opening, and an acoustic-attenuating porous liner disposed within an interior chamber of the casing, thereby dividing the interior chamber into an inner region located between the exhaust gas entrance opening and the exhaust gas exit opening, and an outer region located between the acoustic-attenuating porous liner and the casing, where the cooling air inlet opening is located at the outer region.

Abstract: A system for reducing compressor noise includes a rotor having a plurality of blades. The blades have a nominal geometry characterized by a blade parameter. At least some of the blades are mistuned, such that they differ from the nominal geometry by greater than a manufacturing tolerance in the blade parameter. The blades produce shock waves at a blade passing frequency, and the mistuned blades shift acoustic energy away from the blade passing frequency to multiple lower amplitude tones at other frequencies. The system is configurable to be deployed with an inlet silencer that preferentially absorbs acoustic energy at some of the shifted frequencies.

Abstract: An exhaust silencer assembly comprising a casing having an exhaust gas entrance opening, an exhaust gas exit opening, and a cooling air inlet opening, and an acoustic-attenuating porous liner disposed within an interior chamber of the casing, thereby dividing the interior chamber into an inner region located between the exhaust gas entrance opening and the exhaust gas exit opening, and an outer region located between the acoustic-attenuating porous liner and the casing, where the cooling air inlet opening is located at the outer region.

Abstract: An air inlet assembly comprising an entrance region configured to receive an airflow, an exit region configured to output the airflow, and an attenuation region disposed between the entrance region and the exit region. The attenuation region has a cross section aspect ratio of at least about 5-to-1, and comprises acoustic absorbing material.

Abstract: An exhaust silencer assembly for use with a gas turbine engine, the exhaust silencer assembly comprising an exhaust duct extension disposed downstream from an exhaust diffuser of the gas turbine engine, and an exhaust silencer disposed downstream from the exhaust duct extension. The exhaust duct extension has a length that is at least about 50% of an inner diameter of the exhaust duct extension.

Abstract: An exhaust duct system for a gas turbine engine that mounts within a tail cone of an aircraft, comprises an exhaust exit that exits one side of the tail cone offset from the axial centreline of the tail cone and an exhaust duct that couples the engine to the offset exhaust exit, with a straight section of the exhaust duct extending from the exhaust exit for a length that corresponds to at least one diameter of the exhaust duct.

Abstract: A method of measuring the presence of oil in turbine bleed air that uses an aerosol sampler/size classifier to do a comparative measurement of the engine bleed air to the ambient air entering the engine on a real time basis by comparing quantity and size distribution of suspended particles of engine inlet air with suspended particles in the bleed air throughout the normal operating schedule of the engine and determining the presence of oil in the bleed air when the quantity and size distribution of suspended particles in the bleed air exceeds the quantity and size distribution of suspended particles in the engine inlet air by a predetermined amount.

Abstract: In order to reduce noise transmission through the air inlet duct (16) of a turbine engine (10), the air inlet duct (16) provides a non-linear path defined by a bend (24) for air from a source, and the turbine engine (10) includes a sound attenuation assembly (26) in the form of a splitter dissipative silencer disposed near the bend (24) in the air inlet duct (16). More specifically, the turbine engine (10) is such that the splitter dissipative silencer (26) can be formed as a modular assembly (42) removably securable near the bend (24) in the air inlet duct (16) upstream of a radial compressor (12) for removal and/or replacement or availability as an optional component of the turbine engine (10).

Abstract: An abradable coating is provided for use on a composite substrate which has a coefficient of thermal expansion substantially similar to that of the substrate and which is formed with a matrix resin of the same type of resin used to form the substrate. In particular, with a composite substrate formed from carbon or graphite fibers impregnated with a polyimide resin, an abradable coating formed from carbon or glass microballoons in a polyimide resin matrix has been found to avoid delamination as a result of thermal cycling between -65.degree. F. and 500.degree. F. Accordingly, that abradable coating is particularly suitable for use with composite compressor shrouds in gas turbine engines and aircraft auxiliary power units.

Abstract: In order to reduce noise transmission through the air inlet duct (16) of a turbine engine (10), the air inlet duct (16) provides a non-linear path defined by a bend (24) for air from a source, and the turbine engine (10) includes a sound attenuation assembly (26) in the form of a splitter dissipative silencer disposed near the bend (24) in the air inlet duct (16). More specifically, the turbine engine (10) is such that the splitter dissipative silencer (26) can be formed as a modular assembly (42) removably securable near the bend (24) in the air inlet duct (16) upstream of a radial compressor (12) for removal and/or replacement or availability as an optional component of the turbine engine (10).

Abstract: In order to reduce turbine engine exhaust noise while simultaneously reducing anti-surge airflow noise, a combination noise reduction apparatus or tube (10) is provided having a series of holes (26) in its side. The tube (10) is in communication with a source of anti-surge air through an anti-surge air outlet (22) to be delivered into the exhaust airflow in an exhaust duct (12). The tube (10) diffuses the anti-surge air, shields the noise of the anti-surge air by dissipating the acoustic energy within the tube (10), and provides for an even distribution of the anti-surge air into the exhaust airflow. As a result, a temperature discontinuity is created in the exhaust duct (12) which results in an acoustic impedance that reflects acoustic noise back to the source of the noise.

Abstract: Methods of and apparatus for removing contaminants from heated gases by impact separation. The contaminants are collected by adhering them to a moving surface, and they are thereafter removed from that surface.

Abstract: Methods of and apparatus for removing contaminants from heated gases by impact separation. The contaminants are collected by adhering them to a moving surface, and they are thereafter removed from that surface.