An aircraft engine, has: a high-pressure spool having a high-pressure turbine drivingly engaged to a high-pressure compressor; and a low-pressure spool having: a first low-pressure turbine downstream of the high-pressure turbine; and a second low-pressure turbine downstream of the first low-pressure turbine, one or more of the first low-pressure turbine and the second low-pressure turbine drivingly engaged to a rotatable load, the first low-pressure turbine and the second low-pressure turbine radially offset from one another relative to a central axis of the aircraft engine.

An aircraft engine, has: a high-pressure spool having a high-pressure turbine drivingly engaged to a high-pressure compressor; and a low-pressure spool having: a first low-pressure turbine downstream of the high-pressure turbine; and a second low-pressure turbine downstream of the first low-pressure turbine, one or more of the first low-pressure turbine and the second low-pressure turbine drivingly engaged to a rotatable load, the first low-pressure turbine and the second low-pressure turbine radially offset from one another relative to a central axis of the aircraft engine.

An aircraft engine, has: a high-pressure spool having a high-pressure turbine drivingly engaged to a high-pressure compressor; and a low-pressure spool having: a first low-pressure turbine downstream of the high-pressure turbine; and a second low-pressure turbine downstream of the first low-pressure turbine, one or more of the first low-pressure turbine and the second low-pressure turbine drivingly engaged to a rotatable load, the first low-pressure turbine and the second low-pressure turbine radially offset from one another relative to a central axis of the aircraft engine.

Embodiments of a forward-swept impeller are provide, as are embodiments of a gas turbine engine containing a forward-swept impeller. In one embodiment, the gas turbine engine includes a shaft and a forward-swept impeller mounted to the shaft. The forward-swept impeller includes, in turn, an inboard impeller section, an outboard impeller section circumscribing the inboard impeller section, and a plurality of hub flow paths extending over the forward-swept impeller from the inboard impeller section to the outboard impeller section. The plurality of hub flow paths each have a flow path exit that is tilted in a forward direction, as taken along a line tangent to the flow path exit.

Embodiments of a forward-swept impeller are provide, as are embodiments of a gas turbine engine containing a forward-swept impeller. In one embodiment, the gas turbine engine includes a shaft and a forward-swept impeller mounted to the shaft. The forward-swept impeller includes, in turn, an inboard impeller section, an outboard impeller section circumscribing the inboard impeller section, and a plurality of hub flow paths extending over the forward-swept impeller from the inboard impeller section to the outboard impeller section. The plurality of hub flow paths each have a flow path exit that is tilted in a forward direction, as taken along a line tangent to the flow path exit.

A gas turbine engine has a first spool having a low pressure compressor section disposed forward of an air inlet along a direction of travel of the engine, and a low pressure turbine section disposed forward of the low pressure compressor section and drivingly engaged thereto. A second spool has a high pressure compressor section disposed forward of the low pressure compressor section, and a high pressure turbine section disposed forward of the high pressure compressor section and drivingly engaged thereto. The high pressure turbine section is disposed aft of the low pressure turbine section. An output drive shaft drivingly engages the low pressure turbine section and extends forwardly therefrom to drive a rotatable load. A method of operating a gas turbine engine is also discussed.

A fan rotor has a hub, and a plurality of axial flow fan blades extending radially outwardly of the hub. A radial compressor impeller is positioned radially inwardly of the fan blades. The radial compressor impeller has an upstream inlet which extends generally in an axial direction defined by an axis of rotation of the hub. The radial flow compressor impeller has an outlet that extends radially outwardly of the inlet, and into a supply passage for supplying air to a core engine. An engine is also disclosed.

A fan rotor has a hub, and a plurality of axial flow fan blades extending radially outwardly of the hub. A radial compressor impeller is positioned radially inwardly of the fan blades. The radial compressor impeller has an upstream inlet which extends generally in an axial direction defined by an axis of rotation of the hub. The radial flow compressor impeller has an outlet that extends radially outwardly of the inlet, and into a supply passage for supplying air to a core engine. An engine is also disclosed.

The invention relates to an acoustic insulation assembly for an auxiliary power unit having a centrifugal compressor (1), comprising a ring-shaped casing (8) for an air inlet (3) and comprising a plurality of reinforcing arms (9) connecting its inner walls, a plurality of removable mechanical acoustic insulation parts (10), each mechanical part (10) being ring-shaped and comprising attachment means (11) intended to engage with the casing (8), such that the mechanical part (10) and the flow surface of the casing (8), defined by a pair of reinforcing arms (9), overlie one another.

The invention relates to an acoustic insulation assembly for an auxiliary power unit having a centrifugal compressor (1), comprising a ring-shaped casing (8) for an air inlet (3) and comprising a plurality of reinforcing arms (9) connecting its inner walls, a plurality of removable mechanical acoustic insulation parts (10), each mechanical part (10) being ring-shaped and comprising attachment means (11) intended to engage with the casing (8), such that the mechanical part (10) and the flow surface of the casing (8), defined by a pair of reinforcing arms (9), overlie one another.