Aircraft propulsion system with auxiliary turbine system

1 . An assembly for an aircraft, comprising:

a first propulsor rotor;

a geartrain comprising a plurality of interconnect gear systems;

a rotating assembly rotatable about an axis and comprising a turbine rotor, the rotating assembly coupled to and configured to drive rotation of the first propulsor rotor through the geartrain;

a second propulsor rotor rotatable with the rotating assembly, the rotating assembly configured to drive rotation of the second propulsor rotor through a transmission independent of the first propulsor rotor;

an auxiliary turbine coupled to the first propulsor rotor independent of the geartrain;

a bleed circuit in fluid communication with a compressor section;

an exhaust circuit; and

a gas flowpath extending through the bleed circuit and the exhaust circuit;

wherein the auxiliary turbine is arranged along the gas flowpath between the bleed circuit and the exhaust circuit; and

wherein the geartrain and the transmission are coupled to the rotating assembly in parallel.

2 . The assembly of claim 1 , further comprising:

a combustor section;

a turbine section comprising the turbine rotor; and

a flowpath extending through the compressor section, the combustor section and the turbine section from an inlet into the flowpath to an exhaust from the flowpath;

the auxiliary turbine configured to receive bleed gas from the flowpath.

3 . The assembly of claim 2 , wherein the bleed gas comprises bleed air from a portion of the flowpath along the compressor section.

4 . The assembly of claim 1 , wherein the auxiliary turbine comprises an air turbine.

5 . The assembly of claim 1 , further comprising a clutch configured to selectively couple an auxiliary turbine rotor of the auxiliary turbine to the first propulsor rotor.

6 . The assembly of claim 5 , wherein the clutch comprises a sprag clutch.

7 . The assembly of claim 5 , wherein the clutch comprises a passively actuated clutch.

8 . The assembly of claim 5 , wherein the clutch is configured to

couple the auxiliary turbine rotor to the first propulsor rotor when the auxiliary turbine is powered up; and

decouple the auxiliary turbine rotor from the first propulsor rotor when the auxiliary turbine is powered down.

9 . The assembly of claim 1 , further comprising:

a drive element extending axially along and rotatable about the axis;

the first propulsor rotor coupled to the drive element at a first coupling;

the geartrain coupled to the drive element at second coupling; and

an auxiliary turbine rotor of the auxiliary turbine coupled to the drive element at a position axially between the first coupling and the second coupling.

10 . The assembly of claim 1 , further comprising:

a lock device coupled to the geartrain through a first component;

the geartrain including a plurality of components rotatable about the axis, the plurality of components including the first component, a second component and a third component;

the first propulsor rotor coupled to the geartrain through the second component;

the rotating assembly coupled to the geartrain through the third component; and

the lock device configured to lock rotation of the first component about the axis.

11 . The assembly of claim 1 , further comprising:

a brake coupled to the geartrain through a first component;

the geartrain including a plurality of components rotatable about the axis, the plurality of components including the first component, a second component and a third component;

the first propulsor rotor coupled to the geartrain through the second component;

the rotating assembly coupled to the geartrain through the third component; and

the brake configured to brake rotation of the first component about the axis.

12 . The assembly of claim 1 , wherein

the axis is a first axis, and the first propulsor rotor is rotatable about the first axis; and

the second propulsor rotor is rotatable about a second axis that is angularly offset from the first axis.

13 . An assembly for an aircraft, comprising:

a first propulsor rotor;

a second propulsor rotor;

a geartrain comprising an epicyclic gear system;

a rotating assembly rotatable about an axis and comprising a turbine rotor, the rotating assembly coupled to and configured to drive rotation of the first propulsor rotor through the geartrain, the rotating assembly coupled to and configured to drive rotation of the second propulsor rotor rotatable through a transmission, and wherein the geartrain and the transmission are coupled to the rotating assembly in parallel, and the turbine rotor is disposed in a flowpath;

a first propulsor rotor shaft coupling the first propulsor rotor to the geartrain; and

an auxiliary turbine operatively coupled inline between the first propulsor rotor and one or more components of the geartrain, the auxiliary turbine operatively coupled to the first propulsor rotor and/or the one or more components of the geartrain through a clutch, the clutch configured to selectively couple the auxiliary turbine to the first propulsor rotor shaft;

wherein the auxiliary turbine is fluidly driven by gas bled from the flowpath.

14 . The assembly of claim 13 , wherein the auxiliary turbine is arranged axially between the first propulsor rotor and the geartrain.

15 . An assembly for an aircraft, comprising:

a propulsor rotor;

a geartrain including a first gear system and a second gear system;

an engine core including a compressor section, a combustor section, a turbine section, a flowpath and a rotating assembly, the flowpath extending longitudinally through the compressor section, the combustor section and the turbine section from an inlet into the flowpath to an exhaust from the flowpath, the rotating assembly comprising a turbine rotor arranged within the turbine section, and the rotating assembly configured to drive rotation of the propulsor rotor through the geartrain;

an auxiliary turbine configured to further drive the rotation of the propulsor rotor, the auxiliary turbine coupled to the propulsor rotor independent of the geartrain; and

a clutch configured to couple the auxiliary turbine to the propulsor rotor when the auxiliary turbine is operational, and the clutch configured to decouple the auxiliary turbine from the propulsor rotor when the auxiliary turbine is non-operational;

wherein a bleed gas flow is directed from a bleed circuit arranged with the compressor, through the auxiliary turbine and to an exhaust circuit.