Hybrid aircraft power plant with ventilated exhaust duct cavity
A hybrid aircraft power plant includes an air mover for propelling an aircraft, a gas turbine engine operable to drive the air mover, and an electric machine operable as a motor to drive the air mover. The gas turbine engine includes a turbine disk for extracting energy from a stream of combustion gas and an exhaust duct defining: an exhaust passage for conveying the stream of combustion gas from the turbine disk; and a cavity disposed radially inward of the exhaust passage. A shaft drivingly connects the turbine disk with the electric machine and extends inside the cavity defined by the exhaust duct. A fan is drivingly connected to the shaft and operable to circulate cooling air inside the cavity of the exhaust duct.
1 . A hybrid aircraft power plant comprising:
an air mover for propelling an aircraft;
a gas turbine engine operable to drive the air mover, the gas turbine engine including:
a turbine disk operable to extract energy from an annular stream of combustion gas, the turbine disk being rotatable about a rotation axis;
an exhaust duct defining: an exhaust passage disposed radially outward of the rotation axis for receiving the annular stream of the combustion gas from the turbine disk and conveying the combustion gas away from the turbine disk; and a cavity disposed radially inward of the exhaust passage;
a shaft drivingly connected to the turbine disk and extending inside the cavity defined by the exhaust duct; and
a fan drivingly connected to the shaft and operable to circulate cooling air inside the cavity defined by the exhaust duct; and
an electric machine drivingly connected to the turbine disk via the shaft and operable as a motor to drive the air mover via the shaft,
wherein:
the fan includes a bladed rotor driven by the shaft;
the fan is closer to the electric machine than to the turbine disk; and
the blades of the bladed rotor are oriented to propel the cooling air at the fan axially toward the turbine disk.
2 . The hybrid aircraft power plant as defined in claim 1 , wherein:
a rotor of the electric machine is coaxial with the turbine disk;
the shaft is coaxial with the turbine disk; and
the turbine disk is disposed between the electric machine and the air mover.
3 . The hybrid aircraft power plant as defined in claim 2 , wherein the fan is disposed inside of the cavity defined by the exhaust duct and between the electric machine and the turbine disk.
4 . The hybrid aircraft power plant as defined in claim 2 , wherein the bladed rotor is mounted for common rotation with the shaft.
5 . The hybrid aircraft power plant as defined in claim 4 , comprising a stator vane fixedly mounted to the exhaust duct inside of the cavity defined by the exhaust duct, for interacting with a flow of the cooling air upstream of the bladed rotor of the fan.
6 . The hybrid aircraft power plant as defined in claim 2 , wherein:
the electric machine is mounted to the exhaust duct; and
the electric machine is disposed outside of the cavity defined by the exhaust duct.
7 . The hybrid aircraft power plant as defined in claim 1 , wherein the bladed rotor is mounted for common rotation with the shaft.
8 . The hybrid aircraft power plant as defined in claim 1 , wherein the exhaust duct defines an opening providing fluid communication between the cavity defined by the exhaust duct and a source of the cooling air.
9 . The hybrid aircraft power plant as defined in claim 8 , wherein:
the gas turbine engine is housed inside a nacelle; and
the source of cooling air includes a space between the nacelle and the gas turbine engine.
10 . The hybrid aircraft power plant as defined in claim 8 , wherein:
the gas turbine engine is housed inside a nacelle; and
the source of cooling air includes an ambient environment outside of the nacelle.
11 . The hybrid aircraft power plant as defined in claim 8 , wherein:
the gas turbine engine includes a compressor; and
the source of cooling air includes the compressor of the gas turbine engine.
12 . The hybrid aircraft power plant as defined in claim 1 , comprising an inlet scroll operable to deliver the cooling air to the fan.
13 . A hybrid aircraft power plant comprising:
a propeller for propelling the aircraft;
a compressor for pressurizing air;
a combustor in which the pressurised air is mixed with fuel and ignited for generating combustion gas;
a turbine disk for extracting energy from combustion gas, the turbine disk having a rotation axis and being in torque-transmitting engagement with the propeller;
an exhaust duct for receiving the combustion gas from the turbine disk, the exhaust duct defining: an exhaust passage disposed radially outward of the rotation axis of the turbine disk for receiving the combustion gas from the turbine disk and conveying the combustion gas away from the turbine disk; and a cavity fluidly isolated from the exhaust passage and disposed radially inward of the exhaust passage;
an electric machine in torque-transmitting engagement with the turbine disk via a shaft extending inside the cavity defined by the exhaust duct; and
a fan operable to ventilate the cavity defined by the exhaust duct, the fan including a bladed rotor mounted for common rotation with the shaft and configured to propel cooling air at the fan toward the turbine disk, the fan being closer to the electric machine than to the turbine disk.
14 . The hybrid aircraft power plant as defined in claim 13 , wherein:
the propeller is operable to propel the aircraft in a forward direction;
the exhaust duct is disposed aft of the turbine disk; and
the electric machine is disposed aft of the cavity defined by the exhaust duct.
15 . The hybrid aircraft power plant as defined in claim 14 , wherein:
the electric machine is coaxial with the turbine disk;
the shaft is coaxial with the turbine disk;
the turbine disk is disposed between the electric machine and the propeller; and
the bladed rotor of the fan is disposed between the electric machine and the turbine disk.
16 . A method of propelling an aircraft, the method comprising:
extracting energy from combustion gas using a turbine;
driving an air mover with the turbine to propel the aircraft;
conveying the combustion gas from the turbine in an exhaust passage of an exhaust duct;
driving the air mover with an electric motor via a shaft drivingly connecting the electric motor to the turbine, the shaft extending inside a cavity of the exhaust duct that is fluidly isolated from the exhaust passage of the exhaust duct; and
driving a fan with the shaft to circulate cooling air inside of the cavity of the exhaust duct,
wherein:
driving the air mover with the turbine to propel the aircraft includes propelling the aircraft in a forward direction;
driving the fan includes propelling the cooling air at the fan in the forward direction inside of the cavity of the exhaust duct; and
the fan is closer to the electric motor than to the turbine.
17 . The method as defined in claim 16 , wherein driving the fan includes rotating a bladed rotor of the fan together and coaxially with the shaft.