Propulsive assembly for a multi-engine hybrid aircraft
A propulsive assembly including a first and a second gas turbine each having a gas generator and a free power turbine, a main rotor coupled to the free power turbine of a first and a second main coupling, a first and a second reversible electric machine each coupled to the gas generator, by way of a first deactivatable coupling, and each coupled to the main rotor by way of a second deactivatable coupling, the first deactivatable coupling being activated when the electric machines are rotating in a first direction of rotation, and the second deactivatable coupling being activated when the electric machines are rotating in a second direction of rotation opposite to the first direction of rotation.
1. A propulsive assembly for a hybrid aircraft, particularly a multi-engine helicopter, comprising:
at least a first gas turbine and a second gas turbine each having a gas generator and a free power turbine rotationally driven by a stream of gas generated by the gas generator,
a main rotor coupled to the free power turbine of the first gas turbine and of the second gas turbine by way of a first and a second main coupling means respectively,
a first reversible electric machine and a second reversible electric machine each coupled to the gas generator of the first gas turbine and of the second gas turbine respectively, by way of a first deactivatable coupling means, and each coupled to the main rotor by way of a second deactivatable coupling means, the first deactivatable coupling means being each configured to be activated when the first and the second electric machine are rotating in a first direction of rotation, and the second deactivatable coupling means being configured to be activated when the first and the second electric machine are rotating in a second direction of rotation opposite to the first direction of rotation.
2. The propulsive assembly as claimed in claim 1 , wherein the first electric machine and the second electric machine are configured to operate in motor mode in which they are able to input power to the main rotor or to the gas generator of the first and of the second gas turbine respectively, according to their direction of rotation, or in generator mode in which they are able to be rotationally driven by the main rotor or by said gas generator by locking one or the other of the first or the second deactivatable coupling means, in such a way as to generate electrical energy.
3. The propulsive assembly as claimed in claim 1 , comprising a first coupling means coupled to the main rotor and to the gas generator of the first gas turbine, and a second coupling means coupled to the main rotor and to the gas generator of the second gas turbine, the first and the second coupling means being movable between a decoupling position, and a coupling position in which the main rotor is coupled with the gas generator of the first and of the second gas turbine respectively.
4. The propulsive assembly as claimed in claim 3 , wherein, when one of the first or the second gas turbine is the only one driving the main rotor, the gas generator of the other of the first or the second gas turbine is kept in a standby mode, at a power of less than 5 kW, by way of the first or the second coupling means in the coupling position.
5. The propulsive assembly as claimed in claim 2 , wherein, when the first gas turbine is the only one driving the main rotor, the first electric machine operates in motor mode in such a way as to input power to the gas generator of the first gas turbine, and the second electric machine operates in generator mode in such a way as to input electrical energy to the first electric machine.
6. The propulsive assembly as claimed in claim 2 , configured so that, when the first gas turbine that is the only one driving the main rotor stops, the second electric machine operates in motor mode in such a way as to input a power greater than or equal to 50 KW to the gas generator of the second gas turbine.
7. The propulsive assembly as claimed in claim 1 , comprising a third reversible electric machine able to be coupled to the main rotor and to the free power turbine of the first gas turbine and of the second gas turbine by way of the first main coupling means and the second main coupling means respectively.
8. The propulsive assembly as claimed in claim 7 , wherein the third electric machine is configured to operate in generator mode, in which it is able to be rotationally driven by the main rotor, itself driven by the free power turbine of the first and/or of the second gas turbine by way of the first and/or the second main coupling means, in such a way as to generate electrical energy, or in motor mode in which it is able to input power to the main rotor.
9. The propulsive assembly as claimed in claim 8 wherein, when the first gas turbine is the only one driving the main rotor, the gas generator of the second gas turbine is kept in standby mode, at a power of less than 5 kW, by way of the second electric machine which operates in motor mode, the first electric machine operating in motor mode in such a way as to input power to the gas generator of the first gas turbine, and the third electric machine operates in generator mode in such a way as to input electrical energy to the first and to the second electric machine.
10. The propulsive assembly as claimed in claim 1 , wherein the first and the second main coupling means, and the first and the second deactivatable coupling means associated with each of the first and the second electric machine, comprise a free wheel.
11. A hybrid aircraft comprising a propulsive assembly as claimed in claim 1 , the hybrid aircraft being a multi-engine helicopter, particularly a twin-engine helicopter.