Propulsion system for an aircraft, said propulsion system comprising a fuel cell

1. A propulsion system for an aircraft, the propulsion system comprising:

a nacelle having an air channel which is annular around a longitudinal direction, and which opens at a front at an inlet opening and at a rear at an ejection opening,

an electric motor fixed inside the nacelle and having an output on which is mounted a shaft parallel to the longitudinal direction, a first electrical terminal, and a second electrical terminal,

a propeller placed in front of the inlet opening and driven in rotation by said shaft,

a fuel cell, comprising:

a core around the longitudinal direction and outside the air channel,

open channels around the core, each open channel having an open inlet in the air channel and an open outlet in the air channel downstream of the open inlet, relative to a direction of an air flow in the air channel,

for each open channel, a fuel chamber supplied with fuel,

for each pair comprising an open channel and a fuel chamber, an electrolyte between the open channel and the fuel chamber,

between each open channel and the neighboring electrolyte, a cathode,

between each fuel chamber and the neighboring electrolyte, an anode, the anodes being electrically connected to the first electrical terminal, and the cathodes being electrically connected to the second electrical terminal,

each open channel having an inlet surface area which is less than the surface area of an intermediate area between the inlet and the outlet, the surface area of the outlet being smaller than the surface area of the intermediate area.

2. The propulsion system according to claim 1 ,

wherein the open channels are cylindrical channels which are coaxial with each other around the longitudinal direction,

wherein, between two consecutive open channels, the fuel cell comprises an annular fuel chamber, and

wherein, between the fuel chamber and each open channel, the fuel cell comprises an electrolyte.

3. The propulsion system according to claim 1 ,

wherein the open channels are placed side by side and distributed angularly around the longitudinal direction, and

wherein, around each open channel, the fuel cell comprises an electrolyte which is annular around an axis of the open channel and, around the electrolyte, a fuel chamber which is annular around the axis of the open channel.

4. The propulsion system according to claim 1 further comprising, at the inlet opening in the air channel, a compressor driven in rotation around the longitudinal direction by the shaft.

5. The propulsion system according to claim 1 , further comprising, at the ejection opening in the air channel, a turbine driven in rotation around the longitudinal direction by the shaft.

6. The propulsion system according to claim 5 , further comprising at least one combustion chamber having an inlet fluidly connected to at least one outlet of a fuel chamber and an outlet fluidly connected to the air channel upstream of the turbine.

7. The propulsion system according to claim 1 , wherein the electric motor is fitted with a gearbox located between the motor output and the shaft.

8. The propulsion system according to claim 2 ,

wherein the shaft comprises an upstream shaft integral with the propeller and a downstream shaft integral with the electric motor, and

wherein the propulsion system comprises a clutch device fitted between the downstream shaft and the upstream shaft.

9. The propulsion system according to claim 2 , further comprising a thermally insulating layer which is placed between the fuel cell and the electric motor.

10. An aircraft comprising a fuel tank and a propulsion system according to claim 2 , wherein the inlet of each fuel chamber is fluidly connected to the tank by a supply line.

11. The aircraft according to claim 10 , wherein the supply line is in contact with the electric motor.