Aircraft propulsion system with side flowpath inlet(s)

1 . A propulsion system for an aircraft, comprising:

an open propulsor rotor including a plurality of open propulsor blades arranged circumferentially about a propulsion system axis, each of the plurality of open propulsor blades disposed in an environment external to the propulsion system;

an engine core configured to drive rotation of the open propulsor rotor about the propulsion system axis, the engine core including a compressor section, a combustor section and a turbine section;

an engine flowpath including an end flowpath inlet, a side flowpath inlet and a flowpath exhaust, the engine flowpath extending longitudinally through the compressor section, the combustor section and the turbine section from the end flowpath inlet to the flowpath exhaust, and the side flowpath inlet disposed to a radial outer side of the engine flowpath longitudinally between the end flowpath inlet and the compressor section; and

a flow regulator configured to regulate a flow of air from the environment external to the propulsion system into the engine flowpath through the side flowpath inlet;

wherein the plurality of open propulsor blades are disposed axially between the end flowpath inlet and the side flowpath inlet along the propulsion system axis.

2 . The propulsion system of claim 1 , wherein the end flowpath inlet is an annular inlet extending circumferentially around the propulsion system axis.

3 . The propulsion system of claim 1 , wherein a leg of the engine flowpath projects axially along the propulsion system axis into the propulsion system from the end flowpath inlet.

4 . The propulsion system of claim 1 , wherein a leg of the engine flowpath projects radially inward towards the propulsion system axis into the propulsion system from the side flowpath inlet.

5 . The propulsion system of claim 1 , wherein the side flowpath inlet is one of a plurality of side flowpath inlets into the engine flowpath, the plurality of side flowpath inlets are arranged circumferentially about the propulsion system axis, and each of the plurality of side flowpath inlets is disposed to the radial outer side of the engine flowpath longitudinally between the end flowpath inlet and the compressor section.

6 . The propulsion system of claim 5 , wherein the flow regulator is one of a plurality of flow regulators, and each of the plurality of flow regulators is configured to regulate a respective flow of the air from the environment external to the propulsion system into the engine flowpath through a respective one of the plurality of side flowpath inlets.

7 . The propulsion system of claim 6 , wherein

the plurality of flow regulators include a first flow regulator and a second flow regulator;

the first flow regulator comprises a first door with a first geometry, and the first door is configured to selectively cover and uncover a first of the plurality of side flowpath inlets;

the second flow regulator comprises a second door with a second geometry, and the second door is configured to selectively cover and uncover a second of the plurality of side flowpath inlets; and

the second geometry is different than the first geometry.

8 . The propulsion system of claim 6 , wherein at least two of the plurality of flow regulators comprises a door with a common geometry, and the door of each of the at least two of the plurality of flow regulators is configured to selectively cover and uncover the respective one of the plurality of side flowpath inlets.

9 . The propulsion system of claim 6 , further comprising an actuation system operatively coupled to the plurality of flow regulators, the actuation system configured to actuate the plurality of flow regulators to synchronously open and close the plurality of side flowpath inlets.

10 . The propulsion system of claim 6 , further comprising an actuation system operatively coupled to the plurality of flow regulators, the actuation system configured to actuate the plurality of flow regulators to asynchronously open and close at least two of the plurality of side flowpath inlets.

11 . The propulsion system of claim 5 , wherein the plurality of side flowpath inlets include a first side flowpath inlet and a second side flowpath inlet, the first side flowpath inlet has a first geometry, and the second side flowpath inlet has a second geometry that is different from the first geometry.

12 . The propulsion system of claim 5 , wherein at least two of the plurality of side flowpath inlets have a common geometry.

13 . The propulsion system of claim 1 , wherein

the flow regulator comprises a door configured to selectively cover and uncover the side flowpath inlet; and

the door is adjacent to a first of the plurality of open propulsor blades.

14 . The propulsion system of claim 1 , wherein

the flow regulator comprises a door configured to selectively cover and uncover the side flowpath inlet; and

the door is adjacent a first of the plurality of open propulsor blades, and the door is operatively independent of each of the plurality of open propulsor blades.

15 . The propulsion system of claim 1 , further comprising:

an open guide vane structure including a plurality of open guide vanes, each of the plurality of open guide vanes disposed in the environment external to the propulsion system;

the side flowpath inlet disposed axially between the plurality of open propulsor blades and the open guide vane structure along the propulsion system axis.

16 . The propulsion system of claim 1 , further comprising an actuation system configured to actuate the flow regulator such that the flow regulator

blocks the flow of the air from the environment external to the propulsion system into the engine flowpath through the side flowpath inlet when the open propulsor rotor is configured to provide forward thrust; and

unblocks the flow of the air from the environment external to the propulsion system into the engine flowpath through the side flowpath inlet when the open propulsor rotor is configured to provide reverse thrust.

17 . A propulsion system for an aircraft, comprising:

an open propulsor rotor including a plurality of open propulsor blades arranged circumferentially about a propulsion system axis, each of the plurality of open propulsor blades disposed in an environment external to the propulsion system;

an engine core configured to drive rotation of the open propulsor rotor about the propulsion system axis, the engine core including a compressor section, a combustor section and a turbine section;

an engine flowpath including an end flowpath inlet, a side flowpath inlet and a flowpath exhaust, the engine flowpath extending longitudinally through the compressor section, the combustor section and the turbine section from the end flowpath inlet to the flowpath exhaust, and the side flowpath inlet disposed to a radial outer side of the engine flowpath longitudinally between the end flowpath inlet and the compressor section; and

a flow regulator configured to regulate a flow of air from the environment external to the propulsion system into the engine flowpath through the side flowpath inlet;

wherein the flow regulator comprises a door configured to selectively cover and uncover the side flowpath inlet; and

wherein the door is operatively coupled to a first of the plurality of open propulsor blades.

18 . The propulsion system of claim 17 , wherein a leg of the engine flowpath projects axially along the propulsion system axis into the propulsion system from the end flowpath inlet.

19 . The propulsion system of claim 17 , wherein a leg of the engine flowpath projects radially inward towards the propulsion system axis into the propulsion system from the side flowpath inlet.

20 . A propulsion system for an aircraft, comprising:

an open propulsor rotor including a plurality of open propulsor blades arranged circumferentially about a propulsion system axis, each of the plurality of open propulsor blades disposed in an environment external to the propulsion system;

an engine core configured to drive rotation of the open propulsor rotor about the propulsion system axis, the engine core including a compressor section, a combustor section and a turbine section;

an engine flowpath including a flowpath inlet and a flowpath exhaust, the engine flowpath extending longitudinally through the compressor section, the combustor section and the turbine section between the flowpath inlet and the flowpath exhaust; and

a flow regulator configured to

close the flowpath inlet into the engine flowpath from the environment external to the propulsion system when the open propulsor rotor is configured to provide forward thrust; and

open the flowpath inlet into the engine flowpath from the environment external to the propulsion system when the open propulsor rotor is configured to provide reverse thrust.