Systems and methods for controlling an air flow rate for a propulsion system air intake

1. An air intake for an aircraft propulsion system, the air intake comprising:

an air inlet duct, the air inlet duct including an intake inlet of the air intake;

a core flow duct, the core flow duct including a core flow outlet, the core flow duct extending between and to the air inlet duct and the core flow outlet;

a bypass flow duct, the bypass flow duct including a bypass flow outlet, the bypass flow duct extending between and to the air inlet duct and the bypass flow outlet, the bypass flow duct including an interior surface forming and surrounding a bypass flow passage through the bypass flow duct; and

a flow control device including an inflatable boot configured to variably control an area of a cross-sectional flow area of the bypass flow passage, the inflatable boot is disposed on the interior surface, the inflatable boot is selectively positionable in a fully inflated position, a fully deflated position, and a plurality of intermediate inflation positions between the fully inflated position and the fully deflated position;

wherein a first area of the cross-sectional flow area with the inflatable boot in the fully inflated position is less than five percent of a second area of the cross-sectional flow area with the inflatable boot in the fully deflated position.

2. The air intake of claim 1 , wherein the flow control device circumscribes the cross-sectional flow area.

3. The air intake of claim 1 , wherein the flow control device further includes a fluid regulator, the fluid regulator configured to be in fluid communication with a pressurized fluid source, the fluid regulator configured to direct a pressurized fluid from the pressurized fluid source to the inflatable boot to selectively position the inflatable boot.

4. The air intake of claim 1 , wherein the inflatable boot is disposed at the bypass flow outlet.

5. A method for controlling an air flow rate for an air intake for an aircraft propulsion system, the method comprising:

determining an operating condition of the aircraft propulsion system, the air intake of the aircraft propulsion system including a core flow duct and a bypass flow duct; and

controlling a first air flow rate for the bypass flow duct and a second air flow rate for the core flow duct by controlling a flow control device including an inflatable boot disposed in the bypass duct by selectively positioning the inflatable boot to selectively vary an area of a cross- sectional flow area of a bypass flow passage of the bypass flow duct based on the operating condition, and the inflatable boot is selectively positionable in a fully inflated position, a fully deflated position, and a plurality of intermediate inflation positions between the fully inflated position and the fully deflated position;

wherein the operating condition is an icing condition of the aircraft propulsion system and controlling the flow control device includes selectively positioning the inflatable boot in the fully deflated position based on the icing condition.

6. The method of claim 5 , wherein selectively positioning the inflatable boot includes directing a pressurized fluid to the inflatable boot to inflate the inflatable boot.

7. The method of claim 5 , wherein the operating condition is a cruising condition of the aircraft propulsion system and controlling the flow control device includes selectively positioning the inflatable boot in an inflated position based on the cruising condition.

8. The method of claim 5 , further comprising cycling the inflatable boot between a first inflated position and a second inflated position to remove accumulated foreign matter from the inflatable boot.

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

a gas turbine engine forming a core flow path;

an air intake, the air intake including an air inlet duct, a core flow duct, a bypass flow duct, and a flow control device, the air inlet duct including an intake inlet of the air intake, the core flow duct including a core flow outlet, the core flow duct extending between and to the air inlet duct and the core flow outlet; the core flow duct configured to direct air from the air inlet duct to the core flow path through the core flow outlet, the bypass flow duct includes a bypass flow outlet, the bypass flow duct extending between and to the air inlet duct and the bypass flow outlet, the bypass flow duct forming a bypass flow passage from the air inlet duct to the bypass flow outlet, the flow control device includes an inflatable boot and a fluid regulator, the inflatable boot disposed within the bypass flow passage, the fluid regulator in fluid communication with the inflatable boot, the fluid regulator configured to selectively position the inflatable boot in a fully inflated position, a fully deflated position, and a plurality of intermediate inflation positions between the fully inflated position and the fully deflated position to control the area of a cross-sectional flow area of the bypass flow passage; and

an engine control system in signal communication with the fluid regulator, the engine control system including a processor in communication with a non-transitory memory storing instructions, which instructions when executed by the processor, cause the processor to:

determine an operating condition of the propulsion system; and

control the fluid regulator to selectively position the inflatable boot to control the area of a cross-sectional flow area of the bypass flow passage based the operating condition; and

cycle the inflatable boot between a first inflated position and a second inflated position to remove accumulated foreign matter from the inflatable boot, each of the first inflated position and the second inflated position is one of the fully inflated position, the fully deflated position, or one of the plurality of intermediate inflation positions.

10. The propulsion system of claim 9 , wherein the gas turbine engine includes a compressor forming the core flow path, the fluid regulator in fluid communication with the compressor, the fluid regulator configured to receive a pressurized fluid from the compressor and direct the pressurized fluid to the inflatable boot.

11. The propulsion system of claim 9 , wherein the instructions, when executed by the processor, further cause the processor to control the fluid regulator to cycle the inflatable boot at a selected periodicity based on the operating condition.

12. The propulsion system of claim 9 , wherein the instructions, when executed by the processor, further cause the processor to:

identify foreign matter accumulation on the inflatable boot; and

control the fluid regulator to cycle the inflatable boot based on the identification of foreign matter accumulation.