Supersonic aircraft turbofan

Patent metadata

Field	Value
Publication number	US-11378017-B2
Application number	US-201916448214-A
Country	US
Kind code	B2
Filing date	Jun 21, 2019
Priority date	Jul 20, 2018
Publication date	Jul 5, 2022
Grant date	Jul 5, 2022

Abstract

A turbofan engine has an engine core including in flow series a compressor, a combustor and a turbine. The engine further has a fan located upstream of the engine core, has a supersonic intake for slowing down incoming air to subsonic velocities at an inlet to the fan formed by the intake, has a bypass duct surrounding the engine core, wherein the fan generates a core airflow to the engine core and a bypass airflow through the bypass duct, and has a mixer for mixing an exhaust gas flow exiting the engine core and bypass airflow exiting bypass duct. The engine further has a thrust nozzle rearwards of the mixer for discharging mixed flows, the thrust nozzle having a variable area throat. The engine further has a controller controlling the thrust produced by the engine over a range of flight operations including on-the-ground subsonic take-off and subsequent off-the-ground subsonic climb.

First claim

We claim:

1. A turbofan engine for providing propulsive thrust to a supersonic aircraft, the turbofan engine comprising:
an engine core including, in flow series, a compressor, a combustor, and a turbine;
a fan located upstream of the engine core;
a supersonic intake configured to decrease air velocities of incoming air to subsonic velocities at an inlet to the fan formed by the intake;
a bypass duct surrounding the engine core, the fan being configured to generate a core airflow to the engine core and to generate a cold bypass airflow through the bypass duct;
a variable mixer configured to mix a hot exhaust gas flow exiting the engine core with the cold bypass airflow exiting the bypass duct, the mixer being configured to vary a cross-sectional area of a hot inlet of the mixer for the hot exhaust gas flow and a cross-sectional area of a cold inlet of the mixer for the cold bypass airflow to change a ratio of an amount of the hot exhaust gas flow relative to an amount of the cold bypass airflow that is mixed by the mixer;
a thrust nozzle located rearwards of the mixer, the thrust nozzle being configured to discharge the exhaust gas flow and the bypass airflow mixed by the mixer, the thrust nozzle having a variable area throat defining a cross-sectional throat area, the thrust nozzle being configured to controllably vary the throat area; and
a controller configured to:
perform a ground subsonic take-off operation by controlling the thrust nozzle to reduce the throat area of the variable area throat, which increases the thrust of the turbofan engine, and
perform an off-the-ground subsonic climb operation by controlling the thrust nozzle to increase the throat area of the variable area throat.throat, and controlling the mixer to increase the cross-sectional area of the hot inlet and decrease the cross-sectional area of the cold inlet, which increase the amount of hot exhaust gas flow in the ratio of the hot exhaust gas flow relative to the cold bypass airflow, such that a value of (AHOT after /ACOLD after )/(AHOT before /ACOLD before ) is in a range from 1.1 to 2.5, wherein AHOT is the cross-sectional area of the hot inlet of the mixer, ACOLD is the cross-sectional area of the cold inlet of the mixer, and subscripts “before” and “after” denote respectively immediately before and immediately after the relative increase in cross-sectional area of the hot inlet.

2. The turbofan engine according to claim 1 , wherein the intake has a fixed geometry.

3. The turbofan engine according to claim 1 , wherein the controller is configured to perform the increase of the cross-sectional throat area of the variable area throat at a first predetermined point during the climb operation.

4. The turbofan engine according to claim 3 , wherein the first predetermined point is any one of a predetermined aircraft speed, a predetermined fan speed, a predetermined aircraft altitude, a predetermined aircraft flap position, aircraft landing gear retraction, and a predetermined time.

5. The turbofan engine according to claim 1 , wherein the controller is configured to perform the increase of the cross-sectional throat area of the variable area throat by from 10 % to 70 % of the cross-sectional throat area immediately before performing the increase.

6. The turbofan engine according to claim 1 , wherein during the take-off operation or the climb operation, the controller is configured to reduce fuel flow to the combustor.

7. The turbofan engine according to claim 6 , wherein the controller is configured to perform the reduction of the fuel flow to the combustor at a second predetermined point during the take-off operation or the climb operation.

8. The turbofan engine according to claim 7 , wherein the second predetermined point is any one of a predetermined aircraft speed, a predetermined weight-on-wheels, a predetermined distance along runway, a predetermined aircraft speed, a predetermined fan speed, a predetermined aircraft altitude, a predetermined aircraft flap position, aircraft landing gear retraction, and a predetermined time.

9. The turbofan engine according to claim 1 , wherein the controller is further configured, in the event of an engine failure or malfunction after the reduction of the cross-sectional throat area of the variable area throat, to increase the cross-sectional throat area of the variable area throat.

10. A supersonic aircraft having the turbofan engine according to claim 1 .

11. A method of operating a supersonic aircraft having a turbofan engine which provides propulsive thrust to the supersonic aircraft over a range of flight operations including a transonic push operation during which the supersonic aircraft transitions from subsonic flight to supersonic flight, and a supersonic cruise operation, which has a relatively lower thrust than the transonic push operation, the turbofan engine including:
an engine core including, in flow series, a compressor, a combustor, and a turbine;
a fan located upstream of the engine core;
a supersonic intake configured to decrease air velocities of incoming air to subsonic velocities at an inlet to the fan formed by the intake;
a bypass duct surrounding the engine core, the fan being configured to generate a core airflow to the engine core and to generate a cold bypass airflow through the bypass duct;
a variable mixer configured to mix a hot exhaust gas flow exiting the engine core with the cold bypass airflow exiting the bypass duct, the mixer being configured to vary a cross-sectional area of a hot inlet of the mixer for the hot exhaust gas flow and a cross-sectional area of a cold inlet of the mixer for the cold bypass airflow to change a ratio of an amount of the hot exhaust gas flow relative to an amount of the cold bypass airflow that is mixed by the mixer; and
a thrust nozzle located rearwards of the mixer, the thrust nozzle being configured to discharge the exhaust gas flow and the bypass airflow mixed by the mixer, the thrust nozzle having a variable area throat defining a cross- sectional throat area, the thrust nozzle being configured to controllably vary the throat area,
the method comprising:
performing a ground subsonic take-off operation by controlling the thrust nozzle to reduce the throat area of the variable area throat, which increases the thrust of the turbofan engine; and

transitioning the supersonic aircraft after the take-off operation to perform an off-the-ground subsonic climb operation by controlling the thrust nozzle to increase the throat area of the variable area throat, and controlling the mixer to increase the cross-sectional area of the hot inlet and decrease the cross-sectional area of the cold inlet, which increase the amount of hot exhaust gas flow in the ratio of the hot exhaust gas flow relative to the cold bypass airflow, such that a value of (AHOT after /ACOLD after )/(AHOT before /ACOLD before ) is in a range from 1.1 to 2.5, wherein AHOT is the cross-sectional area of the hot inlet of the mixer, ACOLD is the cross-sectional area of the cold inlet of the mixer, and subscripts “before” and “after” denote respectively immediately before and immediately after the relative increase in cross-sectional area of the hot inlet.

Assignees

• Rolls Royce Plc

Inventors

• Stieger Rory D
• Hickey Conor

Classifications

• B64D31/09

  in response to power plant failure · CPC title

• F02C9/20 Primary

  by throttling; by adjusting vanes · CPC title

• F02K1/06 Primary

  Varying effective area of jet pipe or nozzle (by using fluid jets to influence the jet flow F02K1/30) · CPC title

• F05D2270/71

  synthesized, i.e. parameter computed by a mathematical model · CPC title

• F02K3/06

  with front fan · CPC title