Hybrid gas turbofan powered sub-idle descent mode

Patent metadata

Field	Value
Publication number	US-2020056497-A1
Application number	US-201916431245-A
Country	US
Kind code	A1
Filing date	Jun 4, 2019
Priority date	Aug 17, 2018
Publication date	Feb 20, 2020
Grant date	—

Abstract

A method of operating an aircraft hybrid gas turbofan during an idle mode of operation includes reducing a fuel flow to a primary gas turbine engine and boosting a high spool of the primary gas turbine engine using a secondary gas turbine engine via a first power linkage connecting the primary and secondary gas turbine engines, such that a net fuel reduction is achieved. The net fuel reduction accounts for fuel flow to the primary gas turbine engine and fuel flow to the secondary gas turbine engine.

First claim

1 . A method of operating an aircraft hybrid gas turbofan during an idle mode of operation of a primary gas turbine engine, the method comprising:
reducing a fuel flow to the primary gas turbine engine; and boosting a high spool of the primary gas turbine engine using a secondary gas turbine engine via a first power linkage connecting the primary and secondary gas turbine engines such that a net fuel reduction is achieved, wherein the net fuel reduction accounts for fuel flow to the primary gas turbine engine and fuel flow to the secondary gas turbine engine.

2 . The method of claim 1 , wherein the primary gas turbine engine is a propulsion engine and the secondary gas turbine engine is an auxiliary power unit (APU).

3 . The method of claim 1 , wherein boosting the high spool of the primary gas turbine engine comprises:
driving a generator with the secondary gas turbine engine; coupling a motor to the high spool; and powering the motor via the generator.

4 . The method of claim 1 , wherein boosting the high spool of the primary gas turbine engine comprises:
generating compressed air with the secondary gas turbine engine; and providing the compressed air directly into a turbine of the high spool of the primary gas turbine engine to provide high spool torque.

5 . The method of claim 1 , wherein boosting the high spool of the primary gas turbine engine comprises:
driving a generator with the second engine; coupling a motor to the high spool; powering the motor via the generator; generating compressed air in the secondary gas turbine engine; and providing the compressed air into the turbine of the high spool of the primary gas turbine engine to provide high spool torque.

6 . The method of claim 1 , wherein the idle mode occurs during descent of the aircraft.

7 . The method of claim 1 , wherein reducing the fuel flow to the primary gas turbine engine comprises a reduction of fuel flow greater than 10 percent over a conventional idle mode in which power to the high spool of the primary gas turbine engine is not boosted by the secondary gas turbine engine.

8 . The method of claim 6 , wherein boosting the high spool of the primary gas turbine engine comprises providing supplemental power to the primary gas turbine engine in an amount greater than 100 horsepower.

9 . The method of claim 1 and further comprising restricting an air flow exiting from a compressor section of the primary gas turbine engine.

10 . A method of operating an aircraft hybrid gas turbofan, the method comprising:
providing supplemental power to one of a primary gas turbine engine and a secondary gas turbine engine during a mode of operation of the primary gas turbine engine, wherein the primary gas turbine engine is a propulsion engine and the secondary gas turbine engine is an auxiliary power unit (APU); wherein supplemental power is provided to the primary gas turbine engine by the APU; and wherein supplemental power is provided to the APU by the primary gas turbine engine; and reducing a fuel flow to the primary gas turbine engine when supplemental power is provided to the primary gas turbine engine by the APU such that a net fuel reduction is achieved, wherein the net fuel reduction accounts for fuel flow to the primary gas turbine engine and fuel flow to the APU.

11 . The method of claim 10 , wherein providing supplemental power to the primary gas turbine engine occurs during an idle mode of operation of the aircraft, and wherein providing supplemental power comprises boosting the high spool of a primary gas turbine engine using the secondary gas turbine engine via a first power linkage connecting the primary and secondary gas turbine engines.

12 . The method of claim 11 , wherein boosting the high spool of the primary gas turbine engine comprises at least one of a first power supplementation method and a second power supplementation method;
wherein the first power supplementation method comprises:
driving a generator with the secondary gas turbine engine;
coupling a motor to the high spool; and
powering the motor via the generator; and
wherein the second power supplementation method comprises:
generating compressed air in the secondary gas turbine engine; and
providing the compressed air directly into a turbine of the high spool of the primary gas turbine engine to provide high spool torque.

13 . The method of claim 12 , wherein reducing the fuel flow to the primary gas turbine engine comprises a reduction of fuel flow greater than 10 percent over a conventional idle mode in which power to the high spool of the primary gas turbine engine is not boosted by the secondary gas turbine engine.

14 . The method of claim 13 , wherein boosting the high spool of the primary gas turbine engine comprises supplementing power to the primary gas turbine engine in an amount greater than 100 horsepower.

15 . The method of claim 10 , wherein providing supplemental power to the secondary gas turbine engine comprises:
driving a generator with a high spool of the primary gas turbine engine; coupling a motor to a spool of the APU; and powering the motor via the generator.

16 . The method of claim 15 , wherein the mode of operation is one of a takeoff mode, top of climb mode, or cruise mode.

17 . An aircraft hybrid gas turbofan comprising:
a primary gas turbine engine having a high spool, wherein the primary gas turbine engine is a propulsion engine; a secondary gas turbine engine, wherein the secondary gas turbine engine is an auxiliary power unit (APU); and a means for linking power between the high spool of the primary gas turbine engine and the APU.

18 . The aircraft hybrid gas turbofan of claim 17 , wherein the means for linking power includes at least one of:
an electrical coupling comprising:
a generator driven by the APU; and
a motor coupled to the high spool and powered by the generator; and
a mechanical coupling comprising a bleed air conduit connecting a compressor section of the APU to a core gas path of a turbine of the high spool.

19 . The aircraft hybrid gas turbofan of claim 17 , wherein the power linkage includes a combined motor/generator configured to transfer power from a spool of the primary gas turbine engine to the APU.

20 . A method of operating an aircraft hybrid gas turbofan, the method comprising:
providing supplemental power to a primary gas turbine engine by a secondary gas turbine engine during a mode of operation of the primary gas turbine engine, wherein the primary gas turbine engine is a propulsion engine and the secondary gas turbine engine is an auxiliary power unit (APU); and reducing a response time of the primary gas turbine engine for spooling up when additional thrust output is needed.

Assignees

• United Technologies Corp

Inventors

• Terwilliger Neil
• Kupratis Daniel Bernard
• Romero Michael M

Classifications

• F05D2220/76

  an electrical generator · CPC title

• F02C9/42

  specially adapted for the control of two or more plants simultaneously · CPC title

• F05D2220/50

  for auxiliary power units (APU's) · CPC title

• F01D13/00

  Combinations of two or more machines or engines (F01D15/00 takes precedence; combinations of two or more pumps F04; fluid gearing F16H) · CPC title

• F01D15/10 Primary

  Adaptations for driving, or combinations with, electric generators · CPC title