Multi-engine aircraft power plant with heat recuperation

Patent metadata

Field	Value
Publication number	US-10760484-B2
Application number	US-201615267736-A
Country	US
Kind code	B2
Filing date	Sep 16, 2016
Priority date	Sep 16, 2016
Publication date	Sep 1, 2020
Grant date	Sep 1, 2020

Abstract

Multi-engine aircraft power plants and associated operating methods are disclosed. An exemplary multi-engine power plant comprises a first turboshaft engine and a second turboshaft engine configured to drive a common load such as a rotary wing of an aircraft; and a heat exchanger in thermal communication with an exhaust gas of the first turboshaft engine and in thermal communication with pre-combustion air of the second turboshaft engine. The heat exchanger is configured to permit heat transfer from the exhaust gas of the first turboshaft engine to the pre-combustion air of the second turboshaft engine.

First claim

What is claimed is:

1. A method of operating a multi-engine power plant drivingly coupled to a rotary wing of an aircraft during flight of the aircraft, the method comprising:
operating a first turboshaft engine of the multi-engine power plant to drive the rotary wing of the aircraft during flight while a second turboshaft engine of the multi-engine power plant is idling;
transferring heat from an exhaust gas of the first turboshaft engine to pre-combustion air upstream of a combustor of the idling second turboshaft engine of the multi-engine power plant;
receiving a sensed speed value representative of an actual output speed of the multi-engine power plant where the sensed speed value is lower than a corresponding set point value; and
increasing an output power level of the second turboshaft engine to drive the rotary wing of the aircraft, wherein the first turboshaft engine is operated at a substantially constant output power level while the output power level of the second turboshaft engine is increasing.

2. The method as defined in claim 1 , comprising transferring heat to the pre-combustion air at a location along a gas path of the second turboshaft engine downstream of a compressor stage of the second turboshaft engine.

3. The method as defined in claim 1 , comprising:
receiving the pre-combustion air from a location along a gas path of the second turboshaft engine downstream of a compressor stage of the second turboshaft engine;
directing the pre-combustion air toward a heat exchanger in thermal communication with the exhaust gas of the first turboshaft engine; and
directing the pre-combustion air from the heat exchanger to a location along the gas path of the second turboshaft engine upstream of the combustor of the second turboshaft engine.

4. The method as defined in claim 3 , wherein the heat exchanger is disposed inside an exhaust duct of the first turboshaft engine.

5. The method as defined in claim 1 , further comprising, after increasing the output power level of the second turboshaft engine, modulating the output power level of the second turboshaft engine based on a difference between the sensed speed value representative of the actual output speed of the multi-engine power plant and the corresponding set point value.

6. The method as defined in claim 5 , comprising operating the first turboshaft engine at a substantially constant output power level while the output power level of the second turboshaft engine is modulated.

7. A method of operating a multi-engine power plant of an aircraft, the method comprising:
using a first turboshaft engine of the multi-engine power plant to drive a load while a second turboshaft engine of the multi-engine power plant is idling;
transferring heat from the first turboshaft engine to pre-combustion air upstream of a combustor of the second turboshaft engine of the multi-engine power plant to assist with the idling of the second turboshaft engine;
receiving a sensed operating speed of the load that is lower than a corresponding set point value; and
increasing an output power level of the second turboshaft engine, wherein the first turboshaft engine is operated at a substantially constant output power level while the output power level of the second turboshaft engine is increasing.

8. The method as defined in claim 7 , comprising transferring heat from an exhaust gas of the first turboshaft engine to the pre-combustion air of the second turboshaft engine of the multi-engine power plant.

9. The method as defined in claim 8 , comprising transferring heat to the pre-combustion air at a location along a gas path of the second turboshaft engine downstream of a compressor stage of the second turboshaft engine.

10. The method as defined in claim 7 , wherein the load is a rotary wing of the aircraft and the aircraft is in flight while the second turboshaft engine is idling.

11. The method as defined in claim 7 , further comprising modulating an output power level of the second turboshaft engine based on a difference between an operating speed of the load and a corresponding set point value.

12. The method as defined in claim 11 , comprising operating the first turboshaft engine at a substantially constant output power level while the output power level of the second turboshaft engine is modulated.

13. A multi-engine power plant for an aircraft, the power plant comprising:
a first turboshaft engine and a second turboshaft engine, the first turboshaft engine and the second turboshaft engine being configured to drive a common load;
a heat exchanger in thermal communication with an exhaust gas of the first turboshaft engine and in thermal communication with pre-combustion air of the second turboshaft engine, the heat exchanger being configured to, in use, permit heat transfer from the exhaust gas of the first turboshaft engine to the pre-combustion air of the second turboshaft engine;
a first duct configured to receive the pre-combustion air from a location along a gas path of the second turboshaft engine downstream of a compressor stage of the second turboshaft engine and direct the pre-combustion air toward the heat exchanger;
a second duct configured to direct the pre-combustion air from the heat exchanger to a location along the gas path of the second turboshaft engine upstream of a combustor of the second turboshaft engine;
a first control loop configured to control the first turboshaft engine based on a desired output power level of the first turboshaft engine; and
a second control loop configured to:
control the second turboshaft engine based on the desired operating speed of the common load;
cause the second turboshaft engine to idle when the desired output power level of the first turboshaft engine is sufficient to maintain the desired operating speed of the common load; and
cause an increase in output power level of the second turboshaft engine when the desired output power level of the first turboshaft engine is insufficient to maintain the desired operating speed of the common load.

14. The power plant as defined in claim 13 , wherein the heat exchanger is disposed inside an exhaust duct of the first turboshaft engine.

Assignees

• Pratt & Whitney Canada

Inventors

• Alecu Daniel

Classifications

• F02C9/42

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

• F05D2220/329

  in helicopters · CPC title

• F02C6/02 Primary

  Plural gas-turbine plants having a common power output · CPC title

• F02C7/10

  by means of regenerative heat-exchangers · CPC title

• F02C6/20

  Adaptations of gas-turbine plants for driving vehicles · CPC title