Turboprop engine assembly with combined engine and cooling exhaust

Patent metadata

Field	Value
Publication number	US-10927734-B2
Application number	US-201916292846-A
Country	US
Kind code	B2
Filing date	Mar 5, 2019
Priority date	Aug 7, 2015
Publication date	Feb 23, 2021
Grant date	Feb 23, 2021

Abstract

A turboprop engine assembly for an aircraft, including an internal combustion engine having a liquid coolant system, an air duct in fluid communication with an environment of the aircraft, a heat exchanger received within the air duct having coolant passages in fluid communication with the liquid coolant system and air passages air passages in fluid communication with the air duct, and an exhaust duct in fluid communication with an exhaust of the internal combustion engine. The exhaust duct has an outlet positioned within the air duct downstream of the heat exchanger and upstream of an outlet of the air duct, the outlet of the exhaust duct spaced inwardly from a peripheral wall of the air duct. In use, a flow of cooling air surrounds a flow of exhaust gases. A method of discharging air and exhaust gases in an turboprop engine assembly having an internal combustion engine is also discussed.

First claim

The invention claimed is:

1. A method of flowing air and exhaust gases in a turboprop engine assembly having an internal combustion engine, the method comprising:
admitting a flow of cooling air through an inlet of an air duct of the turboprop engine assembly, channeling said flow of cooling air through a heat exchanger used to cool a liquid coolant of the internal combustion engine, discharging said flow of cooling air downstream of the heat exchanger into the air duct and then out of the turboprop engine assembly; and
discharging a flow of exhaust gases produced by the internal combustion engine to the air duct so that the flow of cooling air surrounds the flow of exhaust gases, a mass flow of the exhaust gases being smaller than a mass flow of the cooling air.

2. The method as defined in claim 1 , wherein discharging the flow of exhaust gases includes discharging the flow of exhaust gases from the internal combustion engine through a turbine section compounded with the internal combustion engine before discharging the flow of exhaust gases to the air duct.

3. The method as defined in claim 2 , wherein discharging the flow of exhaust gases through the turbine section includes discharging the flow of exhaust gases to a first stage turbine and flowing the flow of exhaust gas downstream of the first stage turbine through a second stage turbine before discharging the flow of exhaust gases to the air duct.

4. The method as defined in claim 1 , wherein discharging the flow of exhaust gases with the mass flow of the exhaust gases being smaller than a mass flow of the cooling air includes discharging the flow of exhaust gases at a mass flow of 20% or less of the mass flow of the cooling air.

5. The method as defined in claim 1 , wherein discharging the flow of exhaust gases includes discharging the flow of exhaust gases at a greater velocity than the flow of cooling air surrounding the flow of exhaust gases.

6. The method as defined in claim 1 , wherein the internal combustion engine is a Wankel rotary engine including a rotor having three apex portions mounted for eccentric revolutions within an internal cavity defined in a housing, the internal cavity having an epitrochoid shape with two lobes, the rotor and the internal cavity defining working chambers, wherein discharging the flow of exhaust gases includes discharging a pulsating flow of exhaust gases out of the working chambers.

7. The method as defined in claim 1 , wherein admitting the flow of cooling air includes receiving air flow from a propeller of the turboprop engine assembly upstream of the inlet of the air duct.

8. The method as defined in claim 1 , further comprising modulating the flow of cooling air through the air duct and through the heat exchanger by closing at least part of an outlet of the air duct.

9. The method as defined in claim 1 , further comprising modulating the flow of cooling air by obstructing the flow of cooling air out of the turboprop engine assembly by closing a plurality of selectively movable flaps.

10. The method as defined in claim 9 , wherein modulating the flow of cooling air from the air duct includes discharging the flow of cooling air through a permanently open portion of the outlet of the air duct downstream of the selectively movable flaps.

11. The method as defined in claim 1 , wherein discharging the flow of cooling air from the air duct includes exiting the flow of cooling air horizontally relative to the turboprop engine assembly from the air duct to produce thrust.

12. The method as defined in claim 1 , further comprising entraining the flow of cooling air by discharging the flow of exhaust gases upstream of an outlet of the air duct prior to discharging the flow of exhaust gases out of the turboprop engine assembly.

13. The method as defined in claim 1 , wherein discharging the flow of exhaust gases includes channeling the flow of exhaust gases through an exhaust duct extending inside a portion of the air duct.

14. The method as defined in claim 13 , wherein the exhaust gases are channeled through the exhaust duct from a location upstream of the heat exchanger to a location downstream of the heat exchanger.

15. The method as defined in claim 13 , wherein discharging the flow of exhaust gases includes discharging the exhaust gases inside the air duct through an outlet of the exhaust duct located upstream of an outlet of the air duct.

16. The method as defined in claim 1 , wherein channeling the flow of cooling air through the heat exchanger includes flowing the flow of cooling air of the heat exchanger extending across the air duct.

17. The method as defined in claim 1 , wherein discharging the flow of exhaust gases includes discharging the exhaust gases through an exhaust duct having an exhaust outlet downstream of the heat exchanger and upstream of an outlet of the air duct prior to discharging the flow of exhaust gases out of the turboprop engine assembly.

18. The method as defined in claim 1 , wherein discharging the flows of cooling air and exhaust gases includes discharging the flow of cooling air through an open cross-sectional area of an outlet of an exhaust duct smaller than an open cross-sectional area of the air duct transverse to the flow of cooling air and surrounding radially the outlet of the exhaust duct.

19. The method as defined in claim 1 , wherein discharging the flows of cooling air and exhaust gases includes discharging the flow of cooling air through an annular space defined between an exhaust duct and a peripheral wall of the air duct.

20. The method as defined in claim 19 , wherein the flow of cooling air is discharged through the annular space having a cross-sectional area greater than that of an outlet of the exhaust duct.

Assignees

• Pratt & Whitney Canada

Inventors

• Julien Andre
• Dussault Serge
• Thomassin Jean

Classifications

• F01N3/055 Primary

  without contact between air and exhaust gases · CPC title

• B64D27/02

  Aircraft characterised by the type or position of power plants · CPC title

• F02K1/386 Primary

  mixing devices in the jet pipe, e.g. for mixing primary and secondary flow · CPC title

• F02C5/00

  Gas-turbine plants characterised by the working fluid being generated by intermittent combustion · CPC title

• B64D27/10

  of gas-turbine type  (jet aircraft B64D27/16) · CPC title