Search

EP-4739578-A1 - AIRCRAFT PROPULSION ASSEMBLY AND THERMAL MANAGEMENT METHOD

EP4739578A1EP 4739578 A1EP4739578 A1EP 4739578A1EP-4739578-A1

Abstract

The present disclosure relates to a propulsion assembly (4) for an aircraft (1) and to a method for the thermal management of such a propulsion assembly (4). The propulsion assembly (4) comprises a first engine (5a) with a heat exchanger (16a) through which an air duct (15a) passes, a second engine (5b), which is a heat engine, and an air interconnection duct (21) connecting the air duct (15a), downstream of the heat exchanger (16a) of the first engine (5a), to the second engine (5b). The thermal management method comprises the steps of heating, in the heat exchanger (16a) of the first engine (5a), an air flow circulating in the air duct (15a) passing through the heat exchanger (16a) of the first engine (5a), and diverting the heated air flow downstream of the heat exchanger (16a) of the first engine (5a), through the air interconnection duct (21), to the second engine (5b).

Inventors

  • DEBAT, Alexandre, Paul, Raimond
  • BEDRINE, OLIVIER
  • ROBERT, OLIVIER
  • COMBEBIAS, Sébastien, Mathieu

Assignees

  • Safran Helicopter Engines

Dates

Publication Date
20260513
Application Date
20240702

Claims (13)

  1. [Claim 1] Propulsion assembly (4) for an aircraft (1), comprising: a first engine (5a) with a heat exchanger (16a) crossed by an air duct (15a), a second engine (5b), which is a heat engine, and an air interconnection duct (21) connecting said air duct (15a), downstream of the heat exchanger (16a) of the first engine (5a), to the second engine (5b), the propulsion assembly (4) being characterized in that the first engine (5a) comprises a lubricant circuit (17b) and the heat exchanger (16a) of the first engine (5a) is an air-oil heat exchanger crossed by the lubricant circuit (17b) of the first engine (5a).
  2. [Claim 2] A propulsion unit (4) according to claim 1, wherein the second engine (5b) is a gas turbine engine.
  3. [Claim 3] A propulsion assembly (4) according to claim 2, wherein the second engine (5b) comprises a gas generator (20b) with a combustion chamber (9b) and a shaft (11b) configured to be rotated in a turning mode with the combustion chamber (9b) off.
  4. [Claim 4] Propulsion assembly (4) according to claim 3 in which the air interconnection conduit (21) opens into the gas generator (20b) of the second engine (5b).
  5. [Claim 5] Propulsion assembly (4) according to any one of claims 1 to 4, in which the second engine (5b) also comprises a heat exchanger (16b) and the air interconnection duct (21) opens upstream of the heat exchanger (16b) of the second engine (5b).
  6. [Claim 6] A propulsion unit (4) according to claim 5, wherein the second engine (5b) comprises a lubricant circuit (17b) and the heat exchanger (16b) of the second engine (5b) is a heat exchanger air-oil heat, crossed by the lubricant circuit (17b) of the second engine (5b).
  7. [Claim 7] A propulsion assembly (4) according to any one of claims 1 to 6, comprising at least one valve (22; 22a, 22b, 22c) for redirecting an air flow from said air duct (15a) to the air interconnection duct (21).
  8. [Claim 8] Propulsion assembly (4) according to claim 7, comprising a piloted actuator (23) for actuating the at least one valve (22; 22a, 22b, 22c).
  9. [Claim 9] Aircraft (1) comprising the propulsion unit (4) according to any one of claims 1 to 8.
  10. [Claim 10] A method for thermally managing a propulsion unit (4) comprising the following steps: heating, in a heat exchanger (16a) of a first engine (5a), an air flow circulating in an air duct (15a) passing through a heat exchanger (16a) of the first engine (5a), and diverting the heated air flow downstream of the heat exchanger (16a) of the first engine (5a), through an air interconnection duct (21), to a second engine (5b), which is a heat engine, the method being characterized in that the first engine (5a) comprises a lubricant circuit (17b) and the heat exchanger (16a) of the first engine (5a) is an air-oil heat exchanger crossed by the lubricant circuit (17b) of the first engine (5a).
  11. [Claim 11] A method according to claim 10, wherein the second motor (5b) is running at reduced speed or is switched off.
  12. [Claim 12] A method according to claim 11, wherein the second engine (5b) is a gas turbine engine comprising a gas generator (20b) with an extinguished combustion chamber (9b) and a shaft (11b) driven in rotation in turning mode.
  13. [Claim 13] A method according to claim 12, wherein the heated air flow is supplied to the gas generator (20b) of the second engine (5b). [Claim 14] A method according to any one of claims 11 to 13, wherein the heated air flow is provided upstream of a heat exchanger (16b) of the second engine (5b).

Description

Description Title of the invention: Aircraft propulsion unit and thermal management method Technical Domain [0001] The present invention relates to the field of aeronautical propulsion and in particular to engine assemblies for aircraft comprising at least two engines such as turboshaft engines or turboprops. In particular, the invention relates to the thermal management of the components of a propulsion assembly for aircraft comprising at least two engines, and a method for thermally managing such a propulsion assembly. Previous technique [0001] Climate change is a major concern for many legislative and regulatory bodies around the world. Indeed, various restrictions on carbon emissions have been, are being or will be adopted by various states. In particular, an ambitious standard applies both to new types of aircraft but also to those in circulation requiring the implementation of technological solutions in order to make them compliant with the regulations in force. Civil aviation has been mobilizing for several years now to make a contribution to the fight against climate change. [0002] Technological research efforts have already made it possible to significantly improve the environmental performance of aircraft. The Applicant takes into consideration the impact factors in all phases of design and development to obtain less energy-intensive, more environmentally friendly aeronautical components and products whose integration and use in civil aviation have moderate environmental consequences with the aim of improving the energy efficiency of aircraft. [0003] Consequently, the Applicant is constantly working to reduce its negative climate impact through the use of methods and the use of virtuous development and manufacturing processes and minimizing greenhouse gas emissions to the minimum possible to reduce the environmental footprint of its activity. [0004] The search for minimizing pollutant emissions linked to air transport involves in particular improving all the efficiencies of propulsion systems, and more particularly the propulsive efficiency which characterizes the efficiency with which the energy used is converted into useful thrust. [0005] For reasons of redundancy, among other things, it is common in the aeronautical field to equip aircraft with at least two engines. In particular, it is common to equip rotary wing aircraft such as helicopters or convertiplanes with propulsion systems of at least two engines, typically gas turbine engines, which can be mechanically coupled together. Such multi-engine propulsion systems allow operation in economical mode, known as “ECO” mode. ECO mode is an operating mode, generally corresponding to a cruising flight phase, of a twin-engine architecture, in which one or more of the engines of the propulsion system are put into standby mode to provide very reduced power, or even zero, with one or more other engines of the propulsion system then providing a large part, or even all of the power supply. [0006] As proposed, in particular in French patent applications FR 2 967 132 A1 and FR 2 967 133 A1, the at least one engine in standby mode can be switched off. In order to speed up restarting, in particular to allow a possible emergency start to replace or support another power source that has failed, it has also been proposed, in these disclosures, to keep a shaft of each switched off heat engine rotating, for example with an electric machine. It is nevertheless alternatively conceivable that the standby mode is a super-idle regime at very low speed, for example at a rotation speed of less than 40% of the nominal rotation speed, without switching off. [0007] However, in such a standby mode, the heat engine generates little or no heat and, depending on the atmospheric conditions, particularly at altitude or in cold weather, its temperature is likely to drop rapidly to very low values, with risks of icing, difficulty in re-igniting and/or loss of lubrication. Indeed, these engines typically need adequate lubrication before being able to deliver power, which imposes a minimum temperature of the lubricant, usually of the order of 273 K to 278 K depending on the lubricant. Thus, in French patent application FR 3 01 1 277 A1, it was proposed to provide at least one heat source to warm the lubricant of the heat engine maintained in standby mode. More specifically, this document proposed to use as a heat source the electric machine actuating a shaft of the heat engine in standby mode and/or the electrical power supply of this electric machine. However, it may be appropriate to find other heat sources that are more efficient and/or simpler to integrate into the heat engine intended to be put into standby mode and/or into its lubrication circuit. Disclosure of the invention [0008] The present disclosure is the result of technological research aimed at very significantly improving the performance of aircraft and, in this sense, contributes to reducing their environmental im