ENGINE UNIT FOR AN AIRCRAFT

Description

TECHNICAL FIELD

[0001] The present invention relates to a propulsion assembly for an aircraft, said propulsion assembly comprising a propulsion system having an ejection nozzle ensuring the ejection of combustion gases from the propulsion system and a heat exchange system arranged at the level of the ejection nozzle to ensure a transfer of calories to the dihydrogen of the propulsion system, as well as an aircraft comprising at least one such propulsion system. PREVIOUS STATE OF THE ART

[0002] To move, an aircraft typically includes at least one propulsion system, comprising a propulsion unit housed in a nacelle, which can be either a turbojet or a turboprop engine. In each case, the propulsion system includes a rotating assembly that drives a fan or a propeller. The rotating assembly forms the core of the propulsion system and consists, from front to rear, of an air intake that allows air to be drawn into a channel within the core, a compressor that compresses the incoming air, a combustion chamber where the compressed air is mixed with fuel, and a turbine that expands the combustion gases and generates the rotation that is transmitted to the fan or propeller.

[0003] Downstream of the turbine, an ejection nozzle ensures the ejection of combustion gases.

[0004] It is also known, particularly in the case of dihydrogen, that the combustion efficiency of a fuel is improved if the fuel is heated before combustion. It is also known to use some of the hot combustion gases expelled from the exhaust nozzle to preheat the fuel.

[0005] US document 2013 / 305686 A1 and CN document 116 591 859 A disclose propulsion assemblies according to the prior art. DESCRIPTION OF THE INVENTION

[0006] One object of the present invention is to propose an alternative solution for heating dihydrogen before its combustion.

[0007] To this end, a propulsion system is proposed for an aircraft comprising: a propulsion system comprising a fairing, a rotating assembly including a combustion chamber and housed in the fairing, an ejection nozzle disposed downstream of the combustion chamber and delimited by a rear portion of the fairing, called the nozzle wall, and ensuring the ejection of the combustion gases resulting from the combustion of dihydrogen in the combustion chamber, a dihydrogen tank, a supply pipe which connects the tank and the combustion chamber, and at least one blade disposed inside the ejection nozzle where the supply pipe has a portion of pipe arranged in said blade.

[0008] The supply pipeline is a double-walled pipeline with an inner wall delimiting an internal volume in which dihydrogen circulates and an outer wall delimiting an external volume.

[0009] With such an arrangement, the calories from the combustion gases are transferred to dihydrogen.

[0010] According to a particular embodiment, the external volume contains a fluid.

[0011] Advantageously, the propulsion assembly includes a pump which is fluidly connected to the external volume and which is arranged to move the fluid in the external volume.

[0012] According to a particular embodiment, the external volume is evacuated. Advantageously, said at least one blade is equipped with vanes.

[0013] Advantageously, the propulsion assembly comprises an outer ring integral with the nozzle wall, an inner ring disposed inside the outer ring, and said at least one blade is fixed between the outer ring and the inner ring.

[0014] Advantageously, said at least one blade is hollow and delimits a chamber in which at least a part of the portion of piping is disposed, and the wall of the blade is pierced with at least one upstream orifice arranged to permit the introduction of hot combustion gases into the chamber and with at least one downstream orifice arranged to permit the extraction of hot combustion gases from the chamber.

[0015] The invention also proposes an aircraft comprising at least one propulsion assembly according to one of the preceding variants. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The features of the invention mentioned above, as well as others, will become clearer upon reading the following description of an exemplary embodiment, said description being made in relation to the accompanying drawings, among which: There figure 1 is a side view of an aircraft comprising a propulsion system according to the invention, The figure 2 is a schematic representation, side view and cross-section, of a propulsion assembly according to an embodiment of the invention, The figure 3 is a perspective view of a particular embodiment of the invention, The figure 4 is a front view of the figure 3 , There figure 5 is a cut along the VV line of the figure 4 , and La figure 6 is a schematic representation similar to that of the figure 2 for another embodiment of the invention. DETAILED EXPLANATION OF IMPLEMENTATION METHODS

[0017] In the following description, terms relating to a position are taken with reference to an aircraft in a forward position, that is, as it is represented on the figure 1 where arrow F shows the direction of travel of the aircraft.

[0018] There figure 1 shows an aircraft 100 which has a fuselage 102 on either side of which is fixed a wing 104. Under each wing 104 is fixed at least one propulsion assembly 151.

[0019] There figure 2 Figure 151 shows the propulsion assembly comprising a nacelle 149 and a propulsion system 150 enclosed within the nacelle 149. In the embodiment of the invention presented here, the propulsion system 150 takes the form of a turboprop engine with a propeller 152 driven in rotation by a rotating assembly mounted inside a fairing 172 of the propulsion system 150 housed within the nacelle 149, but the propulsion system 150 can also take the form of a turbojet driving a fan. Thus, generally speaking, the propulsion system 150 comprises a rotating assembly and a moving element 152 (propeller or fan).

[0020] In the following description, and by convention, X is called the longitudinal axis which corresponds to the axis of rotation of the moving element 152 oriented positively in the direction of advance of the aircraft 100, Y is called the transverse axis which is horizontal when the aircraft is on the ground, and Z is called the vertical axis or vertical height when the aircraft is on the ground, these three axes X, Y and Z being orthogonal to each other.

[0021] There figure 2 and the figure 6 Figures 150 show the propulsion system in the case of a turboprop. A rotating assembly 160 forms the core of the propulsion system 150 and comprises, from front to back, an air intake 162 which allows air to be introduced into a channel 164 of the core, a compressor 166 which compresses the air thus introduced, a combustion chamber 168 in which the compressed air and dihydrogen mix and burn, and a turbine 170 which allows the expansion of the combustion gases and generates the rotation which is transmitted to the moving element, here the propeller 152. The elements of the rotating assembly 160 are surrounded by the fairing 172 formed of structural housings mounted around the elements of the rotating assembly 160 and which stiffen it in order in particular to limit its distortions during operation.

[0022] The fairing 172 is, on the one hand, open at the front at the level of the air inlet 162 and delimits the duct 164 and is, on the other hand, open at the rear at the level of an ejection nozzle 174 which is downstream of the turbine 170 and therefore of the combustion chamber 168 and ensures the ejection of the combustion gases resulting from the combustion of dihydrogen and air in the combustion chamber 168. The rear portion of the fairing 172 which surrounds the ejection nozzle 174 forms the nozzle wall 180.

[0023] The space between the nacelle 149 and the fairing 172 is occupied by various systems enabling the operation of the propulsion system 150. In particular, in order to supply the combustion chamber 168 with dihydrogen, the propulsion assembly 151 includes a dihydrogen tank 178, which is housed here in the wing 104, a supply line 176 that connects the tank 178 and the combustion chamber 168, and a pump 179 that moves the dihydrogen from the tank 178 to the combustion chamber 168 through the supply line 176. Without departing from the scope of the invention, the dihydrogen tank 178 can also be housed in another part of the aircraft 100, for example in the fuselage 102.

[0024] In order to heat the dihydrogen before its injection into the combustion chamber 168, and to obtain better combustion, the propulsion assembly 151 also includes a heat exchanger system 200 which is arranged, when the propulsion system 150 is in operation, to ensure an exchange of heat between the hot combustion gases circulating in the ejection nozzle 174 and the cooler dihydrogen circulating in the supply pipe 176.

[0025] In general, the heat exchanger system 200 is arranged inside the ejection nozzle 174.

[0026] In the implementation of the figure 2 , the heat exchanger system 200 is arranged in the ejection nozzle 174 at the rear of the turbine 170.

[0027] In the implementation of the figure 6 , the heat exchanger system 200 is arranged in the ejection nozzle 174 at the turbine 170 and around the latter.

[0028] The propulsion assembly 151 also includes at least one blade 210 arranged inside the ejection nozzle 174, depending on the case around the turbine 170 or behind it, to be immersed in the hot combustion gases and the supply pipe 176 has a portion of pipe 202 which is arranged in said blade 210 in order to ensure a transfer of heat from the hot combustion gases to the dihydrogen circulating in the portion of pipe 202 before arriving at the combustion chamber 168.

[0029] The heat exchanger system 200 thus includes the portion of pipe 202 of the supply pipe 176 and the heat exchange takes place at the level of this portion of pipe 202.

[0030] Coming from the hydrogen tank 178, the supply pipe 176 passes through the nozzle wall 180 to become the portion of pipe 202 which flows in the blade 210. The supply pipe 176 then passes through the nozzle wall 180 again before plunging back towards the combustion chamber 168 by passing through the fairing 172.

[0031] Each blade 210 is fixed inside the nozzle wall 180 by any suitable means of fixing such as nuts, weld points, etc., and one embodiment of which is described below.

[0032] According to a particular embodiment, for safety reasons, it is provided that the supply pipeline 176, and in particular the portion of pipeline 202, is a double-walled pipeline with an inner wall delimiting an internal volume in which dihydrogen circulates and an outer wall which is around the inner wall and where an external volume is delimited between the inner and outer walls not containing dihydrogen under normal operating conditions, i.e. without leakage.

[0033] Thus, even in the event of a leak at the level of the inner skin, the dihydrogen will spread into the outer volume while remaining isolated.

[0034] The outer volume can be evacuated or it can be filled with a fluid that is neutral with respect to dihydrogen, such as dinitrogen for example.

[0035] In the event of a leak at the outer skin level, the neutral fluid will spread out of the outer volume or the outer volume will fill with hot combustion gases.

[0036] To prevent a hydrogen leak at pipe section 202, the heat exchanger system 200 may include leak detection means and a control unit connected to the leak detection means. The heat exchanger system 200 also includes a valve mounted on the supply pipe 176 upstream of pipe section 202 relative to the direction of hydrogen flow, and controlled to open and close by the control unit. The control unit closes the valve when the leak detection means detect a leak.

[0037] Leak detection methods include, for example, pressure sensors placed in the outer volume. A leak in the inner or outer wall will be detected by the pressure sensors due to a change in pressure in the outer volume: for example, a leak in the inner wall will be detected if the pressure in the outer volume is approximately equal to the hydrogen pressure in the inner volume, and a leak in the outer wall will be detected if the pressure in the outer volume is approximately equal to the atmospheric pressure outside the pipe section 202.

[0038] When the external volume is evacuated, the external volume is, for example, fluidly connected to a vacuum pump.

[0039] When an external volume is filled with a fluid, the fluid can be static or in motion. When static, the fluid is not moving within the external volume, and in this case, the external volume is preferably fluidically connected to an expansion vessel that allows the pressure to be adjusted to the fluid temperature.

[0040] According to another embodiment, the heat exchanger system 200 includes a pump 220 which is fluidly connected to the external volume and which is arranged to move the fluid in the external volume.

[0041] The 202 pipeline section can consist of several channels, each double-walled, and the channels are supplied by a double manifold, where a first manifold supplies the different external volumes with fluid and where a second manifold supplies the different internal volumes with dihydrogen.

[0042] THE Figs. 3 à 5 show a particular implementation method for the 210 blades.

[0043] The blade or each blade 210 extends here radially around the longitudinal axis X across the ejection nozzle 174.

[0044] For aerodynamic reasons, each blade 210 is relatively flat and has an aerodynamic profile with a leading edge at the front of the blade 210 and a trailing edge at the rear of the blade 210.

[0045] To achieve better heat exchange between the hot combustion gases and the dihydrogen, each blade 210 is equipped with vanes 302 which are made of a material with high thermal conductivity and attached to the blade 210. The vanes 302 are immersed in the hot combustion gases.

[0046] In the embodiment of the invention presented here, the propulsion assembly 151 comprises an outer ring 210a attached to the nozzle wall 180 and an inner ring 210b arranged concentrically inside the outer ring 210a, which therefore has a diameter greater than that of the inner ring 210b.

[0047] The blade or each blade 210 is fixed radially between the outer ring 210a and the inner ring 210b.

[0048] The outer ring 210a is attached to the nozzle wall 180 by any suitable fastening means such as bolts, spot welds, etc. Similarly, the blade(s) 210 are attached to the outer ring 210a by any suitable fastening means, and the inner ring 210b are attached to the blade(s) 210 by any suitable fastening means. As shown in the figure 4 In the case of a double-walled pipe section 202, there is an inner pipe 402a for dihydrogen and around it, there is an outer pipe 402b. These pipes 402a-b are supplied from the supply pipe 176 coming from the tank 178 upstream of the fairing 172 and supply the supply pipe 176 which goes to the combustion chamber 168 downstream of the fairing 172. The pipes 402a-b run in the outer ring 210a, the inner ring 210b and in at least one blade 210.

[0049] According to a particular embodiment, which is shown in the figure 5 , each 402a-b pipe also runs along the longitudinal axis X between a front part 504a of the blade 210 and a rear part 504b of the blade 210.

[0050] In this embodiment, the blade or blades 210 are hollow and delimit a chamber 502 in which at least part of the portion of piping 202 is disposed.

[0051] The wall of the blade 210, particularly the front part 504a, is pierced with at least one upstream orifice 214 arranged to allow the introduction of hot combustion gases into the chamber 502. Similarly, the wall of the blade 210, particularly the rear part 504b, is pierced with at least one downstream orifice 216 arranged to allow the extraction of hot combustion gases from the chamber 502. The orifices 214 and 216 thus open into the chamber 502. The diameters of the orifices 214 and 216 are preferably between 2 mm and 10 mm to ensure the circulation of hot combustion gases in the chamber 502.

[0052] Thus, the hot combustion gases enter chamber 502 to surround the portion of piping 202 and improve the transfer of heat to the dihydrogen.

[0053] Of course, it is possible to have other openings distributed on the 210 blade.

Claims

1. Propulsion assembly (151) for an aircraft (100), comprising: - a propulsion system (150) comprising a fairing (172), a rotary assembly (160) comprising a combustion chamber (168) and housed in the fairing (172), an exhaust nozzle (174) positioned downstream of the combustion chamber (168) and delimited by a rear portion of the fairing (172), referred to as nozzle wall (180), and configured to discharge the combustion gases produced by the combustion of the dihydrogen in the combustion chamber (168), - a dihydrogen tank (178), - a supply duct (176) which connects the tank (178) and the combustion chamber (168), and - at least one vane (210) arranged inside the exhaust nozzle (174), wherein the supply duct (176) has a duct portion (202) arranged in said vane (210), characterised in that the supply duct (176) is a double-walled duct with an inner wall delimiting an inner volume in which the dihydrogen flows and an outer wall delimiting an outer volume.

2. Propulsion assembly (151) according to Claim 1, characterized in that the outer volume contains a fluid.

3. Propulsion assembly (151) according to Claim 2, characterized in that it comprises a pump (220) which is fluidically connected to the outer volume and is arranged to set the fluid in the outer volume in motion.

4. Propulsion assembly (151) according to Claim 3, characterized in that the outer volume is under vacuum.

5. Propulsion assembly (151) according to one of Claims 1 to 4, characterized in that said at least one vane (210) is equipped with fins (302).

6. Propulsion assembly (151) according to one of Claims 1 to 5, characterized in that it comprises an outer ring (210a) secured to the nozzle wall (180) and an inner ring (210b) positioned inside the outer ring (210a), and in that said at least one vane (210) is fixed between the outer ring (210a) and the inner ring (210b).

7. Propulsion assembly (151) according to one of Claims 1 to 6, characterized in that said at least one vane (210) is hollow and delimits a chamber (502) in which at least a part of the duct portion (202) is positioned, and in that at least one upstream orifice (214), arranged to allow the introduction of the hot combustion gases into the chamber (502), and at least one downstream orifice (216), arranged to allow the discharge of the hot combustion gases from the chamber (502), are formed in the wall of the vane (210).

8. Aircraft (100) having at least one propulsion assembly (151) according to one of the preceding claims.