AIRCRAFT PROPULSION ASSEMBLY

Abstract

AIRCRAFT PROPULSION ASSEMBLY The invention relates to a propulsion assembly (151) comprising a fairing (172), a combustion chamber (168) housed within the fairing (172), an ejection nozzle (174) delimited by a nozzle wall (180), a hydrogen tank (178), a double-walled supply pipe (176) between the tank (178) and the combustion chamber (168) having an inner wall delimiting an internal volume for the circulation of hydrogen and an outer wall delimiting an external volume, and a deflection chamber (212) disposed around the nozzle wall (180) pierced by an upstream orifice (214) for the introduction of combustion gases and a downstream orifice (216) for the extraction of combustion gases, and wherein the supply pipe (176) has a portion (202) arranged in said diversion chamber (212).With such an arrangement, the calories from the combustion gases are transferred to the dihydrogen for better combustion and under good safety conditions. Fig. 2.

Description

Title of the invention: PROPULSION ASSEMBLY FOR AIRCRAFT Technical field

[0001] The present invention relates to a propulsion assembly for an aircraft, said propulsion assembly comprising a propulsion system comprising an ejection nozzle ensuring the ejection of combustion gases from the propulsion system and a heat exchange system arranged at 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. STATE OF THE PRIOR ART

[0002] In order to move, an aircraft conventionally comprises at least one propulsion unit comprising a propulsion system arranged in a nacelle and which may take the form of a turbojet or a turboprop. In each case, the propulsion system comprises a rotating assembly which drives a fan or a propeller. The rotating assembly constitutes a core of the propulsion system and comprises from front to rear an air inlet which allows the introduction of air into a vein of the core, a compressor which compresses the air thus introduced, a combustion chamber in which the air thus compressed and a fuel are mixed, and a turbine which allows the expansion of the combustion gases and which generates the rotation which is transmitted to the fan or to the propeller.

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

[0004] It is also known, particularly in the case of dihydrogen, that the yield of The combustion of a fuel is improved if the fuel is heated before combustion. It is also known to use part of the hot combustion gases discharged through the exhaust nozzle to heat the fuel. Statement of the invention

[0005] An object of the present invention is to propose another solution for heating dihydrogen before its combustion in complete safety.

[0006] For this purpose, a propulsion unit is proposed for an aircraft comprising:

[0007] - a nacelle,

[0008] - a propulsion system arranged inside the nacelle and comprising a fairing, a rotating assembly comprising a combustion chamber and housed in the fairing, an ejection nozzle arranged downstream of the combustion chamber and delimited by a rear portion of the fairing, called the nozzle wall, and ensuring the ejection of combustion gases resulting from the combustion of dihydrogen in the combustion chamber,

[0009] - a hydrogen tank,

[0010] - a supply pipe which connects the tank and the combustion chamber and which is a double-skinned pipeline with an inner skin delimiting an interior volume in which the dihydrogen circulates and around it an outer skin delimiting an exterior volume, and

[0011] - a deflection chamber arranged around the nozzle wall, where the nozzle wall nozzle is pierced with at least one upstream orifice arranged to allow the introduction of hot combustion gases into the deflection chamber and at least one downstream orifice arranged to allow the extraction of hot combustion gases from the deflection chamber, and where the supply pipe has a portion of pipe arranged in said chamber.

[0012] With such an arrangement, the calories from the combustion gases are transferred to the dihydrogen and the installation of a double-skinned pipeline ensures high safety even in the event of a leak.

[0013] According to a particular embodiment, the external volume contains a fluid.

[0014] Advantageously, the propulsion assembly comprises a pump which is fluidically connected to the external volume and which is arranged to set the fluid in motion in the external volume.

[0015] According to a particular embodiment, the external volume is evacuated.

[0016] Advantageously, the outer skin is equipped with fins.

[0017] According to a particular embodiment, the portion of pipe surrounds the nozzle wall.

[0018] According to a particular embodiment, the pipe portion extends around the nozzle wall over an angular portion.

[0019] The invention also proposes an aircraft comprising at least one propulsion unit according to one of the preceding variants. Brief description of the drawings

[0020] The above-mentioned features of the invention, as well as others, will appear more clearly on reading the following description of an exemplary embodiment, said description being made in relation to the attached drawings, among which:

[0021] [Fig-1] is a side view of an aircraft comprising a propulsion unit according to the invention,

[0022] [Fig.2] is a schematic representation seen from the side and in section of a propulsion unit according to the invention, and

[0023] [Fig.3] is a schematic representation of detail III of [Fig.2].

[0024] DETAILED DESCRIPTION OF EMBODIMENTS

[0025] In the following description, terms relating to a position are taken with reference to an aircraft in forward position, that is to say as shown in [Fig.l], where the arrow F shows the direction of forward movement of the aircraft.

[0026] [Fig.l] shows an aircraft 100 which has a fuselage 102 on either side of which a wing 104 is fixed. Under each wing 104 is fixed at least one propulsion unit 151.

[0027] [Fig.2] shows the propulsion assembly 151 which comprises a nacelle 149 and a propulsion system 150 surrounded by the nacelle 149. In the embodiment of the invention presented here, the propulsion system 150 takes the form of a turboprop with a propeller 152 driven in rotation by a rotating assembly mounted inside a fairing 172 of the propulsion system 150 housed inside the nacelle 149, but the propulsion system 150 can also take the form of a turbojet driving a fan. Thus, in general, the propulsion system 150 comprises a rotating assembly and a movable element 152 (propeller or fan).

[0028] In the following description, and by convention, the longitudinal axis which corresponds to the axis of rotation of the mobile element 152 oriented positively in the direction of advancement of the aircraft 100 is called X, the transverse axis which is horizontal when the aircraft is on the ground is called Y, and the vertical axis or vertical height when the aircraft is on the ground is called Z, these three axes X, Y and Z being orthogonal to each other.

[0029] [Fig.2] shows the propulsion system 150 in the case of a turboprop. A rotating assembly 160 constitutes a core of the propulsion system 150 and comprises from front to rear, an air inlet 162 which allows the introduction of air into a vein 164 of the core, a compressor 166 which compresses the air thus introduced, a combustion chamber 168 in which the air thus compressed and dihydrogen mix and burn, and a turbine 170 which allows the expansion of the combustion gases and which generates the rotation which is transmitted to the mobile element, here the propeller 152. The elements of the rotating assembly 160 are surrounded by the fairing 172 formed of structural casings mounted around the elements of the rotating assembly 160 and allow it to be stiffened in order in particular to limit its distortions in operation.

[0030] The fairing 172 is, on the one hand, open at the front at the air inlet 162 and delimits the vein 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 the dihydrogen and the air in the combustion chamber 168. The rear part of the fairing 172 which surrounds the ejection nozzle 174 forms the nozzle wall 180.

[0031] The space between the nacelle 149 and the fairing 172 is occupied by various systems enabling the propulsion system 150 to operate. In particular, in order to supply the combustion chamber 168 with dihydrogen, the propulsion assembly 151 comprises a hydrogen tank 178 which is here housed in the wing 104, a supply pipe 176 which connects the tank 178 and the combustion chamber 168 and a pump 179 which sets the hydrogen in motion from the tank 178 to the combustion chamber 168 through the supply pipe 176. Without departing from the scope of the invention, the hydrogen tank 178 can also be housed in another part of the aircraft 100, for example in the fuselage 102.

[0032] In order to heat the dihydrogen before its injection into the combustion chamber 168, and to obtain better combustion, the propulsion assembly 151 also comprises a heat exchanger system 200, which is arranged in the space between the nacelle 149 and the fairing 172, and which is arranged, when the propulsion system 150 is in operation, to ensure an exchange of calories between the hot combustion gases circulating in the ejection nozzle 174 and the colder dihydrogen circulating in the supply pipe 176.

[0033] The propulsion assembly 151 comprises a cowling 210 which is fixed, preferably in a sealed manner, to the nozzle wall 180 and on the outside thereof, and where the cowling 210 and the nozzle wall 180 define between them a deflection chamber 212 which is thus arranged around the nozzle wall 180. The fixing of the cowling 210 is carried out for example by welding or riveting along the periphery of the cowling 210.

[0034] The nozzle wall 180 is pierced with at least one upstream orifice 214 forming an air inlet towards the deflection chamber 212 and at least one downstream orifice 216 forming an air outlet from the deflection chamber 212 to ensure the circulation of the hot combustion gases in the deflection chamber 212.

[0035] Each upstream orifice 214 is arranged to allow the introduction of hot combustion gases from the ejection nozzle 174 into the deflection chamber 212 and each downstream orifice 216 is arranged to allow the extraction of hot combustion gases from the deflection chamber 212 towards the ejection nozzle 174.

[0036] The or each upstream orifice 214 is located at a front portion of the cowling 210 and the or each downstream orifice 216 is located at a rear portion of the cowling 210.

[0037] The heat exchanger system 200 comprises a portion of pipe 202 which is a portion of the supply pipe 176 arranged in said deflection chamber 212 and the exchange of calories takes place at the level of this portion of pipe 202.

[0038] The portion of pipe 202 thus passes through the cowling 210 a first time coming from the hydrogen tank 178 to enter the deflection chamber 212 and passes through the cowling 210 a second time to exit the deflection chamber 212 and reach the combustion chamber 168.

[0039] Thus, the portion of pipe 202 is fixed in the deflection chamber 212 in the vicinity of the nozzle wall 180 and the heating of the dihydrogen takes place directly in the supply pipe 176.

[0040] The hot combustion gases thus enter the deflection chamber 212 to heat the dihydrogen circulating in the supply pipe 176 before arriving at the combustion chamber 168.

[0041] Furthermore, for safety reasons, it is provided that the supply pipe 176, and in particular the pipe portion 202, is a double-skinned pipe with an inner skin delimiting an inner volume in which the dihydrogen circulates and an outer skin which is around the inner skin and where an outer volume is delimited between the inner skin and the outer skin which does not contain dihydrogen under normal operating conditions, that is to say without leakage.

[0042] 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.

[0043] The external volume can be evacuated or it can be filled with a fluid that is neutral with respect to dihydrogen, such as dinitrogen for example.

[0044] In the event of a leak at the outer skin, the neutral fluid will spread outside the outer volume or the outer volume will fill with hot combustion gases.

[0045] To prevent a leak of dihydrogen at the pipe portion 202, the heat exchanger system 200 may comprise leak detection means and a control unit connected to the leak detection means. The heat exchanger system 200 also comprises a valve mounted on the supply pipe 176 upstream of the pipe portion 202 relative to the direction of flow of the dihydrogen and controlled in opening and closing by the control unit. The control unit controls the closing of the valve when the leak detection means detect a leak.

[0046] The leak detection means are, for example, pressure sensors arranged in the outer volume. A leak from the inner skin or from the outer skin will be detected by the pressure sensors due to a change in the pressure in the outer volume: for example, a leak from the inner skin will be detected if the pressure in the outer volume is substantially equal to the pressure of dihydrogen in the inner volume and a leak from the outer skin will be detected if the pressure in the outer volume is substantially equal to the pressure of the atmosphere outside the pipe portion 202.

[0047] When the external volume is evacuated, the external volume is for example fluidically connected to a vacuum pump.

[0048] When the external volume is filled with a fluid, the latter can be static or in movement. When it is static, the fluid is not in motion inside the external volume and in this case, the external volume is preferentially fluidically connected to an expansion tank which allows the pressure to be adapted to the temperature of the fluid.

[0049] According to another embodiment, the heat exchanger system 200 comprises a pump 220 which is fluidically connected to the external volume and which is arranged to set the fluid in motion in the external volume.

[0050] [Fig.3] shows an enlargement of zone III for a particular embodiment.

[0051] The pipe portion 202 may consist of several channels, each being double-skinned, and the channels are supplied by a double collector, where a first collector supplies the different exterior volumes with fluid and where a second collector supplies the different interior volumes with dihydrogen.

[0052] To have a better heat exchange between the hot combustion gases and the dihydrogen, the outer skin is equipped with fins 302 which are made of a material with high thermal conductivity and integral with the outer skin. The fins are immersed in the hot combustion gases.

[0053] According to a particular embodiment, the pipe portion 202 surrounds the nozzle wall 180 and thus has at least one turn which goes around the nozzle wall 180. Such an arrangement increases the transfer of calories from the hot combustion gases.

[0054] According to another particular embodiment, the pipe portion 202 extends around the nozzle wall 180 but only over an angular portion around the longitudinal axis X.

[0055] In the embodiment of the invention presented in [Fig. 3], the nozzle wall 180 which is between the upstream orifice 214 and the downstream orifice 216 takes the form of an aerodynamic profile having at the level of the upstream orifice 214 and downstream of the latter, a rounded leading edge 304 and at the level of the downstream orifice 216, and upstream of the latter, a trailing edge 306.

[0056] To ensure good penetration of the hot combustion gases through the upstream orifice 214, the leading edge 304 is spaced towards the inside of the ejection nozzle 174 relative to the nozzle wall 180 which is upstream of the upstream orifice 214 to leave a passage for the hot combustion gases. The distance 'd' shows this gap.

[0057] At the upstream orifice 214, the cowling 210 has an angle α of 10° to 15° relative to the nozzle wall 180 which is upstream of the upstream orifice 214.

[0058] At the downstream orifice 216, the cowling 210 has an angle [3 of 30° to 40° relative to the nozzle wall 180 which is downstream of the downstream orifice 216.

Claims

Claims

1. Propulsion assembly (151) for an aircraft (100) comprising: - a nacelle (149), - a propulsion system (150) arranged inside the nacelle (149) and comprising a fairing (172), a rotary assembly (160) comprising a combustion chamber (168) and housed in the fairing (172), an ejection nozzle (174) arranged downstream of the combustion chamber (168) and delimited by a rear portion of the fairing (172), called the nozzle wall (180), and ensuring the ejection of combustion gases resulting from the combustion of dihydrogen in the combustion chamber (168), - a dihydrogen tank (178), - a supply pipe (176) which connects the tank (178) and the combustion chamber (168) and which is a double-skinned pipe with a inner skin delimiting an interior volume in which the dihydrogen circulates and around it an outer skin delimiting an exterior volume,and - a deflection chamber (212) arranged around the nozzle wall (180), where the nozzle wall (180) is pierced with at least one upstream orifice (214) arranged to allow the introduction of hot combustion gases into the deflection chamber (212) and at least one downstream orifice (216) arranged to allow the extraction of hot combustion gases from the deflection chamber (212), and where the supply pipe (176) has a pipe portion (202) arranged in said deflection chamber (212).,

2. Propulsion assembly (151) according to claim 1, characterized in that the external 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 external volume and which is arranged to set the fluid in motion in the external volume.

4. Propulsion assembly (151) according to claim 1, characterized in that the external volume is evacuated.

5. Propulsion assembly (151) according to one of claims 1 to 4, characterized in that the outer skin is equipped with fins (202).

6. Propulsion assembly (151) according to one of claims 1 to 5, characterized in that the pipe portion (202) surrounds the nozzle wall (180).

7. Propulsion assembly (151) according to one of claims 1 to 5, characterized in that the pipe portion (202) extends around the nozzle wall (180) over an angular portion.

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

Images