Cryogenic fuel circuit of an aircraft turbine engine

Abstract

The invention relates to a turbine engine (M) of an aircraft (A), which turbine engine includes a fuel circuit (CC) comprising: a tank (10) of cryogenic fuel in the liquid state; a primary distribution circuit (1) in fluid communication with the tank; a secondary distribution circuit (2) intended to be in fluid communication with a combustion chamber (C) of the turbine engine (M); a fluid-heating device (3) comprising a fluid inlet (31) and a fluid outlet (32) in fluid communication with the primary distribution circuit (1) and the secondary distribution circuit (2), respectively, the heating device (3) being configured such that the cryogenic fuel changes from the liquid state to the gaseous state when it passes through the heating device (3), the cryogenic fuel being in the gaseous state at the fluid outlet in communication with the secondary distribution circuit (2).

Description

[0001] DESCRIPTION

[0002] TITLE Cryogenic fuel circuit of an aircraft turbomachine

[0003] FIELD OF INVENTION AND STATE OF THE ART

[0004] The invention relates to a fuel circuit for a turbomachine. More particularly, it relates to a cryogenic two-phase fuel circuit, stored in liquid form and which can be transformed into a gas for injection into a combustion chamber of an aircraft engine turbomachine.

[0005] The fuel systems integrated into aircraft turbomachinery are generally designed for liquid fuel, such as kerosene, which is stored in liquid form in a fuel tank. However, such fuel is highly polluting.

[0006] DESCRIPTION OF THE INVENTION

[0007] The invention proposes a turbomachine comprising a fuel circuit which uses a fuel which is less polluting than a liquid fuel such as kerosene.

[0008] In this respect, the invention proposes, according to a first aspect, a turbomachine for an aircraft comprising a fuel circuit, said circuit comprising,

[0009] - a cryogenic fuel tank in liquid state;

[0010] - a primary distribution circuit in fluidic communication with the reservoir;

[0011] - a secondary distribution circuit intended to be in fluidic communication with a combustion chamber of the turbomachine,

[0012] - a fluid heating device comprising a fluid inlet in fluidic communication with the primary distribution circuit and a fluid outlet in fluidic communication with the secondary distribution circuit, the primary distribution circuit being configured to introduce, during turbomachine operation, a cryogenic fuel in liquid form into the heating device, the heating device being configured to heat the introduced cryogenic fuel in liquid form such that the cryogenic fuel changes from a liquid to a gaseous state when it passes through the heating device, the cryogenic fuel being in a gaseous state at the fluid outlet in communication with the secondary distribution circuit, the primary distribution circuit,The secondary distribution circuit and the heating device are arranged relative to each other such that, in a ground configuration of the aircraft, the heating device forms a low point relative to both the primary and secondary distribution circuits. The invention according to the first aspect is advantageously complemented by the following features, taken alone or in any technically feasible combination thereof:

[0013] - the primary distribution circuit is inclined relative to the horizontal axis when the aircraft is on the ground: by a non-zero negative angle so as to promote the flow of liquid cryogenic fuel from the tank to the heating device; and by a non-zero positive angle so as to prevent stagnation or retention of gaseous cryogenic fuel in the secondary distribution circuit.

[0014] - the primary distribution circuit and the secondary distribution circuit extend respectively from the fluid inlet and the fluid outlet in opposite directions.

[0015] - the primary distribution circuit and the secondary distribution circuit extend respectively from the fluid inlet and the fluid outlet in the same directions.

[0016] - the reservoir and the primary distribution circuit include means of thermal insulation, the means of thermal insulation comprising: an expanding insulating foam; a thermal blanket enveloping the reservoir and the primary distribution circuit.

[0017] - the primary distribution circuit includes several pipes and fluid connections, the thermal insulation means including a double skin with partial vacuum around the pipes and encapsulation of the fluid connections.

[0018] - the heating device includes a heat exchanger.

[0019] According to a second aspect, the invention relates to an aircraft comprising a turbomachine according to the first aspect of the invention, the aircraft comprising a fuselage and wings parallel to the ground when the aircraft is in ground configuration, in particular in position.

[0020] According to a third aspect, the invention relates to an aircraft according to the second aspect of the invention, in which the fuel circuit is installed entirely or partially on the turbomachine.

[0021] According to one embodiment, the fuel circuit is installed in a wing or in the fuselage of the aircraft according to the third aspect of the invention.

[0022] DESCRIPTION OF THE FIGURES

[0023] Other features, purposes and advantages of the invention will become apparent from the following description, which is purely illustrative and not limiting, and which should be read in conjunction with the accompanying drawings on which:

[0024] Figure 1 illustrates a fuel circuit according to a first embodiment of the invention;

[0025] Figure 2 illustrates a fuel circuit according to a second embodiment of the invention;

[0026] Figure 3 illustrates an aircraft comprising a fuel circuit according to the invention. Throughout the figures, similar elements refer to identical reference numerals.

[0027] DETAILED DESCRIPTION OF THE INVENTION

[0028] Figures 1 and 2 illustrate a cryogenic CC fuel circuit of a turbomachine M of an aircraft A allowing fuel to be supplied to a combustion chamber C of an aircraft A.

[0029] The CC fuel circuit described here allows a two-phase cryogenic fuel to be stored in a liquid state and injected into the combustion chamber C in a gaseous state.

[0030] Cryogenic fuel is a type of fuel that is stored at extremely low temperatures to keep it in a liquid state.

[0031] Such a fuel is preferably hydrogen, which is liquid at a temperature of approximately -253°C. Indeed, storing a fuel in a liquid state is more convenient than storing it in a gaseous state. Furthermore, using a cryogenic fuel such as hydrogen instead of a liquid fuel such as kerosene is less polluting.

[0032] The fuel circuit CC includes a tank 10 configured to store cryogenic fuel in liquid form, a primary distribution circuit 1 in fluidic communication with the tank 10, a secondary distribution circuit 2 intended to be in fluidic communication with the combustion chamber C of the turbomachine M of aircraft A, and a heating device 3 comprising a fluid inlet 31 in fluidic communication with the primary distribution circuit 1 and a fluid outlet 32 ​​in fluidic communication with the secondary distribution circuit 2.

[0033] The fuel circuit CC described here is configured to, in operation of the turbomachine, introduce cryogenic fuel in liquid form into the heating device 3. The heating device 3 is configured to heat the introduced cryogenic fuel in liquid form so that it changes from the liquid to the gaseous state when it passes through the heating device 3, the cryogenic fuel being in the gaseous state at the outlet of fluid 31 in communication with the secondary distribution circuit 2 in fluidic communication with the combustion chamber C.

[0034] Such a DC fuel circuit therefore includes a so-called liquid zone in which the fuel circulates in liquid state and a so-called gaseous zone in which the cryogenic fuel circulates in gaseous state.

[0035] However, in such a DC fuel circuit, the natural flow of the fluid is antagonistic (downward for liquid and upward for gas). Consequently, during normal operation and / or maintenance phases requiring cooling or purging of the fuel in the DC circuit, it is essential to avoid the risk of high or low points in the circuit that could accumulate liquid or gaseous fuel. Indeed, this impairs the efficiency of rotating equipment (cavitation) and poses a risk of fire or leaks at the connections.

[0036] To achieve this, the primary distribution circuit 1, the secondary distribution circuit 2 and the heating device 3 are arranged relative to each other so that in a configuration of the aircraft stationary on the ground (in parking position on the tarmac in particular), the heating device 3 forms a low point relative to the primary distribution circuit 1 and relative to the secondary distribution circuit 2.

[0037] The lowest point corresponds to the point where the cryogenic fuel changes state.

[0038] The idea here is to promote the natural flow of fuel in liquid or gaseous state.

[0039] Liquid zone

[0040] Tank 10 is in particular equipped with a cooling system (not shown) to maintain it at a cryogenic temperature suitable for the fuel used.

[0041] The primary distribution circuit 1 is in fluidic connection with the tank 10 and with the fluid inlet 31 of the heating device 3. It advantageously includes a cryogenic pump 11, a filter 12 and a primary shut-off valve 13. These elements are functional at a cryogenic temperature, i.e. approximately -253 °C for hydrogen in the liquid state, and non-functional otherwise, as they do not allow control of the circulation of the liquid fuel in the primary distribution circuit 1.

[0042] When functional, the cryogenic pump 11 allows fuel to be pumped from the tank 10 at a given pressure.

[0043] The primary shut-off valve 13 allows control of the fuel flow in the primary distribution circuit 1 before it enters the heating device 3.

[0044] Advantageously, to prevent heat loss, the entire liquid zone is thermally insulated. Indeed, it is essential for the cryogenic fuel to flow into the primary distribution circuit 1 that it be maintained in a liquid state in this zone until it reaches the fluid inlet 31 of the heating device 3.

[0045] Such insulation prevents the capture of calories that would heat the liquid cryogenic fuel, thus avoiding cavitation which would impair the operation of pump 11 and increase pressure in the event of non-cryogenic fuel temperature.

[0046] Thermal insulation can be achieved in several ways.

[0047] According to one embodiment, the reservoir 10 and the primary distribution circuit 1 can be encapsulated in a partially vacuum enclosure. Indeed, in the absence of air, thermal conductivity is low.

[0048] According to one embodiment, an insulating foam or a thermal blanket can encase the reservoir 10 and the primary distribution circuit 1. The insulating foam is, for example, a polyurethane foam and the thermal blanket is, for example, a rock wool or multi-layer glass wool.

[0049] The primary distribution circuit 1 comprises several pipes 14, the latter may be surrounded by a double wall with partial vacuum.

[0050] Additionally, encapsulating the connections helps to complete the thermal insulation.

[0051] The primary distribution circuit 1 allows the cryogenic liquid fuel to be conveyed from the tank 10 to the heating device 3.

[0052] Therefore, to facilitate the initial filling of the DC fuel circuit, it is important that the cryogenic fuel flows naturally, without suction or pressurization of the equipment, particularly the pump. Indeed, equipment such as the pump and valves operate at a cryogenic temperature (operating clearance at -253°C), meaning the circuit is filled with cryogenic fuel.

[0053] The primary distribution circuit 1 is inclined with respect to the horizontal axis XX when the aircraft A is on the ground by a non-zero negative angle α so as to promote a flow of the liquid cryogenic fuel from the tank 10 to the heating device 3. The angle α is at least for example 1°.

[0054] In particular, the primary distribution circuit 1 includes primary pipes 14 which extend in a direction Y' from the fluid inlet 31 of the heating device 3. The angle a is taken between a horizontal direction Y extending from the fluid inlet 31 and the direction Y' along which the primary pipes 14 extend.

[0055] The idea is that the primary distribution circuit has a slope between tank 10 and the heater 3 when the aircraft is on the ground. The aircraft is on the ground in the parked position on the tarmac.

[0056] Gaseous zone

[0057] The secondary distribution circuit 2 is in fluidic communication with the fluid outlet 32 ​​of the heating device 3 and the combustion chamber C of the aircraft turbomachine M.

[0058] The secondary distribution circuit 2 advantageously includes a flow valve 21 to control the flow of gaseous fuel and a secondary shut-off valve 23 to control the fuel flow in the secondary distribution circuit 2.

[0059] The secondary distribution circuit 2 allows the gaseous fuel from the heating device 3 to the combustion chamber C.

[0060] During system draining for maintenance, it is important that the gaseous fuel escapes naturally, without risk of stagnation or retention of gas pockets. Therefore, the secondary distribution circuit 2 is inclined relative to the horizontal axis (XX) when aircraft A is on the ground at a non-positive angle ( / 3) to prevent stagnation or retention of the gaseous cryogenic fuel in the secondary distribution circuit 2.

[0061] In particular, the distribution circuit 1 includes secondary pipes 23 which extend in a direction Z” from the fluid outlet 32 ​​of the heating device 3. The angle / 3 is taken between a horizontal direction Z extending from the fluid outlet 32 ​​and the direction Z' in which the secondary pipes 15 extend.

[0062] The angle / 3 is at least, for example, 1°.

[0063] Heating device 3

[0064] The heating device 3 therefore makes it possible to heat the liquid cryogenic fuel so that it changes into a gaseous state.

[0065] This is preferably a heat exchanger of a known type and will not be described further here.

[0066] The idea here is to position the heating device 3 relative to the primary and secondary distribution circuits so that it is at the lowest point when aircraft A is on the ground.

[0067] Configuration examples

[0068] In Figure 1, the CC circuit forms a V, meaning that the primary distribution circuit 1 and the secondary distribution circuit 2 extend from the heating device 3 at opposite angles to the ground when aircraft A is on the ground, with the heating device forming the lowest point of the circuit. According to this configuration, the primary 14 and secondary 15 lines extend from the fluid inlet 31 and fluid outlet 31, respectively, in opposite directions.

[0069] In Figure 2 the CC circuit forms a U, that is to say that the primary distribution circuit 1 and the secondary distribution circuit 2 extend from the heating device 3, each forming a non-zero angle with respect to the ground when the aircraft A is on the ground in identical directions, the heating device 3 forming the lowest point of the circuit.

[0070] According to this configuration, the primary 14 and secondary 15 pipes extend from the fluid inlet 31 and fluid outlet 31, respectively, in the same directions. This second configuration in Figure 2 has the advantage of being less bulky than the first configuration in Figure 1. Furthermore, the liquid and gaseous zones can share support points in aircraft A since they are located in approximately the same area. Aircraft

[0071] Figure 3 schematically illustrates an aircraft A comprising a fuselage F and two engines M, each mounted under a wing W.

[0072] The above-described DC circuit can be mounted directly in the turbomachine M or in the fuselage F or in a cavity made in or on the wings W.

Claims

DEMANDS 1. Turbomachine (M) of an aircraft (A) comprising a fuel circuit (CC), said circuit (CC) comprising, - a tank (10) of cryogenic fuel in liquid form; - a primary distribution circuit (1) in fluidic communication with the reservoir (11); - a secondary distribution circuit (2) intended to be in fluidic communication with a combustion chamber (C) of the turbomachine (M); - a fluid heating device (3) comprising a fluid inlet (31) in fluidic communication with the primary distribution circuit (1) and a fluid outlet (32) in fluidic communication with the secondary distribution circuit (2); the primary distribution circuit (1) being configured to, in operation of the turbomachine (M), introduce a cryogenic fuel in liquid form into the heating device (3), the heating device (3) being configured to heat the introduced cryogenic fuel in liquid form so that the cryogenic fuel changes from liquid to gaseous form when it passes through the heating device (3), the cryogenic fuel being in gaseous form at the fluid outlet in communication with the secondary distribution circuit (2);the primary distribution circuit (1), the secondary distribution circuit (2) and the heating device (3) being arranged relative to each other such that in a ground configuration of the aircraft (A), the heating device (3) forms a low point relative to the primary distribution circuit (1) and relative to the secondary distribution circuit (2).

2. Turbomachine according to claim 1, in which the primary distribution circuit (1) is inclined with respect to the axis (XX) to the horizontal when the aircraft (A) is on the ground: - at a non-zero negative angle (z) so as to promote the flow of liquid cryogenic fuel from the tank (10) to the heating device (3); and in which the secondary distribution circuit (2) is inclined with respect to the axis (XX) to the horizontal when the aircraft (A) is on the ground: - of a non-zero positive angle ( / ?) so as to prevent stagnation or retention of gaseous cryogenic fuel in the secondary distribution circuit (2).

3. System according to any one of claims 1 to 2 in which the primary distribution circuit (1) and the secondary distribution circuit (2) extend respectively from the fluid inlet (31) and the fluid outlet (32) in opposite directions.

4. System according to any one of claims 1 to 2, wherein the primary distribution circuit (1) and the secondary distribution circuit (2) extend respectively from the fluid inlet (31) and the fluid outlet (32) in the same directions.

5. A system according to any one of claims 1 to 4, wherein the reservoir (10) and the primary distribution circuit (1) comprise thermal insulation means, the thermal insulation means comprising: - an expanding insulating foam; - a thermal cover enveloping the reservoir (10) and the primary distribution circuit (1).

6. System one of the preceding claims, wherein the primary distribution circuit (1) comprises several pipes (14) and fluidic connections (15), the thermal insulation means comprising a double skin with partial vacuum around the pipes and encapsulation of the fluidic connections (15).

7. System according to any one of the preceding claims, wherein the heating device (3) comprises a heat exchanger.

8. Aircraft comprising a turbomachine according to any one of the preceding claims, the aircraft (A) comprising a fuselage and wings parallel to the ground when the aircraft (A) is in ground configuration in particular in parking position on the tarmac.

9. Aircraft according to the preceding claim, in which the fuel circuit (CC) is installed wholly or partially on the turbomachine (M).

10. Aircraft according to claim 8, in which the fuel circuit (CC) is installed in a wing (W) or in the fuselage (F).

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