Fuel conditioning system for powering an aircraft turbomachine, aircraft and operating method

Abstract

A fuel conditioning system (SC) configured to supply a main turbomachine (T), from fuel (Q) from a cryogenic tank (R1), comprising a pump (1) configured to operate at a predetermined constant speed, at least one heat exchanger (3), a supply element (6) of the main turbomachine (T) with a fuel flow (Q), the supply element (6) defining a predetermined passage section, the supply element (6) being configured to provide a nominal supply flow rate when the pump (1) operates at a predetermined constant speed, at least one buffer tank (4), a first valve (V1) for controlling the supply of the buffer tank (4), a second valve (V2) for controlling the distribution of the fuel flow (Q) and a control device (5) configured to open the second valve (V2) when the set flow rate is greater than the nominal supply flow rate.Figure from the summary: Figure 2.

Description

Title of the invention: Fuel conditioning system for powering an aircraft turbomachine, aircraft and method of use Technical field

[0001] The present invention relates to the field of aircraft comprising turbo-machines powered by fuel stored in a cryogenic tank.

[0002] It is known to store fuel, in particular hydrogen, in liquid form to limit the size and mass of the aircraft tanks. For example, the fuel is stored at a temperature of the order of 20 to 22 Kelvins (-253 to -251°C) in a cryogenic tank of the aircraft.

[0003] In order to be injected into the combustion chamber of a turbomachine, the fuel must be conditioned, i.e. pressurized and heated, in order to allow optimal combustion. Conditioning is for example necessary to reduce the risk of icing of the water vapor contained in the air circulating in the turbomachine, in particular, at the fuel injectors of the turbomachine. With reference to [Fig.l], there is shown a SCAA conditioning system according to the prior art comprising a fuel circuit 100 connected at the inlet to a cryogenic tank RI and at the outlet to the combustion chamber CC of a turbomachine T. A flow of fuel Q circulating from upstream to downstream in the fuel circuit 100 successively passes through a mechanical pump 101 and a heating module 102.

[0004] In practice, to carry out the pumping, a mechanical pump 101 of the volumetric or centrifugal type is generally used. Such a mechanical pump 101 has many disadvantages in terms of efficiency. A mechanical pump 101 does not allow operation over a wide range of flow rate / pressure for high efficiency. Also, in practice, it is necessary to use a mechanical pump 101 whose operating point is not optimal and which requires moving away from the recommended operating range of said mechanical pump 101, which increases the constraints applied to the mechanical pump 101 and reduces its efficiency. Such a mechanical pump 101 cannot therefore adapt its flow rate optimally according to the needs of the turbomachine T. For example, for a civil transport aircraft, the set flow rate of the turbomachine T in a takeoff phase may be more than three times higher than the set flow rate in a cruising phase.

[0005] Furthermore, the discharge pressure of a mechanical pump 101 reduces as the flow rate increases, which goes against the need of the turbomachine T for which the injection pressure and the injected flow rate both increase with the thrust. generated.

[0006] The invention thus aims to eliminate at least some of these drawbacks by proposing a new fuel conditioning system allowing compression and heating with better efficiency and greater operability. PRESENTATION OF THE INVENTION

[0007] The invention relates to a fuel conditioning system configured to supply an aircraft turbomachine, called the main turbomachine, with fuel from a cryogenic tank, the main turbomachine having a fuel setpoint flow rate which is a function of the movement phase of the aircraft, the conditioning system comprising: • a fuel circuit connected at the inlet to the cryogenic tank and at the outlet to the main turbomachine, • a pump configured to circulate a flow of fuel from upstream to downstream in the fuel circuit, the pump being configured to operate at a predetermined constant speed, • at least one heat exchanger configured to transmit calories from a hot source to the fuel flow via a heating circuit, • a feed member of the main turbomachine with a fuel flow, the feed member defining a predetermined passage section, the feed member being configured to provide a nominal feed flow rate when the pump operates at a predetermined constant speed, • at least one buffer tank configured to supply the main turbomachine in parallel with the supply member, the buffer tank being configured to be supplied by a fuel flow, • at least one first valve for controlling the supply of fuel to the buffer tank, • at least one second valve for controlling the distribution of the fuel flow from the buffer tank, and • a regulating device configured to open the second valve when the set flow rate is greater than the nominal supply flow rate.

[0008] Subsequently, by predetermined constant speed / flow rate, we mean a speed / flow rate whose variation does not exceed + / -10% compared to a determined speed / flow rate value.

[0009] Thanks to the invention, a pump of simple and inexpensive design can be used since it operates at a predetermined constant speed. Advantageously, the conditioning system can follow the set flow rate by dynamically regulating the distribution of fuel from the buffer tank, by particularly during a take-off phase in which fuel requirements are high.

[0010] Preferably, the heat exchanger is positioned upstream of the buffer tank. Alternatively, the heat exchanger is positioned downstream of the buffer tank.

[0011] Preferably, the regulating device is configured to close the second valve when the set flow rate is lower than the nominal supply flow rate. Thus, the fuel from the buffer tank is used sparingly, preferably only during a take-off phase.

[0012] More preferably, the regulating device is configured to close the first valve when the set flow rate is greater than the nominal supply flow rate. Thus, the supply member makes it possible to provide the nominal supply flow rate.

[0013] Preferably, the first valve having a configurable opening degree, the regulation device is configured to vary the opening degree of the first valve as a function of a comparison between the nominal supply flow rate and the set flow rate. Preferably, the opening degree obeys a determined opening law f of the type f(d6n - dT). Advantageously, the surplus fuel is stored dynamically in the buffer tank, which is very advantageous. Thus, when the difference is small, the buffer tank fills gently to absorb the surplus flow rate. This makes it possible to avoid using the pump with too high a speed. Conversely, when the difference is large, the buffer tank fills quickly to absorb the surplus flow rate. The buffer tank thus has sufficient fuel to ensure a new takeoff phase.

[0014] Alternatively, the regulating device is configured to open the first valve according to a first degree of opening when the difference between the nominal supply flow rate and the set flow rate is less than a predetermined difference. Thus, when the difference is small, the buffer tank fills gently to absorb the excess flow rate. This makes it possible to avoid using the pump at too high a speed.

[0015] Alternatively, the regulating device is configured to open the first valve according to a second degree of opening, greater than the first degree of opening, when the difference between the nominal supply flow rate and the set flow rate is greater than the predetermined difference. Thus, when the difference is significant, the buffer tank fills quickly to absorb the excess flow rate. The buffer tank thus has sufficient fuel to ensure a new takeoff phase.

[0016] According to one aspect of the invention, the fuel conditioning system comprises at least one auxiliary heat exchanger mounted between the second valve and the main turbomachine so as to heat the fuel flow prior to its injection into the main turbomachine. Thus, the cooling of the fuel from the buffer tank following its thermodynamic expansion can be compensated so as to inject fuel into the main turbomachine with an optimal, preferably constant, temperature.

[0017] Preferably, the heat source is an auxiliary power generation device powered by the fuel circuit. Thus, the heat source is autonomous.

[0018] Preferably, the auxiliary power generation device is configured to operate at constant speed, in particular, over a reduced operating range. This makes it possible to limit its cost and its size.

[0019] Preferably, the auxiliary power generation device is an auxiliary turbomachine or a fuel cell. A fuel cell has a high efficiency over a reduced operating range, which makes its use very relevant in this context.

[0020] Preferably, the fuel conditioning system comprises at least one propulsion member and a system for driving said propulsion member, the drive system being configured to be powered by the main turbomachine and by the auxiliary power generation device. The power of the auxiliary power generation device can be used to reduce the power of the main turbomachine, which can thus have a less bulky and expensive structure.

[0021] Preferably, the fuel is dihydrogen. Such a fuel is particularly suitable for a fuel cell.

[0022] Preferably, the nominal feed flow rate is determined to be greater than the set flow rate in the cruise phase and less than the set flow rate in the takeoff phase. Thus, there is always a surplus flow rate to fill the buffer tank in the cruise phase.

[0023] The invention also relates to an aircraft comprising a conditioning system as presented previously.

[0024] The invention also relates to a method for supplying fuel to an aircraft turbomachine, called the main turbomachine, using fuel from a cryogenic tank, the main turbomachine having a fuel setpoint flow rate, which is a function of the movement phase of the aircraft, the method comprising steps consisting of: circulating a flow of fuel from upstream to downstream in a fuel circuit by means of a pump operating at a constant pre-set speed determined, the pump providing a nominal feed flow, • transmit calories from a hot source to the fuel flow via a heating circuit, • empty a buffer tank, supplied by the fuel circuit, when the set flow rate is higher than the nominal supply flow rate.

[0025] Preferably, the method comprises a step of supplying the buffer tank with fuel when the set flow rate is lower than the nominal supply flow rate.

[0026] Preferably, the method comprises a step consisting of varying the supply of the buffer tank as a function of a comparison between the nominal supply flow rate and the set flow rate.

[0027] The invention also relates to a method of using a fuel conditioning system as presented previously, the main turbomachine having a set flow rate which is a function of the movement phase of the aircraft, the pump operating at a predetermined constant speed, the method comprising at least one step consisting of opening the second valve when the set flow rate is greater than the nominal supply flow rate. PRESENTATION OF FIGURES

[0028] The invention will be better understood on reading the description which follows, given by way of example, and referring to the following figures, given by way of non-limiting examples, in which identical references are given to similar objects.

[0029] [Fig.l] is a schematic representation of a fuel conditioning system according to the prior art.

[0030] [Fig.2] is a schematic representation of a fuel conditioning system according to a first embodiment of the invention, the heat exchanger being in the downstream position.

[0031] [Fig. 3] is a schematic representation of different fuel flow rates during the different phases of use of the main turbomachine.

[0032] [Fig.4] is a schematic representation of the evolution of the pressure in the buffer tank during the different phases of use of the main turbomachine.

[0033] [Fig.5] is a schematic representation of different temperatures during the different phases of use of the main turbomachine.

[0034] [Fig.6] is a schematic representation of a fuel conditioning system according to a second embodiment of the invention.

[0035] [Fig.7] is a schematic representation of a conditioning system of fuel according to a third embodiment of the invention.

[0036] [Fig.8] is a schematic representation of the steps of implementing a method of using a fuel conditioning system.

[0037] [Fig.9] is a schematic representation of a fuel conditioning system according to a variant of the first embodiment of the invention, the heat exchanger being in the upstream position.

[0038] It should be noted that the figures set out the invention in detail to implement the invention, said figures can of course be used to better define the invention where appropriate. DETAILED DESCRIPTION OF THE INVENTION

[0039] With reference to [Fig. 2], there is shown a fuel conditioning system SC configured to supply an aircraft turbomachine, called the main turbomachine T, from fuel Q from a cryogenic tank RL. The main turbomachine T is configured to provide propulsion for the aircraft, in particular, by driving at least one propulsion member (not shown in [Fig. 2]).

[0040] The main turbomachine T has a setpoint flow rate dT of fuel Q which is a function of the phase of use of the main turbomachine T. Thus, with reference to [Fig.3], the setpoint flow rate dT is very high during a takeoff phase S1, medium during a cruise phase S2 and low during a landing phase S3.

[0041] In this example, the fuel is liquid hydrogen but the invention applies to other types of fuel, for example, liquid methane or liquefied natural gas.

[0042] First embodiment ([Fig.2])

[0043] According to a first embodiment, with reference to [Fig. 2], the conditioning system SC comprises a fuel circuit CQ (solid line in [Fig. 2]) connected at the inlet to the cryogenic tank RI and at the outlet to the main turbomachine T. The conditioning system SC also comprises a pump 1, preferably high pressure, configured to circulate a flow of fuel Q from upstream to downstream in the fuel circuit CQ.

[0044] Preferably, the pump 1 is configured to operate at a constant speed, in particular, corresponding to a high efficiency. The pump 1 advantageously provides a constant overpressure. Such a constant speed makes it possible to generate a constant flow of fuel by the supply member 6 as will be presented later. Such a pump 1, having a restricted operating range, has high reliability, a small footprint and a reduced cost.

[0045] With reference to [Fig.2], the packaging system SC further comprises a heat exchanger 3 configured to transmit calories from a hot source to the fuel flow Q taken by pump 1 in order to heat it to allow its optimal injection into the main turbomachine T.

[0046] In this example, the heat source is in the form of an auxiliary power generation device 2 which is configured to generate calories and supply them to the heat exchanger 3. In other words, the auxiliary power generation device 2 performs a heating function in order to increase the temperature of the fuel flow Q so that it can be injected into the main turbomachine T. In this example, the auxiliary power generation device 2 is directly powered by the fuel circuit Q and is thus autonomous. The auxiliary power generation device 2 is powered by a fraction of the heated fuel flow Q. In this example, the fuel conditioning system SC comprises an expander 7 configured to expand the fuel flow Q before powering the auxiliary power generation device 2.Thus, the auxiliary power generation device 2 is optimally supplied.

[0047] Preferably, the calories from the auxiliary power generation device 2 are transmitted to the fuel flow Q via a heating circuit C2, for example, a cooling circuit of the auxiliary power generation device 2 such as an oil circuit or an exhaust air circuit. For example, the calories generated by the auxiliary power generation device 2 may come from the fatal heat of said auxiliary power generation device 2 or from one of its cooling circuits (oil, etc.).

[0048] Preferably, the auxiliary power generation device 2 operates at a constant speed, in particular, corresponding to a high efficiency. Its speed is determined to provide suitable heating. Such an auxiliary power generation device 2, having a restricted operating range, has high reliability, a small footprint and a reduced cost.

[0049] According to one aspect, the auxiliary power generation device 2 is an auxiliary turbomachine and makes it possible to produce mechanical power that can be used by the aircraft. The exhaust gases or the oil of the auxiliary turbomachine can in particular be used as heating circuit C2. According to another aspect, the auxiliary power generation device 2 is a fuel cell, in particular, supplied with dihydrogen. Such a fuel cell 2 makes it possible to generate electrical power that can be used by the aircraft. Examples of use will be presented later.

[0050] The conditioning system SC further comprises a supply member 6 of the main turbomachine T with a heated fuel flow Q, the supply member 6 defining a predetermined passage section. In a manner preferred, the feed member 6 is an orifice having a predetermined passage section. Advantageously, since the pump 1 operates at a constant flow rate, the predetermined passage section of the feed member 6 makes it possible to provide a feed flow rate d6 which is constant to the main turbomachine T when there is no other draw. Preferably, the flow rate of the pump 1 as well as the predetermined passage section of the feed member 6 are determined so as to provide a nominal feed flow rate d6n, this being determined to be, on the one hand, lower than the set flow rate of the turbomachine dT in the take-off phase SI and, on the other hand, higher than the set flow rate of the turbomachine dT in the cruise phase S2 but insufficient on its own in the take-off phase SI. Thus, the nominal feed flow rate d6n is sufficient to meet the needs of the main turbomachine T in the cruise phase S2.Preferably, the nominal feed flow d6n is between 0% and 10% higher than the set flow rate of the turbomachine dT in cruise phase S2. Such a nominal feed flow d6n makes it possible to reduce the speed of the pump 1 and therefore to reduce its size and cost.

[0051] Still with reference to [Fig.2], the conditioning system SC comprises at least one buffer tank 4 configured to supply the main turbomachine T in parallel with the supply member 6. The buffer tank 4 is configured to be supplied with a heated fuel flow Q. Thus, the buffer tank 4 makes it possible to provide an additional flow rate to supplement the supply flow rate d6, in particular, in the takeoff phase S1 as will be presented later.

[0052] The buffer tank 4, also called “gas capacity”, has the advantage of conditioning the fuel Q in the gaseous state, which makes it possible to have fuel Q which can be made immediately available to the main turbomachine T.

[0053] With reference to [Fig. 2], the conditioning system SC comprises a first valve VI for controlling the supply of the buffer tank 4 with heated fuel flow Q, positioned upstream of the buffer tank 4, and a second valve V2 for controlling the distribution of the heated fuel flow Q from the buffer tank 4, positioned downstream of the buffer tank 4. The valves VI, V2 thus make it possible to control respectively the inlet and outlet of heated fuel Q to adapt dynamically to the set flow rate dT while the pump 1 operates at a constant speed. Thus, the first valve VI makes it possible to control an inlet flow rate d4e of the buffer tank 4 while the second valve V2 makes it possible to control an outlet flow rate d4s of the buffer tank 4. Preferably, the second valve V2 comprises a sonic orifice making it possible to make the flow rate in the second valve V2 independent of the downstream conditions.The first valve V1 has a configurable opening degree as will be presented later.

[0054] With reference to [Fig. 2], the conditioning system SC comprises a regulation device 5 configured to control the valves VI, V2. Preferably, the regulation device 5 is in the form of an electronic computer and the valves VI, V2 are in the form of solenoid valves.

[0055] The regulation device 5 is notably configured to: • open the second valve V2 when the set flow rate dT is greater than the nominal supply flow rate d6n, and • close the second valve V2 when the set flow rate dT is lower than the nominal supply flow rate d6n.

[0056] Thus, the buffer tank 4 makes it possible to dynamically and reactively supplement the supply member 6 to follow the set flow rate dT. The second valve V2 is thus open during the takeoff phase S1 to increase the outlet flow rate d4s from the buffer tank 4 ([Fig. 3]). Preferably, the fuel flows from the supply member 6 and the buffer tank 4 are mixed prior to their injection into the main turbomachine T. The second valve V2 is conversely closed during the other phases S2, S3, the outlet flow rate d4s from the buffer tank 4 then being zero ([Fig. 3]).

[0057] Preferably, the regulating device 5 is also configured to open / close the second valve V2 as a function of the pressure P4 ([Fig.4]) and the temperature T4 ([Fig.5]) in the buffer tank 4 in order to ensure an optimal output flow rate d4s.

[0058] The regulation device 5 is further configured to: • close the first valve V1 when the set flow rate dT is greater than the nominal supply flow rate d6n, • vary the degree of opening of the first valve VI based on a comparison between the nominal supply flow d6n and the set flow dT.

[0059] Preferably, the degree of opening obeys a determined opening law f of the type f(d6n - dT). Advantageously, the surplus fuel is stored dynamically in the buffer tank 4, which is very advantageous. Thus, when the difference is small, the buffer tank fills gently to absorb the surplus flow. This makes it possible to avoid using the pump with too high a speed. Conversely, when the difference is large, the buffer tank fills quickly to absorb the surplus flow. The buffer tank 4 thus has sufficient fuel to ensure a new takeoff phase.

[0060] Alternatively, the regulating device 5 is configured to • open the first valve V1 according to a first degree of opening when the difference between the nominal supply flow d6n and the set flow dT is less than a predetermined deviation e (d6n-dT <e ou d6n-e<dT<d6n) et • ouvrir la première vanne V1 selon un deuxième degré d’ouverture, supérieur au premier degré d’ouverture, lorsque la différence entre le débit d’alimentation nominal d6n et le débit de consigne dT est supérieure à un écart prédéterminé e (d6n-dT> e or dT <d6n-e).

[0061] In this example, the difference e is predetermined to control an opening of the first valve VI according to a first degree of opening during the cruise phase S2 and to control an opening of the first valve V1 according to a second degree of opening during the landing phase S3. Thus, the lower the set flow rate dT, the more the first valve V1 can be opened to fill the buffer tank 4.

[0062] The first valve V1 is closed during the takeoff phase S1 then opened according to a first degree of opening during the cruise phase S2 then according to a second degree of opening (greater than the first) during the landing phase S3 in order to optimize the filling of the buffer tank 4 when the needs are lower. There is thus always a buffer tank 4 sufficiently filled for a new takeoff phase S1.

[0063] With reference to [Fig. 4], the pressure P4 in the buffer tank 4 thus decreases during the takeoff phase S1, then can increase slightly during the cruise phase S2 before increasing significantly during the landing phase S3. During the takeoff phase S1, the pressure P4 in the buffer tank 4 decreases due to the thermodynamic expansion of the fuel flow Q, which leads to a drop in the temperature T4 of the buffer tank 4 ([Fig. 5]). The temperature T4 then increases slightly during the cruise phase S2 before increasing significantly during the landing phase S3 due to the filling of the buffer tank 4.

[0064] Second embodiment ([Fig.6])

[0065] Referring to [Fig. 6], a second embodiment of the fuel conditioning system SC is shown. For the sake of clarity and conciseness, elements common or similar to the first embodiment are not shown again.

[0066] As illustrated in [Fig. 6], the fuel conditioning system SC comprises an auxiliary heat exchanger 8 mounted between the second valve V2 and the main turbomachine T configured to heat the fuel flow Q coming from the buffer tank 4 and coming from the supply member 6 so that the temperature of the fuel at injection into the turbomachine T, called the turbomachine temperature TT, is substantially constant during the cruising phase S2.

[0067] Thus, the drop in temperature T4 of the fuel flow Q from the buffer tank 4, linked to its thermodynamic expansion, can be practically compensated in order to to supply the main turbomachine T. The auxiliary heat exchanger 8 can supply calories from different heat sources, in particular, from the main turbomachine T. Preferably, the auxiliary heat exchanger 8 is configurable, in particular by the regulation device 5, so as to allow the supply of calories to be regulated according to the phases of use.

[0068] Third embodiment ([Fig.7])

[0069] Referring to [Fig. 7], a third embodiment of the fuel conditioning system SC is shown. For the sake of clarity and conciseness, elements common or similar to the first embodiment are not shown again.

[0070] In the first embodiment, the main turbomachine T is preferably connected to a propulsion member which it drives, for example, a propeller or a fan.

[0071] With reference to [Fig. 7], the fuel conditioning system SC comprises a propulsion member OP and a drive system 9 for said propulsion member OP. The drive system 9 is configured to be powered by the main turbomachine T and by the auxiliary power generation device 2. Thus, advantage is taken of the energy generated by the auxiliary power generation device 2 to participate in the propulsion. This advantageously makes it possible to reduce the size of the main turbomachine T.

[0072] In the example of [Fig.7], the auxiliary power generation device 2 is a fuel cell which provides electrical power. The drive system 9 comprises for this purpose an electrical network 91 which supplies an electric motor 92 in order to convert the electrical power into a mechanical torque. The drive system 9 further comprises a transmission box 93 configured to provide an overall mechanical torque to the propulsion member OP from the mechanical torques of the electric motor 92 and the main turbomachine T. Preferably, an electric battery 94 is provided to allow the excess electrical energy to be stored or to provide additional electrical power during the regime change phases.

[0073] When the auxiliary power generation device 2 is an auxiliary turbomachine, the drive system 9 can advantageously be in the form of a transmission box configured to provide an overall mechanical torque to the propulsion member OP from the mechanical torques of the auxiliary turbomachine and the main turbomachine T.

[0074] A heat exchanger 3 positioned upstream of the buffer tank 4 ([Fig.2]) has been previously presented, but it goes without saying that it could be positioned downstream of said buffer tank 4 ([Fig.9]). This advantageously makes it possible to store the fuel in the buffer tank 4 in the liquid state with less bulk. When the heat exchanger 3 is positioned downstream of said buffer tank 4, the auxiliary power generation device 2 is supplied with heated fuel. In other words, the auxiliary power generation device 2 is positioned downstream of the heat exchanger 3 as illustrated in [Fig.9].

[0075] Method of use ([Fig.8])

[0076] An example of implementation of the invention will be presented with reference to [Fig. 8]. In this example, the pump 1 and the auxiliary power generation device 2 both operate at a predetermined constant high-efficiency speed. Thus, their operation is optimized. It is thus possible to use a pump 1 and an auxiliary power generation device 2 of simple designs and reduced costs given that they do not have to operate over a large operating range. This is particularly advantageous for a fuel cell whose efficiency is optimal over a reduced speed range. Preferably, the flow rate of the pump 1 is chosen in an intermediate range between the minimum flow rate and the maximum flow rate required by the main turbomachine T and the auxiliary power generation device 2 over the operating range.

[0077] In this example, the nominal feed flow d6n is lower than the set flow rate of the turbomachine dT in the take-off phase S1 and higher than the set flow rate of the turbomachine dT in the cruise phase S2.

[0078] With reference to figures 3 and 8, the method comprises a step E1 consisting of comparing the nominal feed flow rate d6n with the set flow rate of the turbomachine dT.

[0079] During the take-off phase SI, the flow rate setpoint dT is greater than the nominal supply flow rate d6n, the method comprises a step E2 consisting of opening the second valve V2 to distribute the fuel from the buffer tank 4 and closing the first valve VL. Thus, the buffer tank 4 provides an outlet flow rate d4s which is added to the nominal supply flow rate d6n.

[0080] During the cruising phase S2, the flow rate setpoint dT is lower than the nominal supply flow rate d6n. The method comprises a step E3 consisting of closing the second valve V2 and opening the first valve V1 according to a first degree of opening so as to gradually fill the buffer tank 4 with the excess flow rate.

[0081] During the landing phase S3, the flow rate setpoint dT is lower than the nominal supply flow rate d6n. The method comprises a step E4 consisting of closing the second valve V2 and opening the first valve VI according to a second degree of opening so as to quickly fill the buffer tank 4 with the excess flow rate.

[0082] Advantageously, the mechanical / electrical power of the ge- Auxiliary power generation 2 can be used as shown in [Fig.7].

[0083] Thanks to the invention, the fuel Q is packaged in a practical manner with high efficiency, which allows the use of optimized and reliable equipment having a reduced operating range. During the takeoff phase SI, the buffer tank 4 allows the rapid and practical mobilization of heated fuel.

Claims

Claims

1. Fuel conditioning system (SC) configured to supply an aircraft turbomachine, called the main turbomachine (T), with fuel (Q) from a cryogenic tank (RI), the main turbomachine (T) having a set flow rate (dT) of fuel (Q), which is a function of the movement phase of the aircraft, the conditioning system (SC) comprising: • a fuel circuit (CQ) connected at the inlet to the cryogenic tank (RI) and at the outlet to the main turbomachine (T), • a pump (1) configured to circulate a flow of fuel (Q) from upstream to downstream in the fuel circuit (CQ), the pump (1) being configured to operate at a predetermined constant speed, • at least one heat exchanger (3) configured to transmit calories from a hot source (2) to the fuel flow (Q) via a heating circuit (C2), • a feed member (6) of the main turbomachine (T) with a fuel flow (Q), the feed member (6) defining a predetermined passage section, the feed member (6) being configured to provide a nominal feed flow rate (d6n) when the pump (1) operates at a predetermined constant speed, • at least one buffer tank (4) configured to supply the main turbomachine (T) in parallel with the supply member (6), the buffer tank (4) being configured to be supplied by a fuel flow (Q), • at least one first valve (VI) for controlling the supply of fuel flow (Q) to the buffer tank (4), • at least one second valve (V2) for controlling the distribution of the fuel flow (Q) from the buffer tank (4), and • a regulating device (5) configured to open the second valve (V2) when the set flow rate (dT) is greater than the nominal supply flow rate (dôn).

2. Fuel conditioning system (SC) according to claim 1, wherein the regulating device (5) is configured to close the second valve (V2) when the set flow rate (dT) is lower than the nominal supply flow rate (d6n).

3. Fuel conditioning system (SC) according to one of claims 1 to 2, wherein the regulating device (5) is configured to close the first valve (VI) when the set flow rate (dT) is greater than the nominal supply flow rate (d6n).

4. Fuel conditioning system (SC) according to one of claims 1 to 3, wherein, the first valve (VI) having a configurable degree of opening, the regulation device (5) is configured to vary the degree of opening of the first valve (VI) as a function of a comparison between the nominal supply flow rate (d6n) and the set flow rate (dT).

5. Fuel conditioning system (SC) according to one of claims 1 to 4, comprising at least one auxiliary heat exchanger (8) mounted between the second valve (V2) and the main turbomachine (T) so as to heat the fuel flow (Q) prior to its injection into the main turbomachine (T).

6. Fuel conditioning system (SC) according to one of claims 1 to 5, wherein the hot source is an auxiliary power generation device (2) supplied by the fuel circuit (Q).

7. A fuel conditioning system (SC) according to claim 6, wherein the auxiliary power generating device (2) is configured to operate at constant speed.

8. Fuel conditioning system (SC) according to one of claims 6 to 7, wherein the auxiliary power generation device (2) is an auxiliary turbomachine or a fuel cell.

9. Fuel conditioning system (SC) according to one of claims 6 to 8, comprising at least one propulsion member (OP) and a drive system (9) for said propulsion member (OP), the drive system (9) being configured to be powered by the main turbomachine (T) and by the auxiliary power generation device (2).

10. A fuel conditioning system (SC) according to one of claims 1 to 9, wherein the fuel is dihydrogen.

11. A fuel conditioning system (FC) according to one of the claims- indications 1 to 10, in which the nominal feed flow rate (d6n) is determined to be greater than the set flow rate (dT) in the cruise phase and less than the set flow rate (dT) in the take-off phase.

12. Method for supplying fuel to an aircraft turbomachine, called the main turbomachine (T), using fuel (Q) from a cryogenic tank (RI), the main turbomachine (T) having a set flow rate (dT) of fuel (Q), which is a function of the movement phase of the aircraft, the method comprising steps consisting of: • circulating a flow of fuel (Q) from upstream to downstream in a fuel circuit (CQ) by means of a pump (1) operating at a predetermined constant speed, the pump (1) providing a nominal supply flow rate (d6n), • transmit calories from a hot source (2) to the fuel flow (Q) via a heating circuit (C2), • empty a buffer tank (4), supplied by the fuel circuit (CQ), when the set flow rate (dT) is greater than the nominal supply flow rate (d6n).

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