Method and device for optimizing a climb phase of an aircraft, in particular in terms of fuel consumption.

Abstract

- Device and method for optimizing a climb phase of an aircraft, in particular in terms of fuel consumption.- The method (P) for optimizing a climb phase of an aircraft, implemented repetitively during said climb phase, comprises an acquisition step (E1) for acquiring current values ​​of input parameters, a determination step (E2) for determining a current optimized DTflex value from the current values ​​of the input parameters and optimized DTflex values ​​recorded in a database (3) and a transmission step (E3) for transmitting the determined current optimized DTflex value to a user system for controlling the thrust of the aircraft, said method (P) making it possible to continuously adapt, during the climb phase, the optimized DTflex value so that it corresponds to the current conditions of the aircraft so as to maximize its performance, in particular in terms of fuel consumption. Figure for abstract: Figure 2.

Description

Title of the invention: Method and device for optimizing a climb phase of an aircraft, in particular in terms of fuel consumption. Technical field

[0001] The present invention relates to a device and a method for optimizing a climb phase of an aircraft, for example a transport aircraft, in particular in terms of fuel consumption. State of the art

[0002] Aircraft engines are subjected to high stresses when operating at very high speeds, i.e. close to the maximum available thrust. This is particularly the case for phases relating to takeoff and climb, during which significant thrust is required. These stresses are caused by a high temperature of the exhaust gases which is generated at high speeds. It is therefore desirable to limit, as much as possible, the use of the maximum available thrust in order to protect the engines, limit their maintenance costs and increase their service life.

[0003] Several methods are known for limiting the thrust during the phases relating to the takeoff and climb of an aircraft such as a transport plane.

[0004] For example, a common method is to use a predefined thrust limit rate during takeoff. The aircraft then takes off using a certain fixed percentage of its maximum available thrust up to a predetermined altitude, then continues its climb with usual thrust. However, the use of a fixed thrust limit rate is not suitable for a wide range of takeoff masses.

[0005] Another method, called the Autoderate method or the “Flex Temp” method (for “Flexible Temperature” in English), implemented by the FMS type flight management system (for “Flight Management System” in English) of the aircraft, consists of calculating a fictitious temperature (called Flex temperature) which must be taken into account by the aircraft systems as being the actual ambient temperature. Indeed, the available thrust of an aircraft depends on the ambient temperature. Above a certain temperature, the higher the ambient temperature, the lower the maximum available thrust. Thus, when possible, a fictitious temperature higher than the actual ambient temperature is calculated from certain characteristics (the mass of the aircraft, the altitude that one wishes to reach, a reference ambient temperature, etc.) and used so as to allow the aircraft to take off with reduced thrust.Although this method provides flexibility in choosing the thrust. reduced that we want to apply during takeoff, allowing us to take into account in particular the mass of the aircraft, it leads to using a constant Flex temperature which is not the most suitable at all times during the climb phase.

[0006] In any case, these known methods are not optimal in terms of costs, in particular in terms of fuel consumption. Indeed, they lead to the use of thrust which is not always effective during the climb phase, which results in excess fuel consumption.

[0007] The known solutions are therefore not completely satisfactory. Statement of the invention

[0008] The present invention aims to remedy the aforementioned drawbacks. It relates to a method for optimizing a climb phase of an aircraft comprising the determination of an optimized DTflex value corresponding to a temperature differential used to control the thrust of the aircraft.

[0009] According to the invention, the method comprises at least the following series of steps implemented by an avionics computer in a repetitive manner during the climb phase: - an acquisition step for acquiring current values ​​of input parameters including at least the mass of the aircraft, the speed of the aircraft, the altitude of the aircraft and a reference temperature; - a determination step for determining a current optimized DTflex value from the current values ​​of the input parameters acquired in the acquisition step and from optimized DTflex values ​​recorded in a database integrated in the avionics computer, the database having been previously created by associating an optimized DTflex value with each combination of input parameters for a predefined number of combinations of input parameters; and - a transmission step for transmitting the current optimized DTflex value determined in the determination step to a user system capable of using said current optimized DTfleX value to control the thrust of the aircraft.

[0010] Thus, thanks to the invention, it is possible to continuously adapt, during the climb phase, the optimized DTflex value so that it corresponds to the current conditions of the aircraft. This adaptation makes it possible to modulate the thrust of the aircraft so as to maximize its performance in terms of costs, in particular in terms of fuel consumption.

[0011] Furthermore, in a particular embodiment, the method comprises a preliminary step implementing a creation method for creating said database, said preliminary step comprising a set of sub-steps implemented for each of said combinations of input parameters and comprising: - a first sub-step of calculation to calculate sets of climb parameters characterizing the climb phase of the aircraft with the considered input parameters, the climb parameters comprising at least an aircraft fuel flow rate, an aircraft net thrust and an aircraft drag, a set of climb parameters being calculated for each DTflex value among a predefined number of DTflex values; - a second calculation sub-step for calculating at least one value representing the cost of the climb phase for each set of climb parameters calculated in the first calculation sub-step; and - a selection sub-step to select the DTflex value for which the cost of the ramp-up phase is minimal and to record this DTflex value in the database as the optimized DTflex value associated with the considered combination of input parameters.

[0012] Advantageously, the value representing the cost of the rise phase is calculated from the following mathematical formula: J = - .( FF-Aref.V ) in which: Ê is a specific energy of the aircraft; FF is the aircraft fuel flow rate; Àref is a reference factor; and V is the aircraft speed.

[0013] Furthermore, in the first calculation sub-step, the DTflex values ​​for which a set of climb parameters is calculated are between a minimum DTflex value and a maximum DTflex value, the minimum DTflex value corresponding to a DTflex value for which the thrust is maximum and the maximum DTflex value corresponding to a DTflex value for which the rate of climb of the aircraft is equal to a predefined minimum rate of climb.

[0014] In a particular embodiment, the method comprises a verification step, implemented after the determination step, for: - determining a theoretical value of the aircraft exhaust gas temperature which would be obtained with the current optimized DTflex value determined in the determination step, from predetermined exhaust gas temperature values; - compare the theoretical exhaust gas temperature value with a limit exhaust gas temperature value; and • if the theoretical exhaust gas temperature value is less than or equal to the exhaust gas temperature limit value, transmit the current optimized DTfleX value to the transmission step; and • if the theoretical exhaust gas temperature value is higher than the exhaust gas temperature limit value, transmit the DTflex value for which the theoretical exhaust gas temperature value is equal to the exhaust gas temperature limit value as the current optimized DTflex value at the transmission stage.

[0015] Furthermore, in another particular embodiment, the method comprises a measurement step, implemented before the acquisition step, to measure the current values ​​of the input parameters and to transmit said current values ​​of the input parameters to the avionics computer.

[0016] The present invention also relates to a device for optimizing a climb phase of an aircraft to determine an optimized DTflex value corresponding to a temperature differential used to control the thrust of said aircraft.

[0017] According to the invention, the device comprises at least one avionics computer configured to: - acquire current values ​​of input parameters including at least the aircraft mass, the aircraft speed, the aircraft altitude and a reference temperature; - determining a current optimized DTflex value from the current values ​​of the input parameters acquired in the acquisition step and from optimized DTflex values ​​recorded in a database integrated in the avionics computer, the database having been previously created by associating an optimized DTflex value with each combination of input parameters for a predefined number of combinations of input parameters; and - transmitting the current optimized DTflex value determined in the determination step to a user system capable of using said current optimized DTflex value to control the thrust of the aircraft. Brief description of the figures

[0018] The attached figures will make it clear how the invention can be implemented. In these figures, identical references designate similar elements.

[0019] [Fig.l] is a schematic perspective view of an aircraft comprising a device for optimizing a climb phase.

[0020] [Fig.2] is a block diagram of a method for optimizing a phase of climb.

[0021] [Fig.3] is a diagram illustrating a method of creating a database comprising optimized DTflex values ​​associated with combinations of input parameters.

[0022] [Fig.4] is a graph illustrating an example of a portion of information included in a database created by the method of [Fig.3].

[0023] [Fig.5] is a graph illustrating an example of an advantageous effect of the method optimization of a climb phase on the rotation speed of the blades of an aircraft engine compared to a usual process.

[0024] [Fig.6] is a graph illustrating an example of an advantageous effect of the method for optimizing a climb phase on the temperature of the exhaust gases of an aircraft engine compared to a usual method. Detailed description

[0025] A device for optimizing a climb phase of an AC aircraft (hereinafter device 1) making it possible to illustrate the invention is shown schematically in [Fig. 1]. This device 1 which equips the AC aircraft makes it possible to determine an optimized DTfies value which is intended to be used to control the thrust of the AC aircraft during the climb phase.

[0026] In the context of the present invention, and for the sake of simplicity, the term "climb phase" means a flight phase of the aircraft AC comprising a takeoff from a runway of an aerodrome and a climbing phase during which the aircraft AC gains altitude (generally from 1500 feet) until reaching a desired altitude called TOC altitude (for "Top of Climb" in English).

[0027] Furthermore, the DTflex value corresponds to a usual temperature differential making it possible to generate a setpoint for controlling the thrust of the aircraft AC. More precisely, the DTflex value corresponds to the difference between a reference temperature representing the actual ambient temperature and a fictitious temperature (called “Flex Temperature” or “Flex Temperature” in English) representing the temperature that one wishes to take into account as the ambient temperature for generating the thrust control setpoint of the aircraft AC. This setpoint is used to control the propulsion system of the aircraft AC comprising at least one engine, for example of the turbojet type.

[0028] The reference temperature is given by the standard atmosphere system (or ISA for "International Standard Atmosphere" in English) defining normal temperatures and pressures making it possible to overcome variations due to geographical position and altitude.

[0029] As for the Flex temperature, it is chosen so as to respect a minimum climb rate, namely a vertical speed allowing the aircraft AC to reach the TOC altitude within a desired time. Thus, depending on the climb phase, several DTflex values ​​can be considered.

[0030] The objective of the device 1 is to determine, continuously during the rise phase, the DTflex value for which the cost of the rise phase is minimal.

[0031] To do this, the device 1 comprises an avionics computer 2 mounted on the aircraft AC and configured to determine a current optimized DTflex value, namely a DTflex value to achieve optimal aircraft performance during the climb phase. The optimized DTflex value is called current because it is determined based on current aircraft parameters AC as detailed below.

[0032] In the context of the present invention, it is considered that the performance of the aircraft AC is optimal when the cost of the climb phase is minimal. Depending on the embodiment considered, the cost of the climb phase may comprise several components. Preferably, this is the fuel consumption during the climb phase. However, the cost may also take into account other criteria such as the time required to reach the TOC altitude.

[0033] Furthermore, the avionics computer 2 preferably corresponds to an on-board avionics system of the flight management system type (“FMS” for “Flight Management System” in English).

[0034] In a preferred embodiment, the avionics computer 2 is configured to perform the operations described below repetitively throughout the climb phase.

[0035] To do this, the avionics computer 2 is configured to acquire current values ​​of input parameters characterizing the current situation of the aircraft AC. The input parameters comprise at least the following parameters: the mass of the aircraft AC, the speed of the aircraft AC, the altitude of the aircraft AC and the reference temperature.

[0036] Certain input parameters are intended to vary during the climb phase. Their current value must therefore be measured repeatedly during the climb phase. Other input parameters may be predefined constants. In this case, their value is stored in a memory so as to be accessible by the avionics computer 2.

[0037] In a particular embodiment, the device 1 comprises usual measuring systems or devices equipping the aircraft AC and capable of measuring, in a usual manner, the current values ​​of the input parameters. These systems or devices are also capable of transmitting the current measured values ​​to the avionics computer 2.

[0038] In addition, the avionics computer 2 is configured to determine a current optimized DTflex value from the current values ​​of the input parameters and from optimized DTflex values ​​recorded in a database 3.

[0039] Preferably, the database 3 is integrated into the avionics computer 2. It comprises optimized DTflex values, each of which is associated with a particular combination of input parameters.

[0040] Database 3 is created beforehand by recording optimized DTflex values ​​for a predefined number of input parameter combinations. A method of creating database 3 is described in more detail in the following description.

[0041] Furthermore, the avionics computer 2 is configured to transmit the current optimized DTflex value to a user system 4 capable of using said current optimized DTflex value to control the thrust of the aircraft AC. This may be a usual unit of the aircraft AC configured to control the propulsion systems of said aircraft AC. For example, the user system 4 may correspond to a FADEC (Full Authority Digital Engine Control) system.

[0042] The user system 4 is intended to use the current optimized DTflex value to determine a setpoint for the propulsion systems of the aircraft AC during the climb phase. The optimized DTflex value transmitted by the avionics computer 2 is continuously updated throughout the climb phase so as to take into account, at all times, the evolution of the input parameters. In this way, the thrust setpoint of the aircraft AC is constantly adjusted with the current optimized DTflex value.

[0043] Thus, thanks to the device 1, it is possible to continuously adapt, during the climb phase, the optimized DTflex value so that it corresponds to the current conditions of the aircraft AC. This adaptation makes it possible to modulate the thrust of the aircraft AC so as to maximize its performance in terms of costs, in particular in terms of fuel consumption.

[0044] The device 1 as described above is configured to implement a method P shown schematically, in a particular embodiment, in [Fig. 2]. In this particular embodiment, the method P comprises a series of steps E1, E2 and E3 implemented repetitively by the avionics computer 2 during the climb phase.

[0045] More precisely, step El carries out the acquisition of the current values ​​of the input parameters.

[0046] In addition, step E2 determines the current optimized DTflex value from the current values ​​of the input parameters acquired in step E1 and from the optimized DTflex values ​​recorded in the database 3.

[0047] Furthermore, step E3 carries out the transmission of the current optimized DTflex value determined in step E2 to the user system 4 capable of using said current optimized DTflex value to control the thrust of the aircraft AC.

[0048] In a particular embodiment, the method P is also capable of implementing a method M for creating the database 3. In this particular embodiment, shown in [Fig.2], the method P thus comprises a preliminary step E0 carried out before the series of steps E1, E2 and E3. Step E0 implements the method M to create the database 3.

[0049] Method M, shown schematically in [Fig.3], comprises a series of sub-steps E01, E02 and E03 to create the database 3. Method M consists, for a predefined number of combinations of input parameters, in associating an optimized DTflex value with each of said combinations of input parameters.

[0050] Indeed, for a given combination of input parameters and a given climb phase, it is possible to determine, analytically, the thrust sufficient to reach the TOC altitude with minimal cost. This calculation can be carried out, in the usual way, in particular from the specific energy method and optimal control theory. It is then possible to deduce the DTflex value allowing this sufficient thrust to be obtained. This is the optimized DTflex value associated with the combination of input parameters considered.

[0051] As shown in [Fig.3], we denote (Al, A2, ..., Am) the combinations of input parameters to which we wish to associate optimized DTflex values, m being a positive integer corresponding to the predefined number of combinations of input parameters.

[0052] Sub-step E01 performs the calculation of sets of climb parameters characterizing the climb phase of the aircraft AC with the considered input parameters. The climb parameters comprise at least the fuel flow rate of the aircraft AC, the net thrust of the aircraft AC and the drag of the aircraft AC. For each combination of input parameters (A1, A2, ..., Am), sub-step E01 performs the calculation of several sets of climb parameters. As shown in [Fig. 3], (B1, B2, ..., Bn) denote the sets of climb parameters, n being a positive integer corresponding to the number of sets of climb parameters calculated per combination of input parameters.

[0053] Each set of climb parameters (B 1, B2, ..., Bn) corresponds to the climb parameters obtained for a particular DTflex value. Indeed, for a given combination of input parameters, there are several possible DTflex values ​​which make it possible to satisfy the minimum climb rate to be respected for the climb phase. As shown in [Fig.3], we note (Dl, D2, ... Dn) the DTflex values ​​for which we calculate respectively the sets of climb parameters (Bl, B2, ..., Bn).

[0054] The number n of climb parameter sets that are calculated by combining input parameters corresponds to the number of possible DTflex values ​​that are to be taken into account. The possible DTflex values ​​are between a minimum DTflex value and a maximum DTflex value. Preferably, the minimum DTflex value corresponds to zero, namely the DTflex value for which maximum thrust is obtained, and the maximum DTflex value corresponds to the DTflex value for which thrust is obtained generating the minimum climb rate to be respected for the climb phase.

[0055] As an illustrative example, for a given combination of input parameters, the possible DTflex values ​​can be between 10°C (maximum thrust) and 30°C (thrust generating the minimum climb rate to be respected). Among these possible DT fiex values, one can choose to calculate climb parameters every degree Celsius. This represents the calculation of thirty-one sets of parameters (in this case m = 31).

[0056] In addition, sub-step E02 performs the calculation of a cost value representing the cost of the climb phase for each set of climb parameters (B 1, B2, ..., Bn) calculated in sub-step E01. As shown in [Fig.3], the cost values ​​calculated for the sets of climb parameters (Bl, B2, ..., Bn) are denoted, respectively, (Jl, J2, ..., Jn).

[0057] In a preferred embodiment, the cost value, for a given set of climb parameters, is calculated from the following mathematical formula: J = - .( FF-Aref.V ) in which: Ê is a specific energy of the aircraft AC; FF is the aircraft fuel flow AC; Àref is a reference factor; and V is the speed of the aircraft AC.

[0058] The reference factor Àref corresponds to a ratio between a reference fuel flow rate and a reference speed. These parameters represent ideal flight conditions for the aircraft AC, namely the conditions generating minimal cost. The reference factor Àref serves as a point of comparison to quantify the difference in cost between the current flight conditions of the aircraft AC and the ideal flight conditions (generally the conditions that one seeks to obtain for the cruise flight phase).

[0059] Furthermore, the specific energy E of the aircraft AC can be calculated from the following mathematical formula: £ — yj in which: V is the speed of the aircraft AC; FN is the net thrust of the aircraft AC; D is the drag of aircraft AC; and m is the mass of aircraft AC.

[0060] Furthermore, sub-step E03 performs the selection, for each combination of input parameters (Al, A2, ... Am), of the DTSex value for which the cost of the rise phase is minimal. Each of the selected DTflex values ​​is specific to a combination of input parameters. As shown in [Fig. 3], the selected DTfleX values ​​are noted Dopt(Al), Dopt(A2), ..., Dopt(Am). They are recorded in the database 3 as being, each time, the DTSex value optimized associated with their own combination of input parameters.

[0061] In the preferred embodiment described above, the selected DTflex values ​​Dopt(Al), Dopt(A2), ..Dopt(Am) to be recorded in the database 3 correspond to the DTfiex values ​​for which the cost value (Jl, J2, Jn) is the lowest. As shown in [Fig.3], the lowest cost value (Jmin(Al), Jmin(A2), ... Jmin(Am)) is noted, respectively for each combination of input parameters (Al, A2, ..., Am).

[0062] Thus, method M makes it possible to create the database 3 comprising a multitude of optimized DTflex values, each being associated with a combination of input parameters. The greater the number of combinations of input parameters taken into account to create the database 3, the more it is capable of providing an optimized DTflex value for varied situations.

[0063] An example illustrating a portion of the database 3 is shown in [Fig. 4]. This portion of the database 3 is presented in the form of a graph comprising a plurality of curves, each representing optimized DTflex values ​​as a function of the aircraft altitude AC for a particular aircraft mass. In [Fig. 4], the y-axis, denoted "DTflex - opt", gives the optimized DTf iex value expressed in degrees Celsius (°C). The x-axis, denoted "ALT", gives the aircraft altitude expressed in feet (ft).

[0064] Furthermore, [Fig.4] includes the DTflex values ​​optimized for a particular reference temperature and a particular aircraft speed (AC). Also, it will be understood that this graph represents part of the information in database 3. The latter includes a multitude of DTflex values ​​optimized for a large number of combinations of input parameters. This multitude of optimized DTflex values ​​makes it possible to cover a large number of possible situations but also to determine a DTflex value corresponding precisely to a particular situation.

[0065] As an example, the graph in [Fig.4] includes twenty-eight curves representing optimized DTflex values ​​for aircraft masses between 300 tonnes (curve denoted Cl) and 570 tonnes (curve denoted C2). The mass interval between two curves is therefore 10 tonnes. Thus, the database 3 makes it possible to give the optimized DTflex value with an accuracy of 10 tonnes for this input parameter, namely the mass of the aircraft AC.

[0066] In a particular embodiment, shown in [Fig. 2], the method P also comprises a verification step E4 implemented after step E2 and before step E3. Step E4 makes it possible to verify whether the current optimized DTflex value, determined in step E2, generates an exhaust gas temperature (or EGT for “Exhaust Gas Temperature” in English) which exceeds or does not exceed a predefined limit.

[0067] To do this, step E4 determines a theoretical value of the exhaust gas temperature that would be obtained with the current optimized DTflex value determined in step E3. This theoretical value is determined from predetermined exhaust gas temperature values. Indeed, depending on the characteristics of the propulsion systems of an aircraft, it is possible to deduce the exhaust gas temperature generated for a given thrust. Also, it is possible to provide predetermined exhaust gas temperature values ​​depending on the thrust used. These predetermined values ​​can be recorded so as to be accessible by the avionics computer 2, for example in the database 3 or in another memory provided for this purpose.

[0068] Then, step E4 compares this theoretical exhaust gas temperature value with an exhaust gas temperature limit value. This limit value corresponds to the exhaust gas temperature value that it is desired not to exceed. It can be defined according to the characteristics of the propulsion systems of the aircraft AC and corresponds to a temperature beyond which it is considered that there is an increase in the constraints on the engines likely to increase their maintenance cost and / or reduce their service life.

[0069] Furthermore, step E4 carries out or not the transmission to step E3 of the current optimized DTflex value determined in step E2 according to the result of the aforementioned comparison.

[0070] If the theoretical value of the exhaust gas temperature is less than or equal to the limit value of the exhaust gas temperature, then the current optimized DTflex value determined in step E2 is transmitted to step E3.

[0071] If the theoretical value of the exhaust gas temperature is greater than the limit value of the exhaust gas temperature, then the current optimized DTflex value that is transmitted in step E3 is not the one that was determined in step E2. The DTflex value that is transmitted in step E3 is the DTflex value for which the theoretical value of the exhaust gas temperature is equal to the limit value of the exhaust gas temperature.

[0072] Thus, in the case where the current optimized DTflex value determined in step E2 would generate an exhaust gas temperature that is too high, a compromise is made. As explained above, another DTflex value (which is higher than the optimized DTflex value determined in step E2) is then considered as the current optimized DTflex value so that the exhaust gas temperature does not exceed the predefined limit value. This makes it possible to keep the cost as low as possible. Indeed, the loss in terms of fuel consumption is offset by the gain in terms of maintenance costs and engine lifespan.

[0073] In a non-limiting manner, examples of advantageous effects obtained thanks to the device 1 implementing method P are shown in [Fig.5] and [Fig.6]. For information purposes, these examples concern an aircraft with a mass equal to 560 tonnes.

[0074] [Fig.5] corresponds to a graph representing the rotation speed of the engine blades of an aircraft during a climb phase as a function of the flight time. The ordinate axis, denoted Ni, represents the rotation speed of the blades expressed as a percentage of the maximum rotation speed of said blades. The abscissa axis, denoted Te, represents the flight time during the climb phase expressed in minutes, zero designating the start of the climb phase.

[0075] [Fig. 5] comprises two curves E1 and E2. Curve E1 represents the rotation speed of the engine blades of an aircraft using a conventional thrust management method. Curve E2 represents the rotation speed of the engine blades of an aircraft using method P. It can be seen that curve E1 increases continuously throughout the climb phase. Conversely, curve E2 increases up to a time T1 (at approximately 13 min), then decreases down to a time T2 (at approximately 19 min) before increasing again until the end of the climb phase. Curve E2 joins curve E1 after a time T3 (at approximately 28 min) so that the rotation speeds of the blades of the two curves are substantially identical from time T3.

[0076] Although the rotation speed of the blades obtained using method P is slightly higher than that obtained with a usual method before time T1 (due to a choice of rapid rise), it remains much lower during the rest of the rise phase.

[0077] Thus, the method P makes it possible to reduce the rotation speed of the blades during the ascent phase compared to a usual method. In the example of [Fig.5], the rotation speed of the blades is reduced between times T1 and T3, which represents a reduction of sixteen minutes over a ascent phase that lasts approximately thirty minutes. In addition, it is noted that at the maximum of the reduction, at time T2, the rotation speed of the blades is approximately 91% for curve E1 and 86% for curve E2. A maximum reduction, denoted Rb, of the order of 5% is therefore obtained.

[0078] Furthermore, [Fig.6] corresponds to a graph representing the temperature of the exhaust gases of an aircraft during a climb phase as a function of the flight time. The ordinate axis, noted EGT, represents the temperature of the exhaust gases expressed in degrees Celsius. The abscissa axis, noted Te, represents the flight time during the climb phase expressed in minutes, zero designating the start of the climb phase.

[0079] [Fig.6] has two curves F1 and F2. Curve F1 represents the exhaust gas temperature of an aircraft using a conventional thrust management method. Curve F2 represents the exhaust gas temperature of an aircraft using method P. It can be seen that curve F1 remains relatively constant. throughout the rise phase around a value equal to 850°C. Conversely, the F2 curve is relatively constant around 850°C up to a time T4 (at approximately 13 min), then decreases to a time T5 (at approximately 18 min) before increasing to a time T6 (at approximately 27 min) from which it substantially rejoins the F2 curve.

[0080] Thus, the method P also makes it possible to reduce the temperature of the exhaust gases during the rise phase compared to a usual method. In the example of [Fig.6], the temperature of the exhaust gases is reduced between times T4 and T6, which represents a reduction for a duration of approximately fourteen minutes over a rise phase which lasts approximately thirty minutes. In addition, it is noted that at the maximum of the reduction, at time T5, the temperature of the exhaust gases of the curve F2 is approximately 790°C. A maximum reduction, denoted R2, of the order of 60°C is therefore obtained compared to the temperature of the exhaust gases generated with a usual method.

[0081] For information purposes, in the example considered above, method P makes it possible to save approximately 73 kg of fuel compared to a usual climb phase. Obviously, this gain varies depending on the aircraft and the flight conditions considered.

[0082] The device 1 implementing the method P as described above has numerous advantages. In particular: - it allows to minimize the cost of the climb phase, in particular in terms of fuel consumption; - it is suitable for implementation for a wide variety of rise phase configurations; and - it is simple and inexpensive to implement.

Claims

Claims

1. Method for optimizing a climb phase of an aircraft (AC) comprising the determination of an optimized DTflex value corresponding to a temperature differential used to control the thrust of the aircraft (AC), characterized in that it comprises at least the following series of steps implemented by an avionics computer (2) repeatedly during the climb phase: - an acquisition step (El) for acquiring current values ​​of input parameters comprising at least the mass of the aircraft (AC), the speed of the aircraft (AC), the altitude of the aircraft (AC) and a reference temperature; - a determination step (E2) for determining a current optimized DTflex value from the current values ​​of the input parameters acquired in the acquisition step (El) and from optimized DTflex values ​​recorded in a database (3) integrated in the avionics computer (2), the database (3) having been previously created by associating an optimized DTflex value with each combination of input parameters for a predefined number of combinations of input parameters; and - a transmission step (E3) for transmitting the current optimized DT fiex value determined in the determination step (E2) to a user system (4) capable of using said current optimized DTfles value to control the thrust of the aircraft (AC).

2. A method according to claim 1, characterized in that it comprises a preliminary step (EO) implementing a creation method (M) for creating said database (3), said preliminary step (EO) comprising a set of sub-steps implemented for each of said combinations of input parameters and comprising: - a first sub-step (E01) of calculation to calculate sets of climb parameters characterizing the climb phase of the aircraft (AC) with the input parameters considered, the pa- climb parameters comprising at least an aircraft fuel flow (AC), an aircraft net thrust (AC) and an aircraft drag (AC), a set of climb parameters being calculated for each DTfles value among a predefined number of DTfiex values; - a second calculation sub-step (E02) for calculating at least one value representing a cost of the climb phase for each set of climb parameters calculated in the first calculation sub-step (E01); and - a selection sub-step (E03) for selecting the DTfiex value for which the cost of the climb phase is minimal and for recording this DTflex value in the database (3) as being the optimized DTflex value associated with the combination of input parameters considered.

3. Method according to claim 2, characterized in that the value J representing the cost of the climb phase is calculated from the following mathematical formula: j=j(FF-irefy) in which: Ê is a specific energy of the aircraft (AC); FF is the fuel flow rate of the aircraft (AC); Àref is a reference factor; and V is the speed of the aircraft (AC).

4. Method according to any one of claims 2 and 3, characterized in that in the first calculation sub-step (E01), the DTflex values ​​for which a set of climb parameters is calculated are between a minimum DTflex value and a maximum DTflex value, the minimum DTflex value corresponding to a DTflex value for which the thrust is maximum and the maximum DTflex value corresponding to a DTflex value for which the rate of climb of the aircraft (AC) is equal to a predefined minimum rate of climb.

5. Method according to any one of the preceding claims, characterized in that it comprises a verification step (E4), implemented after the determination step (E2), for: - determining a theoretical value of the temperature of the gases aircraft exhaust (AC) that would be obtained with the current optimized DTfles value determined in the determination step (E2), from predetermined exhaust gas temperature values; - compare the theoretical exhaust gas temperature value with an exhaust gas temperature limit value; and • if the theoretical exhaust gas temperature value is less than or equal to the exhaust gas temperature limit value, transmit the current optimized DTflex value to the transmission step (E3); and • if the theoretical exhaust gas temperature value is greater than the exhaust gas temperature limit value, transmit the DTflex value for which the theoretical exhaust gas temperature value is equal to the exhaust gas temperature limit value as the current optimized DTflex value to the transmission step (E3).

6. Method according to any one of the preceding claims, characterized in that it comprises a measurement step (E5), implemented before the acquisition step (El), to measure the current values ​​of the input parameters and to transmit said current values ​​of the input parameters to the avionics computer (2).

7. Device for optimizing a climb phase of an aircraft (AC) to determine an optimized DTflex value corresponding to a temperature differential used to control the thrust of the aircraft (AC), characterized in that it comprises at least one avionics computer (2) configured to: - acquire current values ​​of input parameters comprising at least the mass of the aircraft (AC), the speed of the aircraft (AC), the altitude of the aircraft (AC) and a reference temperature; - determine a current optimized DTflex value from the current values ​​of the input parameters acquired in the acquisition step (El) and from optimized DTflex values ​​recorded in a database (3) integrated in the avionics computer (2), the database (3) having been previously created by associating an optimized DTfles value with each combination of input parameters for a predefined number of combinations of input parameters; and transmitting the current optimized DTflex value determined in the determination step (E2) to a user system (4) capable of using said current optimized DTflex value to control the thrust of the aircraft (AC).

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