Management of the drawing of mechanical power from a two-spool or three-spool turbine engine
Patent Information
- Application Number
- EP2023764356
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2022-07-13
- Filing Date
- 2023-07-13
- Publication Date
- 2025-05-21
AI Technical Summary
Current systems for managing mechanical power withdrawals from aircraft turbomachines are not compatible with the reduced idle thrust requirements of modern aircraft, leading to constraints on fuel consumption and compressor operation, particularly during descent phases.
A system and method for managing mechanical power withdrawals from double or triple body turbomachines, utilizing a control unit to dynamically distribute electrical power between generators attached to high pressure, low pressure, and intermediate pressure shafts based on flight phases, optimizing fuel consumption, thrust, and turbine outlet temperature.
This approach optimizes fuel consumption per power unit, thrust, and acceleration times, while minimizing turbine outlet temperature and wear on aircraft components, enhancing the compatibility of mechanical and electrical power management with reduced idle thrust.
Smart Images
Figure 1.1
Abstract
Description
[0001] Description
[0002] Management of mechanical power draws on a double or triple body turbomachine
[0003] FIELD OF THE INVENTION
[0004] The present invention relates to a system and a method for managing mechanical power draws on a double or triple body turbomachine.
[0005] STATE OF THE ART
[0006] Traditionally, in addition to generating thrust, an aircraft turbomachine is also used as a source of mechanical power to generate the electrical power required for the aircraft's needs. Generally, this mechanical power from the turbomachine is extracted from the high-pressure shaft, which imposes strong constraints on the operability of the high-pressure compressor, as well as that of the low-pressure compressor ("booster" in English terminology).
[0007] Furthermore, power management systems consider motors as always-available sources. As long as consumption demands are within acceptable current ranges, there is no attempt to control or optimize the power levels drawn.
[0008] Such operation is nevertheless less and less compatible with the significant reductions in the need for thrust at idle in the latest generations of aircraft which are the consequence of the increase in the finesse of the aircraft.
[0009] The descent phase is particularly impacted. This phase, in fact, characterized by its rate (in feet / minute) or its gradient (in degrees) of descent, is essentially constrained by the aircraft's glide ratio, which impacts up to 90% of the descent rate. Thus, an increase in glide ratio must be compensated by a significant reduction in idle thrust to maintain a target descent rate. However, the reduction in idle thrust is contradictory to the needs for power drawdowns: the pumping margin and the acceleration capacity of the HP compressor are constrained by the power drawdowns relative to the power of the HP turbine, the engine components, the HP compressor and the LP compressor ("booster") having to be sized to withstand the failure of the electrical generators.
[0010] New architectures have also recently been proposed for hybrid powertrains that use multiple mechanical draws. The first mechanical draw remains unchanged: power is extracted from the HP shaft. A second mechanical draw is also made from the LP shaft.
[0011] STATEMENT OF THE INVENTION
[0012] A general aim of the invention is to improve the management of mechanical and electrical power draws, in order to make as much as possible compatible the developments in reduction of thrust at idle and the draw requirements for electrical power.
[0013] According to one aspect, the invention proposes for this purpose a system for managing the extraction of mechanical power from a double or triple body turbomachine for aircraft comprising at least a first turbine and a second turbine, in which at least a first electrical machine and a second electrical machine are adapted to recover mechanical energy from said first electrical machine on a shaft driven by the first turbine of the turbomachine, said second electrical machine on a shaft driven by the second turbine of the turbomachine,
[0014] Said system comprises: a management unit which controls the electrical power draws and the electrical distribution on the various equipment and consumer systems of the aircraft, and a control unit adapted to transmit a distribution of draws which it determines according to the flight phase of the aircraft, to said management unit.
[0015] It has in fact been identified by the inventors that the distribution of the samples has an effect on the operation of the turbomachine. Indeed, the mechanical samples influence the operating points of the components and the overall adaptation of the turbomachine. Thus, for the same overall mechanical power requirement, the distribution will influence the fuel consumption or even the engine thrust.
[0016] Typically, for example, in the case of a twin-spool turbomachine, with two generators adapted to recover mechanical energy, one on the HP shaft, the other on the LP shaft, the generator on the LP shaft has different impacts from those of the generator on the HP shaft, in particular on the compressor margins, on the thrust and on the fuel consumption per unit of power (“SFC” or “Specific Fuel Consumption” according to English terminology).
[0017] The proposed system has the advantage of allowing the following optimizations: optimization of fuel consumption per unit of power (SFC); optimization of thrust; optimization of acceleration times optimization of turbine outlet temperature.
[0018] In particular, the presence of the generator on the BP tree therefore adds a degree of freedom allowing the best compromise to be found depending on the desired criterion.
[0019] The invention also proposes a method for managing mechanical power draws on a double or triple body turbomachine for aircraft comprising at least a first turbine and a second turbine, in which at least a first electrical machine and a second electrical machine are adapted to recover mechanical energy,
[0020] - the first electrical machine on a shaft driven by the first turbine of the turbomachine, and - the second electrical machine on a shaft driven by the second turbine of the turbomachine, the method implementing control of the electrical power draws and the electrical distribution on the various consumer equipment and systems of the aircraft, in which the distribution of these draws between the first electrical machine and the second electrical machine is controlled dynamically according to the flight phase.
[0021] It further relates to an assembly comprising a double or triple body turbomachine for aircraft comprising at least a first turbine and a second turbine, in which at least a first electrical machine and a second electrical machine are adapted to recover mechanical energy,
[0022] - the first electric machine on a shaft driven by the first turbine of the turbomachine, and
[0023] - the second electric machine on a shaft driven by the second turbine of the turbomachine, in which said assembly further comprises a management system as described previously.
[0024] At least one of the electrical machines can be a generator.
[0025] In the case where the turbomachine is of the double-body type, the electrical machines are adapted to recover mechanical energy, one from the high-pressure shaft, the other from the low-pressure shaft.
[0026] In the case of a turbomachine with a triple body architecture, a third electric machine takes mechanical energy from the IP shaft.
[0027] DESCRIPTION OF FIGURES
[0028] Other characteristics, aims and advantages of the invention will emerge from the following description, which is purely illustrative and non-limiting, and which must be read in conjunction with the appended drawings in which:
[0029] Figure 1 schematically illustrates an example of a management system in accordance with a possible embodiment and implementation of the invention;
[0030] Figure 2 schematically illustrates in more detail a possible implementation for the system of Figure 1. DETAILED DESCRIPTION OF THE INVENTION
[0031] The assembly illustrated in Figure 1 comprises a twin-spool turboshaft engine 1, a control unit 2, a generator 3 which, thanks to a power transmission system (not shown), recovers mechanical energy on the High Pressure HP shaft, a generator 4 which recovers, thanks to another power transmission system (also not shown), mechanical energy on the Low Pressure LP shaft.
[0032] A management unit 5 controls the electrical power draws from the output of generators 3 and 4 and the electrical distribution to the various consumer equipment and systems of the aircraft.
[0033] Control unit 2 and management unit 5 constitute the management system of the proposed assembly.
[0034] The distribution between the power draws that the management unit 5 makes on the generators 3 and 4 is determined by the engine control unit 2 and transmitted to said management unit 5.
[0035] Typically, the input data taken into account for this purpose by unit 2 are the following: the aircraft flight data (block "AD" for "Air Data" in figure 1), which participate in the reconstruction of the flight phase; the position of the lever M, which provides in particular information on the thrust requirement, W data provided by aircraft sensors, such as "Weight on Wheel" data or landing gear extended and landing gear flattened, TM data provided by the turbomachine sensors, in particular to define the transient / stabilized state of the latter, as well as to provide information on the constraints linked to the operability of the compressors.
[0036] These different data are used by unit 2 to determine the flight phase and the mechanical power level required from the engine for the flight. Said unit 2 deduces the power draw distribution to be applied between the two generators 3 and 4. In stabilized operation of the turbomachine, for each flight phase and each expected mechanical power level, there corresponds an optimized power distribution previously determined and stored in unit 2.
[0037] Identification of flight phases by unit 2 can be done as follows:
[0038] Take-off: M lever in take-off position, altitude and speed in the take-off area;
[0039] Climb: M lever in minimum “climb” position or beyond; altitude and speed outside takeoff phase conditions;
[0040] Cruise: speed (or position of the M lever) between a cruise minimum and a climb threshold, altitude above a cruise threshold altitude;
[0041] Descent: speed (or position of the M lever) below a threshold, landing gear retracted and altitude above a cruising threshold altitude;
[0042] Approach: speed (or position of the M lever) below a threshold, landing gear extended and not crushed
[0043] Idle Ground: RPM (or position of the M lever) below a threshold, landing gear extended and flattened.
[0044] Thus, the distribution of the samples is dynamically managed by flight phase, according to specific engine needs, while meeting the overall aircraft power needs.
[0045] An example of distribution for different flight phases is given in the table below.
[0046] Where: • ENP denotes the non-propulsive energy and the level of mechanical power taken from the engine requested from the engine,
[0047] • 100% ENP designates the reference level in relation to which the distribution is made between the power taken from the HP shaft and that from the HP shaft.
[0048] This distribution is determined by unit 2 based on the rules it has in memory. The example given below allows optimization of the samples with the objective of minimizing the SFC consumption of the engine.
[0049] It is particularly suitable in the case of a streamlined engine configuration with a very high dilution ratio (IIHBR or “Ultra High By Pass Ratio” in English terminology).
[0050] • Take-off phase (TKOF): o the electrical power is taken 100% from generator 3 (HP shaft);
[0051] • Climb phases o up to 21,000 feet (6,400 m), the electrical power is taken at 100% from generator 3 (HP shaft) (phases “Climb 1500ft (457 m) / M0.388 and “Climb 10kft (3,048 m) / M0.488” in the table above); o up to 29,700 feet (9,052 m), the electrical power is taken at 40% from generator 3 (HP shaft) and at 60% from generator 4 (LP shaft) (phase “Climb 21,111 ft (6,434 m) / M0.602” in the table above); o from 29,700 Feet (9,052 m) up to 35,000 Feet (10,668 m), the electrical power is taken at 60% from generator 3 (HP shaft) and at 40% from generator 4 (LP shaft) (phase “Climb 29753ft (9,068 m) / M0.714” in the table above); o beyond 35,000 Feet (10,668 m), the electrical power is taken at 80% from generator 3 (HP shaft) and at 20% from generator 4 (LP shaft) (phase “Climb 35kft (10,668 m) / M0.77” in the table above).
[0052] • Cruise (from 21,000 feet (6,400 m)): o the electrical power is taken 40% from generator 3 (HP shaft) and 60% from generator 4 (LP shaft) (“Cruise” phase in the table above).
[0053] For example, the challenge in terms of SFC consumption for such an IIHBR engine is as follows:
[0054] More generally, the distribution rules available to the control unit 2 are determined for a given engine or type of turbomachine, based on a desired optimization, according to the level of mechanical power required from the engine for the flight and following the flight phase.
[0055] Optimizing SFC consumption is a possible optimization objective for a double or triple spool turbomachine.
[0056] An optimization table is then as follows:
[0057] Optimization can also depend on the overall level of power drawn. The optimum HP / LP distribution can then change depending on this level of draw.
[0058] Other optimization objectives are of course possible.
[0059] In particular, optimization logic can be very different from one phase to another.
[0060] In particular, a judicious choice of the distribution of samples to minimize the thrust on the idle points (ground & descent).
[0061] In the case of descent thrust optimization, the distribution of the samples is established according to the architecture of the aircraft and in particular its idle thrust specifications linked, among other things, to the finesse of the wing.
[0062] For example, a descent thrust optimization table might be: where a negative distribution corresponds to power injection, the values being chosen so that the power transfer between the shafts balances and the engine does not take power from other sources in the aircraft.
[0063] Minimizing the “Ground Idle” thrust helps limit wear and brake temperature during aircraft taxi phases.
[0064] Another possibility is to optimize the distribution of samples to limit the turbine outlet temperature (TGT). Ground idle operation in hot ambient temperature conditions is traditionally limited by the turbine outlet temperature, which requires increasing the idle level to obtain an acceptable turbine outlet temperature for the materials of the turbomachine's afterbody. A judiciously chosen dynamic distribution of samples makes it possible to limit the turbine outlet temperature.
[0065] An optimized distribution for this goal is: 60%HP / 40%BP.
[0066] Also, another possible optimization, especially for the approach phase, is the minimization of acceleration times.
[0067] An optimized distribution for this goal is: 0%HP / 100%BP
[0068] As illustrated in Figure 2, the control unit 2 integrates optimization sub-units 6a to 6e according to the different possible logics, as well as a selection logic 7, a sub-unit 8 for determining the flight phase and a sub-unit 9 for determining the stabilized state of the turbomachine.
[0069] Subunits 6a to 6e are supplied with flight data (altitude, speed, etc.), as well as TM data from the sensors of turbomachine 1 (turbine outlet temperature, for example)
[0070] The flight phase determination sub-unit 8 receives data such as the position of the lever M, which provides information on the thrust requirement, or W data provided by aircraft sensors such as "gear extended" and "gear flattened".
[0071] Sub-unit 9 receives TM engine data provided by the turbomachine sensors, in particular to define the transient / stabilized state of the latter, as well as to provide information on the constraints linked to the operability of the compressors.
[0072] The output of said flight phase determination sub-unit 8 is sent to the selection logic 7 which interrogates one of the sub-units 6a to 6e as a function of the identified flight phase so that the selected sub-unit provides, using the stored optimization tables, an optimized sampling distribution as a function of this data and the optimization objective which corresponds to it and which corresponds to the flight phase.
[0073] An example of a phase-dependent optimization choice can be the following (stabilized engine): Take-off: optimization of fuel consumption by a power unit (SFC) (sub-unit 6a);
[0074] Climb: optimization of fuel consumption per unit of power (SFC) (sub-unit 6a); - Cruise: optimization of fuel consumption per unit of power (SFC) (sub-unit 6a);
[0075] Descent: optimization of the thrust (sub-unit 6b);
[0076] Landing approach: optimization of acceleration times (sub-unit 6c); - Ground idle: optimization of the TGT temperature at the turbine outlet
[0077] (subunit 6d).
[0078] Other optimization choices are of course possible (under unit 6e).
[0079] In particular, for the idle phase, optimization can also be done on the residual thrust or on a compromise between optimization on the residual thrust and optimization of the TGT temperature at the turbine outlet.
Claims
CLAIMS System for managing mechanical power draws on a double or triple body turbomachine (1) for aircraft comprising at least a first turbine and a second turbine, in which at least a first electrical machine (3) and a second electrical machine (4) are adapted to recover mechanical energy: for said first electrical machine (3), on a shaft driven by the first turbine of the turbomachine, for said second electrical machine (4), on a shaft driven by the second turbine of the turbomachine, in which said system comprises: a management unit (5) which controls the electrical power draws and the electrical distribution on the various equipment and consumer systems of the aircraft, and a control unit adapted to transmit a distribution of draws which it determines according to the flight phase of the aircraft, to said management unit (5),said control unit (2) being adapted to store rules for distributing samples for different optimization logics, said stored rules for distributing samples corresponding to optimization logics chosen from the following group: optimization of fuel consumption per unit of power (SFC) and / or optimization of thrust and / or optimization of acceleration times and / or optimization of turbine outlet temperature. Method for managing mechanical power withdrawals on a double or triple body turbomachine (1) for aircraft comprising at least a first turbine and a second turbine, in which at least a first electrical machine (3) and a second electrical machine (4) are adapted to recover mechanical energy:, - for the first electric machine (3), on a shaft driven by the first turbine of the turbomachine (1), and - for the second electric machine (4), on a shaft driven by the second turbine of the turbomachine, the method implementing a control of the electrical power draws and the electrical distribution on the different equipment and consumer systems of the aircraft, in which the distribution of these draws between the first electric machine (3) and the second electric machine (4) is controlled dynamically according to the flight phase, in which a control unit (2) stores rules for distributing draws for different optimization logics, said stored rules for distributing draws corresponding to optimization logics chosen from the following group: optimization of fuel consumption per unit of power (SFC) and / or optimization of thrust and / or optimization of acceleration times and / or optimization of the turbine outlet temperature.
3. Method according to claim 2, in which the control unit (2) implements, in particular as a function of information (AD) transmitted by the aircraft, a determination of the flight phase in which the aircraft is located and transmits to a management system (5) which controls the electrical power draws, a distribution to be applied, said distribution being a function of an optimization logic specific to the flight phase thus determined.
4. Method according to claim 3, in which the determination of the flight phase and the distribution by the control unit is a function of input data comprising flight data of the aircraft (AD); the thrust requirement and / or the position of the throttle lever (M); data (W) provided by sensors of the aircraft such as extended and flattened landing gear, data (TM) provided by the sensors of the turbomachine (1), in particular to define the transient / stabilized state thereof.
5. Method according to claim 4, in which the logics for optimizing the different flight phases comprise: Take-off: optimization of fuel consumption per unit of thrust (SFC); Climb: optimization of fuel consumption per unit of thrust (SFC); Cruise: optimization of fuel consumption per unit of thrust (SFC); 6. Method according to the preceding claim, in which the optimization logics of the different flight phases further comprise: Descent: optimization of thrust; Landing approach: optimization of acceleration times; Ground idle: optimization of the TGT temperature at the turbine outlet.
7. Method according to one of claims 5 or 6, in which said stored sampling distribution rules take into account the altitude of said aircraft.
8. Assembly comprising a double or triple body turbomachine (1) for aircraft comprising at least a first turbine and a second turbine, in which at least a first electric machine (3) and a second electric machine (4) are adapted to recover mechanical energy, - the first electric machine (3) on a shaft driven by the first turbine of the turbomachine (1), and - the second electric machine (4) on a shaft driven by the second turbine of the turbomachine, in which said assembly further comprises a management system according to claim 1.
9. Assembly according to claim 8, in which the turbomachine is of the double-body type, the electrical machines being two generators adapted to recover mechanical energy one from the high pressure shaft of the turbomachine, the other from the low pressure shaft. Aircraft comprising a system according to claim 1 or an assembly according to one of claims 8 or 9.