RU2806953C2 - Gas turbine engine with uncapped counter-rotating propellers - Google Patents

Abstract

FIELD: gas turbine engine.

SUBSTANCE: invention is related to a gas turbine engine of an aircraft containing an outer casing (2) that, together with the internal central part (3), limits the flow path (1) for the passage of a gas flow, in which a low-pressure turbine is located, configured to drive the low-pressure shaft into rotation. Said gas turbine engine contains, in the direction of gas flow, a first propeller (31) and a second propeller (32) located behind the first propeller, wherein the first propeller (31) is driven by said low-pressure shaft, and the second propeller is driven by rotated by an electric motor (70). The second propeller (32) is located at a distance of 1.5 to 4 chord lengths (LC1) of the first propeller (31) and determined between the corresponding axes of the angle setting (A31, A32) of each of the first and second propellers. This gap between the two propellers (31, 32) provides an aerodynamic connection that can effectively contribute to the thrust of the gas turbine engine. This gap is also the result of an aero-acoustic trade-off between: the distance between the two propellers being large enough to limit the intensity of the acoustic interaction bands between the propellers; the distance between the two propellers that is small enough to minimize the dissipation of the velocity profiles at the exit of the first propeller (input propeller) and facilitate their immediate use by deflecting the second propeller (exit propeller).

EFFECT: by configuring the variable interactions between the two propellers, the performance of the gas turbine engine is improved.

12 cl, 11 dwg

Description

Field of technology to which the invention relates

The invention relates to the field of gas turbine engines and, in particular, relates to gas turbine engines of the uncapped type (“open rotor” in English).

State of the art

Uncapped gas turbine engines fit into the context of architectures designed to maximize energy efficiency while being able to be properly integrated (in terms of geometry and aerodynamics) into the aircraft.

Many solutions are known in this context.

The first solution is a gas turbine engine with twin counter-rotating propellers (in English “counter rotating open rotor” (CROR)), described, for example, in document FR 2 941 492. Such a gas turbine engine contains an air intake and a gas flow path limited outer body and inner central part. The flow path passes through a gas generator, in this case a twin-shaft gas generator, which powers a turbine that turns two counter-rotating propellers. According to this document, these two counter-rotating propellers are connected in rotation to a gas generator turbine. The advantage of the gas turbine engine disclosed herein is the excellent thrust efficiency associated with the generation of thrust through propellers with a very low compression ratio, as well as outer dimensions smaller than the outer dimensions of a gas turbine engine with a single propeller at the same thrust, which facilitates its physical integration into aircraft. However, this architecture based on twin counter-rotating propellers has some limitations, in particular due to the complexity of the subsystems required for its application (dual propeller pitch system, rotating housings under each propeller rotor, ...).

Another solution, which is a version with a twin counter-rotating propeller architecture, is the USF architecture (in English “Unducted Single Fan”), which contains a propeller rotor and a stator located in its wake vortex with a variable blade angle, designed to straighten the residual rotation of the rotor screw This version can be thought of as a CROR type architecture in which the rotation of the output propeller is stopped. Although this solution offers greater architectural simplicity, it still suffers from lower low-pressure module efficiency than the CROR solution and requires larger diameters to support rotor loads equivalent to the CROR solution (this rotor load is what primarily accounts for the perceived noise levels) .

Finally, both of the above architectural solutions have the following disadvantages:

1. Almost bijective operation of the gas generator and propulsion parts: when the thrust demand for the aircraft is reduced (during the end-of-flight phases at cruising speed and in idle mode), all rotating parts operate at low energy levels (low compression ratio, low rotation modes) , which negatively affects the intrinsic efficiency of each component, in particular inside the gas generator, and leads to a decrease in the overall efficiency of the power plant.

2. Difficulty in selecting significant mechanical power on the shafts of a gas turbine engine without significantly affecting the controllability of the compressors. Indeed, in the context of increasing demand for mechanical power for aircraft sections that consume increasingly more electricity, it is necessary to adapt the gas turbine engine architecture to drive increasingly powerful electrical generators. This leads to an increase in stress on the compressors and forces them to increase their required parameters, which affects their absolute performance.

Disclosure of the invention

The invention is intended to propose a gas turbine engine architecture with two uncapped propellers, which overcomes the above-mentioned disadvantages.

For this purpose, the first object of the invention is a gas turbine engine of an aircraft, comprising an outer casing that, together with the internal central part, defines a flow path for the passage of a gas flow, in which a low-pressure turbine is located, configured to drive a low-pressure shaft; wherein said gas turbine engine comprises, in the direction of gas flow, a first propeller and a second propeller at the outlet of the first propeller, wherein the first propeller is driven by said low-pressure shaft, and the second propeller is driven by an electric motor, wherein the second the propeller is located at a distance ranging from 1.5 to 4 chord lengths of the first propeller and determined between the corresponding axes of the angle of each of the first and second propellers.

Preferably, the invention according to its first object is supplemented by the following distinctive features, considered separately or in any technically possible combination:

- The second propeller has an outer diameter that is 0.8 to 1 times the outer diameter of the first propeller.

- The gas turbine engine includes an inner central part from which blades of a second propeller extend, the second propeller having a central part radius/outer blade radius ratio of 0.22 to 0.40.

- The second propeller has a chord length ranging from 0.8 to 1.2 times the chord length of the first propeller.

- The gas turbine engine includes a first electric motor/generator configured to participate in driving a low pressure shaft, wherein the first propeller is driven by said low pressure shaft through a gearbox.

The power plant comprises or is coupled to an energy storage device coupled to the first and/or second electric motor/generator, the energy storage device preferably having a capacity of from 200 to 500 kWh.

The first and second propellers are located in front of the entrance of the gas flow path.

The first and second propellers are located at the outlet of the flow path and outside the flow path of the gas flow.

The gas turbine engine contains a gas generator, a control unit for the second electric motor/generator, and a control unit for the installation angle of the second propeller, wherein these control units are configured to control the second engine and the installation angle of the second propeller depending on the following operating modes:

- a first mode of operation requiring a first predetermined propulsion power, wherein in the first mode of operation the second engine/generator drives the second propeller in a direction opposite to the direction of rotation of the first propeller, and the installation angle of the second propeller is set so that the second the propeller provided 20% to 40% of the specified specified propulsion power;

- a second mode of operation requiring a second predetermined propulsion power, wherein in the second mode of operation the second engine/generator does not drive the second propeller, and the installation angle of the second propeller is set so as to maximize the efficiency of the aerodynamic connection with the first propeller;

- a third operating mode requiring a third predetermined propulsion power, wherein in the third mode the gas generator and the first propeller are adjusted to provide a propulsive power greater than the third predetermined propulsion power;

- a fourth operating mode, in which the installation angle of the first propeller 31 is set to a negative value and in which the second propeller is set to a neutral setting, while the gas generator operates in the high pressure mode range of 90% to 100%, while in the fourth mode the first propeller is in a reverse thrust position, and the second propeller is configured to reverse the air flow to power the first propeller;

- a fifth operating mode, in which the overall power level is maintained due to exclusively electrical power supply to the second propeller for a given time;

- the sixth operating mode, in which the second propeller exhibits malfunction:

- if the second propeller angle drive is faulty, in which case the second propeller angle is blocked;

- if the second engine/generator of the second propeller is faulty, in which case the second propeller is commanded to enter the free wheel state.

In the third operating mode, the installation angle of the second propeller can be set so as to obtain an angle of attack of the blades less than 0° so as to rotate the second propeller in a rotation direction opposite to the rotation direction of the first propeller. The second propeller may also be controlled to obtain an angle of attack of the blades greater than 0° so as to rotate the second propeller in a direction of rotation identical to the direction of rotation of the first propeller.

Due to this configuration of variable interactions between the two propellers, the performance of the gas turbine engine is improved.

In addition, the first and second propellers can be controlled differently depending on the operating conditions of the gas turbine engine.

Brief description of drawings

Other features, objects and advantages of the invention will be more apparent from the following description, given solely by way of illustrative and non-limiting example, with reference to the accompanying drawings, in which:

in fig. 1 schematically shows the claimed gas turbine engine in the first configuration;

in fig. 2 schematically shows an alternative version of the claimed gas turbine engine;

in fig. 3 schematically shows the claimed gas turbine engine in the second configuration;

in fig. Figure 4 shows the location of the propellers of a gas turbine engine;

in fig. 5 shows the operating modes of the claimed gas turbine engine;

in fig. 6 schematically shows the first operating mode of the claimed gas turbine engine, corresponding to the take-off of the aircraft;

in fig. 7 schematically shows the second operating mode of the claimed gas turbine engine, corresponding to flight at cruising speed of the aircraft;

in fig. 8 schematically shows the third operating mode of the claimed gas turbine engine according to the first embodiment, corresponding to the idle mode when the aircraft is descending;

in fig. 9 schematically shows the deflection profile of the propeller blade of the claimed gas turbine engine;

in fig. 10 schematically shows the leading edge of the propeller of the inventive gas turbine engine;

in fig. 11 schematically shows the third operating mode of the claimed gas turbine engine according to the second embodiment, corresponding to the idle mode when the aircraft is descending.

In all figures, similar elements have the same designations.

Disclosure of the invention

As shown in FIG. 1, 2 and 3, the gas turbine engine of an aircraft contains an annular space 1 for the passage of a gas flow, limited by an outer housing 2 and an internal central part 3. In the following, such an annular space 1 will be called a flow path for the passage of a gas flow.

The gas flow flow path 1 contains, from inlet to outlet in the direction of gas flow (along the axis AA', shown by arrow F), a low-pressure compressor 11, a high-pressure compressor 12, a combustion chamber 13, a high-pressure turbine 14 and a low-pressure turbine 15.

The low pressure turbine 15 is configured to drive the low pressure shaft 25, while the high pressure turbine 14 is configured to drive the high pressure shaft 24.

In the direction of gas flow, the gas turbine engine contains a first propeller 31 and a second propeller 32 located behind the first propeller 31. The first and second propellers are not cowled (according to English terminology, this architecture is called “open rotor”).

The first and second propellers 31, 32 extend from the inner central part 3 and comprise a plurality of blades extending from the inner central part 3.

The following will be a description of two configurations, namely the first configuration with reference to FIGS. 1 and 2 and the second configuration with reference to FIGS. 3.

According to the first configuration, the first and second propellers 31, 32 are located in front of the entrance to the gas flow path 1.

Alternatively, according to the second configuration, the first and second propellers 31, 32 are located at the outlet of the gas flow path. In particular, the first and second propellers 31, 32 are located at the outlet and outside behind and above the gas flow path 1.

These two configurations differ from each other in the position of the first and second propellers with respect to the inlet and outlet of the gas flow path 1 (the inlet and outlet are determined in the direction of the gas flow).

Preferably, according to one or the other of the above two configurations, the second propeller 32 is located at a distance of 1.5 to 4 chord lengths of the first propeller determined between the respective mounting axes of each of the first and second propellers 31, 32, which will is described below with reference to FIGS. 4.

In fig. Figure 4 shows the location of the first 31 and second 32 propellers along the longitudinal axis AA' of the gas turbine engine. In accordance with this figure, it can be clarified that the chord length LCi (i=1 for the first propeller, i=2 for the second propeller) should be understood as the length of the chord 42, that is, the length of the segment (or chord) between the leading edge 41 and the trailing edge edge 43 of the propeller. In addition, the distance between the two propellers 31, 32 is measured between the corresponding installation axes A31, A32 of each of the propellers 31, 32. In this figure, the propellers are spaced from each other by three chord lengths LC.

This gap between the two propellers 31, 32 provides an aerodynamic link that can effectively contribute to the thrust of the gas turbine engine.

This gap is also the result of an aero-acoustic compromise between:

- a distance between the two propellers sufficiently large to limit the intensity of the acoustic interaction bands between the propellers;

- a distance between the two propellers that is small enough to minimize the dissipation of the velocity profiles at the exit of the first propeller (input propeller) and facilitate their immediate use by deflecting the second propeller (exit propeller).

In addition, this gap takes into account the need to integrate the pitch control mechanisms of each propeller, which require a certain axial volume to accommodate them.

Preferably, the second propeller 32 has the following geometric characteristics:

- outer diameter, ranging from 0.8 to 1 outer diameter of the first, inlet propeller 31;

- relative diameter of the bushing (the ratio of the inner radius/outer radius of the blade), ranging from 0.22 to 0.40;

- average chord, ranging from 0.8 to 1.2 times the average chord of the first, input propeller 31.

Preferably, the first propeller 31 is driven by the low pressure turbine 15 via the low pressure shaft 25 and the first gearbox 50 alone, or by a combination of the first electric motor/generator 60 and the low pressure turbine 15 via the same first gearbox 50. Thus, the first motor/generator 60 and the low pressure turbine 15 via the same first gearbox 50. generator 60 allows you to compensate for possible malfunctions of the low pressure shaft 25.

In this embodiment, in the event of a malfunction of the low pressure turbine involved in powering the first propeller 31, the engine/generator 60 provides a portion of the energy required for the first propeller 31.

This configuration shown in FIG. 2 can also be applied to the configuration shown in FIG. 3, where the propellers are located at the exit of the annular space for the passage of the gas flow.

The second propeller 32 is driven only by the second electric motor/generator 70 through the second gearbox 80.

Preferably, the first gearbox 50 and the second gearbox 80 are:

- mechanical (epicyclic or planetary type) with a gear ratio in rotation mode ranging from 8 to 12; or

- electromagnetic.

Depending on configurations, the gas turbine engine may include a first electric motor/generator 60 and a second electric motor/generator 70 that can operate as a “motor” as well as an “electricity generator.”

In this regard, it should be noted that the power plant includes an energy storage device 90 coupled to the first and/or second electric motor/generator, the energy storage device preferably having a capacity of from 200 to 500 kWh.

When the electric motor/generator 60, 70 operates in motor mode, the energy storage device 90 provides power to the electric motor/generator 60, 70, whereas when the propellers 31, 32 are not rotated by the electric motor/generator 60, 70, the electric motor /generator provides recharging of the energy storage device 90.

Indeed, the electric motor/generator 60, 70 may have operating modes during which it is not operating as a “motor” to recharge the storage device 90.

Regardless of the configuration, the gas turbine engine may contain a propeller angle control unit associated with each propeller (blocks UC1 and UC'1 in the figures), which is characterized by:

- for the first propeller - a deflection, preferably between -30° and +30°;

- for the second propeller - deflection, preferably limited to positive installation angles, typically from 0° to +90° / maximum from 0° to 110°.

In this case, the term "propeller angle" is used to refer to the angle of each propeller blade.

Preferably, the second propeller 32 is used differently depending on several modes of operation of the aircraft propulsion system. As will be described below (with reference to FIG. 5), the second propeller 32 may have multiple functions to participate in the operation of the aircraft in accordance with these different configurations.

Thus, the gas turbine engine includes a control unit UC2 for a second engine/generator coupled to a second propeller 32, wherein the control unit UC2 for a second engine/generator 70 allows the electrical power supply to that second engine/generator to be continuously controlled between the extreme cases of zero supply and supply, the corresponding maximum power of the second engine/generator 70, which it is capable of delivering, based on its size.

The first operating mode M1 corresponds to the take-off/climb of the aircraft, when the gas turbine engine needs high traction power, called the given traction power:

- the second engine/generator 70 is in "motor" mode and uses the energy of the storage device 90 as a power source to drive the second propeller 32;

- the angle of installation of the second propeller is adjusted so that the second propeller 32 provides thrust at a level of approximately 20-40% of the specified thrust power (that is, ~5 MW maximum for the short/medium range aircraft class) and that the angle of attack of the blades Ai exceeds 0° (as shown in Fig. 6);

- the gas generator operates in a reduced range of high pressure mode (N2K), ranging from 90 to 100% depending on the fuel flow supplied to the combustion chamber.

During this first mode of operation M1, driving the second propeller 32 reduces the level of energy required for the first propeller 31 to provide the total thrust expected from the power plant, thereby limiting the diameter of the first propeller 31 to a value less than required in a known solution, in the absence of additional thrust being supplied through the propeller 32. This reduction in diameter allows for a first propeller 31 that can be easily integrated while maintaining high energy efficiency of the overall propulsion system.

In addition, the required energy level at the low pressure shaft has become lower, as has the energy level expected from the gas generator, whereby the gas flow annulus can be limited to a smaller value adapted to this lower expected energy level. There is a gain in the weight of the gas turbine engine along with higher performance, as well as a reduction in the sound impact associated with the release of gases at the outlet of the gas generator.

The second operating mode M2 corresponds to flight at cruising speed of the aircraft, when the gas turbine engine requires intermediate thrust power:

- the second engine/generator 70 is not used, the second propeller 32 does not receive mechanical power and is in a “free wheel” state;

- the installation angle of the second propeller 32 is set in accordance with the installation angle of the first propeller 31 in order to maximize the propulsion efficiency of its combination with the first, input propeller 31, again so that the angle of attack of the blades Ai exceeds 0° (as shown in Fig. 7). Thus, the second propeller 32 operates as a straightener. Its rotation mode is free and depends on the aerodynamic connection with the first propeller 31: it either does not rotate or rotates very slowly. The gas generator and the first propeller 31 are adjusted to precisely meet the expected energy requirement. Installation angles are obtained as a result of preliminary aerodynamic design.

- the gas generator operates in a reduced range of high pressure mode, ranging from 80 to 90%.

During this second operating mode M2, the propulsion efficiency of the first propeller 31 is maximized by utilizing its residual rotation. The rotation of the flow (undesirable, since it does not contribute to increasing the flow speed along the traction axis) emanating from the first propeller is recovered through interaction with the blades of the second propeller (in this case almost stationary) and is used in the form of a flow speed vector oriented along the main traction axle.

The third operating mode M3 corresponds to the idle mode when the aircraft is descending, when the gas turbine engine needs little power:

- the gas generator and the first propeller 31 are adjusted to an operating point that exceeds the actual traction requirement;

- the excess generated energy manifests itself in the form of excess enthalpy and rotational motion at the output of the first propeller 31. This excess energy is recovered at the second propeller 32, which in this case is driven into rotation and operates as a wind generator through an appropriate choice of installation angle. The mechanical energy thus recovered from the second propeller 32 powers the second engine/generator 70, which then operates in generator mode to recharge the storage device 90.

- the gas generator operates in a reduced range of high pressure mode, amounting to 90-100% depending on the fuel consumption supplied to the combustion chamber.

During this third operating mode M3, the energetic decoupling of the thrust demand and the operating point of the gas generator and the first propeller 31 allows the latter to be placed in performance zones much more favorable than in the classic idle configuration. This also allows for movement away from critical areas of compressor operation by regulating the gasifier at medium/high power levels where operation is less critical than at idle conditions.

This operating mode M3 can be obtained in accordance with two embodiments:

- in the first embodiment (shown in Fig. 8), the installation angle of the second propeller 32 is changed so that the angle of attack of the blades Ai is less than 0°. This change in the angle of attack Ai of the blades makes it possible to obtain a lift coefficient of less than 0° and allows the second propeller 32 to be driven in a direction opposite to the direction of rotation of the first propeller 31. This embodiment makes it possible to maintain the same direction of rotation of the second propeller 32, which and in other operating modes, and avoids complicating the gearbox. On the other hand, it forces a change in the geometry of the propeller by reducing the deflection Fl of the airfoil profile, corresponding to the maximum distance between the chord and the bend line (shown in Fig. 9). In addition, to avoid stalling, it is necessary to provide blades with a wide leading edge Ba (shown in Fig. 10);

- In the second embodiment (shown in Fig. 11), the installation angle of the second propeller 32 is changed so that the angle of attack of the blades Ai exceeds 0°. This change in the angle of attack Ai of the blades allows the second propeller 32 to be driven in the same direction as the first propeller 31. This embodiment involves designing a gearbox that allows the second propeller 32 to rotate in both directions, but on the other hand, it does not involve changing the geometry of the propeller, given that its aerodynamic performance remains the same as in other operating modes.

The fourth mode of operation of M4 corresponds to the braking of the aircraft:

- the first propeller 31 is adjusted with a negative installation angle;

- the second propeller 32 is left in the neutral position (in English “windmilling”), which allows no mechanical power to be generated on the propeller;

- the gas generator operates in a reduced range of high pressure mode, ranging from 90 to 100%.

During this fourth operating mode M4, the thrust of the first propeller 31 is reversed, and the second propeller 32 has an installation angle selected to reverse the air flow feeding the first propeller 31.

The fifth operating mode corresponds to a malfunction in the operation of the first propeller 31 or a malfunction in the operation of the gas generator:

- the installation angle of the first propeller 31 is set to the neutral installation position (“windmilling”), if the malfunction of this first propeller allows this, or is maintained at its installation angle value at the time of the malfunction;

- the installation angle of the second propeller 32 is set in the full thrust position, that is, in accordance with the installation angle similar to the installation angle of the first propeller 31 when it operates under maximum power conditions;

- the second engine/generator 70 is commanded to provide maximum power to the second propeller 32.

During this fifth mode of operation M5, a minimum overall thrust level is maintained for a period of time (by powering the second propeller 32 to maintain its propulsive power, the thrust being generated solely by the second propeller 32), the time being determined by the power of the second electric motor. /generator 70 and the available power in the associated storage device 90. This fifth operating mode minimizes the effect of loss of thrust of the first propeller 31 or loss of primary energy input from the gas generator.

The sixth operating mode of M6 also corresponds to a malfunction, but this time of the second propeller 32:

- if the malfunction is due to the fact that it is impossible to set the installation angle of the second propeller 32, then the installation angle of the second propeller 32 is kept locked in its last occupied position;

- if a malfunction occurs in the second engine/generator 70, then the second propeller 32 is left in a free wheel state as long as the mounting angle range allows for thrust.

This sixth mode of operation of the M6 makes it possible to provide a gas turbine engine architecture that is resistant to failure of the second propeller.

As discussed above, the first engine/generator 60 coupled to the first propeller 31 may be used in addition to being driven by the low pressure turbine 15 (see FIG. 2).

This configuration provides:

- strengthening the low pressure shaft (the first input propeller 31) from the side of the first electric motor/generator 60;

- in the case of the first operating mode: amplification during take-off simultaneously with the work already performed by the second propeller 32;

- in the event of a malfunction of the gas generator during the fifth operating mode: the ability to rotate the first propeller for a time limited by the capacity of the energy storage device;

- real-time energy transfer between the second propeller 32 and the low-pressure shaft: even if the storage unit associated with the first engine/generator is empty in the “generator” mode, the second propeller 32 can receive mechanical energy according to the needs;

- a more efficient charging profile for the first engine/generator in “engine” mode, since it is directly connected to the low pressure turbine.

Claims (20)

1. A gas turbine engine of an aircraft, comprising an outer casing (2) that, together with the inner central part (3), limits the flow path (1) for the passage of a gas flow, in which a low-pressure turbine is located, configured to drive the low-pressure shaft into rotation; wherein said gas turbine engine comprises, in the direction of gas flow, a first propeller (31) and a second propeller (32) located behind the first propeller, wherein the first propeller (31) is driven by said low-pressure shaft, and the second propeller is driven by an electric motor (70), wherein the second propeller (32) is located at a distance from the first propeller of 1.5 to 4 chord lengths (LC1) of the first propeller (31), wherein said distance is determined between the corresponding axes for setting the angle (A31, A32) of each of the first and second propellers. 2. The gas turbine engine according to claim 1, wherein the second propeller (32) has an outer diameter of 0.8 to 1 times the outer diameter of the first propeller (31). 3. Gas turbine engine according to claim 1 or 2, containing an internal central part (3), from which the blades of the second propeller (32) extend, while for the second propeller (32) the ratio of the radius of the central part to the outer radius of the blade is from 0 .22 to .40. 4. Gas turbine engine according to any one of paragraphs. 1-3, wherein the second propeller (32) has a chord length (LC2) of 0.8 to 1.2 times the chord length (LC1) of the first propeller (31). 5. Gas turbine engine according to any one of paragraphs. 1-4, comprising a first electric motor/generator (60) configured to participate in driving a low pressure shaft, wherein the first propeller (31) is driven by said low pressure shaft (25) via a gearbox (50) . 6. Gas turbine engine according to any one of paragraphs. 1-5, comprising an energy storage device (90) coupled to a first and/or second electric motor/generator (60, 70), the energy storage device preferably having a capacity of from 200 to 500 kWh. 7. Gas turbine engine according to any one of paragraphs. 1-6, in which the first and second propellers (31, 32) are located at the entrance to the flow path (1) of the gas flow. 8. Gas turbine engine according to any one of paragraphs. 1-6, in which the first and second propellers (31, 32) are located at the outlet of the flow path (1) and outside the flow path (1) of the gas flow. 9. Gas turbine engine according to any one of paragraphs. 1-8, comprising a gas generator, a control unit (uc2) for the second electric motor/generator (70), a unit (uc2') for controlling the installation angle of the second propeller (32), wherein said control units are configured to control the second motor and the installation angle the second propeller depending on the following operating modes: - a first operating mode (M1), requiring a first specified traction power, wherein in the first operating mode, the second engine/generator rotates the second propeller in the direction opposite to the direction of rotation of the first propeller, and the installation angle of the second propeller is set as follows: so that the second propeller provides 20% to 40% of the specified specified propulsion power; - a second mode of operation (M2), requiring a second specified propulsion power, wherein in the second mode of operation the second engine/generator does not drive the second propeller, and the angle of installation of the second propeller is set so as to maximize the efficiency of the aerodynamic connection with the first propeller ; - a third mode of operation (M3), requiring a third set propulsive power, wherein in the third mode the gas generator and the first propeller are adjusted to provide a propulsive power greater than the third set propulsive power; - a fourth operating mode (M4), in which the angle of the first propeller (31) is set to a negative value and the second propeller is set to a neutral position, while the gas generator operates in the high pressure mode range of 90% to 100%, in this case, in the fourth mode, the first propeller is in the thrust reverse position, and the second propeller is configured to reverse the air flow, feeding the first propeller; - the fifth operating mode (M5), in which the overall power level is maintained solely by the electrical power supply of the second propeller for a given time; - sixth operating mode (M6), in which the second propeller has a malfunction: - if the second propeller angle drive is faulty, in which case the second propeller angle is blocked; - if the second engine/generator of the second propeller is faulty, in which case the second propeller is commanded to enter the free wheel state. 10. The gas turbine engine according to claim 9, in which in the third operating mode (M3) the installation angle of the second propeller is set so as to obtain an angle of attack of the blades of less than 0° in order to drive the second propeller in a direction of rotation opposite to the direction of rotation the first propeller. 11. The gas turbine engine according to claim 9, in which in the third operating mode (M3) the installation angle of the second propeller is set so as to obtain an angle of attack of the blades exceeding 0° in order to rotate the second propeller in a direction of rotation identical to the direction of rotation the first propeller. 12. A power plant containing a gas turbine engine according to any one of paragraphs. 1-5 and further comprising an energy storage device (90) coupled to the first and/or second electric motor/generator (60, 70), the energy storage device preferably having a capacity of from 200 to 500 kWh.

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