PROPEL GROUP, AIRCRAFT AND IN-FLIGHT OPERATION

Abstract

PROPULSION UNIT, AIRCRAFT AND IN-FLIGHT OPERATION The present invention relates to a propulsion unit (100) for a fixed-wing aircraft, the propulsion unit comprising a nacelle (112) housing at least two non-coaxial fans (14), said nacelle comprising an upper wall (116) having a span overhanging the two fans, notable in that the upper wall comprises a nozzle pivotable (116.2) about an axis (116.3) parallel to the span of the upper wall. The invention also relates to a method of operating an aircraft comprising a climb phase during which the nozzle is radially inclined outwards, and potentially a cruise flight phase during which the nozzle remains stationary, the speed of the aircraft's fans varies, the inclination of the nozzle relative to the upper wall varying proportionally to the speed of the fans. (Figure to be published with the abbreviation: Figure 4)

Description

Title of the invention: PROPULSION GROUP, AIRCRAFT AND IN-FLIGHT OPERATION technical field

[0001] This application relates to the field of fixed-wing aircraft and their implementation. Previous art

[0002] Document WO 2021 / 074516 Al introduces a modern aircraft architecture in which two oblong, lifting nacelles are arranged on either side of the fuselage. Each nacelle incorporates several fans driven in rotation by a gas turbine, itself supplied with gas by a compressor.

[0003] Such a design provides for the positioning of a lower wall of the nacelle in line with the fixed wing of the aircraft, which makes it possible to ensure low drag and increased lift during the flight of the aircraft.

[0004] However, this positioning generates a distortion of the natural streamline entering the nacelle under certain thrust conditions. In particular, the nacelle air intake is designed to properly capture the airflow under the aircraft's cruise conditions, i.e., the reference incoming airflow rate. On the other hand, this air intake is not suitable for capturing a high-flow airflow, which is the case, in particular, during the aircraft's climb. Indeed, a high flow rate causes a large deflection of the airflow at the nozzle, which leads to separation of the airflow from the upper wall of the nacelle. In addition to the detrimental impact of such separation on the flow within the turbomachine (and therefore the thrust), this separation also results in an increase in the drag generated by the nacelle.

[0005] Thus, the aircraft architecture initiated by document WO 2021 / 074516 Al presents a margin for improvement aimed at mitigating the phenomenon of air separation at the nacelle inlet. Description of the invention

[0006] The present invention aims to provide a propulsion group for an aircraft which benefits from the advantages of the prior art in terms of low drag and increased lift and which also allows the drag which can be generated in the aircraft's climb condition to be limited, advantageously resulting in a reduction, at equal speed or acceleration, of fuel consumption.

[0007] The invention relates to a propulsion unit for a fixed-wing aircraft, the propulsion unit comprising a nacelle housing at least two non-coaxial fans, said nacelle comprising an upper wall having a span overhanging the two blowers, remarkable in that the upper wall includes a nozzle pivoting around an axis parallel to the span of the upper wall.

[0008] The nacelle profile is not substantially circular but rather oblong, the nacelle housing at least two non-coaxial blowers. The upper and lower walls of the nacelle are load-bearing.

[0009] Advantageously, the pivoting nozzle makes it possible to increase the cross-section of the nacelle (viewed from the front) and thus the volume of air entering the nacelle, which leads to a maximization of the amount of airflow directed towards the blowers.

[0010] According to an advantageous embodiment of the invention, the nozzle is pivotable through an angle α between 0° and 50° relative to a reference position.

[0011] The reference position may correspond to a neutral position of the nozzle during cruise. This position may be one in which the nozzle is parallel to the lower wall of the nacelle. This reference position may also correspond to a position in which the nozzle is substantially parallel to an axis of rotation of one or more fans. Alternatively, the reference position may differ from this axis and have an angle of at most 20° or 10° with said axis.

[0012] When the aircraft is in a flight phase under cruise conditions, in which the airflow entering the nacelle is considered to be a normal flow, the angle a is preferably close to 0°, and more preferably zero.

[0013] According to an advantageous embodiment of the invention, the spout is radially pivotable externally.

[0014] The nozzle is capable of pivoting upwards, i.e. radially outwards, in a direction perpendicular to an axis of rotation of one or more blowers.

[0015] According to an advantageous embodiment of the invention, the nozzle extends over the entire span of the upper wall. In this configuration, the nozzle comprises a span extending over the two blowers. Alternatively, the nozzle may comprise several segments, each corresponding to a portion of the nacelle's span, and the nozzle segments may be actuated independently of each other to fine-tune the nacelle's air intake area.

[0016] The invention also relates to a fixed-wing aircraft comprising a fuselage, two wings and two propulsion units arranged respectively on either side of the fuselage, downstream and at a distance from the wings, each of the propulsion units comprising a nacelle housing at least two non-coaxial fans, said nacelle comprising an upper wall and a lower wall, said lower wall being located substantially in line with the wing, notable in that the upper wall comprises a slat pivotable about an axis substantially parallel to the wingspan.

[0017] Preferably, the aircraft wing is substantially parallel to the upper wall and their longest dimension directions (their wingspans) are parallel. Alternatively, the wingspan can have at most an angle of 20° with the upper wall span.

[0018] According to an advantageous embodiment of the invention, each of the propulsion groups conforms to the embodiments mentioned above.

[0019] Advantageously, the pivoting of the pivoting nozzle minimizes the phenomenon of air separation while increasing the volume of air directed towards the blowers, thus improving thrust without diminishing it by an increase in drag, particularly during the ascent phases.

[0020] According to an advantageous embodiment of the invention, the beak extends over at least 10% of the axial dimension of the gondola.

[0021] According to an advantageous embodiment of the invention, the pivot axis of the nozzle has an axial position substantially identical to that of the blowers.

[0022] The invention also relates to a method of implementing an aircraft remarkable in that the aircraft conforms to one of the embodiments described above, the method comprising an upward phase during which the beak is inclined radially outwards at an angle α between 10° and 50°.

[0023] The inclination of the nozzle may be, with respect to a principal direction substantially parallel to the extension of the wing and / or parallel to the axis of the fans. In this respect, during the aircraft's climb phase, the angle α is preferably close to 50°.

[0024] The angle a is more preferably between 0° and 30°, and even more preferably is equal to 20° during the aircraft's ascent phase.

[0025] The angle can vary during the ascent to be close to its maximum opening (for example, 20°, 30° or 50°) on the ground and to be close to 0° at 1500 feet.

[0026] The invention also relates to a method of implementing an aircraft remarkable in that the aircraft is according to the invention, the method comprising a flight phase during which the speed of the aircraft's fans varies, the inclination of the nozzle relative to the upper wall varying linearly with the speed of the fans.

[0027] Thus, the higher the rotation speed of the blowers, the higher the pivot angle of the nozzle, and vice versa, allowing a significant airflow without detachment during the upward phases.

[0028] Preferably, the invention also relates to a method for implementing an aircraft notable in that the aircraft conforms to one of the embodiments described above, the method comprising a cruise flight phase during which the nose cone remains stationary relative to the upper wall. Here, "stationary" means that the nose cone remains stationary in rotation within a frame of reference attached to the aircraft.

[0029] Preferably, the pivoting slat according to the method of the invention is operated only during the aircraft's ascent phase. To this end, during the aircraft's flight in cruise flight conditions, i.e., after takeoff, the pivoting slat is in a stationary position and preferably forms a zero angle with the principal direction.

[0030] Alternatively, control means may be provided to detect the separation of the airflow and to actuate a pivoting of the nozzle in the event of separation.

[0031] In addition to the technical advantages discussed above, the invention incidentally allows a reduction in fuel consumption because the thrust generated is not hindered by a disturbed airflow and the drag of the nacelle is limited.

[0032] The invention is also advantageous because it is adaptable to existing aircraft, as it does not require modification of a standard wing or fuselage. Brief description of the drawings

[0033] [Fig.1] represents an aircraft according to the invention;

[0034] [Fig.2] illustrates a cross-sectional view of a state-of-the-art propulsion unit in condition of aircraft cruise flight;

[0035] [Fig.3] illustrates a cross-sectional view of the state-of-the-art propulsion unit during a aircraft ascent phase;

[0036] [Fig.4] illustrates a cross-sectional view of a propulsion unit according to the invention during a aircraft ascent phase;

[0037] [Fig. 5] illustrates a cross-sectional view of the propulsion unit according to the invention under conditions of aircraft cruise flight. Detailed description

[0038] The figures represent the elements schematically. Some dimensions may be exaggerated to facilitate reading the drawings.

[0039] Upstream and downstream are understood in the direction of airflow. The longitudinal direction is the direction of the aircraft's longest dimension, i.e., parallel to the fuselage (corresponding to the X-axis of [Fig. 1]). The transverse direction (Y-axis of [Fig. 1]) is perpendicular to the fuselage and horizontal when the aircraft is on the ground.

[0040] It is understood that particular embodiments of the invention are drawn but that the figures do not in any way limit the scope of protection which is only dictated by the claims.

[0041] Also, each element of each figure can be combined with each other element of each other figure according to all technically possible combinations.

[0042] Fig. 1 shows an aircraft 2. This consists of a fuselage 4 and two wings 6, fixed relative to the fuselage 4. The wings are equipped with flaps 8.

[0043] On either side of the fuselage 4 and downstream of the wings 6 are located two propulsion units 10. By "propulsion unit" is meant a module capable of generating thrust necessary for the flight of the aircraft 2.

[0044] The propulsion group 100 includes a nacelle 112. This includes, among other things, a lower wall, an upper wall and vertical walls connecting the lower wall to the upper wall.

[0045] The nacelle 112 can be mechanically connected to the fuselage 4 and / or the wing 6 by means of connecting devices. An arm extending substantially transversely from the fuselage 4 can, for example, connect the nacelle 112 to the fuselage 4 on the downstream side of the nacelle 112.

[0046] The nacelle 112 comprises a plurality of fans. These can be driven in rotation by a respective turbine. Each fan can be part of a self-contained unit (turbine-jet type with compressor, combustion chamber, and turbines). Alternatively, the turbines driving the fans can be driven by a pressurized gas produced elsewhere in the aircraft: for example, a common compressor for several fans can supply the nacelle turbines with pressurized gas. In another embodiment, the fans are driven by an electric motor.

[0047] Fig. 2 illustrates a cross-sectional view of a state-of-the-art propulsion unit 10 in cruise flight condition of the aircraft.

[0048] It should be noted that from an architectural point of view, the gondola of the present invention differs from that of the prior art at least in that the upper wall is different, this difference and other aspects distinguishing the invention from the prior art will be detailed more fully later in this description.

[0049] With reference to [Fig.2], the nacelle 12 of the propulsion group 10 comprises at least two non-coaxial blowers 14, only one of which is visible in this section along an axis 14.1 of the blower 14.

[0050] The blower 14 is attached to a shaft supported by bearings. Support arms can be arranged downstream of the blower 14 in order to connect the bearings to the upper wall 16 and lower wall 18.

[0051] The blower 14 generates an annular airflow Fl whose main direction is coaxial with the axis 14.1 of the blower.

[0052] The lower wall 18 of the nacelle 12 is arranged in line with the wing 6 in order to ensure sufficient lift and drag reduction for all flight conditions of the aircraft.

[0053] In this regard, the nacelle 12 is positioned so that the lower wall 18 is substantially at the same height (along Z) as a trailing edge of the wing 6.

[0054] Wing 6 has an extrados 6.1 and an intrados 6.2.

[0055] The distance H represents the gap between the trailing edge of the wing 6 and a leading edge of the lower wall 18. The distance H can measure between a few tens of centimeters and several meters.

[0056] During the flight of the aircraft in cruise condition illustrated in [Fig.2], the incoming airflow F into the nacelle 12 can be pictured by a stream tube, the latter comprising an upper stream line 20 which comes into contact with a leading edge of the upper wall 16, and a lower stream line 21 guided by the upper surface 6.1 of the wing 6 towards a leading edge of the lower wall 18.

[0057] It can be observed that the upper streamline 21 is substantially parallel to a longitudinal direction 16.1 of the leading edge of the upper wall 16.

[0058] Preferably, the longitudinal direction 16.1 of the leading edge of the upper wall 16 is substantially parallel to the axis 14.1 of the blower 14 (which is substantially parallel to the longitudinal axis X of the [Fig.1]), but said direction 16.1 may have an angle of at most 20° or 10° with the axis 14.1.

[0059] Under these conditions, the incoming airflow F allows the propulsion unit 10 to generate sufficient thrust for the proper functioning of the aircraft.

[0060] The streamline 20 is not, or is only slightly, deflected upon entering the nacelle. The flow therefore remains attached at the level of the leading edge of the upper wall 16.

[0061] Fig. 3 illustrates a cross-sectional view of the state-of-the-art propulsion unit during an ascent phase of the aircraft.

[0062] With reference to [Fig.3], the incoming airflow stream tube F in the aircraft's climb condition comprises a larger cross-section than the stream tube in the cruise condition, this is due to the high airflow drawn into the nacelle in these conditions.

[0063] Indeed, during an upward phase of the aircraft, the turbomachines can operate at full load and the fans 14 thus rotate at speeds above the cruising speed, in order to allow the aircraft to generate a large thrust necessary to overcome gravity.

[0064] In this respect, the airflow rate of the incoming flow F during ascent is significantly higher than the cruising flow rate. Similarly, the rotational speed of the fans 14 during ascent is higher than the speed of the fans during cruising.

[0065] In this configuration, the lower airflow line 21 guided by the upper surface 6.1 of the wing 6 towards the leading edge of the lower wall 18 remains substantially unchanged compared to cruise flight, while the upper airflow line 20 exhibits a strong deviation with the longitudinal direction 16.1 of the upper wall 16, this deviation is at least 20° and can reach 50° between the upper wall 16 and the upper airflow line 21.

[0066] The deviation produces a detachment 22 of the flow from the upper wall 16 inside the nacelle 12.

[0067] The separation 22 may be adjacent to the blowers 14, which may disrupt the operation of the latter and reduce the thrust.

[0068] Indeed, the separation 22 causes a pressure drop that can reach at least 20% of an air inlet cross-section in the nacelle 12. The separation 22 also increases the drag of the nacelle 12. The reduction in thrust and the increased drag require the state-of-the-art aircraft to increase the rotational speed of the fans 14 accordingly to obtain the same speed / acceleration. This increase in speed is naturally accompanied by a significant increase in fuel consumption.

[0069] It should be noted that from an architectural point of view, the gondola of the present invention differs from that of the prior art at least in that the upper wall is different, this difference and other aspects distinguishing the invention from the prior art will be detailed more fully later in this description.

[0070] The invention described in the following figures aims to eliminate this detachment.

[0071] Figure 4 illustrates a cross-sectional view of a propulsion unit according to the invention during of an ascent phase of the aircraft.

[0072] The gondola according to the invention differs from the prior art gondola illustrated in Figures 3 and 4 by its upper wall. In this respect, similar elements between the two gondolas will retain the same reference numeral, while elements with differences will be incremented by 100.

[0073] With reference to [Fig.4], the gondola 112 according to the invention comprises an upper wall 116 having a pivoting beak 116.2 pivotable about an axis 116.3 parallel to the span of the upper wall 116 (the span extends along the Y axis of [Fig.1]).

[0074] Preferably, the swiveling nozzle 116.2 extends over at least 80% of the span of the upper wall 116, and more preferably, the swiveling nozzle 116.2 extends over the entire span of the upper wall 116.

[0075] Also, the axis of rotation of the pivoting beak 116.2 is substantially parallel to the span of the wing 6. Preferably, the span of the wing 6 is substantially parallel to the span of the nacelle. However, said spans may have an offset of a few degrees, up to 10° or 20°, and the pivoting axis 116.3 of the beak 116.2 may be parallel to the span of the wing or the nacelle.

[0076] The pivoting nozzle 116.2 has an angle of inclination a with respect to a longitudinal direction 116.3. The longitudinal direction 116.1 extends from the leading edge of the upper wall 116 in a direction substantially parallel to the axis 14.1 of the blower 14 (axis X on the [Fig.1]), but may have an angle of up to 10° or 20° with the axis 14.1.

[0077] During the ascent phase of the aircraft of the invention, the angle of inclination a is at most 50° and / or at least 10°, the angle a is preferably 30° and more preferably 20° during the ascent phase.

[0078] In this configuration, the airflow stream tube F (identical to that of [Fig.3]) entering the nacelle 112 includes the upper airflow line 20, the latter having a strong deviation with the longitudinal direction 116.1 of the upper wall 16, this deviation is at least 20° and can reach 50°.

[0079] However, this deviation between the upper airflow line 20 and the swiveling nozzle 116.2 is less, due to the orientation of the nozzle 116.2.

[0080] Indeed, the angle of inclination a makes it possible to substantially align the pivoting nozzle 116.2 with the upper streamline 20 in order to guide the incoming airflow with the upper wall 116 and directly towards the blowers 4.

[0081] The swiveling nozzle 116.2 can be radially inclined outwards or radially inclined inwards with the angle of inclination a about the axis 14.1 of the blowers. Preferably, the swiveling nozzle 116.2 is radially inclined outwards, i.e. upwards (along Z).

[0082] Preferably, the axis 116.3 of the swiveling nozzle 116.2 is adjacent to the blower 14.

[0083] In this respect, the pivot axis 116.3 of the pivoting nozzle 116.2 can assume a axial position substantially identical to that of blowers 14.

[0084] Indeed, the swiveling beak 116.2 extends over at least 10% and at most 30% of the axial dimension of the nacelle.

[0085] Advantageously, this makes it possible to avoid possible air separations that may occur near the blower 14.

[0086] In this configuration, the occurrence of separations 22 can be avoided, and the nacelle 112 significantly reduces drag. This makes it possible to obtain the same speed / acceleration at high flow rates while conserving fuel.

[0087] In parallel, the lower airflow line 21 guided by the upper surface 6.1 of the wing 6 towards the leading edge of the lower wall 18 remains substantially unchanged compared to cruise flight.

[0088] Under these conditions, the incoming airflow F allows the propulsion unit of the invention to generate sufficient thrust for the proper functioning of the aircraft.

[0089] Fig. 5 illustrates a cross-sectional view of the propulsion unit according to the invention under cruise flight conditions of the aircraft.

[0090] The pivoting nozzle 116.2 is here in a reference position in which said nozzle 116.2 is parallel to the longitudinal direction 116.1 of the leading edge of the upper wall 116.

[0091] The advantages obtained during takeoff by pivoting the slat 116.2 do not therefore impair the proper functioning of the nacelle during cruise because the slat can also to assume an optimal cruising position.

[0092] The transition from the ascent phase illustrated in [Fig.4], to the cruise flight phase illustrated in [Fig.5], can occur by a transition during which the pivoting of the nozzle 116.2 varies linearly with the speed of the blowers 14.

[0093] During the ascent phase, the blowers 14 have a maximum speed and the nozzle 116.2 is inclined radially outwards at an angle a.

[0094] The gradual reduction of the speed of the fans 14 at the end of takeoff leads to a reduction in the value of the angle a, until the cruise flight phase is reached, in which the angle a is preferentially zero.

[0095] This linearity can be managed by a servo system of the aircraft of the invention to relieve the pilot of this operation.

[0096] Alternatively or in addition, the control can be achieved by linearly linking the value of the angle a with the attitude of the aircraft: once the climb is complete, the angle a is zero; during a descent, the angle a becomes negative (the pivoting slat 116.2 is then radially inclined internally) to compensate for the low flow rate and to avoid the phenomenon of spillway drag.

[0097] During the cruise flight phase, the fans 14 have a cruising speed and the nozzle 116.2 remains stationary relative to the upper wall 116.

[0098] The increase in the speed of the blowers 14 can be linearly proportional to an increase in the value of the angle a, until the upward phase is reached, in which the angle a is preferably equal to 20°.

Claims

Demands

1. Propulsion unit (100) for fixed-wing aircraft (2), the propulsion unit (100) comprising a nacelle (112) housing at least two non-coaxial fans (14), said nacelle (112) comprising an upper wall (116) having a span overhanging the two fans (14), characterized in that the upper wall (116) comprises a nozzle (116.2) pivotable radially outwardly about an axis (116.3) parallel to the span of the upper wall (116).

2. Propulsion unit (100) according to claim 1, characterized in that the nozzle (116.2) is pivotable through an angle (a) between 0° and 50° relative to a reference position.

3. Propulsion unit (100) according to any one of claims 1 or 2, characterized in that the nozzle (116.2) extends over the entire span of the upper wall (116).

4. Fixed-wing aircraft (2) comprising a fuselage (4), two wings (6) and two propulsion units (100) disposed respectively on either side of the fuselage (4), downstream and at a distance from the wings (6), each of the propulsion units (100) comprising a nacelle (112) housing at least two non-coaxial fans (14), said nacelle (112) comprising an upper wall (116) and a lower wall (18), said lower wall (18) being situated substantially in the extension of the wing (6), characterized in that the upper wall (116) comprises a nose (116.2) pivotable radially outwardly about an axis substantially parallel to the wingspan (6).

5. Aircraft (2) according to claim 5, characterized in that each of the propulsion groups (100) is according to any one of claims 1 to 3.

6. Aircraft (2) according to any one of claims 4 and 5, characterized in that the nose (116.2) extends over at least 10% of the axial dimension of the nacelle (112).

7. Aircraft (2) according to any one of claims 4 to 6, characterized in that the pivot axis (116.3) of the nozzle (116.2) has an axial position substantially identical to that of the blowers (14).

8. Method of implementing an aircraft (2) characterized in that the aircraft (2) is according to any one of claims 4 to 7, the method comprising an upward phase during which the beak (116.2) is inclined radially outwards at an angle (a) between 10° and 50°.

9. Method of implementing an aircraft (2) characterized in that the aircraft (2) is according to any one of claims 4 to 7, the method comprising a flight phase during which the speed of the fans (14) of the aircraft (2) varies, the inclination of the nozzle (116.2) relative to the upper wall (116) varying linearly with the speed of the fans (14).