AIRCRAFT WITH MULTIPLE FAN PROPULSION ASSEMBLY FIXED UNDER THE WING

Abstract

The present invention relates to an aircraft comprising a fuselage, a lateral support wing (1) and propulsion assembly (100) mounted under the wing, the wing comprising at least two structural spars (11ba, 11bf) extending from the fuselage toward the tip of the wing, one of these (11ba) being upstream and the other (11bf) downstream, and the propulsion assembly comprising a gas generator (106) and at least two offset fans (102, 104) arranged on either side of the axis of the gas generator. The aircraft is characterized in that the offset fans (102, 104) are attached directly to one of the said spars (11ba, 11bf) and the gas generator (106) is attached directly to the two spars. In particular, with the leading edge of the wing forming a given sweep of angle () with the axis of the fuselage, the two offset fans (102, 104) are axially offset from one another.

Claims

1. Aircraft comprising a fuselage, a lateral lifting wing and a powerplant mounted under the wing, the wing comprising at least two structural spars extending from the fuselage towards the tip of the wing, one being upstream and the other downstream, with the powerplant comprising a gas generator and at least two offset fans arranged on either side of the axis of the gas generator, characterized in that the offset fans are attached directly to one of said spars and the gas generator is attached directly to both spars.

2. Aircraft according to claim 1, wherein the offset fans are attached to the upstream spar.

3. Aircraft according to claim 2, wherein each fan comprises a housing supported by the upstream spar via a suspension device that connects the housing to said upstream spar directly.

4. Aircraft according to claim 1, wherein the leading edge of the wing forms a sweepback of a given angle () with the axis of the fuselage, the two offset fans being displaced axially relative to one another.

5. Aircraft according to claim 4, wherein the air intakes of the two offset fans are under and close to the leading edge of the wing.

6. Aircraft according to claim 1, wherein the axis of the gas generator is located at a higher level than the axes of the two offset fans.

7. Aircraft according to claim 6, wherein the gas generator is integral with the wing, an outer envelope of the gas generator being formed at least partly by a part of the wall forming the lower surface and/or the upper surface of the wing.

8. Aircraft according to claim 7, wherein at least part of the envelope of at least one of the fans is formed by a part of the wall forming the lower surface and/or the upper surface of the wing.

9. Aircraft according to claim 1, wherein the gas generator comprises a gas ejection nozzle, the axis of the ejected gas stream forming an angle () between 5 and 25 downwards with the horizontal plane.

10. Aircraft according to claim 1, wherein the gas generator comprises a gas ejection channel directing the gas flow along the upper surface of the wing.

Description

DESCRIPTION OF THE FIGURES

[0031] Other features and advantages will become clearer from the following description of embodiments of the invention, which are not limiting, referring to the appended drawings, in which

[0032] FIG. 1 shows an aircraft, on which a conventional powerplant with two upstream fans is mounted under the wing by means of a strut;

[0033] FIG. 2 shows a conventional powerplant with two upstream fans, which are offset relative to the axis of the gas generator;

[0034] FIG. 3 shows the position of the conventional powerplant relative to the leading edge of the wing;

[0035] FIG. 4 shows a schematic cross-section of the wing with powerplant attachment according to the invention;

[0036] FIG. 5 shows the axially displaced arrangement of the offset fans so that they are located near the leading edge;

[0037] FIG. 6 shows schematically the arrangement of a powerplant under the wing with envelope;

[0038] FIG. 7 shows schematically a side view of one embodiment of the orientation of the gas jet from the powerplant;

[0039] FIG. 8 shows schematically a side view of a variant of guidance of the gas stream from the powerplant.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

[0040] FIG. 1 shows an aircraft, in this case an aeroplane, with its fuselage and its two lateral lifting wings 1, under which powerplants 2 are mounted, for improving the specific consumption of the engines and the level of noise. A single powerplant 2 is shown in this figure, but a second one is provided under the other wing.

[0041] The powerplant 2 of this type, namely with two offset fans on either side of a gas generator, conventionally comprises a gas generator 5 flanked by two fans, 3 and 4, one on each side of the axis of the gas generator. Here, the axis of the gas generator is roughly parallel to the axis of the fuselage. The gas generator 5 is formed by a gas turbine engine with at least one air intake, a compressor, a combustion chamber and a turbine. It ends downstream with a gas ejector nozzle. It may be mono- or multiflow, single- or multi-body depending on requirements. The fans are driven either mechanically by a shaft of the gas generator via a suitable mechanical transmission mechanism, or by a gas stream taken from the gas generator. The manner of driving the fans does not form part of the subject matter of the present application. Its description is not developed further. The same applies to the connection between the fan modules and the gas generator. In FIG. 1 corresponding to the prior art, the powerplant is joined to the wing to which it is attached via a strut 6. The drawbacks of this mounting arrangement were mentioned above. In particular, mounting upstream relative to the wing tends to amplify the engine pod drag effects, and the weight has a considerable effect.

[0042] FIG. 2 shows a single powerplant 10 that is developed relative to the solution in FIG. 1. The fans 12 and 14, of which only the housings are shown, which surround the fan rotors, which cannot be seen, and the central hubs are side by side. The gas generator 15 is arranged straddling the two fan housings and extends backwards, the front of the assembly being on the left-hand side relative to the figure. Once again, the means for driving the fans 12 and 14 by the gas generator 15 are not specified, nor are the means connecting them together. In this case the intake of the gas generator does not have a fan. In a variant embodiment with three fans, two of which are offset, a fan that is not offset may be arranged upstream of the gas generator concentrically with the latter.

[0043] In FIG. 3, the powerplant is arranged under the wings of an aeroplane that have a sweepback, as is usual in the field of commercial aircraft, of the order of 30. It can be seen that the fans 16, called inner because they are alongside the fuselage, are partly masked by the upstream edge of the wing, precisely owing to the sweepback angle of the wings. In the flight phases, for example when climbing, when the aeroplane is led to form an angle with its relative wind, this upstream zone is the site of strong disturbances in the flow of the airstream along the wings. These disturbances are detrimental to the proper operation of the engine.

[0044] This problem is corrected, according to the invention, by optimizing the integration of the powerplant relative to the wing so as to minimize the surfaces contributing to drag. This is achieved by fixing the powerplant 100 directly to the wing spars without an intervening strut. Thus, the term directly is used to mean that a strut is not used for suspending the powerplant on the wing spars.

[0045] FIG. 4 shows, in section, the wing 1 and its two spars, one upstream 11ba and the other downstream 11bf. Upstream and downstream are defined relative to the direction of travel of the aeroplane. The powerplant 100 comprises two fans 102 and 104 as well as the gas generator 106. The whole assembly is attached directly to the wing spars. The two fans are fixed directly to the upstream spar 11ba near the leading edge of the wing; the gas generator 106 is attached directly to both spars 11ba and 11bf. The attaching means are not described in more detail; they are within the capability of a person skilled in the art. The housing of a fan is a structural stator element, inside which the fan rotor is mounted. Fan fixed directly to a spar means that the fan housing is supported by the spar via a suspension device 108 that connects the housing directly to the spar, i.e. without a structure such as a strut or similar mast being interposed in the path of forces between the housing and the spar. The suspension device 108, which is shown schematically, may be similar to a conventional suspension device joining a turbine engine housing to a strut.

[0046] Each of the two fans is essentially supported by the upstream spar 11ba. A linkage joining the housing of a fan to the housing of the gas generator, which may incorporate a passage for the transmission shaft of the gas generator to the fan, may be designed for supporting a small part of the weight of the fan. Nevertheless, the largest part of the weight of each fan is supported by the upstream spar, which makes it possible to limit considerably or even avoid completely the phenomenon encountered in the prior art, of the appearance of a simultaneous beating motion of the two fans in certain conditions.

[0047] If applicable, the drag produced by the engine is further minimized by incorporating at least part of the powerplant in the wing, as for example in the embodiment described hereunder with reference to FIG. 6.

[0048] The second feature of the solution of the invention is illustrated in FIG. 5. With the wing 1 generally forming a sweepback of angle (alpha) of the order of 30, the two fans of the engine 100 are arranged with axial offset relative to one another. The outer fan 102 is displaced relative to fan 104, which is located alongside the fuselage. More precisely, it can be seen that the inner fan 104 is farther upstream than the outer fan 102. This axial difference makes it possible to arrange the engine under the wing while being as close as possible to the leading edge, favouring compact installation without overhang and allowing shrouding of the powerplant to reduce aerodynamic drag.

[0049] FIG. 6 illustrates the aspect of the invention that aims to minimize the drag produced by the engine, in an embodiment in which the powerplant 100 is integrated in an envelope I forming a pod 110 that forms part of the surface of the wing, here the lower surface of the wing. At least the upstream spar 11ba out of the two wing spars has a curvilinear portion forming a concavity directed downwards. In this way, the gas generator 106 is integrated at least partially in the wing while still being attached directly to the two spars, and more particularly suspended from the spars. According to other variants, only the gas generator is integrated in the wing and its envelope forms part of the lower surface and/or upper surface of the wing.

[0050] FIG. 7 shows a side view of the engine 100 with one of the fans, and with the gas generator 106 mounted close to the lower surface of the wing 1. It can be seen that the downstream edge of the wing is provided with flaps 1f, movable about a horizontal axis, perpendicular to the axis of the fuselage, as is known. To prevent the stream of gas from the gas generator 106 interfering with the plane of the flaps 1f when the latter are in the active position, it is specified in this variant embodiment that the exhaust gases are inclined downwards by an angle of the order of 10 to 20. The nozzle 106T for ejection of the gases from the generator 106 is also oriented downwards at said angle .

[0051] In FIG. 8, the exhaust gases from the gas generator are deflected so that they sweep over the upper face of the wing 1, creating a Coanda effect and improving the lift of the wing. The gas generator 106 is in this case provided with a gas ejection channel 105 passing through the wing and opening parallel to the upper surface of the wing. In particular, the air intake of the gas generator is located under the wing and the gas jet nozzle is located above the wing. In this example, the ejection channel is of approximately S-shaped section.