Noise attenuation panel

Abstract

A noise attenuation element can be arranged for connection to an air directing structure such as a wing flap. The element has a non-uniform lattice density across at least a portion of the body of the element.

Claims

1. A flap side edge module for attachment to a wing flap, the module comprising: a leading edge; a trailing edge; and a body portion located between the leading edge and the trailing edge, the body portion comprising a central portion and two transition regions, wherein the body portion is formed of a lattice structure wherein the central portion comprises a first lattice density throughout, wherein the body portion is connected to each of the leading edge and the trailing edge by a respective one of the two transition regions, wherein each transition region has a lattice structure density gradient such that a lattice density varies between a second lattice density adjacent to regions proximate to a leading edge or trailing edge and the first lattice density at a portion of the transition region adjacent to the central portion, wherein the first lattice density is lower than the second lattice density.

2. The flap side edge module of claim 1, wherein the leading edge and the trailing edge are formed of a solid material.

3. The flap side edge module of claim 1, wherein the lattice structure is formed of a non-uniform formation.

4. The flap side edge module of claim 1, wherein: the lattice structure is formed of a titanium or titanium alloy, the flap side edge module comprises at least one coupling configured in use to attach the module to an edge of a flap, one of the at least one couplings is formed in the leading edge and/or the trailing edge and/or one of the at least one couplings is formed in the body portion, and the at least one coupling comprises a shaft extending through the body portion and arranged to receive an attachment member extending through the body portion.

5. The flap side edge module of claim 4, wherein: the at least one coupling comprises a shaft extending through the body portion and arranged to receive an attachment member extending through the body portion, the shaft comprises a first layer and a second surrounding layer, wherein each of the first layer and the second layer extends around the perimeter of the shaft, and wherein the first layer has a higher lattice density than the second surrounding layer, and the shaft further comprises a transition layer between the first layer and second surrounding layer, in which the lattice density reduces towards the surrounding second layer across the transition layer.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The present teachings will now be described, by way of example only, with reference to the following figures in which like parts are depicted by like reference numerals:

(2) FIG. 1 shows a vortex generation scenario for an aircraft wing;

(3) FIG. 2 shows a perspective view of an aircraft wing flap side edge module connected to a flap;

(4) FIG. 3 shows an end view of the flap side edge module;

(5) FIG. 4 is a plan view of the flap side edge module and wing flap;

(6) FIG. 5 is a cross-section through E-E′ in FIG. 3;

(7) FIG. 6 is a cross-section through D-D′ in FIG. 3;

(8) FIG. 7 shows an example lattice structure;

(9) FIG. 8 shows a transition region lattice structure;

(10) FIG. 9 shows an example lattice density distribution of the flap side edge module;

(11) FIG. 10 shows an example lattice density distribution around a coupling; and

(12) FIG. 11 shows example positions of transitional regions for a flap side edge module.

(13) While the present teachings are susceptible to various modifications and alternative forms, specific embodiments are shown by way of example in the drawings and are herein described in detail. It should be understood, however, that drawings and detailed description thereto are not intended to limit the scope to the particular form disclosed, but on the contrary, the scope is to cover all modifications, equivalents and alternatives falling within the spirit and scope defined by the appended claims.

(14) As used in this specification, the words “comprises”, “comprising”, and similar words, are not to be interpreted in an exclusive or exhaustive sense. In other words, they are intended to mean “including, but not limited to”.

(15) It will be recognised that the features of the aspects of the invention(s) described herein can conveniently and interchangeably be used in any suitable combination. It will also be recognised that the present disclosure covers not only individual embodiments but also combinations of the embodiments that have been discussed herein.

(16) The work leading to this invention has received funding from the European Union Seventh Framework Programme (FP7/2007-2013) under grant agreement n° 604013.

DETAILED DESCRIPTION

(17) The present teaching relates generally to a noise attenuation element or component and a method for manufacturing such a noise attenuation element.

(18) An embodiment will be described in which the element is applied to a wing flap edge structure where noise attenuation can be realised. Furthermore, the wing flap edge can also be optimised for strength, stiffness, durability and connectability as well as acoustic performance. It will be recognised that the present disclosure may also be used in other applications as discussed herein.

(19) According to the present teaching, a flap side edge module is provided which is suitable for connecting to a flap on the wing of an aeroplane. The flap side edge module of the present disclosure reduces airframe noise caused by the edges of flaps when they are in extended form such that their edges are exposed at lift off and landing.

(20) Referring to FIG. 1, one half of a passenger aircraft 1 is shown. The aircraft comprises a wing 2 and a pair of flaps 3, 4. The flaps shown are in an extended state; a state most frequently used on landing and take-off to generate more lift for a given airspeed.

(21) When the flaps are extended the outer flap edge 5 is exposed and interacts with the airflow passing under and over the wing. The flow of air over the edge of the flap creates a vortex 6 as shown in FIG. 1. This vortex is undesirable since it is a source of unwanted aircraft noise.

(22) FIG. 2 shows the edge of a wing flap and a flap side edge module extending from the end or edge of the flap. The module is shown in see-through form in FIG. 2 to illustrate the internal components which will be described below.

(23) A flap side edge module has a body 8, a leading edge 9, and a trailing edge 10 which align with the corresponding leading and trailing edges of the flap 7. The flap has an upper surface and a lower surface, wherein the upper surface and lower surface extend between the leading edge and the trailing edge. When attached to the flap of the aircraft, the upper surface faces substantially upwards and the lower surface faces substantially downwards.

(24) As shown in FIG. 2 the module has a leading edge portion 11 which is substantially solid in form i.e. it is formed of a solid material. Similarly the module has a trailing edge portion 12 which also has a substantially solid construction.

(25) Example materials which may be used are aluminium, titanium or alloys thereof which may be conveniently processed as described further below.

(26) FIG. 2 also illustrates a plurality of couplings which are used to selectively couple and de-couple the module from the flap. FIG. 2 shows 3 couplings, a first coupling 13 extending through the leading edge portion 11 and a pair of second and third couplings 14, 15 extending through the interior 16 of module body 8.

(27) Any suitable coupling may be used but the couplings shown in FIG. 2 are in the form of elongate bolts which extend through holes or shafts formed in the body 8. The shafts each terminate at the side 17 of the module which aligns with the end of the wing flap. The shafts and couplings are described in further detail below.

(28) The module may or may not be a structural part of the flap i.e. it merely functions as a noise attenuation device at the end of the flap. Alternatively, the module may be integrated into the flap to also function as a structural part and to generate lift for example or direction air in the same way the remainder of the flap directs air.

(29) FIG. 3 shows an end view of the wing flap module showing the aerodynamic profile and couplings at the leading edge and within the body. Sections E-E′ and D-D′ are described below.

(30) FIG. 4 is a plan view of the module and wing flap. FIG. 4 illustrates the tapered profile of the module from the leading edge 9 to trailing edge 10. As shown by the arrows the width (along the flap span-wise direction) is smaller at the leading edge than the trailing edge. The purpose for this is to compensate for the change in pressure differential from leading edge to trailing edge. The footprint of the pressure difference at the leading edge is smaller than the footprint of the pressure differential at the trailing edge

(31) FIG. 5 is a cross-section through section E-E′ in FIG. 3. A shown the module body 8 is in abutment with the flap 7. The flap 7 comprises a stud 18 which is arranged to receive a bolt 19 which extends through the interior 16 of the module body 8. A bush 20 is provided for connection to the bolt which allows for ease of replacement/repair.

(32) As shown the bolt is elongate and has a distal end 21 which engages with the outer surface 22 of the module body 8. The bolt 19 is located inside a shaft 18 which is formed of a substantially solid outer wall (in one example a titanium shaft). The shaft receives the elongate bolt which allows the module body 8 to be coupled and de-coupled to the flap 7.

(33) FIG. 6 shows a cross-section through section D-D′ from FIG. 3. Here the outer periphery 24 of the module body 8 is shown in abutment with the flap 7. The periphery is formed of a lattice structure (described further below) which has a different density to a solid formed of the same material and specifically a lower density.

(34) A transition region 25, again described further below, is a region in which the material density changes from a first density to a second density by changing the density of the lattice structure. As shown in FIG. 6 the outer periphery 24 defines a hollow interior space 16 within the module.

(35) The internal lattice or mesh structure will now be described.

(36) A feature of the present disclosure is a lattice structure which allows the porosity and density of the body of the module to be controlled and adapted. Intricate internal lattice structures can be formed in a metallic form using additive manufacturing techniques i.e. techniques where shapes are progressively built up layer by layer. Conveniently metal powders such as aluminium and titanium can be used to build complex geometrical shapes and structures. More specifically complex internal lattice like structures may be formed.

(37) FIG. 7 shows such a lattice or matrix structure in which a network of intersecting strips or beams of metal can be seen in a generally repeating pattern. Any suitable pattern may be used depending on the desired porosity (that is the spaces between the structural members of the lattice) and the desired strength and rigidity. As can be seen in FIG. 7 the structure defines open spaces which provides the porosity (and which reduces density) and which allows air to flow freely into and out of the structure.

(38) The pattern may be any suitable pattern. Once the geometry is determined this can be programmed into the additive manufacturing equipment and the body can be formed.

(39) According to the present disclosure this porous structure advantageously suppresses the vortex generation from an outer surface of a module being formed with this porosity.

(40) By introducing a lattice structure into the flap side edge module it reduces the pressure difference between the upper and lower surface of the wing flap. The pressure difference also fluctuates in a chord-wise direction from leading edge to trailing edge. By tailoring the lattice density according to the local pressure difference an optimal noise reduction is obtained.

(41) A further aspect of an present disclosure described herein is the transition zone or region which extends between regions of different lattice density. This is illustrated in FIG. 8 where a first zone on the left has a higher lattice density than the zone on the right. Adapting the lattice density in this way allows the body strength and or stiffness to be optimised for the particular part of the module as well as allowing the porosity to be increased at areas where high strength and or stiffness is not needed. This allows for acoustic optimisation. It will be recognised from FIG. 8 that the left hand zone allows the body to be coupled structurally to the leading edge or trailing edge with greater strength.

(42) FIG. 9 corresponds generally to FIG. 2 and illustrates how the lattice density can be selectively modified across the module body 8.

(43) As shown in FIG. 9 the leading and trailing edges 9 and 10 sit either end of the body 8 of the module. The dotted portions of the body illustrate the increasing density of the lattice. Specifically the body comprise a central portion 26 and two transitional portions 27 which are sandwiched between the ends of the body and the trailing/leading edges 9, 10. The trailing and leading portions are substantially solid section 28. The transition regions 27 exhibit a form generally similar to FIG. 8 and have an increasing lattice density as illustrated by the dotted regions in FIG. 9.

(44) The exact lattice density gradient i.e. the rate of increase in density from region 26 to region 28 will depend on the predetermined lattice geometry, strength and or stiffness required.

(45) A similar approach to the couplings may also be used as illustrated in FIG. 10 in combination with FIG. 5. As shown the shaft 23 is formed of a solid titanium portion. This is surrounded by a transition zone 27 where the lattice density decreases until it corresponds to the density of the body around the coupling.

(46) The inside of the body may be hollow as discussed above or alternatively could be filled with a low density lattice. As shown in FIG. 11 multiple transition zones may be provided around the coupling portions and between the body and leading/trailing edges.

(47) In effect the lattice density is increased at appropriate portions of the body where additional strength and or stiffness is required, where a connection is required or where a coupling shaft has to be defined. Similarly the lattice density/porosity can be controlled according to the acoustic effects at the remained of the body.

(48) A variety of additive manufacturing techniques could be used to form a structure described herein. For example, powder bed fusion, electron beam melting or laser melting powder bed additive manufacturing machines could be used. An example material could be titanium Ti64 having an example density of between 10 and 50 pores per inch and a density between 3% and 40%.

(49) In one arrangement the module could be deposited directly onto the distance end of a flap, for example using additive manufacturing technique. Thus, a fully integrated since piece flap and noise attenuation module may be provided.

(50) Alternatives

(51) In other examples, the flap side edge module may not extend along the full length of the flap.

(52) In still further examples, the flap side edge module may be incorporated on both the first flap side edge and the second flap side edge, defined above.

(53) Depending on the specific part or area concerned, the pressure difference (footprint) may vary and therefore an optimal lattice density per specific pressure difference can be implemented for optimal acoustic performance.

(54) Noise Attenuation Panel

(55) The noise attenuation panel of the present disclosure may be configured for use in other situations. For example, the noise attenuation panel may be used in landing gear components. Furthermore, the noise attenuation panel may be used in non-aerospace applications, for example wind turbines

(56) In an aircraft application the structure may be applied to various parts of an aircraft, including but not limited to: Engine cowlings Winglets Landing gear struts Aerostructures Spoilers Aileron Elevator Transmitter housings

(57) The noise attenuation panel of the present disclosure comprises a porous mesh or lattice region and a transition region substantially as hereinbefore described. For example, the transition region has a mesh or lattice density gradient such that the mesh or lattice density varies from a coarse mesh or lattice at one end to a fine mesh or lattice at the other.

(58) The various embodiments described herein are presented only to assist in understanding and teaching the claimed features. These embodiments are provided as a representative sample of embodiments only, and are not exhaustive and/or exclusive. It is to be understood that advantages, embodiments, examples, functions, features, structures, and/or other aspects described herein are not to be considered limitations on the scope of the present disclosure as defined by the claims or limitations on equivalents to the claims, and that other embodiments may be utilised and modifications may be made without departing from the spirit and scope of the claimed invention. Various embodiments of the present disclosure may suitably comprise, consist of, or consist essentially of, appropriate combinations of the disclosed elements, components, features, parts, steps, means, etc, other than those specifically described herein. In addition, this disclosure may include other inventions not presently claimed, but which may be claimed in future.