Aircraft sound absorbing coating including anti-icing system exploiting joule effect

FIELD: transport.

SUBSTANCE: invention relates to aircraft engineering, particularly, to power plant air intake and aircraft sound-absorbing coating. Said coating may close air intake front edge and comprises, on one side, reflecting layer extending from inside to outside, cellular structure and sound-absorbing structure. On the other side, coating incorporates ice processing system made up of heating layer containing open zones to transmit acoustic waves. Sound-isolation structure comprises structural layer with holes. Note that heating layer is located under said structural layer.

EFFECT: better sound absorption and anti-icing protection.

10 cl, 22 dwg

The present invention relates to sound-absorbing coating for an aircraft that includes a processing system icing under the influence of the Joule effect, with the above-mentioned coating is designed, in particular, for closing the front edges of the aircraft and, in particular, the air intake of the nacelle of the aircraft.

The power plant of the aircraft contains a gondola, which is essentially concentric is the motor that spins the fan mounted on its shaft.

The gondola contains an internal wall bounding a channel with the air intake in front, with the first part of the incoming air flow, called primary flow passes through the engine, participating in the combustion, and the second part of the air flow, called secondary flow, is discharged by the fan and passes into the annular channel bounded by the internal wall of the nacelle and the outside wall of the engine.

The noise generated by the power plant, decomposes, on the one hand, to the noise of the jet stream produced outside of the channels due to the mixing of different air flows and gaseous products of combustion, and, on the other hand, the noise generated by the internal parts, called internal noise generated by the fan, compressors, turbines, and combustion and which is cranaodes inside the channels.

To limit the impact sound effects near airports lately, increasingly strict regulations to reduce sound level.

Were developed technology to reduce internal noise, in particular, by performing at the level of the walls of the channels of coatings designed to absorb part of the sound energy, in particular, using the principle of Helmholtz resonators. As you know, this is a sound-absorbing coating contains from the inside outwards reflecting layer, at least one honeycomb structure and sound structure.

Under the layer should be understood one or more layers of same or different nature.

Sound-proof structure is a porous structure that performs the function of scattering, partially transforming in the warmth of acoustic energy passing through it, the sound waves. It contains the so-called open areas made with the possibility of transmission of acoustic waves, and other areas, called closed or solid, which do not pass sound waves and are intended to ensure the mechanical strength of the mentioned layer. This sound insulation layer is characterized, in particular, the ratio of open surface, which largely varies depending on the engine and the components forming the said layer.

To increase the effectiveness of the acoustic treatment, according to the technical solution, increase the surface area covered with sound-absorbing coating. However, at the level of the inlet or the edge of the gondola application of sound-absorbing coating is not possible, in particular, as mentioned coating is not compatible with systems to prevent the formation and/or accumulation of ice and/or frost and necessary in these areas.

These systems are divided into two groups, the first are called anti-icing systems to limit the formation of ice and/or frost, and the latter are called systems de-icing, limiting the accumulation of ice and/or frost and acting after the formation of ice and/or frost. In the further description text processing system ice will be called anti-icing or de-icing, the term ice includes ice and frost.

When de-icing handling aircraft process on earth, COI is lsua gas or liquid, applied on the treated surface. Despite the effectiveness of this treatment, particularly at takeoff it has a limited duration. However, systems will need to handle ice were also on Board the aircraft, as the ice can be formed at the level of the aerodynamic surfaces of the aircraft and, in particular, at the level of the front edges of the wings, nacelles, empennage, etc. when the aircraft passes through areas with specific meteorological conditions.

The present invention relates, in particular, to anti-icing system electric type using the Joule effect.

In this processing system ice electrical resistors of conductive material covered with an insulator to heat the workpiece surface due to the Joule effect. This type of systems is not satisfactory, as they are relatively fragile and can be damaged in collisions with birds, during a castle or from shock during maintenance. In damaged areas of the processing system ice may fail, resulting in the possible formation and accumulation of ice or frost. Finally, it is not compatible with the coating for the acoustic treatment, as it prisutstvie surface affects the overall characteristics of the sound-absorbing coating.

The present invention is intended to eliminate the disadvantages of the known technical solutions and to offer a sound-absorbing coating for aircraft, comprising a processing system of the ice, allowing to optimize the performance of each of the processing types.

In this regard, an object of the present invention is a sound-absorbing coating for aircraft, made with the possibility of closing the front edge, such as the air intake of the nacelle propulsion, these sound-absorbing coating contains, on the one hand, from the inside outwards reflecting layer, at least one honeycomb structure and sound-proof structure with a certain ratio of open surface, and, on the other hand, at least one processing system ice in the form of at least one heating layer containing the open area made with the possibility of transmission of acoustic waves and at least partially interacting with open zones sound insulating structure, wherein the insulation structure contains at least one structural layer with holes, and the fact that the said at least one heating layer is located underneath the structural layer.

This embodiment allows you to make compatible with the considered acoustic processing and handling of ice.

Preferably insulation structure provides structural layer containing the open zone, and the heating layer have under-mentioned structural layer. According to this configuration, the processing system ice is protected, thereby reducing the maintenance and Parking of aircraft on the ground.

Other distinctive features and advantages of the present invention will be more apparent from the following description, provided solely as an example, with reference to the accompanying drawings, on which:

figure 1 is a perspective view of the power unit of the aircraft;

figure 2 is a view in longitudinal section of the air intake of a nacelle in accordance with the present invention;

figa - view in the context of different layers of sound-absorbing coatings, including ice carving according to the first variant implementation;

figb - view in the context of different layers of sound-absorbing coatings, including ice carving according to another variant implementation;

4 is a view illustrating the relative position of the conductive element processing system of ice and holes sound insulation layer;

5 is a view illustrating, on the one hand, the option of holes sound insulation layer and, on the other hand, a variant of the heating layer;

Fig.7 is a view in section, illustrating another variation of the sound-absorbing coatings, including ice carving;

Fig is a view in section, illustrating another version of the sound-absorbing coatings, including ice carving;

Fig.9 is a view in section, illustrating another version of the sound-absorbing coatings, including ice carving;

figure 10 is a view illustrating a first variant of the heating layer, providing the function processing of the ice by means of the Joule effect;

figa - view in the context of the first version of the runtime options, shown in figure 10;

figb - view in section of another version of the runtime options, shown in figure 10;

Fig view illustrating another variant of the heating layer, providing the function processing of the ice;

figa - view in the context of the first version of the runtime options, shown in Fig;

figb - view in section of another version of the runtime options, shown in Fig;

Fig is another variation of the heating layer, providing the function processing of the ice by means of the Joule effect;

Fig is another variant of the heating layer, providing processing function of ice using the playing technique Joule;

Fig - view in section of the heating layer, shown in Fig;

Fig view of another version of the heating layer, providing the function processing of the ice by means of the Joule effect;

Fig - view in longitudinal section illustrating the installation of various processing systems ice on the level of intake;

Fig is a view in transverse section illustrating the installation of various processing systems ice on the level of intake.

The description of the present invention is presented in the version of application for air intake of the power plant of the aircraft. However, it can be used for various front edges of the aircraft and for the various surfaces of the aircraft, at the level of which produce acoustic processing and handling of ice.

In the further description text under the icing should be understood as ice and frost of any nature of any structure and any thickness.

Figure 1 shows the power plant 10 of the aircraft, fixed under a wing by means of the rack 12. However, this power unit can be mounted in other areas of the aircraft.

This power pack contains the gondola 14, which is essentially concentric with the engine, torque fan mounted on its shaft 16. The longitudinal axis of the nacelle denoted by p is a position 18.

The gondola 14 includes an inner wall 20, limiting the channel inlet 22 in the front, with the first part of the incoming air flow, called primary flow passes through the engine, participating in the combustion, and the second part of the air flow, called secondary flow, is discharged by the fan and passes into the annular channel bounded by the inner wall 20 of the nacelle and the outside wall of the engine.

The top part 24 of the air intake 22 describes essentially circular shape, in the plane, which can be essentially perpendicular to the longitudinal axis 18, as shown in figure 2, or not perpendicular at the apical part of 12 hours, slightly forward, as shown in Fig. However, it is possible to provide for other forms of intake.

In the further description text under aerodynamic surface should understand the trim of the aircraft in contact with the aerodynamic flow.

To limit the noise impact, in particular, on the level of aerodynamic surfaces, provide coating 26 that is designed to absorb sound energy, in particular, using the principle of Helmholtz resonators. As you know, this is a sound-absorbing coating, also called the sound-absorbing panel, contains in the direction from the inside naru is the reflecting layer 28, a honeycomb structure 30 and sound insulating structure 32.

In the variant sound-absorbing coating can contain multiple cellular structures 30, separated by sound-proof layers, called the septum.

According to a variant of execution of the reflective layer 28 can be made in the form of sheet metal or in the form of a shell containing at least one layer of woven or nonwoven fibers embedded in a matrix of resin.

The honeycomb structure may be made in the form of a metal honeycomb or honeycomb composite metal, for example, in the form of a honeycomb structure manufactured in the market under the name Nida Namex.

Detailed description reflecting layer and the honeycomb structure is omitted, as they are well known to specialists.

Sound insulation structure 32 includes at least one porous structure that performs the scattering function and partially transforming in the warmth of acoustic energy passing through it, the sound waves.

According to one variant of execution of the sound structure contains at least one layer of woven or nonwoven fibers, while the fibers are preferably impregnated with resin to ensure the perception of effort in different directions of the fibers.

According to other variant perform insulation structure 32 includes at least one porous with the Oh 34 and, at least one structural layer 36, giving a sound-proof structure required mechanical characteristics.

The porous layer 34 may be performed, for example, in the form of a metallic woven or nonwoven material, such as Wiremesh.

Structural layer 36 may be made of metal or composite sheet containing on the surface of the hole 38 or pinholes providing acoustic waves passing through the mentioned structural layer. According to non-limiting variants perform structural layer 36 may be made in the form of a metallic sheet or a composite sheet, for example, of carbon fibers embedded in a resin, if necessary, reinforced amplifying layer 40, for example, on the basis of optical fibers, as shown in Fig.7.

Structural layer 36 includes holes 38 or holes of different shapes and sizes, for example, having an elongated shape, as shown in figure 4 and 6, or round holes, grouped as shown in figure 5. The shape and size of the holes 38 define thus, in order to reduce disturbances affecting the passage of air flow, to provide the necessary mechanical strength, in particular the resistance to delamination, and facilitate passage of sound waves to ensure good performance the performance sound-absorbing coating.

Preferably, the structural layer 36 fitted on the outside of the porous layer 34 is placed between the aforementioned structural layer 36 and cellular structure 36. This configuration helps to protect porous layer 34.

In one embodiment, the porous layer 34 can be positioned between two structural layers 36, as shown in figa.

According to another variant implementation, the coating may contain at least one gain, for example, the winding of the carbon filaments 42, executed between the cellular structure and sound structure, as shown in Fig.7.

In all cases, the insulation structure 32 includes a so-called open areas made with the possibility of transmission of acoustic waves, and other so-called closed or solid zones, designed to provide mechanical strength mentioned layer. This sound insulation layer is characterized, in particular, the ratio of open surface, which varies mainly depending on the engine and the components forming the said layer.

As shown in figure 2 and 18 to further reduce unwanted sound effects, air intake 22 contains sound-absorbing coating 26, at least part of the aerodynamic surface.

According to a variant of execution of this sound-absorbing coating 26 will is both from the inner wall 20 of the gondola up to the terminal part 24 of the air intake on the periphery of the air inlet. Preferably, as shown in figure 2 and 18, sound-absorbing coating 26 extends beyond the distal portion 24 of the air intake and overlaps a portion of the outer surface 44 of the gondola.

Detailed description perform a sound-absorbing coating is omitted, as it is known in the art.

To limit the formation of ice or to prevent its accumulation at the level of the inlet 22 include at least one processing system of ice.

In the further description text under the processing system ice should understand anti-icing system or system de-icing.

To ensure compatibility between the sound-absorbing coating and processing system of the ice and to work one of these means does not interfere with another, the processing system ice is a processing system of the ice by means of the Joule effect in the form of at least one heating layer 46 containing the open areas, which are made with the possibility of transmission of acoustic waves and which at least partially interact with open zones sound patterns so that the change of the coefficient of surface acoustic layer was less than 35%.

Preferably the heating layer 46 have under structural layer 36, so that protection is be it from external influences, such as collisions with birds, hail or shocks during maintenance.

This configuration allows to provide more reliable operation of the processing system of ice and to reduce the time of Parking the aircraft on the ground by reducing the risk of damage.

As shown in Fig.9, the heating layer can be positioned between the reflective layer 28 and the cellular structure 30. However, this option is less desirable because of the heating layer is more remote from the treated surface, i.e. drag the layer on which can be formed ice.

According to another variant of the heating layer 46 may also perform the function of sound insulation layer, as shown in Fig. In this case, the heating layer 46 contains a porous zone, made with the possibility of transmission of acoustic waves.

According to the first version, shown in figure 4, 12, 14, 16 and 17, a sound-proof structure contains the public areas in such a way as to create approximately linear continuous zone, and the heating layer contains at least one planar, linear conductive element 48, the width of which is less than or equal to the width of the solid areas of the structural layer 36, as shown in figure 4.

Run flat linear conductive elements 48 allows the reduction is to be the thickness of the heating layer, not affecting the sound-absorbing coating.

In addition, the fact that the conductive elements 48 of the heating layer does not overlap the holes 40 of the structural layer, allows not to change the ratio of open surface of the sound insulating structure 32.

In addition, this design allows to reduce the risks of damage, since the conductive elements 48 are closed and protected structural layer 36.

Depending on the case, the heating layer can contain only one linear conductive element 48 in the form of a serpentine through the entire treated area, as shown in Fig, or more linear conductive elements 48 connected in series, as shown in Fig, or connected in parallel, as shown in Fig and 15.

According to the first variant implementation of linear conductive elements 48 connect the two electrode or grid 50, 50'. Each grid has a U-shape and connected to the wire 52 of the power supply, located between the branches of the U. According to the first decision of the conductive elements 48 inserted between the branches of the U, as shown in figa. According to another solution of the linear conductive elements installed in pairs, with each branch of the U include one conductive element 48, as shown in figb.

According to another variant, shown in figure 5, 6 and 10, the heating with the OI contains, at least one heating canvas 54 containing holes 56, which are made with the possibility of transmission of acoustic waves and which at least partially interact with open areas of sound patterns in such a way as to reduce the change of the coefficient of surface acoustic layer.

According to the first variant implementation, shown in figure 5, solid (not open) zone heating layer does not overlap the open area soundproof layer and, in particular, the holes of the structural layer.

According to another variant implementation, shown in Fig.6, the intermediate zone provided between the holes made at the level of the heating layer are very small, so the open surface of the structural layer, closed mentioned intermediate zones is very small.

The execution of a conductive element in the form of a cloth to reduce the thickness of the heating layer and to reduce disturbances at the level of the sound-absorbing coating.

Besides, the conductive element in the form of cloth you can limit the risks of proliferation of the damaged zone in the case of point damage.

Finally, because the visible layer is protected structural layer, and the area of the heating layer, visible che is ez holes of the structural layer, are very small, the risk of damaging the heating layer.

According to the first technical solution shown in figa, the heating layer contains two stacked on top of each conductive cloth 54, stretched between two electrodes or grids 58, 58' U-shape, with the wire 60 of the power supply are located between the branches of the U of each of the electrode 58, 58'.

According to another technical solution shown in figb, the heating layer contains conductive fabric 54, protjanutoe between two electrodes or grids 58, 58' U-shape, with the wire 60 of the power supply are located between the branches of the U of each of the electrode 58, 58'.

According to another distinctive feature of the present invention, the heating layer contains at least one insulating element 62, enveloping conductive member or conductive elements.

According to variants of the heating layer may contain two insulating sheath 62, located on both sides of the conductive member or conductive elements, these membranes contain open areas corresponding to the open areas of the heating layer.

According to another distinctive feature of the present invention, the processing system ice by means of the Joule effect, shown by the dotted line in figure 2 and 18, may be connected with other systems is the processing of ice, in particular, the point type, at least one of the emitter 64 of vibrations.

Thus, the emitters 64 vibrations have on the level of the outer surface 44 of the gondola, as shown in Fig, and/or inside the gondola at the level of the angular sectors 66, located approximately between 2 and 4 hours and between about 8 and 10 o'clock as shown in Fig.

Thus, the emitters 64 vibrations, which are characterized by relatively low energy consumption, are located at the level of the outer surface, because the risk of falling into the engine of a piece of ice in this area is limited. Similarly, the formation of ice or frost is limited inside the gondola at the level of the angular sectors identified position 66, so you can use the emitter of vibration with a frequency sweep.

As icing or ice has a more pronounced tendency to form zones inside the gondola between the angular sectors 66 to reduce the risk of ingestion of large pieces in the engine, in these zones, use the processing system electric ice type with the Joule effect, which is more reliable and which prevents the formation of ice or frost, even if this type of processing systems, ice is more energy-intensive.

This interaction of different processing systems ice allows to optimize processing limited is EPA energy consumption while ensuring reliable and efficient operation.

1. Sound-absorbing coating for aircraft, made with the possibility of closing the front edge, in particular, such as the inlet (22) of the nacelle (14) of the power plant (10), and containing, on the one hand, from the inside outwards reflective layer (28), at least one honeycomb structure (30) and sound structure (32)having a specific ratio of open surface, and, on the other hand, at least one processing system ice in the form of at least one of the heating layer (46), containing the open area made with the possibility of transmission of acoustic waves and at least partially interacting with open zones sound insulating structure, wherein the insulation structure (32) contains at least one structural layer (36) with holes (38), and at least one heating layer (46) is located underneath the structural layer (36).

2. Sound-absorbing coating according to claim 1, characterized in that the acoustic structure contains the public areas in such a way as to create approximately linear continuous zone, and the heating layer (46) includes at least one flat linear conductive heating element whose width is less than or equal to the width of the solid zones constructive the Loya (36).

3. Sound-absorbing coating according to claim 2, characterized in that the heating layer (46) contains the linear conductive element in the form of serpentine, passing through the treated area.

4. Sound-absorbing coating according to claim 2, characterized in that the heating layer (46) contains several series-connected linear conductive elements (48).

5. Sound-absorbing coating according to claim 2, characterized in that the heating layer (46) contains several parallel connected linear conductive elements (48).

6. Sound-absorbing coating according to claim 1, characterized in that the heating layer contains at least one conductive cloth (54)containing holes (56), made with the possibility of transmission of acoustic waves and at least partially interacting with open zones sound patterns so that the change of the coefficient of surface acoustic layer was negligible.

7. Sound-absorbing coating according to any one of claim 2 to 6, characterized in that the heating layer (46) contains at least one insulating element (62), enveloping conductive member or conductive elements (48).

8. The inlet (22) of the nacelle (14) of the power plant (10) of the aircraft, covered, at least partially coating (26) for acoustic treatment, with the holding, on the one hand, from the inside outwards reflective layer (28), at least one honeycomb structure (30) and sound structure (32)having a specific ratio of open surface, and, on the other hand, at least one processing system ice in the form of at least one of the heating layer (46)containing the open area made with the possibility of transmission of acoustic waves and at least partially interacting with open zones sound insulating structure, wherein the insulation structure (32) contains, at least one structural layer (36) with holes (38), and the aforementioned at least one heating layer (46) is located underneath the structural layer (36).

9. The air intake of the nacelle of the power plant (10) of the aircraft, characterized in that it partially close the sound-absorbing coating containing, on the one hand, from the inside outwards reflective layer (28), at least one honeycomb structure (30) and sound structure (32), at least one structural layer (36) with holes (38) and, on the other hand, at least one processing system ice in the form of at least one of the heating layer (46)located under constructive layer (36) and containing the open zone, made with an option of transmission of acoustic waves and, at least partially interacting with open zones sound patterns, and at least one processing system ice point type, at least one emitter (64) vibrations.

10. The air intake of a nacelle according to claim 9, characterized in that the said at least one processing system ice point type is located at the level of the outer surface (44) of the nacelle and/or inside the gondola at the level of the angular sectors (66), located approximately between 2 and 4 hours and between about 8 and 10 hours.