DE102007019762A1 - Soundproofing device for a jet engine or a turbine - Google Patents

Abstract

The invention relates to a soundproofing device for a jet engine or a turbine, in particular a turbo propulsion plant (2) of an aircraft, for attenuating a sound field in a directional region (32), in particular for shielding sound radiated towards the ground. For this purpose, an engine lining (4) with such unevenly distributed surface structures (26, 30) is proposed that sound is deflected away from the directional region (32) by an impedance jump and / or by reflection.

Description

The The present invention relates to a soundproofing apparatus for a jet engine or a turbine, in particular for a turbofan engine of an aircraft, to mitigate a sound field in a directional area, in particular for shielding of sound radiated towards the floor. It also concerns the invention provided with such a soundproofing device Engine casing and a with such a soundproofing device provided engine.

Known Soundproofing devices of turbines have liners, which are also referred to as liners. Such liners are designed that they absorb sound. It is possible by Design and arrangement of liners specific properties to obtain a soundproofing device. Here are different Differentiate approaches to improving the properties.

The so-called "zero-splice liners" aim to reduce or avoid the hard transitions between the production-related necessary liner sections in the circumferential direction. This is exemplified in the EP 1 621 752 A2 described. On the one hand, such liners increase the effective absorptive area and, on the other hand, avoid the occurrence of so-called "mode scattering", a redistribution of the modal acoustic energy, which can adversely affect the achievable noise reduction.

Such Liners are particularly advantageous when starting an aircraft, because the rotor harmonics predominate among the generated frequencies, This type of liner is well tuned and works well because the Rotorharmonic have a large propagation angle. The dominant in the approach leaf sequence frequencies are stronger capable of propagation, and can from the Zero Splice Liners are not so effectively steamed.

The reverse approach is taken by liner systems that have a certain number of fixed sections, called "splices", in the circumferential direction and thus aim to stimulate higher circumferential modes by means of targeted "mode scattering", which can be absorbed more effectively by absorptive liner elements. This is in the US 3,937,590 described. In this case, in an engine duct at the height of the fan of the engine, a plurality of circumferentially spaced apart, extending in the axial direction strips of sound-absorbing material introduced into the outer wall of the engine duct. This stimulates the rotating propagating acoustic modes scattering and higher order fields which are less propagatory and easier to attenuate.

The EP 1 411 225 B1 shows an arrangement of liner segments, in front of the fan, two annular liner segments are embedded in the engine duct, which have a different impedance. Sound stimulated by the fan, which moves in the axial direction, first encounters a first liner segment that excites certain modes that can be more effectively absorbed by the subsequent second segment. For the effect used, the respective impedances and the relative impedance jump at the interface of the two segments are decisive.

The EP 1 701 016 A1 moreover teaches to achieve a smooth or stepped transition between different impedances through different hole sizes of the perforated cover layer of the liner and / or the depth of the honeycomb core behind this cover layer. This aims to influence the angle at which the radiated sound is reflected by the liner. This will cause a different effect, depending on the position in the engine intake. Near the sound source (fan) the sound is deflected at a greater angle to the engine axis, as this results in a longer path of sound through the engine inlet and thus a higher absorption. In contrast, the propagation angle near the entry lip should be reduced as much as possible to radiate more in the axial direction, thereby increasing the running length of the sound to the bottom. However, the production of such liners is much more complicated than that of a homogeneous liner. Further, such configurations are tuned to particular incident modes. It can not be ruled out that the performance of the liner decreases or even negative effects can be achieved with deviating sound fields.

The available for attaching additional liners Areas are limited or have other problems yourself. So it would be possible in the area of the inlet lip to arrange a liner (lip liner). However, it is also in the same place housed the technically complex anti-icing system, which would have to be integrated into a liner to be developed.

In order to reduce the sound radiation to the ground, therefore, in the prior art, the lower lip of the engine inlet is extended forward. Such a "negatively scarfed inlet" is in the US 5 058 617 shown. From such a configuration, however, there are disadvantages in terms of aerodynamic properties. Thus, the thickness of the inlet lip to prevent stalling must be increased. This in turn leads to one increased air resistance of the construction.

To mitigate these disadvantages are from the EP 1 071 608 B1 and the US 3,946,830 aerodynamically favorable contouring of the inlet geometry known, however, which bring a much higher design and manufacturing effort with it.

In front This background results in the task of a soundproofing device to create, which allows for the same aerodynamic Properties of a conventional liner a reduction of to reach sound emitted towards the ground.

to Solution to this problem is a soundproofing device proposed according to claim 1. Advantageous embodiments the soundproofing device according to the invention are the subject of the dependent claims. Thus provided engine systems as advantageous uses of the soundproofing device are the subject the ancillary claims.

According to the invention sound-influencing surfaces on a turbine housing so unevenly distributed that sound preferably by an impedance jump between different surface structures and / or directed by reflection directed away from the directional area to be shielded becomes.

The Soundproofing device according to the invention is in Turbine housings of conventional design can be used, so they face constructions with preferential inlet lip both aerodynamically cheaper, and lighter. Next is at least in a particular sector, due to the influence the directional characteristic of the sound field, a higher sound reduction as achievable in the prior art.

The Surface structures may be related to one another a central or rotational axis of the jet engine or the turbine Radial direction range on a surface facing the axis be distributed unevenly in the circumferential direction.

so arranged surface structures have the advantage that Sound coming directly from the direction of the axis is reliable is distracted.

Further can be advantageously provided that the surface structures in a direction away from the axis A surface in the circumferential direction unevenly are distributed. This is particularly advantageous when sound from air-carrying housing elements that are off the axis to be deflected.

It is advantageously provided that the sound-influencing surface structures are provided on or in an inlet of the turbine. Thereby are they are arranged between the sound source and the sound outlet, which allows a particularly efficient sound influence.

As well can the sound-influencing surface structures advantageous on or in a bypass duct of the jet engine, especially in the area of an engine outlet and in particular in the form of an engine lining, be provided.

In In a further advantageous embodiment, the surface structures a sound absorbing lining on or are by such educated. This additionally reduces the radiated Sound.

The Surface structures advantageously have at least one Reflection segment for targeted deflection of the shielded in the Direction range radiated sound on.

Especially it is advantageous if the reflection segment has an impedance, the clear of the impedance of the sound-absorbing lining deviates. This makes it possible to distract the sound without achieving geometric changes.

Advantageous the lining is arranged on a surface that directed towards the axis of rotation of the turbine and with respect the axis of rotation of the turbine extends in the circumferential direction. The reflection segment is preferably in a peripheral area that is defined by the directional area, in which sound radiation is to be reduced is determined in used the lining. This arrangement becomes a reliable one Distraction of the sound in the desired directional range reached.

In Particularly advantageously, the reflection segment is in the axial Direction on a side of the lining facing away from the turbine arranged.

Thereby The sound generated by the turbine must first be the sound-absorbing Lining happen that dampens certain frequencies already. The remaining sound afterwards can be cheaper in his Be influenced direction.

The impedance of the reflection segment is preferably lower than the impedance of the surrounding cladding. The impedance jump deflects the sound away from the reflection segment. Furthermore, the surface structure is preferably changeable. Thus, the Schallschutzvorrich be adapted to different installation situations or operating conditions and environmental conditions. For example, for this purpose, the or at least one of a plurality of reflection segments, in particular its arrangement, orientation or, more preferably, its impedance can be set. This allows you to react to different flight situations, such as takeoff and landing.

The Soundproofing device is advantageously on an inner surface an inlet section of the turbine or the engine arranged.

The Turbine housing, for example, an engine nacelle an aircraft or other aircraft. For others Finishes is the turbine housing in the fuselage embedded in an aircraft.

Of the Inlet area advantageously has an inlet lip, in whose Area a sound deflecting element, in particular the reflection segment, arranged is. As a result, the sound passes the greatest possible absorptive-looking track and is only at the exit or short distracted from that.

Farther the reflection segment is advantageous in a lower region of the Inlet lip arranged. This will deflect the sound upwards.

A further advantageous embodiment or another field of application the described soundproofing device with reflection segment represents the engine exhaust, for example, a twin-stream jet engine (Turbofan engine) dar. Here are sound-absorbing linings preferably on the inner and on the outer wall of a bypass channel (bypass duct) attached to the largest possible To achieve absorption of the escaping sound. In the core stream (core duct), which contains the hot combustion gases, are conventional liners due to environmental conditions currently not usable. Therefore, an arrangement in the bypass duct prefers.

According to one advantageous embodiment of the invention are reflection segments each at the lower limit of the bypass channel directly before arranged at the outlet of the engine. This means in the case of Upper sector of the bypass channel on the wall between bypass channel and Core current, in the case of the lower sector on the outer Wall of the engine nacelle. As with other embodiments (in the inlet), the expansion of the reflection segments in the circumferential direction according to the application or the conditions of use be chosen favorably. Furthermore, a change the surface structure or impedance are provided.

Especially advantageous is a reflection section in a peripheral region from -90 ° to + 90 ° from the vertical, more especially in the range ± 45 ° and most preferably about ± 30 °, arranged.

The Soundproofing device is especially for turbofan engines suitable, in particular for arrangement on an engine casing, for example, an (interior of a) engine housing (s).

in the The invention will be described below with reference to exemplary embodiments explained in more detail in the drawings schematically are shown. Show it:

1 a radial longitudinal section of an inlet region of an engine nacelle with a soundproofing device according to a first embodiment of the present invention;

2 a section along II-II through the engine nacelle 1 ;

3 a cut like in 1 by an engine nacelle with a soundproofing device according to a second embodiment of the present invention and

4 a radial longitudinal section of an outlet of an engine with a soundproofing device according to a third embodiment of the present invention.

In the attached figures are exemplary embodiments of soundproofing devices 1 for jet engines or for turbines, such as gas turbines or turbofan engines, using the example of a turbofan engine 2 represented an aircraft. The soundproofing device 1 has unevenly distributed surface structures for targeted sound control 3 on. The surface structures 3 are in the illustrated examples by an engine lining 4 on an inward facing inner surface 5 a turbine casing element or a turbine casing element 6 educated.

In the illustrated examples, the turbine shroud is 6 an engine nacelle 12 (also called Nacelle), in which the turbofan engine 2 is housed.

As in 1 shown has the turbofan engine 2 a fan 18 on, the shovels 20 and a hub portion 22 having. The hub section 22 with the blades 20 is part of a rotor of the engine and rotates in operation about its axis A, which is the axis of rotation of the turbofan engine 2 bil det. The fan promotes this 18 Air from an inlet area 14 in the direction of a flow 24 to a turbine, not shown, or in the bypass channel.

1 shows a first embodiment of the inlet area 14 having engine intake 10 one here as a turbofan engine 2 trained aircraft engine. The turbofan engine 2 is from the engine gondola 12 enclosed and points to the axis A directed towards and extending in the circumferential direction inner surface 5 the soundproofing device 1 with the engine lining 4 on. The this soundproofing device 1 having inlet area 14 of the turbofan engine 2 ranges from one to one exit level 16 of sound forming circumferential front edge 17 the engine nacelle 12 up to the fan 18 ,

1 shows a side view of a first embodiment of the soundproofing device 1 . 2 shows a section along the line II-II of 1 in this first embodiment. 3 shows one 1 comparative representation of the engine intake 10 with a second embodiment of the soundproofing device 1 ,

The engine lining 4 in both embodiments has a sound absorbing lining 26 and a reflective-acting liner segment, hereinafter referred to as (reflection segment 30 referred to as. The nacelle or engine nacelle 2 is aerodynamically contoured in both embodiments and surrounds the engine to direct the free flow of air into the engine.

In a turbofan engine 2 There is, as is generally known, in the further, not shown here on the fan 18 In the flow direction following area two paths of the incoming air through the engine. A certain amount passes after flowing through the fan 18 in the inner part of the engine and is there compressed and mixed with fuel to drive the combustion. This amount of air (core stream) flows after combustion through the turbine of the engine and thus drives a (also not shown) compressor and the fan 18 at. The core stream has a high temperature and high momentum upon exit. The remaining, far greater proportion of the ambient air flowing into the engine passes over the radially outer part of the fan 18 in a so-called "bypass duct" and flows out at the back of the Nacelle (bypass current). The ratio of the amount of air flowing through the bypass duct per unit time to the amount of air flowing through the engine core is referred to as a "bypass ratio."

Regarding the sound emitted by the engine, the fan plays 18 due to a steadily increasing bypass ratio during takeoff and landing over the years a more and more important role. In this case, the sound field in these two flight conditions fundamentally different, since each modal tonal sound fields of different cause represent the dominant parts. At start-up, where the engine is running at high speed, supersonic speeds and turbulence occur at the tips of the blades 20 (Leaf tips) of the fan 18 , which produce a characteristic noise, the so-called "Buzz Saw Noise". This occurs at the harmonics of the rotor speed and corresponds in its circumferential order to the number of rotor blades.

On the other hand, the engine is adjusted to a much lower speed on approach. The rotor harmonics are "cut off", ie not capable of propagation. Rather dominate the blade repetition frequencies ("blade passage frequencies", abbreviated BPF short), which from an interaction of the rotor blades of the fan 18 and the subsequent (not shown) vanes ("stators") arise. Their frequencies correspond to the product of rotor speed and number of rotor blades.

The sound absorbing lining 26 gets in the engine intake 10 attached to reduce the sound emitted by the engine sound. The sound absorbing lining 26 (also called absorptive liner) is usually optimized for a flight condition to the fan blade sequence BPF 18 (as dominant tonal components). For this, the impedance of the materials of the sound-absorbing lining is 26 selected accordingly. The technique of tuning resistances of liners to certain dominant tonal components for absorption thereof is well known in the art discussed above and will not be described further here.

In the embodiments shown here is such a sound-absorbing lining 26 with a liner segment or liner segment - the reflective segment 30 - with clearly the impedance of the sound absorbing lining 26 deviating impedance combined. The impedance of the reflection segment 30 is set very low here. The reflection segment 30 is here as part of the engine lining 4 educated. It is at the in 1 and 2 shown first embodiment in the front region of the engine inlet 10 at one of the fan 18 facing away, here front side of the sound-absorbing lining 26 attached (see 1 ). At the in 3 illustrated second embodiment, the reflection segment in the region of the inlet lip, so to speak as a "lip-liner", ie as lips lining. The aim of this reflection segment 30 from the resulting impedance jump at the interface, here at the interface 27 between the sound-absorbing lining 26 and the reflection segment 30 to achieve a directional influence of the incident sound field. In the examples shown here in the form of aircraft engines, in particular the noise radiated towards the ground is thereby to be reduced and the noise pollution of an area surrounding an airport is to be reduced.

The mode of action here corresponds to that of a "negatively scarfed inlets", ie an engine intake with an advanced lower lip, but dispenses with the additional structure of the extended lower lip and thus on weight penalties. In contrast, the acoustic effect is achieved by the targeted positioning of the reflective liner segment - reflection segment 30 - achieved.

Other embodiments not shown here allow a variation of the impedance of the sound-absorbing lining 26 (absorptive liner portion), to adjust the most favorable impedance according to the flight condition and thus to achieve the highest possible absorption, before the fan 18 forward propagating sound to the reflection segment 30 meets. This adjustment of impedance can be achieved either by adjusting the entire sound-absorbing lining 26 or even the entire engine lining 4 (sound absorbing lining 26 with reflection segment 30 ) respectively. Additionally or alternatively, adjusting devices are provided with which an adjustment discrete, in the engine lining 4 distributed, adaptive elements occurs, resulting in averaged over the area ratio impedance.

The above-described embodiments and effects of the soundproofing device described herein 1 will be described below with reference to the 1 and 2 illustrated embodiment explained in more detail.

In the illustrated turbofan engine 2 is due to the interaction of the flow 24 with the engine intake 10 and the fan 18 Sound generated in the engine intake 10 against the direction of the flow 24 propagates substantially along the axis A in the axial direction. In this way, the sound passes through the engine lining 4 and in particular the sound absorbing lining 26 , The sound absorbing lining 26 is relative to the axis A in the circumferential direction on the inside of the engine nacelle 12 arranged. In a lower area 28 of the inlet area 14 is on the side of the sound-absorbing lining 26 extending axially along the axis A from the fan 18 turned away, the reflection segment 30 used. The reflection segment 30 points towards the sound-absorbing lining 26 a much lower impedance.

2 shows a view from the exit plane 16 off in the direction of the axis A on the engine intake 10 and the fan 18 , Clearly the blades are 20 and the hub portion 22 to see. Next is the circumferentially arranged sound absorbing lining 26 visible, noticeable. In the area below 28 is in the sound absorbing lining 26 the reflection segment 30 used.

At the in 3 shown second embodiment of a sound insulation system is the entire engine lining 4 and thus also the sound-absorbing lining 26 up to the inlet lip 25 preferred. The reflection segment 30 is now on an inlet lip 25 arranged.

The function of the reflection segment 30 works well with 1 explain. As already explained spreads from the fan 18 generated sound against the direction of the flow 24 in the direction of the axis A out. He passes the sound-absorbing lining 26 that absorbs frequencies in a certain frequency range. Upon further progression towards the exit plane 16 the sound hits the reflection segment 30 which has a much lower impedance than the sound absorbing lining 26 , Passing this hard impedance jump will deflect the sound upwards.

By the arrangement of the reflection segment 30 near the exit level 16 is the sound when passing through the exit plane 16 radiated upwards, without once again, for example, from the engine nacelle 12 to be distracted or reflected. This ground noise is also avoided.

In the 3 shown second embodiment goes one step further and arranges the sound-absorbing lining 26 additionally in the area of the inlet lip 25 at. This is the effective absorptive route on which the sound through the sound-absorbing lining 26 is attenuated, increased. Furthermore, the reflection segment 30 at the inlet lip 25 which makes it possible to deflect an even larger portion of the downward sound upwards, since there is no longer any possibility of the upwardly deflected sound from the upper area of the engine nacelle 12 is thrown back down.

The embodiments show soundproofing devices 1 with a single reflexi onssegment 30 , However, it is also conceivable, several reflection segments 30 at various positions in the circumferential direction in the lining 26 to adapt the sound insulation device to the respective installation situation and arrangement of the engine.

Furthermore, in the exemplary embodiment, the reflection segment extends 30 in the circumferential direction to an angle of about ± 40 ° from the vertical V (see 2 ).

A third embodiment of the invention is as in 4 shown, also at an engine outlet 34 usable. The engine exhaust 34 of the turbofan engine 2 includes end sections of the engine nacelle 12 , A circumferential bypass duct in the circumferential direction 36 inside the engine nacelle 12 is arranged and one of the bypass channel 36 by a substantially cylindrical wall separated core stream 38 ,

The core stream 38 leads hot combustion gases 40 of the engine 2 while the bypass duct 36 ambient air 42 leads.

At the the bypass channel 36 facing surfaces of the wall 37 and the engine nacelle 12 is as an engine lining 4 a sound absorbing lining 26 provided as a soundproofing device 1 acts. To deflect the sound from the directional area 32 are gone at the end edges 44 the Wall 37 and the engine nacelle 12 into the sound-absorbing lining 26 used reflection segments 30 intended.

By the extension of the reflection segment 30 in the circumferential direction, the directional range can be 32 , in which a sound emission should be reduced. This directional area 32 is in 2 indicated by arrows. As shown, the directional area 32 Here is a extending over a certain angle in the circumferential direction radial region. Depending on the installation situation, it is possible to use the reflection segment 30 very narrow form, so for example, to extend only in a range of ± 10 ° around the vertical V around. It may also be appropriate in certain installation situations that the reflection segment 30 extends from -90 ° to + 90 ° from the vertical V. It is also conceivable, the reflection segment 30 to perform asymmetrically with respect to the vertical V.

The reflection segment 30 and / or the lining 26 can be designed so that their impedance is adjustable. This could be achieved, for example, by having the surface of the lining 26 consists of two mutually displaceable, abutting, perforated plates. If the perforated plates are shifted against each other, the hole size of the surface of the lining changes 26 or the reflection segment 30 , With such a variable surface structure, the radiated sound field can be adapted to a variety of flight situations.

In contrast to conventional soundproofing systems for engines, in the solution proposed here, a suitable non-uniform distribution of sound-absorbing lining is achieved 26 and reflection segment 30 in the inlet area 14 the engine nacelle 12 a directional influence of the radiated sound field achieved, which causes a greater noise reduction on the ground, as with conventional measures. In particular, a liner segment - here, for example, the reflection segment 30 - in the lower part of the engine intake 10 near the exit level 16 or in the area of the inlet lip 25 used, which is a sound-absorbing lining surrounding it 26 , which is formed by an absorptive liner, has significantly different impedance and thereby achieves a reflective effect. The effect achieved is similar to that of the "negatively scarfed inlet", but avoids the use of additional structure (and thus weight) and possible aerodynamic disadvantages by the lower inlet area 14 by the impedance jump between the lining 26 and the reflection segment 30 only virtual acoustically extended.

1

Noise protection device

2

Turbofan

3

surface structure

4

Engine liner

5

inner surface

6

casing member

10

Engine Intake

12

Engine nacelle

14

intake area

16

exit plane

17

front edge

18

fan

20

shovel

22

next section

24

inflow

25

intake lip

26

sound-absorbing lining

27

interface

28

lower Area

30

reflecting segment

32

directional range

34

Triebwerksauslass

36

Bypass duct

37

wall

38

nuclear power

39

surface

40

combustion gases

42

ambient air

44

edge

A

axis of rotation

V

vertical

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - EP 1621752 A2 [0003]
• US 3937590 [0005]
• - EP 1411225 B1 [0006]
• EP 1701016 A1 [0007]
• - US 5058617 [0009]
• - EP 1071608 B1 [0010]
• US 3946830 [0010]

Claims (25)

Soundproofing device ( 1 ) for a jet engine or a turbine, in particular for a turbofan engine ( 2 ) of an aircraft for attenuating a sound field in a directional area ( 32 ), in particular for attenuating sound directed in the direction of the ground, characterized by an uneven distribution of sound-influencing surface structures ( 26 . 30 ) on a housing or casing element ( 6 ) such that sound is transmitted through at least one impedance jump at an interface ( 27 ) of the surface structures ( 26 . 30 ) and / or by reflection targeted by the directional area ( 32 ) is steered away. Soundproofing device ( 1 ) according to claim 1, characterized in that for the attenuation of sound in a relative to a central or rotational axis (A) of the jet engine or the turbine radial direction range ( 32 ) Surface structures ( 26 . 30 ) on a surface facing the axis (A) ( 5 ) are distributed unevenly in the circumferential direction. Soundproofing device ( 1 ) according to claim 1 or 2, characterized in that for the attenuation of sound in a relative to a central or rotational axis (A) of the jet engine or the turbine radial direction range ( 32 ) Surface structures ( 26 . 30 ) on a surface facing away from the axis (A) ( 39 ) are distributed unevenly in the circumferential direction. Soundproofing device ( 1 ) according to one of claims 1 to 3, characterized in that the or part of the sound-influencing surface structures ( 26 . 30 ) at or in an inlet area ( 14 ) of the jet engine or the turbine, in particular in the form of an engine lining ( 4 ) are provided. Soundproofing device ( 1 ) according to one of claims 1 to 4, characterized in that the or part of the sound-influencing surface structures ( 26 . 30 ) in the region of an engine outlet ( 34 ) of the jet engine or the turbine, in particular in the form of an engine lining ( 4 ) are provided. Soundproofing device ( 1 ) according to claim 5, characterized in that the or part of the sound-influencing surface structures ( 26 . 30 ) on or in a bypass channel ( 36 ) is trained. Soundproofing device ( 1 ) according to one of the preceding claims, characterized in that the surface structures ( 26 . 30 ) a sound-absorbing lining ( 26 ) exhibit. Soundproofing device ( 1 ) according to one of the preceding claims, characterized in that the surface structures ( 26 . 30 ) at least one reflection segment ( 30 ) for selectively deflecting one into the directional area ( 32 ) radiated sound. Soundproofing device according to claim 7 and claim 8, characterized in that the reflection segment ( 30 ) has an impedance substantially different from the impedance of the sound absorbing lining ( 26 ) deviates. Soundproofing device according to claim 7 and 8 or according to claim 9, characterized in that the impedance of the reflection segment ( 30 ) lower than the impedance of the lining ( 26 ). Soundproofing device according to claim 7 and 8 or according to claim 9 or 10, characterized in that the sound-absorbing lining ( 26 ) on a surface extending in the circumferential direction with respect to the central or rotational axis (A) of the jet engine or the turbine ( 5 ) and that the reflection segment ( 30 ) in a peripheral area that is defined by the directional area ( 32 ) into the sound absorbing lining ( 26 ) is used. Soundproofing device according to claim 7 and 8 or according to one of claims 9 to 11, characterized in that the reflection segment ( 30 ) in the axial direction on a side facing away from the jet engine or the turbine side of the sound-absorbing lining ( 26 ) is arranged. Soundproofing device according to claim 7 and 7 or according to one of claims 9 to 12, characterized in that the reflection segment ( 30 ) in a recess of the sound-absorbing lining ( 26 ) is used. Soundproofing device according to claim 4 and any one of claims 8 to 13, characterized in that the inlet area ( 14 ) an inlet lip ( 25 ), in the region of which the reflection segment ( 30 ) is arranged. Soundproofing device according to claim 14, characterized in that the inlet lip ( 25 ) by a constriction which is substantially perpendicular to the direction of an incoming flow ( 24 ) runs in the circumferential direction, is formed. Soundproofing device according to claim 15, characterized in that the reflection segment ( 30 ) in a lower area ( 28 ) of the inlet lip ( 25 ) is arranged. Soundproofing device according to claim 16, characterized in that the reflection segment ( 30 ) is arranged in a circumferential range of -90 ° to + 90 ° from the vertical. Soundproofing device according to one of the preceding claims, characterized in that at least one of the surface structures ( 26 . 30 ) is formed changeable. Soundproofing device according to claim 7 or any one of claims 8 to 18, as far as dependent on claim 7, characterized in that the sound-absorbing lining ( 26 ) is adjustable. Soundproofing device according to claim 18, characterized characterized in that the impedance of the sound-absorbing lining is adjustable. Soundproofing device according to one of the preceding claims, characterized in that the soundproofing device for arrangement on an inner surface of an inlet region ( 14 ) of the turbofan engine ( 2 ) is trained. Soundproofing device according to one of the preceding claims, characterized in that the housing or sheathing element ( 6 ) an engine nacelle ( 12 ) which is the unevenly distributed surface structures ( 26 . 30 ) having. Engine casing ( 6 ), characterized by a soundproofing device ( 2 ) according to any one of the preceding claims. Engine ( 2 ) with a soundproofing device ( 1 ) according to one of claims 1 to 19 and / or with an engine casing ( 6 ) according to claim 20. Engine according to claim 23, characterized in that it is used as a turbofan engine ( 2 ), in particular for aircraft or spacecraft, is formed.