Aircraft auxiliary power device exhaust silencer and aircraft

Abstract

The invention relates to an aircraft auxiliary power device exhaust silencer and an aircraft. The exhaust silencer of the airplane auxiliary power device comprises an exhaust pipe acoustic liner, a shell, a heat insulation and sound absorption layer and a partition plate. Wherein the exhaust pipe acoustic liner is connected with an exhaust port of an airplane auxiliary power device, the exhaust pipe acoustic liner is tubular, a plurality of small holes are formed in the pipe wall of the exhaust pipe acoustic liner, the shell is arranged on the outer side of the exhaust pipe acoustic liner, so that a cavity is formed between the shell and the exhaust pipe acoustic liner, and the partition plate is installed between the shell and the exhaust pipe acoustic liner. The heat insulation and sound absorption layer is fixed to the inner side face of the shell.

Description

TECHNICAL FIELD

[0001] The present application relates to an aircraft auxiliary power unit exhaust muffler, and belongs to the field of aircraft auxiliary power unit installation design. BACKGROUND

[0002] The aircraft auxiliary power unit (hereinafter referred to as APU) mainly provides generator shaft power for the power supply system and bleed air for the air supply system on the ground and in the air. The aircraft usually sets a muffler on the APU exhaust pipe section to reduce exhaust noise. In addition, since the APU exhaust is high-temperature gas, the surface temperature of the exhaust muffler also needs to be limited to prevent the liquid from being ignited when the aircraft leaks flammable liquid and contacts the high-temperature surface, and limiting the surface temperature of the exhaust muffler can also prevent the high temperature from affecting the surrounding structure.

[0003] At present, the aircraft exhaust muffler mainly utilizes the sound lining inside the muffler and the shell to form a Helmholtz resonance cavity or fill some sound-absorbing materials to achieve the purpose of reducing noise. In order to reduce the temperature of the muffler, a thermal insulation layer is wrapped outside the muffler to prevent the liquid from being ignited when the aircraft leaks flammable liquid and contacts the high-temperature surface, and limiting the surface temperature of the exhaust muffler can also prevent the high temperature from affecting the surrounding structure.

[0004] In the prior art, the thermal insulation layer wrapped outside the muffler mainly plays a heat insulation role and does not contribute to the noise reduction function, that is, the thermal insulation layer cannot increase the noise reduction effect. In addition, the thermal insulation layer is arranged outside the muffler, which is easy to be damaged due to factors such as wear and tear or impact of foreign objects. SUMMARY

[0005] An object of the present application is to provide an aircraft auxiliary power unit exhaust muffler which can achieve the effect of heat insulation while further reducing exhaust noise and increasing the noise reduction effect, and can also avoid damage to the thermal and sound-absorbing layer due to factors such as wear and tear or impact of foreign objects.

[0006] The above object of the present application is achieved by an aircraft auxiliary power unit exhaust muffler, which comprises an exhaust pipe sound lining, a shell, a thermal and sound-absorbing layer, and a partition plate.

[0007] The exhaust pipe sound lining is connected to the exhaust port of the aircraft auxiliary power unit, the exhaust pipe sound lining is in the form of a pipe and has a plurality of small holes formed in the pipe wall, the shell is arranged outside the exhaust pipe sound lining to form a cavity between the shell and the exhaust pipe sound lining, the partition plate is installed between the shell and the exhaust pipe sound lining to divide the cavity into a plurality of sub-cavities, and the thermal and sound-absorbing layer is fixed to the inner side of the shell.

[0008] According to the technical scheme, the aircraft auxiliary power device exhaust muffler can achieve the following beneficial technical effects: the heat insulation effect can be achieved, the exhaust noise can be further reduced, the noise reduction effect can be increased, and the heat insulation and sound absorption layer can be prevented from being damaged due to abrasion or impact of foreign objects.

[0009] Preferably, the thickness of the heat insulation and sound absorption layer is less than 20% of the thickness of the cavity.

[0010] Preferably, the heat conductivity coefficient of the heat insulation and sound absorption layer is less than 0.05 W / mK, and the sound absorption coefficient of the heat insulation and sound absorption layer is greater than 0.2.

[0011] Preferably, the thickness of the heat insulation and sound absorption layer is 5-10 mm.

[0012] Preferably, the aircraft auxiliary power device exhaust muffler further comprises a liquid discharge port, and the liquid discharge port is arranged near the lowest point of the aircraft auxiliary power device exhaust muffler when the aircraft auxiliary power device exhaust muffler is installed in the aircraft.

[0013] Preferably, the partition plate is provided with a liquid discharge groove at the bottom of the partition plate, so that the liquid can flow to the liquid discharge port through the liquid discharge groove.

[0014] Preferably, the exhaust pipe sound lining is connected to the exhaust port of the aircraft auxiliary power device through a flexible connecting piece.

[0015] Preferably, the exhaust pipe sound lining has different perforation rates in different sub-cavities according to different frequency band noise reduction requirements.

[0016] Preferably, the perforation rate of the exhaust pipe sound lining is maintained at 5%-15%.

[0017] Preferably, the end of the shell in the exhaust direction is tapered.

[0018] The above object of the application is also achieved by an aircraft comprising the aircraft auxiliary power device exhaust muffler according to any one of the above aspects.

[0019] According to the technical scheme, the aircraft auxiliary power device exhaust muffler can achieve the following beneficial technical effects: the heat insulation effect can be achieved, the exhaust noise can be further reduced, the noise reduction effect can be increased, and the heat insulation and sound absorption layer can be prevented from being damaged due to abrasion or impact of foreign objects. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 is a longitudinal sectional view of an aircraft auxiliary power device exhaust muffler according to an embodiment of the application.

[0021] Figure 2Fig. 1 is a perspective view of an auxiliary power unit exhaust muffler of an aircraft according to an embodiment of the present application.

[0022] List of reference signs

[0023] 1: Exhaust pipe sound insulation

[0024] 2: Shell

[0025] 3: Heat-insulating sound-absorbing layer

[0026] 4: Partition

[0027] 5: Drainage port

[0028] 11: First sub-cavity

[0029] 12: Second sub-cavity

[0030] 13: Third sub-cavity

[0031] 14: Fourth sub-cavity

[0032] 15: Fifth sub-cavity

[0033] 100: Exhaust direction DETAILED DESCRIPTION

[0034] The specific embodiments of the present application will be described hereinafter, and it should be noted that, in the specific description of these embodiments, the present specification cannot possibly describe all the features of the actual embodiments in detail for the sake of brevity and conciseness. It should be understood that, in the actual implementation of any one of the embodiments, as in the process of any engineering or design project, various specific decisions must be made in order to achieve the specific goals of the developers, to meet the system-related or business-related constraints, and these decisions will vary from one embodiment to another. In addition, it should be understood that, although the efforts made in this development process can be complex and lengthy, some design, manufacturing or production changes made on the basis of the disclosed technology should be understood by those skilled in the art related to the disclosed content as routine technical means, and should not be understood as insufficient disclosure.

[0035] Unless otherwise defined, technical and scientific terms used in the claims and specification shall have the meaning commonly understood by one of ordinary skill in the art to which this application belongs. The use of the terms "first", "second", and "like" in the specification and claims of this patent application does not imply any order, quantity, or importance, but rather is used to distinguish one element from another. The use of the terms "a" and "an" and the like in the specification and claims of this patent application does not limit the number of elements to one, but rather means "at least one". The use of the terms "including", "containing", and the like in the specification and claims of this patent application does not limit the number of elements included in the described compositions, methods, and the like, but rather means "comprising." The use of the terms "connected" and "coupled" and the like in the specification and claims of this patent application are intended to be used in their broadest sense, and are not limited to a direct connection or coupling.

[0036] In the following description, for the purposes of the present application, relative terms are used to describe the structure and working of the present application, and the terms "front", "back", "left", "right", "outer", "inner", "outward", "inward", "upper", "lower", and the like are used as convenient terms, and should not be construed as limiting terms. In particular, it should be noted that "front" and "back" are determined according to the direction of the exhaust gas.

[0037] Figure 1 is a longitudinal sectional view of an exhaust muffler of an auxiliary power unit of an aircraft according to an embodiment of the present application. Figure 2 is a perspective view of an exhaust muffler of an auxiliary power unit of an aircraft according to an embodiment of the present application.

[0038] As shown in Figures 1 to 2 , an exhaust muffler of an auxiliary power unit of an aircraft according to an embodiment of the present application comprises an exhaust pipe liner 1, a housing 2, a heat-insulating and sound-absorbing layer 3, and a partition plate 4.

[0039] The exhaust pipe liner 1 is connected to an exhaust port of the auxiliary power unit of the aircraft, and is in the form of a pipe with a plurality of small holes formed in the pipe wall. The housing 2 is disposed (preferably concentrically) outside the exhaust pipe liner 1, so as to form a cavity between the housing 2 and the exhaust pipe liner 1. The partition plate 4 is installed between the housing 2 and the exhaust pipe liner 1, so as to divide the cavity into a plurality of sub-cavities, such as a first sub-cavity 11, a second sub-cavity 12, a third sub-cavity 13, a fourth sub-cavity 14, and a fifth sub-cavity 15. The heat-insulating and sound-absorbing layer 3 is fixed to the inner side of the housing 2.

[0040] It should be noted that the exhaust direction 100 of the high-temperature exhaust gas of the APU has been shown in Figures 1 to 2 , and is consistent with the longitudinal direction of the entire exhaust muffler. The orientation perpendicular to the longitudinal direction of the exhaust muffler can be defined as the radial direction of the exhaust muffler.

[0041] According to the technical scheme, the aircraft auxiliary power unit exhaust muffler can achieve the following beneficial technical effects: the heat insulation effect is achieved, the exhaust noise is further reduced, the noise reduction effect is increased, and damage to the heat insulation and sound absorption layer caused by wear or impact of foreign objects is avoided.

[0042] Specifically, the aircraft auxiliary power unit exhaust muffler has the following innovations and advantages compared with the prior art:

[0043] (1) Compared with the prior art exhaust muffler scheme, the heat insulation layer is added inside the muffler instead of outside. Compared with the prior art exhaust muffler scheme, the heat insulation and sound absorption layer is added inside, which can use the exhaust pipe sound insulation, partition, heat insulation and sound absorption layer and the shell to form a better sound insulation cavity, thereby achieving the heat insulation effect and further reducing the exhaust noise.

[0044] (2) The heat insulation and sound absorption layer is placed inside the exhaust muffler, which can avoid damage to the heat insulation layer caused by wear or impact of foreign objects, thereby further improving the service life and reliability of the exhaust muffler.

[0045] In some embodiments, as shown in Figures 1 to 2 The thickness of the heat insulation and sound absorption layer 3 is less than 20% of the thickness of the cavity.

[0046] The "thickness" of the heat insulation and sound absorption layer refers to the size of the heat insulation and sound absorption layer in the radial direction of the exhaust muffler. Similarly, the "thickness" of the cavity refers to the size of the cavity in the radial direction of the exhaust muffler.

[0047] In the present application, the heat insulation and sound absorption layer is fixed to the inner side of the shell, and the thickness of the heat insulation and sound absorption layer is only less than 20% of the thickness of the cavity, without completely filling the cavity, and even can be said that the majority (more than 80%) of the original thickness of the cavity (i.e. the sound insulation cavity) is basically retained. The built-in heat insulation and sound absorption layer and the sound insulation cavity with most of the original thickness are combined to further reduce the exhaust noise and increase the noise reduction effect.

[0048] In some embodiments, as shown in Figures 1 to 2 The exhaust pipe sound insulation 1 is connected to the exhaust port of the aircraft auxiliary power unit through a flexible connecting piece, so that the high-temperature exhaust gas of the APU is discharged to the outside of the fuselage along the exhaust direction 100 through the exhaust pipe sound insulation 1.

[0049] Preferably, the exhaust pipe sound insulation 1 is connected to the exhaust port of the aircraft auxiliary power unit through a metal bellows.

[0050] Preferably, the exhaust pipe sound insulation 1 can be made of high-temperature-resistant nickel-based alloy or other materials.

[0051] In some embodiments, as shown inFigures 1 to 2 As shown, the shell 2 is an outer structure of the entire exhaust muffler, and together with the inner exhaust pipe sound insulation 1 and the partitions 4, forms the main structure of the exhaust muffler.

[0052] Preferably, the shell 2 can be formed by a stainless steel sheet material and connected by riveting or welding.

[0053] In some embodiments, as shown, the thermal conductivity of the heat and sound insulation layer 3 is less than or equal to 0.05 W / mK, and the sound absorption coefficient of the heat and sound insulation layer 3 is greater than or equal to 0.2. Therefore, the heat and sound insulation layer 3 can reduce the heat conduction of the exhaust gas to the outer surface of the shell 2 to reduce the temperature, thereby avoiding the temperature exceeding the limit. On the other hand, the heat and sound insulation layer 3 itself can also play a role in sound absorption, which can further reduce noise. Figures 1 to 2 Preferably, the heat and sound insulation layer 3 can be made of a metal fiber felt material. The metal fiber felt material satisfies the thermal conductivity of less than or equal to 0.05 W / mK, and the sound absorption coefficient of greater than or equal to 0.2. Preferably, the metal fiber felt material can be made of stainless steel fiber, nickel fiber, titanium fiber, etc.

[0054] In some embodiments, as shown, the thickness of the heat and sound insulation layer 3 is 5-10 mm. The thickness of the heat and sound insulation layer 3 can be further adjusted according to the heat insulation and sound absorption requirements. Preferably, a typical application of the heat and sound insulation layer 3 can have a thickness of 6.35 mm.

[0055] Figures 1 to 2 Preferably, the heat and sound insulation layer 3 is fixed to the inner side of the shell 2 by a strip or a fastener. For example, the heat and sound insulation layer 3 can be directly fixed to the inner side of the shell 2 by a strip or a fastener; the heat and sound insulation layer 3 can also be fixed to the inner side of the shell 2 by a strip or a fastener, and then by the flange of the partition 4.

[0056] In some embodiments, as shown, four partitions 4 are installed between the shell 2 (or the heat and sound insulation layer 3) and the exhaust pipe sound insulation 1 to divide the cavity into five sub-cavities, such as a first sub-cavity 11, a second sub-cavity 12, a third sub-cavity 13, a fourth sub-cavity 14, and a fifth sub-cavity 15. Of course, the above-mentioned number of partitions and the number of sub-cavities are only a preferred form, and those skilled in the art can understand that other suitable numbers of partitions and sub-cavities (for example, one partition and two sub-cavities, two partitions and three sub-cavities, three partitions and four sub-cavities, five partitions and six sub-cavities, etc.) can also be used without departing from the protection scope of the claims of the present application.

[0057] In some embodiments, as shown, four partitions 4 are installed between the shell 2 (or the heat and sound insulation layer 3) and the exhaust pipe sound insulation 1 to divide the cavity into five sub-cavities, such as a first sub-cavity 11, a second sub-cavity 12, a third sub-cavity 13, a fourth sub-cavity 14, and a fifth sub-cavity 15. Of course, the above-mentioned number of partitions and the number of sub-cavities are only a preferred form, and those skilled in the art can understand that other suitable numbers of partitions and sub-cavities (for example, one partition and two sub-cavities, two partitions and three sub-cavities, three partitions and four sub-cavities, five partitions and six sub-cavities, etc.) can also be used without departing from the protection scope of the claims of the present application. Figures 1 to 2 In some embodiments, as shown, four partitions 4 are installed between the shell 2 (or the heat and sound insulation layer 3) and the exhaust pipe sound insulation 1 to divide the cavity into five sub-cavities, such as a first sub-cavity 11, a second sub-cavity 12, a third sub-cavity 13, a fourth sub-cavity 14, and a fifth sub-cavity 15. Of course, the above-mentioned number of partitions and the number of sub-cavities are only a preferred form, and those skilled in the art can understand that other suitable numbers of partitions and sub-cavities (for example, one partition and two sub-cavities, two partitions and three sub-cavities, three partitions and four sub-cavities, five partitions and six sub-cavities, etc.) can also be used without departing from the protection scope of the claims of the present application.

[0058] Figures 1 to 2 ​​As shown, the exhaust pipe acoustic liner 1 can have different perforation ratios in different sub-cavities to meet the noise reduction requirements of different frequency bands. It should be noted that the perforation ratio refers to the ratio of the perforated area to the total area of ​​the exhaust pipe acoustic liner.

[0059] In some embodiments, such as Figures 1 to 2 As shown, the perforation rate of the exhaust pipe acoustic liner 1 is maintained at 5% to 15% to match the peak frequency of exhaust noise and further reduce the exhaust noise of the APU.

[0060] Preferably, the perforation diameter of the exhaust pipe acoustic liner 1 is maintained between 0.5 and 2.4 mm.

[0061] In some embodiments, such as Figures 1 to 2 As shown, the aircraft auxiliary power unit exhaust muffler also includes a drain port 5, which is located near the lowest point of the aircraft auxiliary power unit exhaust muffler when it is installed in the aircraft, so that the internal liquid can be discharged.

[0062] Preferably, such as Figure 2 As shown, since the downstream end of the aircraft auxiliary power unit exhaust muffler is usually slightly higher than the upstream end when it is installed in the aircraft, the drain port 5 is usually located on the lower side of the housing 2 near the upstream end.

[0063] In some embodiments, such as Figures 1 to 2 As shown, the partition 4 has a drain trough at its bottom so that liquid can flow through the drain trough to the drain outlet 5.

[0064] Preferably, the drain trough extends through the baffle 4 along the longitudinal direction of the exhaust muffler, so that liquid can flow through the drain trough to the drain port 5. Preferably, each baffle 4 has a drain trough at its bottom.

[0065] In some embodiments, such as Figures 1 to 2 As shown, the housing 2 is tapered at the end (downstream end) in the exhaust direction to adapt to the typical aircraft structural shape.

[0066] According to an embodiment of the present invention, the aircraft includes an exhaust muffler for the aircraft auxiliary power unit as described in any of the above aspects. Based on the above technical solution, the aircraft of the present invention can achieve the following beneficial technical effects: while achieving heat insulation in the exhaust muffler, it can further reduce exhaust noise and increase noise reduction effect, and at the same time, it can prevent damage to the heat insulation and sound absorption layer due to wear or impact from foreign objects.

[0067] The specific embodiments of the present invention have been described above. However, those skilled in the art will understand that the above specific embodiments do not constitute a limitation on the present invention. Those skilled in the art can make various modifications based on the above disclosure without exceeding the scope of the present invention.

Claims

1. An aircraft auxiliary power unit exhaust muffler, comprising an exhaust pipe acoustic lining, a shell, a heat-insulating and sound-absorbing layer, and a partition plate; the exhaust pipe acoustic lining is connected to an exhaust port of an aircraft auxiliary power unit, the exhaust pipe acoustic lining is tubular and has a plurality of small holes in its wall, the shell is arranged outside the exhaust pipe acoustic lining, thereby forming a cavity between the shell and the exhaust pipe acoustic lining, the partition plate is installed between the shell and the exhaust pipe acoustic lining to divide the cavity into a plurality of sub-cavities, and the heat-insulating and sound-absorbing layer is fixed to the inner side of the shell. wherein The thickness of the heat-insulating and sound-absorbing layer is 20% or less of the thickness of the cavity.

2. The aircraft auxiliary power unit exhaust silencer of Claim 1, wherein, The heat-insulating and sound-absorbing layer has a thermal conductivity of 0.05 W / mK or less and a sound absorption coefficient of 0.2 or more.

3. The aircraft auxiliary power unit exhaust silencer of claim 1, wherein, The thickness of the heat-insulating and sound-absorbing layer is 5-10 mm.

4. The aircraft auxiliary power unit exhaust silencer of claim 1, wherein, The aircraft auxiliary power unit exhaust muffler further comprises a liquid discharge port arranged near the lowest point of the aircraft auxiliary power unit exhaust muffler when installed in an aircraft.

5. The aircraft auxiliary power unit exhaust silencer of claim 1, wherein, The exhaust pipe acoustic lining is connected to the exhaust port of the aircraft auxiliary power unit through a flexible connecting piece.

6. The aircraft auxiliary power unit exhaust silencer of claim 1, wherein, The exhaust pipe acoustic lining has different perforation rates in different sub-cavities to meet different sound attenuation requirements for different frequency bands.

7. The aircraft auxiliary power unit exhaust silencer of claim 1, wherein, The perforation rate of the exhaust pipe acoustic lining is maintained at 5-15%.

8. An aircraft auxiliary power unit exhaust silencer as claimed in claim 7, characterised in that, The shell is tapered at the end in the exhaust direction.

9. The aircraft auxiliary power unit exhaust silencer of claim 1, wherein, 10. An aircraft comprising the aircraft auxiliary power unit exhaust muffler according to any one of claims 1-9. ​

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