Engine exhaust muffler structure based on acoustic metamaterials
By using an engine exhaust muffler structure based on acoustic metamaterials and by designing the shell and insert pipe, the problem that existing mufflers cannot effectively eliminate broadband noise in the mid-to-low frequency range is solved, and a significant noise reduction effect is achieved for high-temperature exhaust.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- CHINA AIRPLANT STRENGTH RES INST
- Filing Date
- 2025-10-28
- Publication Date
- 2026-07-31
AI Technical Summary
Existing reactive mufflers cannot effectively eliminate the mid-to-low frequency broadband noise of engine exhaust, and there are passing frequencies in certain frequency bands, resulting in reduced noise cancellation efficiency.
An engine exhaust muffler structure based on acoustic metamaterials is adopted, including a housing, an insertion tube, and an exhaust pipe. By dividing the housing into a hollow part and a non-hollow part, and setting an array of holes on the inner annular surface of the insertion tube, and using an isolation plate to divide the hollow part into two regions, the noise of high-temperature exhaust noise at odd and even multiples of half the wavelength can be eliminated.
It significantly reduces engine exhaust noise in the 300-1000Hz range, effectively eliminates broadband noise in the mid-low frequency band, achieves a noise reduction effect of 13.03dB(A), and reduces engine power loss by no more than 10%.
Smart Images
Figure CN121382381B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the technical field of mufflers, and particularly relates to an engine exhaust muffler structure based on acoustic metamaterials. Background Technology
[0002] Aircraft noise has always been a crucial issue for the aviation industry. Sustained high-frequency noise not only damages aircraft structures, reduces stealth performance, and interferes with various avionics, but also has a detrimental impact on the surrounding environment. Engine noise is the primary source of aircraft noise, composed of various noise sources including combustion chamber noise, structural vibration noise, and aerodynamic noise, with exhaust noise being the most significant. Currently, exhaust mufflers are commonly used for noise reduction. These mufflers often employ reactive silencers, achieving good noise reduction through different structural combinations. However, reactive silencers are primarily suitable for narrowband noise in the low-to-mid frequency range and cannot achieve broadband noise cancellation in this range. Furthermore, they may even exhibit passing frequencies in certain frequency bands, reducing noise cancellation efficiency.
[0003] In view of this, the present invention is hereby proposed. Summary of the Invention
[0004] The engine exhaust muffler structure based on acoustic metamaterials provided by this invention solves the technical problem of low efficiency in eliminating engine exhaust noise in existing devices. The technical solution of this invention has many beneficial effects, as described below: An engine exhaust muffler structure based on acoustic metamaterials, suitable for noise cancellation of high-temperature engine exhaust, includes a housing, an insert pipe, an intake pipe, and an exhaust pipe. The housing is divided into a hollow part and a non-hollow part. The non-hollow part has cavities spaced along the axial direction. The inner ring surface of the insert pipe has multiple arrayed holes spaced along the axial direction. The hollow part is divided into two independent first regions and second regions by the isolation plate. One end of the exhaust pipe is installed in the circumferential direction of the shell and located in the first region, and the other end passes through the isolation plate and is connected to the second region. The noise of the high temperature exhaust can be eliminated by odd multiples of 1 / 2 wavelength through the second region. The insertion tube is installed on the isolation plate at a position away from the air intake pipe. The first region and the second region are connected through the insertion tube. The noise of high temperature exhaust can be eliminated by odd multiples of 1 / 2 wavelength under the combined action of the insertion tube and the first region. The exhaust pipe is installed axially within the non-hollow section of the housing and has protruding sections at both ends. The position of the exhaust pipe is offset from that of the insertion pipe. After the high-temperature exhaust enters the exhaust pipe, it passes through the array of holes and enters the corresponding cavity to absorb the noise of the high-temperature exhaust at different frequency bands, thereby eliminating the mid- and low-frequency bandwidth of the high-temperature exhaust noise.
[0005] Compared with the prior art, the technical solution provided by the present invention has the following beneficial effects: The structure, which divides the housing into a hollow part and a non-hollow part, and the non-hollow part is provided with cavities spaced along the axial direction, and the inner ring surface of the insertion tube is provided with multiple array holes spaced along the axial direction, can have a significant effect on eliminating engine exhaust noise in the range of 300-1000Hz. When the exhaust passes through the structure of this invention, its noise is greatly reduced, and broadband noise in the mid and low frequency ranges of engine exhaust can be eliminated. Attached Figure Description
[0006] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0007] Figure 1 This is a perspective view of a quarter section of the structure of the present invention; Figure 2 This is the front view of the present invention, wherein, 1. Intake pipe; 2. Insertion pipe; 3. First region; 4. Absorption hole; 5. Fourth chamber; 6. Exhaust pipe; 7. Third chamber; 8. Second chamber; 9. First chamber; 10. Second region. Detailed Implementation
[0008] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.
[0009] It should be noted that various aspects of embodiments within the scope of the appended claims are described below. It will be apparent that the aspects described herein can be embodied in a wide variety of forms, and any particular structure and / or function described herein is merely illustrative. Based on this invention, those skilled in the art will understand that one aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number of aspects set forth herein can be used to implement the device and / or practice the method. Additionally, this device and / or method can be implemented using structures and / or functionalities other than one or more of the aspects set forth herein.
[0010] It should also be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. The drawings only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.
[0011] Furthermore, specific details are provided in the following description to facilitate a thorough understanding of the examples. However, those skilled in the art will understand that aspects can be practiced without these specific details. To enable those skilled in the art to better understand the invention, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined as "first" and "second" may explicitly or implicitly include one or more of that feature. In the description of the invention, unless otherwise stated, "a plurality of" means two or more.
[0012] like Figures 1 to 2 The engine exhaust muffler structure based on acoustic metamaterials shown is suitable for noise cancellation of high-temperature engine exhaust. It includes a housing, an insertion pipe 2, an intake pipe 1, and an exhaust pipe 6. The housing is divided into a hollow section and a non-hollow section. The non-hollow section has cavities spaced axially. The inner annular surface of the insertion pipe 2 has multiple arrayed holes spaced axially, such as 3*3, 3*4, 4*4, or other hole arrays, with a micro-perforation rate of 0.002. The hollow part is divided into two independent first region 3 and second region 10 by the partition plate. One end of the exhaust pipe 6 is installed in the circumferential direction of the shell and is located in the first region 3. The other end passes through the partition plate and is connected to the second region 10. The noise of the high temperature exhaust can be eliminated by odd multiples of 1 / 2 wavelength through the second region 10. An insertion tube 2 is installed on the isolation plate at a position away from the intake pipe 1. The first region 3 and the second region 10 are connected through the insertion tube 2. The noise of the high-temperature exhaust can be eliminated by odd multiples of 1 / 2 wavelength under the combined action of the insertion tube 2 and the first region 3. The exhaust pipe 6 is installed along the axial direction of the shell inside the non-hollow part and has protruding sections at both ends. The position of the exhaust pipe 6 is staggered from the position of the insertion pipe 2. After the high-temperature exhaust enters the exhaust pipe 6, it enters the corresponding cavity through the array of holes to absorb the noise of the high-temperature exhaust at different frequency bands, thereby eliminating the mid- and low-frequency bandwidth of the high-temperature exhaust noise.
[0013] In one embodiment, the intake pipe 1 is configured in an L-shape, and the intake end is connected to the exhaust component of the engine via a flange. Preferably, the length of the intake pipe 1 in the first region 3 is less than the length of the intake pipe 1 in the second region 10, thereby improving the efficiency of noise absorption during the flow of high-temperature exhaust gas into the second region 10.
[0014] Furthermore, the length of the insertion tube 2 in the first region 3 is greater than the length in the second region 10, which improves the efficiency of noise absorption during the process of high-temperature exhaust flowing from the second region 10 into the first region 3.
[0015] In one embodiment, the cavity sequentially includes a first cavity 9, a second cavity 8, a third cavity 7, and a fourth cavity 5 along the exhaust direction, and the exhaust pipe 6 is connected to the first cavity 9, the second cavity 8, the third cavity 7, and the fourth cavity 5 respectively through an array of holes.
[0016] Preferably, the length of the intake pipe 1 is half the length of the second region 10, which can eliminate odd multiples of the wavelength passing through the pipe; the length of the insertion pipe 2 in the first region 3 is half the length of the first region 3, which can eliminate odd multiples of the wavelength passing through the pipe; the length of the insertion pipe 2 in the second region 10 is one-quarter the length of the second region 10, which can eliminate even multiples of the wavelength passing through the pipe.
[0017] In summary, it can achieve complete absorption of the mid- and low-frequency bandwidth of noise.
[0018] Working process: All the above materials are made of high temperature resistant metal. The high temperature exhaust first enters the intake pipe 1 and then passes through the second region 10. Since the length of the intake pipe 1 is 1 / 2 of the length of the second region 10, the odd multiple of the wavelength passing through the pipe is eliminated. Then, it enters the first region 3 through the insertion tube 2. Since the length of the insertion tube 2 in the first region 3 is 1 / 2 of the length of the first region 3, it can eliminate the odd multiple of the passing frequency of 1 / 2 wavelength. And the length of the insertion tube 2 in the second region 10 is 1 / 4 of the length of the second region 10, which eliminates the even multiple of the passing frequency of 1 / 2 wavelength. Then, the exhaust noise enters the first cavity 9, the second cavity 8, the third cavity 7, and the fourth cavity 5 through the array of holes on the exhaust pipe 6, and performs broadband cancellation of different frequency bands in sequence, such as low-frequency noise in the 300-1000Hz band. Finally, it flows out through the exhaust pipe 6, thereby achieving the purpose of exhaust noise elimination and solving the exhaust noise problem of a certain type of piston engine. It can effectively suppress exhaust noise while ensuring that the engine power loss does not exceed 10%, with a total noise reduction of 13.03dB(A), which can be regarded as complete elimination.
[0019] The product provided by this invention has been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the embodiments above are merely for the purpose of helping to understand the core ideas of this invention. It should be noted that those skilled in the art can make various improvements and modifications to the invention without departing from the principles of the invention, and these improvements and modifications also fall within the protection scope of the invention claims.
Claims
1. An engine exhaust muffler structure based on acoustic metamaterials, suitable for noise elimination of high-temperature engine exhaust, characterized in that, The system includes a housing, an insertion tube, an intake tube, and an exhaust tube. The housing is divided into a hollow section and a non-hollow section. The non-hollow section has cavities spaced apart along the axial direction. The inner ring surface of the insertion tube has multiple arrayed holes spaced apart along the axial direction. The hollow part is divided into a first region and a second region by a partition plate. One end of the exhaust pipe is installed in the circumferential direction of the shell and located in the first region, while the other end passes through the partition plate and is connected to the second region. The noise of the high-temperature exhaust can be eliminated by odd multiples of 1 / 2 wavelength through the second region. The insertion tube is installed on the isolation plate at a position away from the air intake pipe. The first region and the second region are connected through the insertion tube. The noise of high temperature exhaust can be eliminated by odd multiples of 1 / 2 wavelength under the combined action of the insertion tube and the first region. The exhaust pipe is installed axially within the non-hollow section of the housing and has protruding sections at both ends. The position of the exhaust pipe is offset from that of the insertion pipe. After the high-temperature exhaust enters the exhaust pipe, it passes through the array of holes and enters the corresponding cavity to absorb the noise of the high-temperature exhaust at different frequency bands, thereby eliminating the mid- and low-frequency bandwidth of the high-temperature exhaust noise.
2. The engine exhaust muffler structure according to claim 1, characterized by, The intake pipe is designed in an L-shape, and the intake end is connected to the engine's exhaust components via a flange.
3. The engine exhaust muffler structure according to claim 2, characterized by, The insertion tube is longer in the first region than in the second region, which improves the efficiency of noise absorption.
4. The engine exhaust muffler structure according to claim 3, characterized by The cavity includes a first cavity, a second cavity, a third cavity, and a fourth cavity in sequence along the exhaust direction, and the exhaust pipe is connected to the first cavity, the second cavity, the third cavity, and the fourth cavity respectively through an array of holes.
5. The engine exhaust muffler structure according to claim 4, characterized by The length of the intake pipe is half the length of the second region.
6. The engine exhaust muffler structure according to claim 5, characterized by The length of the insertion tube placed in the first region is half the length of the first region.
7. The engine exhaust muffler structure according to claim 6, characterized by The length of the insertion tube placed in the second region is one-quarter of the length of the second region.