Diesel engine exhaust silencer for small test ship

Abstract

The utility model belongs to the technical field of diesel engine parts for small test ships, and particularly relates to a diesel engine exhaust silencer for a small test ship, which comprises three acoustic black hole expansion cavities with different sizes. A damping layer is laid in the acoustic black hole expansion cavity; a silencing device shell is arranged outside the damping layer; the micro-perforated silencing pipe is installed at the position of a center shaft of the silencing device, an inlet is formed in one end of the micro-perforated silencing pipe, an outlet is formed in the other end of the micro-perforated silencing pipe, and air inlets are distributed in the micro-perforated silencing pipe. While the total mass of the silencing device is reduced, the noise reduction effect of the silencing device is improved.

Description

TECHNICAL FIELD

[0001] The utility model belongs to small -size test ship diesel engine part technical field, concretely relates to a small -size test ship diesel engine exhaust silencer. BACKGROUND

[0002] The diesel engine is widely applied in the small -size test ship because of high reliability, power performance is good, fuel economy is good, technology is mature and many advantages. However, the small -size test ship is because test test requirement and many scientific research personnel long -term follow the ship debugging test, the noise of diesel engine produces seriously influences the debugging test work and daily life of scientific research personnel, especially the noise caused by the diesel engine inlet and outlet pipeline is very outstanding, therefore can be through installing the silencer to carry out the noise reduction treatment to the exhaust pipe.

[0003] The acoustic black hole is the black hole view of astrophysics introduced into the field of acoustics, and its essence is that in a thin plate structure, if the thickness of the plate decreases in a certain power law form, the bending wave speed will gradually decrease with the decrease of the thickness. In an ideal case, the local thickness of the plate structure can be reduced to zero, at which time the bending wave speed is reduced to zero, and the bending wave aggregation phenomenon occurs in the local area of the structure. In this case, the bending wave cannot continue to propagate forward or be reflected, so the reflection coefficient of the bending wave in this ideal tapered structure is zero. The tapered part in this structure is called an acoustic black hole.

[0004] Kry1ov et al. first applied this acoustic black hole structure to a one-dimensional beam structure, and verified that when the thickness and position relationship of the beam edge satisfies h(x) = εx m (m≥2), a small amount of damping material can be added to the edge to effectively dissipate the bending wave in the plate structure, achieving excellent vibration and noise reduction effect. In this way, the thickness change in the structure can be used to manipulate the bending wave to capture the energy transmitted by the bending wave, so as to produce energy aggregation phenomenon in the local area of the structure. In this case, only a small amount of damping material can achieve good energy dissipation effect, and has higher energy dissipation efficiency.

[0005] Therefore, in view of the above situation, the utility model solves the noise problem of the diesel engine exhaust pipe by combining the acoustic black hole with the noise generated by the diesel engine exhaust pipe. UTILITY MODEL CONTENTS

[0006] The utility model aims at providing a kind of small -size test ship diesel engine exhaust silencer, by the flexible application of acoustic black hole to the expansion cavity of silencer, to reduce the noise of diesel engine exhaust pipe.

[0007] In order to realize the above object, the utility model provides the following technical scheme: a small -size test ship diesel engine exhaust silencer, including three acoustic black hole expansion chamber and its size is different, damping layer is laid in the acoustic black hole expansion chamber, the damping layer is equipped with the silencer shell, the micro -perforated sound -absorbing pipe is installed in the central axis position of the silencer, one end is the entrance, the other end is the exit, and the micro -perforated sound -absorbing pipe is distributed with the air inlet.

[0008] The acoustic black hole expansion chamber is a wedge-shaped structure obtained by stretching a one-dimensional acoustic black hole along the normal direction, and the acoustic black hole expansion chamber is rotated 360° along the x-axis of the one-dimensional acoustic black hole to obtain a cavity structure.

[0009] The acoustic black hole expansion chamber is embedded with an acoustic black hole, and the acoustic black hole region satisfies h(x) = εx m +h0(m≥2); wherein, h(x) is the thickness of the black hole region when the central horizontal distance is x; h0 is the truncated thickness of the acoustic black hole region; r ABH is the radius of the acoustic black hole, the power law m takes a positive rational number 2-4, and the acoustic black hole truncated thickness h0 takes 0.05mm.

[0010] The cavity length of the first acoustic black hole expansion chamber is 30-50mm, the cavity length of the second acoustic black hole expansion chamber is 80-120mm, and the cavity length of the third acoustic black hole expansion chamber is 150-200mm; the acoustic black hole radius r ABH In the first acoustic black hole expansion chamber, 10-20mm is taken, in the second acoustic black hole expansion chamber, 35-55mm is taken, and in the third acoustic black hole expansion chamber, 70-95mm is taken.

[0011] The micro-perforated sound-absorbing pipe is a micro-perforated cylindrical pipe made of a pure metal sheet with a thickness of 1mm, and the air inlet through holes with a hole diameter of 1-3mm are uniformly distributed in the radial direction on the sound-absorbing pipe.

[0012] The micro-perforated sound-absorbing pipe selects different perforation rates.

[0013] The thickness of the damping layer is 5-10 times the acoustic black hole truncated thickness h0, and the material is selected to be a viscoelastic damping material.

[0014] The acoustic black hole expansion chamber is made of a steel plate and is connected in sequence by welding or bolt fixing.

[0015] The silencer is manufactured by integral casting.

[0016] Compared with the prior art, the micro-perforated sound attenuation pipe used in the utility model has high sound absorption coefficient, wide absorption frequency band, small pressure loss, low airflow regeneration noise and is easy to control; the utility model is used for widening the frequency band and improving the noise absorption effect, three expansion cavities are arranged to absorb noise of different frequency bands, so that the frequencies of different expansion cavities are different; the utility model utilizes the energy gathering effect of the acoustic black hole, gathers the bending wave to the tip of the acoustic black hole, uses damping material in the acoustic black hole expansion cavity to dissipate sound energy, realizes noise reduction, and compared with the ordinary sound attenuation device, the sound attenuation effect of the sound attenuation device using the acoustic black hole is more remarkable; the acoustic black hole expansion cavity used in the utility model reduces the use of materials and the cost of materials, and better sound attenuation effect is achieved while the total mass of the sound attenuation device is reduced.

[0017] To make the functional characteristics and structural parameters of the utility model clearer, the following further describes the utility model in combination with the drawings and specific embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0018] The drawings described herein are used to provide further understanding of the utility model, form part of the present application, and the illustrative embodiments of the utility model and the description thereof are used to explain the utility model and do not constitute improper limitation on the utility model. In the drawings:

[0019] Figure 1 It is the front view of the utility model;

[0020] Figure 2 It is the sectional view of the utility model;

[0021] Figure 3 It is the left view of the utility model;

[0022] Figure 4 It is the front view of the micro-perforated sound attenuation pipe of the utility model;

[0023] Figure 5 It is the sectional view of the utility model.

[0024] In the drawings, the reference signs are: 1-inlet; 2-micro-perforated sound attenuation pipe; 3-sound attenuation device shell; 4-damping layer; 5-micro hole; 6-outlet; 7-third acoustic black hole expansion cavity; 8-second acoustic black hole expansion cavity; 9-first acoustic black hole expansion cavity. DETAILED DESCRIPTION

[0025] Clearly, the described embodiments are merely a part of the embodiments of the present application, rather than all the embodiments; based on the embodiments of the present application, all the other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0026] The application discloses a small-sized test ship diesel engine exhaust silencer, which comprises three acoustic black hole expansion cavities with different sizes; a damping layer 4 is arranged in the acoustic black hole expansion cavities; an exhaust silencer shell 3 is arranged outside the damping layer 4; the exhaust silencer shell 3 is in a cylindrical shape; a micro-perforated silencer pipe 2 is arranged at the central axis of the exhaust silencer, one end of the micro-perforated silencer pipe 2 is an inlet 1, the other end is an outlet 6, and air inlets are arranged on the micro-perforated silencer pipe 2; the micro-perforated silencer pipe 2 is connected with the expansion cavities of the exhaust silencer by welding, and the sealing performance is good; the three acoustic black hole expansion cavities are connected closely and used for dissipating sound energy.

[0027] The acoustic black hole expansion cavity is a wedge-shaped structure obtained by stretching a one-dimensional acoustic black hole along a normal direction, and the acoustic black hole expansion cavity is rotated by 360 degrees along the x-axis of the one-dimensional acoustic black hole to obtain a cavity structure.

[0028] The acoustic black hole expansion cavity is embedded with an acoustic black hole, and the acoustic black hole area satisfies h(x) = epsilon x m +h0(m >= 2); wherein h(x) is the thickness of the black hole area when the central horizontal distance is x; h0 is the truncated thickness of the acoustic black hole area; r ABH is the radius of the acoustic black hole, the power law m takes a positive rational number 2-4, and the acoustic black hole truncated thickness h0 takes 0.05 mm.

[0029] The cavity length of the first acoustic black hole expansion cavity 9 is 30-50 mm, the cavity length of the second acoustic black hole expansion cavity 8 is 80-120 mm, and the cavity length of the third acoustic black hole expansion cavity 7 is 150-200 mm; the acoustic black hole radius r ABH The length of the first acoustic black hole expansion cavity 9 is 10-20 mm, the length of the second acoustic black hole expansion cavity 8 is 35-55 mm, and the length of the third acoustic black hole expansion cavity 7 is 70-95 mm.

[0030] The micro-perforated silencer pipe 2 is a micro-perforated cylindrical pipe, which is made of a pure metal sheet with a thickness of 1 mm, and the air inlet through holes with a diameter of 1-3 mm are uniformly distributed in the radial direction of the silencer pipe.

[0031] The micro-perforated muffler 2 selects different perforation rates, which can control the frequency spectrum performance of the muffler, so that good muffling effect is obtained in the required frequency range.

[0032] The thickness of the damping layer 4 is 5-10 times of the acoustic black hole cutoff thickness h0, and the material is selected from viscoelastic damping materials, which can be made of asphalt, water-soluble material, latex or epoxy resin with appropriate addition of fillers and solvents, and the acoustic black hole inflation cavity and the damping layer form an integral structure after being bonded by high-strength glue.

[0033] The acoustic black hole inflation cavity is made of steel plates and connected in sequence by welding or bolt fixing.

[0034] The muffling device is manufactured by integral casting.

[0035] The working principle of the present application is as follows:

[0036] The exhaust gas of the diesel engine enters the inlet of the micro-perforated muffler, enters the first acoustic black hole inflation cavity through the micro-hole 5, and the inflation cavity mainly eliminates high-frequency noise; the gas enters the second acoustic black hole inflation cavity through the micro-hole 5, and the inflation cavity mainly eliminates mid-frequency noise; the gas enters the third acoustic black hole inflation cavity through the micro-hole 5, and the inflation cavity mainly eliminates low-frequency noise; when the cross-sectional area of the chamber and the pipe micro-perforated muffler changes, the sound energy is reflected and expanded multiple times in the inflation chamber, so that the muffling effect is achieved. Secondly, when the noise enters the acoustic black hole inflation cavity, the bending wave propagates along the wedge shape of the acoustic black hole, and the bending wave speed gradually decreases with the decrease of the wedge thickness, and the wave is gathered in the local area of the black hole, at this time the damping can convert the sound energy into heat energy, and the second sound attenuation effect is achieved.

[0037] It should be noted that, in the present text, relational terms such as first and second and the like can merely be used to differentiate one entity or action from another, without necessarily requiring or implying any such actual relationship or order between or among the entities or actions. Moreover, the terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can include other elements not expressly listed or inherent to such process, method, article, or apparatus.

[0038] Although the embodiments of the present application have been shown and described, it should be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A small experimental marine diesel engine exhaust muffler, characterized in that, It includes three acoustic black hole expansion cavities of different sizes; a damping layer is laid inside the acoustic black hole expansion cavity; a silencing device shell is provided outside the damping layer; a micro-perforated silencing tube is installed at the central axis of the silencing device, with one end as the inlet and the other end as the outlet, and air inlets are distributed on the micro-perforated silencing tube.

2. The exhaust muffler for a small experimental marine diesel engine according to claim 1, characterized in that, The acoustic black hole expansion cavity is a wedge-shaped structure formed by stretching a one-dimensional acoustic black hole along its normal direction, and the cavity structure is obtained by rotating the acoustic black hole expansion cavity 360° along the x-axis of the one-dimensional acoustic black hole.

3. The exhaust muffler for a small experimental marine diesel engine according to claim 1, characterized in that, An acoustic black hole is embedded in the acoustic black hole expansion cavity, and its acoustic black hole region satisfies h(x) = εx. m +h0(m≥2); where h(x) is the thickness of the black hole region at a horizontal distance x from the center; h0 is the cutoff thickness of the acoustic black hole region; r ABH Let m be the radius of the acoustic black hole, m be a positive rational number from 2 to 4, and h0 be the truncation thickness of the acoustic black hole, which is 0.05 mm.

4. The exhaust muffler for a small experimental marine diesel engine according to claim 3, characterized in that, The acoustic black hole expansion cavity has a length of 30–50 mm for the first cavity, 80–120 mm for the second cavity, and 150–200 mm for the third cavity; the acoustic black hole radius r ABH A 10-20 mm sample is taken inside the first acoustic black hole expansion cavity, a 35-55 mm sample is taken inside the second acoustic black hole expansion cavity, and a 70-95 mm sample is taken inside the third acoustic black hole expansion cavity.

5. The exhaust muffler for a small experimental marine diesel engine according to claim 1, characterized in that, The micro-perforated silencer tube is a micro-perforated cylindrical tube made of pure metal sheet with a thickness of 1 mm. There are air inlet holes with a diameter of 1 to 3 mm on the wall of the sheet. The air inlet holes are evenly distributed in the radial direction on the silencer tube.

6. The exhaust muffler for a small experimental marine diesel engine according to claim 1, characterized in that, The micro-perforated silencer tubes are selected with different perforation rates.

7. The exhaust muffler for a small experimental marine diesel engine according to claim 1, characterized in that, The thickness of the damping layer is 5 to 10 times the cutoff thickness h0 of the acoustic black hole, and the material is selected as a viscoelastic damping material.

8. The exhaust muffler for a small experimental marine diesel engine according to claim 1, characterized in that, The acoustic black hole expansion cavity is made of steel plates and is connected sequentially by welding or bolting.

9. The exhaust muffler for a small experimental marine diesel engine according to claim 1, characterized in that, The silencing device is manufactured using an integral casting method.

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