Noise reduction device at pipeline elbow

Abstract

The invention relates to the technical field of pipeline noise elimination, in particular to a pipeline elbow noise reduction device which comprises a connecting elbow, an inner silencer is embedded in a bend of an inner cavity of the connecting elbow, a cavity exists between the inner silencer and the inner wall of the connecting elbow, and a neck bush is arranged between the inner silencer and the inner cavity of the connecting elbow. The inner silencer comprises an inflow part, an inward shrinkage part, a flow guide part and a discharge part which are integrally formed through flexible rubber, the inner diameters of the inflow part, the inward shrinkage part, the flow guide part and the discharge part are smoothly and gradually changed in the flow direction, and the outer wall of the inner silencer and the inner wall of the neck bush are seamlessly attached together. The silencer has the beneficial effects that the gradual change section design of the inner silencer maintains a laminar flow boundary layer through continuous curvature change, and flow separation is effectively reduced; the spiral flow guide fins are used for disassembling macroscopic vortex into micro-scale turbulent flow, so that energy dissipation is accelerated, and medium-high frequency noise is improved in a targeted manner; the sound absorption part is filled with an efficient sound absorption material, and a complementary silencing mechanism is formed with flow field optimization.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of pipeline noise reduction, in particular to a pipeline elbow noise reduction device. BACKGROUND

[0002] The noise generated by the operation of the fan of a smelting plant, an oil refinery, a heat exchange system of a coal-fired power plant, an air conditioning system and other ventilation systems is partly transmitted to the surrounding space environment through the fan and the pipe wall, and most of the noise is propagated along the pipeline system and radiated to the outside space through the pipeline inlet. At the same time, the secondary noise generated by the airflow in the pipeline system is also radiated to the surrounding space through the above two ways; the two parts of noise will have a great adverse effect on the surrounding environment and the work and life of personnel.

[0003] The elbow, as a key disturbance point of the pipeline system, is prone to the following problems due to the sudden change of fluid flow direction:

[0004] 1. Turbulent noise amplification: flow separation and vortex shedding occur in the elbow, forming medium-high frequency aerodynamic noise, and the sound pressure level is significantly higher than that of the straight pipe section;

[0005] 2. Structure vibration transmission: pressure pulsation impacts the pipe wall, exciting the elbow shell vibration and secondary radiating low-frequency noise;

[0006] 3. Traditional noise reduction bottleneck: the external wrapped noise reduction structure cannot suppress the internal turbulent sound source, and the built-in rigid silencer aggravates the pressure loss and is prone to regenerative noise.

[0007] Although the prior art attempts to use internal lining sound-absorbing materials or guide vanes, such as the one disclosed in the publication No. CN113153817B, which installs an elbow guide vane at the pipeline elbow, there are still defects such as large flow resistance, narrow frequency band coverage, and easy to fall off. Therefore, it is urgent to develop a special noise reduction device for elbows that combines flow field optimization and multi-modal noise reduction to achieve efficient suppression from the sound source generation, propagation and radiation. SUMMARY

[0008] The present application is a pipeline elbow noise reduction device.

[0009] The technical solution of the present application is as follows:

[0010] The utility model provides a pipeline elbow place noise reduction device, including connecting elbow, the inner chamber elbow of connecting elbow is nested with internal muffler, and the cavity exists between internal muffler and connecting elbow inner wall, and the inner lining is arranged between internal muffler and connecting elbow inner chamber, and the inner lining fills cavity and supports and fixes internal muffler, and connecting elbow includes curved part, and the both ends of curved part are integrally formed with connecting part, and the inside of connecting part near one end of curved part is integrally formed with step groove, and internal muffler includes the inflow part of flexible rubber, and the inner shrinkage part, and the flow guide part and the discharge part, and the inner diameter of inflow part, inner shrinkage part, flow guide part, discharge part presents smooth gradual change along the flow direction, and the outer end of inflow part is integrally formed with the second limiting portion that abuts at the inner step groove of connecting part, and the outer wall of internal muffler and the inner wall of inner lining are seamlessly bonded together.

[0011] Further, the total length of the inflow part, the inner shrinkage part and the flow guide part is the same as the length of the curved part, and the discharge part extends beyond the curved part.

[0012] Further, the inner lining includes a sound absorbing part that seamlessly fits the inner wall of the curved part, and the sound absorbing part is integrally formed with a first limiting part at one end.

[0013] Further, the sound absorbing part is made of high-efficiency sound-absorbing material (such as centrifugal glass wool, rock wool, polyester fiber cotton), and the first limiting part is made of rubber material, and the first limiting part is integrally injection molded as a limiting structure with the sound absorbing part.

[0014] Further, a support metal mesh is arranged inside the internal muffler, and flexible rubber is cast on the outer wall of the support metal mesh, and the support metal mesh penetrates the inflow part, the inner shrinkage part, the flow guide part and the discharge part.

[0015] Further, a plurality of spiral flow guide fins are formed on the inner wall of the end of the internal muffler near the discharge part, and the flow guide fins disassemble the fluid into micro-scale turbulent flow.

[0016] Further, an external noise reduction device is detachably connected and installed on the outside of the curved part, the external noise reduction device includes an inner lining damping layer, a sound absorbing layer and a sound insulation layer fixed on the outer wall of the curved part from inside to outside, the sound insulation layer is provided with an outer protective layer, the outer protective layer is composed of two symmetrical half rings, a fixing flange is formed on the abutting end face of the outer protective layer, a fixing screw hole is formed on the fixing flange, and a sealing gasket is arranged on the abutting end face of the fixing flange.

[0017] Further, the inner lining damping layer is made of high-density and high-damping flexible material (such as butyl rubber damping rubber plate and composite damping felt), which is closely attached to the pipe wall of the bending part to suppress the vibration of the pipe wall.

[0018] Further, the sound absorption layer is made of flexible, flame-retardant and environmentally friendly sound absorption material (such as closed-cell rubber foam and flexible polyester fiber felt), which fills the cavity outside the bending part and absorbs internal sound energy.

[0019] Further, the sound insulation layer is made of high-area-density flexible sound insulation material (such as high-density EPDM rubber plate and lead-aluminum composite sound insulation felt), which blocks the radiation of sound outward.

[0020] Further, the outer protective layer is made of engineering plastic or thin stainless steel plate.

[0021] With the above technical solutions, the present application has the following advantages:

[0022] 1. The gradually changing cross-section design of the inner muffler maintains the laminar boundary layer through continuous curvature change, effectively reducing flow separation; the spiral guide fin disassembles macro-vortex into micro-scale turbulent flow, accelerating energy dissipation and improving mid-high frequency noise; the sound absorbing part is filled with high-efficiency sound absorbing material, which forms a complementary noise reduction mechanism with flow field optimization.

[0023] 2. The inner lining damping layer closely attaches to the pipe wall, converting the bending vibration energy into heat energy; the three-layer structure of damping layer + sound absorption layer + sound insulation layer realizes the synergistic effect of vibration suppression, sound energy absorption and sound insulation; the split flange connection and sealing gasket design of the outer protective layer consider the convenience and sealing performance of maintenance.

[0024] 3. The integrated pouring design of the supporting metal mesh and flexible rubber ensures the stability of the flow channel shape after the installation of the inner muffler, and can also avoid the falling of the inner muffler; the extended structure of the discharge part maintains the smoothness of the downstream flow field, significantly reducing pressure loss. BRIEF DESCRIPTION OF DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0026] Figure 1 is the explosion of the present application;

[0027] Figure 2 is the first perspective view of the present application;

[0028] Figure 3is a second perspective view of the present application;

[0029] Figure 4 is a perspective view of the inner muffler of the present application;

[0030] Figure 5 is a front view of the inner muffler of the present application;

[0031] Figure 6 is a sectional view of the connecting elbow of the present application;

[0032] Figure 7 is a sectional view of the inner sleeve of the present application;

[0033] Figure 8 is a sectional view of the inner muffler of the present application;

[0034] Figure 9 is a sectional view of the soundproofing device of the present application.

[0035] The reference signs are explained as follows:

[0036] 1, connecting elbow; 11, bending part; 12, connecting part; 2, inner sleeve; 21, sound absorbing part; 22, first limiting part; 3, inner muffler; 31, inflow part; 32, inwardly-retracted part; 33, flow guiding part; 34, discharge part; 35, second limiting part; 36, supporting metal mesh; 37, flow guiding fin; 4, soundproofing device; 41, inner damping layer; 42, sound absorbing layer; 43, soundproofing layer; 44, outer protective layer; 45, fixing flange. DETAILED DESCRIPTION

[0037] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in 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.

[0038] As Figures 1-3 , Figure 6As shown in the figure, a pipeline elbow noise reduction device includes a connecting elbow 1, an inner silencer 3 is nested in the inner cavity of the connecting elbow 1, there is a cavity between the inner silencer 3 and the inner wall of the connecting elbow 1, an inner bushing 2 is arranged between the inner silencer 3 and the inner cavity of the connecting elbow 1, the inner bushing 2 fills the cavity and supports and fixes the inner silencer 3, and the cavity and the inner bushing 2 jointly constitute a sound absorption cavity structure, the connecting elbow 1 includes a curved part 11, the curved part 11 is integrally formed with a connecting part 12 at both ends, the connecting part 12 is used for connecting with upstream and downstream pipelines, the connecting part can be any one of a flange, an inner thread sleeve and an outer thread sleeve, a stepped groove is formed in the inner end of the connecting part 12 close to the curved part 11, and the stepped groove is used for axial positioning and limiting the inner bushing 2 and the inner silencer 3.

[0039] As shown in Figures 4-5 , Figure 8 As shown in the figure, the inner silencer 3 includes an inflow part 31, an inner shrink part 32, a flow guide part 33 and a discharge part 34 which are integrally formed of flexible rubber, the inner diameters of the inflow part 31, the inner shrink part 32, the flow guide part 33 and the discharge part 34 are smoothly and gradually changed along the flow direction (such as from a circular shape to an oval shape and then back to a circular shape, or a continuously changing curvature radius is adopted, so that fluid flow separation and turbulence are minimized), the smooth and gradual change of the streamline design can significantly reduce vortex, impact and flow separation noise of fluid at the elbow due to sudden change of flow direction and sharp change of cross section, and is a key to reducing source aerodynamic noise, a second limiting part 35 is formed at the outer end of the inflow part 31 and abuts against the inner stepped groove of the connecting part 12, the second limiting part 35 cooperates with the stepped groove to realize positioning and fixing of the inner silencer 3 in the axial direction of the pipeline and prevent displacement of the inner silencer 3 under fluid impact, the outer wall of the inner silencer 3 is seamlessly attached to the inner wall of the inner bushing 2, so that the two are in close contact, on the one hand, the inner silencer 3 is stably supported, and on the other hand, sound energy is more effectively transmitted to the sound absorption material inner bushing 2.

[0040] As another preferred embodiment of the present application, the total length of the inflow part 31, the inner shrink part 32 and the flow guide part 33 is the same as the length of the curved part 11, so that the active noise reduction part (the inflow part 31 to the flow guide part 33) of the inner silencer 3 completely covers the core curved area of the elbow, and the high noise area is processed in a targeted manner, and the discharge part 34 extends beyond the curved part 11, so that the fluid can have a smooth recovery section after leaving the core area of the elbow, further stabilizing the flow field and reducing outlet turbulent noise.

[0041] As another preferred embodiment of the present application, as shown in Figure 7As shown, the inner sleeve 2 includes a sound absorption part 21 which is seamlessly attached to the inner wall of the bending part 11, and the sound absorption part 21 is tightly filled in the annular cavity between the inner wall of the connecting elbow 1 and the outer wall of the inner silencer 3, and its main function is to absorb the middle and high frequency noise waves transmitted through the wall of the inner silencer 3, and one end of the sound absorption part 21 is formed with a first limiting part 22 which abuts against the inner stepped groove of the connecting part 12, and the first limiting part 22 cooperates with the stepped groove to realize the positioning and fixing of the inner sleeve 2 in the axial direction of the pipeline.

[0042] As another preferred embodiment of the present application, the sound absorption part 21 is made of high-efficiency sound absorption material (such as centrifugal glass wool, rock wool, polyester fiber cotton), which has a porous structure and can convert sound wave energy into heat energy through friction and viscous action, and is particularly effective for middle and high frequency noise, and the first limiting part 22 is made of rubber material which has good elasticity and sealing property, and can realize reliable limiting and fixing and also has certain damping and sealing effect to prevent fluid or sound wave from leaking from the limiting part, and the first limiting part 22 is integrally injection molded with the sound absorption part 21 as a limiting structure, which ensures firm combination and good integrity and convenient installation.

[0043] As another preferred embodiment of the present application, as shown in Figure 8 The inner silencer 3 is internally provided with a support metal wire mesh 36 made of memory alloy, and flexible rubber is poured on the outer wall of the support metal wire mesh 36, and the support metal wire mesh 36 serves as a framework structure which greatly enhances the structural strength and rigidity of the flexible rubber inner silencer 3, so that it can withstand the pressure, impact and vibration of the fluid inside the pipeline without collapsing or excessive deformation, and ensures the stability of the flow passage shape and the durability of the noise reduction effect, and the support metal wire mesh 36 penetrates into the inflow part 31, the inwardly-retracted part 32, the flow guiding part 33 and the discharge part 34 to provide uniform and continuous support for the entire inner silencer 3.

[0044] As another preferred embodiment of the present application, as shown in Figure 2 , Figure 8 The inner wall of one end of the inner silencer 3 near the discharge part 34 is formed with a plurality of helically distributed flow guiding fins 37, and the main function of the flow guiding fins 37 is to exert a tangential force on the fluid flowing out of the core area of the elbow to induce the fluid to generate rotational flow (circumferential flow), and this helical micro-cyclone structure can effectively disintegrate and break large-scale high-energy turbulent vortexes into smaller micro-turbulent flows (micro-scale turbulent flows), and the micro-turbulent flow has higher energy dissipation rate and lower radiation noise efficiency, thereby significantly reducing the turbulent noise (especially low frequency broadband noise) generated in the process of restoring the straight pipe flow of the fluid.

[0045] As another preferred embodiment of the present application, as shown in Figures 1-3 , Figure 9As shown, the outer part of the bending part 11 is provided with the sound attenuation device 4 through detachable connection, the sound attenuation device 4 constitutes a second noise reduction barrier, mainly aiming at the noise (especially low-frequency noise and pipe wall vibration radiation noise) that cannot be completely eliminated by the inner muffler 3 and the inner liner 2, and inhibiting the internal noise from spreading outward through the pipe wall, the sound attenuation device 4 comprises, from inside to outside, the inner lining damping layer 41, the sound absorption layer 42 and the sound insulation layer 43 fixed on the outer wall of the bending part 11, the three layers are respectively used for inhibiting different noise propagation and radiation mechanisms, forming a composite noise reduction mechanism of “inhibiting vibration-absorbing sound energy-blocking propagation”, the outer part of the sound insulation layer 43 is provided with the outer protective layer 44, the outer protective layer 44 mainly plays a mechanical protection, environmental protection (moisture-proof, corrosion-proof) and aesthetic effect, the outer protective layer 44 is composed of two symmetrical semicircular rings, which is convenient for assembling and disassembling on the outer part of the installed elbow pipe, facilitating maintenance and maintenance, the outer protective layer 44 is formed with a fixed flange 45 at the abutting end face, the fixed flange 45 is formed with a fixed screw hole, and the two semicircular rings are fastened into a whole through bolt connection, and the fixed flange 45 is provided with a sealing gasket at the abutting end face, so as to ensure the sealing performance of the connecting part of the outer protective layer 44 and prevent sound wave leakage.

[0046] As another preferred embodiment of the present application, the inner lining damping layer 41 is made of high-density and high-damping flexible material (such as butyl rubber damping rubber plate, composite damping felt), which is closely attached to the pipe wall of the bending part 11, and its core function is to increase the structural damping of the pipe wall, and the vibration mechanical energy generated by the pipe wall due to fluid pulsation and sound wave excitation is efficiently converted into heat energy dissipation through the internal molecular friction of the material, thereby significantly inhibiting the pipe wall vibration and the structural noise (secondary noise) radiated to the outside space.

[0047] As another preferred embodiment of the present application, the sound absorption layer 42 is made of flexible, flame-retardant and environmentally friendly sound-absorbing material (such as closed-cell rubber-plastic foam, flexible polyester fiber cotton felt), which fills the cavity outside the bending part 11 and absorbs internal sound energy, mainly absorbing air sound waves that penetrate the inner lining damping layer 41 or escape from the pipe wall gap, especially for medium and high frequency noise. The effect is remarkable. The material is flexible to adapt to the curved surface of the elbow pipe, and the flame-retardant and environmentally friendly material meets the safety standards.

[0048] As another preferred embodiment of the present application, the sound insulation layer 43 is made of high-face-density flexible sound insulation material (such as high-density EPDM rubber plate, lead-aluminum composite sound insulation felt), which blocks the sound radiation outward, and its principle is “mass law”, that is, by using the high face density and high internal loss characteristics of the material, the remaining sound energy (especially low-frequency sound energy) is effectively reflected and hindered from spreading outward, which is the last important barrier to prevent noise leakage. The flexibility ensures that it can wrap the curved surface.

[0049] As another preferred embodiment of the present application, the outer protective layer 44 is made of engineering plastic or thin stainless steel plate, providing strong physical protection against external impact, wear and tear and harsh environments (such as corrosion, ultraviolet light), while also having a certain sound insulation effect. Engineering plastics (such as glass fiber reinforced nylon) are light in weight and corrosion resistant, while stainless steel plates are high in strength and good in durability.

[0050] The working principle of the present application is as follows:

[0051] During installation, the inner sleeve 2 is first inserted into one end of the connecting elbow 1, covering the curved portion 11, and then the inner muffler 3 is inserted into the other end of the connecting elbow 1, so that the discharge portion 34 passes through the curved portion 11 completely and is automatically attached to the inner wall of the inner sleeve 2 under the action of the supporting metal mesh 36. Then, the outer muffling device 4 is installed outside the connecting elbow 1, and after the entire device is assembled, the connecting elbow 1 is connected to the upstream pipeline near the inflow portion 31 and to the downstream pipeline near the discharge portion 34, thereby realizing the assembly of the device and the pipeline.

[0052] The inner muffler 3 has a streamlined and smoothly changing internal flow channel design (inflow portion 31, inner contraction portion 32, flow guide portion 33, discharge portion 34), which fundamentally reduces flow separation, vortex shedding and turbulence intensity from the perspective of fluid dynamics, significantly reducing the energy of the aerodynamic noise source. The flexible rubber material combined with the built-in supporting metal mesh 36 ensures the stability of the flow channel shape, pressure resistance and impact resistance. The spiral flow guide fin 37 further actively controls the downstream flow state, breaks up large vortexes and accelerates the dissipation of turbulent kinetic energy, reducing turbulent noise.

[0053] The inner sleeve 2 fills the cavity between the inner muffler 3 and the elbow pipe, and its high-efficiency sound-absorbing material (sound-absorbing portion 21) directly absorbs sound waves (mainly medium and high frequencies) that transmit through the inner muffler wall or propagate along the cavity. The limiting structure (first limiting portion 22) ensures stable installation.

[0054] The outer muffling device 4 adopts a "damping-sound absorption-sound insulation" composite layer structure, which is tightly attached to the outer wall of the elbow pipe. The inner damping layer 41 directly suppresses pipe wall vibration, converting and dissipating vibration energy to reduce structural noise radiation. The sound-absorbing layer 42 absorbs air sound (medium and high frequencies) that penetrates through the damping layer or escapes from the gap. The sound insulation layer 43 blocks the remaining sound energy (especially low frequency) from spreading outward with high surface density. The outer protective layer 44 provides mechanical and environmental protection, and the detachable design facilitates maintenance.

[0055] Through the stepped groove of the connecting portion 12 and the first limiting portion 22 and the second limiting portion 35, reliable axial positioning and fixation of the inner sleeve 2 and the inner muffler 3 are achieved, preventing displacement failure during operation.

[0056] Components not described in detail in this document are prior art.

[0057] The above merely provides the preferred embodiment of the present application, and is not used to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A noise reduction device for a pipe bend, comprising a connecting bend (1), characterized in that: An inner muffler (3) is nested inside the inner cavity of the connecting elbow (1). There is a cavity between the inner muffler (3) and the inner wall of the connecting elbow (1). An inner bushing (2) is provided between the inner muffler (3) and the inner cavity of the connecting elbow (1). The inner bushing (2) fills the cavity and supports and fixes the inner muffler (3). The connecting elbow (1) includes a bent portion (11). Both ends of the bent portion (11) are integrally formed with connecting portions (12). The connecting portion (12) is internally formed at one end near the bent portion (11). The inner muffler (3) has a stepped groove and includes an inlet section (31), an inner shrink section (32), a guide section (33), and an outlet section (34) integrally molded from flexible rubber. The inner diameters of the inlet section (31), the inner shrink section (32), the guide section (33), and the outlet section (34) gradually change smoothly along the flow direction. The outer end of the inlet section (31) is formed with a second limiting part (35) that abuts against the stepped groove in the connecting part (12). The outer wall of the inner muffler (3) is seamlessly fitted to the inner wall of the inner bushing (2).

2. The noise reduction device at a pipe bend according to claim 1, characterized in that: The total length of the inlet section (31), the concave section (32), and the guide section (33) is the same as the length of the curved section (11), and the outlet section (34) extends beyond the curved section (11).

3. The noise reduction device at a pipe bend according to claim 1, characterized in that: The inner liner (2) includes a sound-absorbing part (21) that fits seamlessly with the inner wall of the curved part (11), and one end of the sound-absorbing part (21) is formed with a first limiting part (22) that abuts against the stepped groove in the connecting part (12).

4. The noise reduction device at a pipe bend according to claim 3, characterized in that: The sound-absorbing part (21) is made of high-efficiency sound-absorbing material, and the first limiting part (22) is made of rubber material. The first limiting part (22) serves as a limiting structure and is integrally injection molded with the sound-absorbing part (21).

5. A noise reduction device for pipe bends according to claim 1, characterized in that: The internal silencer (3) is provided with a supporting metal wire mesh (36), and flexible rubber is cast on the outer wall of the supporting metal wire mesh (36). The supporting metal wire mesh (36) passes through the inlet (31), the inner constriction (32), the guide (33) and the outlet (34).

6. The noise reduction device at a pipe bend according to claim 1, characterized in that: The inner muffler (3) has several spirally distributed guide fins (37) formed on the inner wall of one end near the discharge part (34). The guide fins (37) decompose the fluid into microscale turbulence.

7. A noise reduction device for pipe bends according to claim 1, characterized in that: The curved part (11) is detachably connected to an external noise reduction device (4). The external noise reduction device (4) includes an inner lining damping layer (41), a sound-absorbing layer (42), and a sound insulation layer (43) that are fixed to the outer wall of the curved part (11) from the inside to the outside. An external protective layer (44) is provided on the outside of the sound insulation layer (43). The external protective layer (44) is composed of two symmetrical semi-circular rings. A fixing flange (45) is formed at the end face of the external protective layer (44). A fixing screw hole is formed on the fixing flange (45). A sealing gasket is provided at the end face of the fixing flange (45).

8. A noise reduction device for pipe bends according to claim 7, characterized in that: The inner lining damping layer (41) is made of a high-density, high-damping flexible material, which fits tightly against the wall of the bend (11) to suppress the vibration of the wall; the sound-absorbing layer (42) is made of a flexible, flame-retardant, and environmentally friendly sound-absorbing material, which fills the cavity outside the bend (11) and absorbs the internal sound energy; the sound insulation layer (43) is made of a high surface density flexible sound insulation material, which blocks the sound from radiating outward; the outer protective layer (44) is made of engineering plastic or thin stainless steel plate.

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