A noise reduction and current stabilization device with a large-angle diffusion section

Abstract

This invention discloses a noise reduction and flow stabilization device for a large-angle diffusion section, comprising: a small flange, a large-angle cone, a large flange, an aramid mesh, a conical sintered mesh plate, a Y-shaped support rib, a manhole, a positioning ring, a triaxial vibration sensor, and a pulsating pressure sensor. This invention reduces flow and aerodynamic noise in the large-angle diffusion section by controlling the angle difference between the large-angle cone and the 20-mesh to 200-mesh porous conical sintered mesh plate to below 15 degrees, achieving a noise reduction of approximately 20 dB. The invention's flow stabilization device features a reasonable and simple structure, strong load-bearing capacity, and high safety and reliability, making it suitable for applications with high noise reduction requirements.

Description

Technical Field

[0001] This invention is a filtration, rectification, and noise reduction device installed in pipelines for flowing gas or liquid, belonging to the field of experimental aerodynamics. Background Technology

[0002] The flow field quality requirements within pipes such as wind tunnels or water tunnels necessitate low noise, low turbulence, and flow deflection angles of less than 0.05°. In the future, designing pipe flows with turbulence as low as 0.05% and local airflow deflection angles of less than ±0.1° will be particularly important. The flow field after a pressure regulating valve is extremely turbulent and non-uniform; for example, in a subsonic or transonic wind tunnel, the aerodynamic noise after the pressure regulating valve reaches approximately 180 dB. For sub-span wind tunnels or to save axial pipe length, large-angle diffuser sections are often used after the pressure regulating valve. Large-angle diffuser sections result in flow separation and increased aerodynamic noise. Conventional noise reduction methods use "guide cone + multi-layer perforated plate", which reduces noise by about 10dB. These are often integrally welded to the outer cone. Because the cone is subjected to severe turbulent impact loads, cracks are prone to appear in the guide cone support. For large structures, the number of times the same location can be welded is limited. Cracked parts will accelerate failure. Welding cannot effectively solve the structural damage problem, leading to the scrapping of the entire large-angle diffuser section. It cannot be replaced quickly and does not meet the requirements for long-term use of the equipment. Summary of the Invention

[0003] The technical problem solved by this invention: This invention overcomes the shortcomings of existing technologies and provides a noise reduction and flow stabilization device for a large-angle diffusion section, applicable to sub-transverse and hypersonic wind tunnel pipelines. It utilizes a sintered mesh plate formed from multiple layers of sintered wire mesh ranging from 20 to 200 mesh, achieving a noise reduction of up to 20 dB at different Mach numbers. Simultaneously, the support structure is optimized for structural strength using Y-shaped supports. The noise reduction modules of the sintered mesh plate are detachable from the outer cone, and the sintered mesh plate is connected in sections, allowing for individual replacement of each sintered mesh plate section, thus saving costs.

[0004] The technical solution adopted in this invention is as follows:

[0005] A noise reduction and flow stabilization device for a large-angle diffusion section includes: a small flange, a large-angle cone, a large flange, an aramid mesh, a conical sintered mesh plate, a Y-shaped support rib, a positioning ring, a three-dimensional vibration sensor, and a pulsating pressure sensor.

[0006] The small and large ends of the large-angle cone are fixedly connected to the small flange and the large flange, respectively. The end with the small flange is in the air inlet direction, and the large-angle cone is the inlet of the large-angle diffuser section. The aramid mesh is set on the small flange. The conical sintered mesh plate is set inside the large-angle cone, and the large end of the conical sintered mesh plate is fixed on the large flange. The conical sintered mesh plate is supported and connected to the large-angle cone through Y-shaped support ribs. Multiple positioning rings are sleeved on the conical sintered mesh plate at certain intervals to prevent deformation of the conical sintered mesh plate. A certain number of triaxial vibration sensors are arranged behind the cone tip of the conical sintered mesh plate to monitor the vibration and dynamic load of the conical sintered mesh plate. Pulsating pressure sensors are arranged at the inlet and outlet of the large-angle diffuser section, and the pulsating pressure sensors are flush with the inner wall surface of their location to monitor the noise reduction performance of the sintered mesh plate.

[0007] Furthermore, the cone angle A of the large-angle cone is 30 to 90 degrees, the cone angle B of the conical sintered mesh plate is 45 to 90 degrees, B>A and BA≤15°, the airflow enters from the small end of the large-angle cone and exits from the large end, and the ratio of the outlet area to the inlet area is less than 12.

[0008] Furthermore, the tangential angle at the same cross-section of the large-angle cone and the inner cone of the cone-shaped sintered mesh plate is less than 7.5 degrees.

[0009] Furthermore, aramid mesh is made of 0-3000D yarns woven into a 0-200 mesh planar mesh. Due to the action of airflow, the aramid mesh will slightly deform to form a spherical surface, changing the airflow outlet angle. Aramid mesh is used to block upstream oil pollution and for initial noise reduction.

[0010] Furthermore, it also includes manholes, which are installed on the side wall of the large-angle cone cylinder, for checking the overall operating status of the cone-shaped sintered mesh plate structure and for repairing and maintaining the sensors in the large-angle diffusion section.

[0011] Furthermore, the conical sintered mesh plate is made of 20-200 mesh multi-layer porous stainless steel sintered together. It breaks up the large vortex of the incoming flow into smaller vortices, and the airflow becomes more uniform after passing through the conical sintered mesh plate, thus reducing noise. The thickness of the conical sintered mesh plate is 1 to 5 mm, and it is made by integral welding or segment splicing. When splicing in segments, the segment size is smaller than the size of the manhole, so as to ensure that it can be quickly replaced online by entering and exiting through the manhole.

[0012] Furthermore, both the small flange and the large flange are equipped with two seals for sealing the pipes at both ends: a low-temperature resistant silicone rubber VMQ sealing ring and a high-temperature resistant perfluoroether FFKM combined sealing ring, to achieve full-temperature range sealing from low temperature to high temperature. The sealing pressure is not less than the maximum pressure of the gas in the pipeline, and the rated temperature is greater than the maximum temperature of the gas in the pipeline.

[0013] Furthermore, the absolute value of the difference between the pulsating pressure sensors placed at the inlet and outlet of the outer conical surface of the large-angle diffusion section is the noise reduction amount. When the noise reduction amount is lower than 70% of the normal value, the conical sintered mesh plate is removed, and ultrasonic cleaning is used to clean it to restore the normal noise reduction level before reinstallation and use.

[0014] Furthermore, when the conical sintered mesh plate is used at the small end of the large-angle cone, the aramid mesh is located at the gas outlet end, the large end of the conical sintered mesh plate is connected to the small end of the large-angle cone, the cone angle B of the conical sintered mesh plate is 30 degrees to 90 degrees, the cone angle B of the conical sintered mesh plate is smaller than the cone angle A of the large-angle cone, and AB≤15 degrees; to avoid flow separation.

[0015] Furthermore, when multiple layers of conical sintered mesh are arranged, their axial spacing is greater than 0.4 times the large end diameter of the conical sintered mesh.

[0016] Advantages of this invention compared to other technologies:

[0017] 1. Compared with the conventional noise reduction method of large-angle diffusion section which uses "guide cone + multi-layer perforated plate" and welded to the outer cone surface to form an integral whole, this solution reduces the actual angle through which the airflow passes in the large-angle diffusion section by the difference BA between the cone angle A of the large-angle cone (2) and the cone angle B of the cone sintered mesh plate (5), thereby reducing the occurrence of flow separation.

[0018] 2. The noise reduction range achieved by using a conical sintered mesh plate is large, and the noise reduction amount can reach 20dB. The noise reduction bandwidth is wide, and it has a good noise reduction effect on the wide frequency range of 0-40000Hz. The conical sintered mesh plate (5) made of stainless steel with a multi-layer porous structure of 20-200 mesh breaks the large vortex of the incoming airflow into small vortices. The airflow becomes uniform after passing through the conical sintered mesh plate (5), and the noise reduction amount is more than 20dB. Because the pore size of the conical sintered mesh plate (5) is extremely small, it can filter out excessively large impurities and ensure the cleanliness of the downstream flow field medium.

[0019] 3. The conical sintered mesh plate (5) can be laser-processed with regularly arranged through holes or slots to ensure that its opening (the ratio of the open area to the total area) is appropriate. An excessively large opening may cause the flow velocity through the opening to be too high, forming a strong jet and noise, and may damage the flow straightening device in the stable section. The opening should be selected to ensure that the flow velocity through the opening is kept at Ma < 0.5. Attention should also be paid to the distribution of the openings to ensure that there is as uniform an airflow as possible in the entire diffuser section cross section.

[0020] 4. Absolute pulsating pressure sensors (10) are arranged on the inner wall surface at the inlet and outlet of the large-angle diffusion section to monitor the noise reduction performance of the sintered mesh plate. When the noise reduction is lower than 70% of the normal value, the metal mesh of the conical sintered mesh plate (5) is removed, and it is cleaned with ultrasonic cleaning technology and instruments to restore it to the normal noise reduction level before reinstallation. A certain number of triaxial vibration sensors (9) are arranged on the conical sintered mesh plate (5) to monitor the structural vibration.

[0021] 5. The conical sintered mesh plate (5) and the large-angle cone (2) are fixed by Y-shaped support ribs (6) to make the conical sintered mesh plate have impact resistance. On this basis, spring steel material can be selected for processing.

[0022] 6. The aramid mesh (4) at the entrance of the large-angle cone (2) is slightly deformed by the airflow to form a spherical surface, which changes the airflow outlet angle and makes the actual airflow injection angle smaller. Because the aramid mesh (4) is easy to fold, flame retardant, and has high specific strength, the aramid mesh composed of its warp and weft threads is also a microporous structure, which can achieve a certain degree of primary noise reduction. It can adsorb oil stains and has the function of filtering impurities. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the noise reduction and current stabilization device for the large-angle diffusion section.

[0024] Figure 2 A schematic diagram of the cross-section of the noise reduction and current stabilization device in the large-angle diffusion section;

[0025] Figure 3 Detailed view of a part of the Y-shaped support rib;

[0026] Figure 4 A simplified diagram illustrating the arrangement principle of the large-angle outer cone and the outlet cone-shaped sintered mesh plate;

[0027] Figure 5 Three-dimensional outline diagram of the layout of the large-angle outer cone cylinder and the outlet cone-shaped sintered mesh plate;

[0028] Figure 6 A simplified diagram illustrating the arrangement principle of the large-angle outer cone and the inlet cone-shaped sintered mesh plate. Detailed Implementation

[0029] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. However, these embodiments are not intended to limit the scope of the invention. Contents not described in detail in this specification are well-known to those skilled in the art.

[0030] like Figure 1 , 2As shown in Figures 3, 4, and 5, this invention proposes a noise reduction and flow stabilization device for a large-angle diffusion section, which mainly includes a small flange 1, a large-angle cone 2, a large flange 3, an aramid mesh 4, a conical sintered mesh plate 5, a Y-shaped support rib 6, a manhole 7, a positioning ring 8, a three-dimensional vibration sensor 9, and a pulsating pressure sensor 10.

[0031] The small and large ends of the large-angle cone 2 are fixedly connected to the small flange 1 and the large flange 3, respectively. The end where the small flange 1 is located is in the air intake direction, and the large-angle cone 2 is the inlet of the large-angle diffusion section. The aramid mesh 4 is set on the small flange 1. The conical sintered mesh plate 5 is set inside the large-angle cone 2. The large end of the conical sintered mesh plate 5 is fixed on the large flange 3, and the conical sintered mesh plate 5 is supported and connected to the large-angle cone 2 through the Y-shaped support rib 6. Multiple positioning rings 8 are sleeved on the conical sintered mesh plate 5 at a certain distance to prevent the conical sintered mesh plate 5 from deforming. A certain number of triaxial vibration sensors 9 are arranged behind the cone tip of the conical sintered mesh plate 5 to monitor the vibration and dynamic load of the conical sintered mesh plate. Pulsating pressure sensors 10 are arranged at the inlet and outlet of the large-angle diffusion section, and the pulsating pressure sensors 10 are flush with the inner wall surface at their location to monitor the noise reduction performance of the sintered mesh plate.

[0032] The conical sintered mesh plate 5 includes a conical surface and a connecting flange. The conical surface is a multi-layer porous sintered mesh plate, and the bottom of the conical surface is an annular connecting flange. This connecting flange is in close contact with the large end flange 3 through end face sealing.

[0033] Furthermore, it also includes a manhole 7, which is installed on the side wall of the large-angle cone 2, and is used to check the overall operating status of the cone sintered mesh plate structure and to repair and maintain the sensors in the large-angle diffusion section.

[0034] The difference BA between the cone angle A of the large-angle cone 2 and the cone angle B of the cone sintered mesh plate 5 reduces the actual angle through which the airflow passes in the large-angle diffuser section, thus reducing flow separation. The cone sintered mesh plate 5, made of stainless steel with a multi-layer porous structure of 20-200 mesh, breaks the large vortex of the incoming airflow into small vortices, making the airflow more uniform after passing through the cone sintered mesh plate 5, achieving a noise reduction of more than 20dB. The cone sintered mesh plate 5, due to its extremely small pore size, can filter out excessively large impurities, ensuring the cleanliness of the downstream flow medium. The cone sintered mesh plate (5) can be processed with regularly arranged through holes or through slots to make its opening (the ratio of the open area to the total area) appropriate. An excessively large opening may cause the flow velocity through the opening to be too high, forming a strong jet and noise, and may damage the flow straightening device in the stable section. The opening should be selected to ensure that the flow velocity through the opening is kept at Ma < 0.5. Attention should also be paid to the distribution of the openings to ensure that there is as uniform an airflow as possible in the entire diffuser section cross section.

[0035] The large-angle diffusion section includes a large-angle cone 2 and a channel section behind it. The large-angle cone 2 is the entrance of the large-angle diffusion section, and the exit is located on the channel section.

[0036] Absolute pulsating pressure sensors 10 are arranged on the inner wall surface at the inlet and outlet of the large-angle diffusion section. The specific location at the inlet is on the side wall of the large-angle cone at the axial middle position. This is used to monitor the noise reduction performance of the sintered mesh plate. When the noise reduction is lower than 70% of the normal value, the metal mesh is removed, and ultrasonic cleaning technology and instruments are used to clean it to restore the normal noise reduction level before reinstallation and use.

[0037] A certain number of triaxial vibration sensors 9 are arranged on the conical sintered mesh plate 5 to monitor the structural vibration.

[0038] Y-shaped support ribs 6 are used to fix the conical sintered mesh plate 5 and the large-angle cone 2, giving it impact resistance. Based on this, spring steel material can be selected for processing.

[0039] Example:

[0040] Small flange 1, large-angle cone 2, and large flange 3 are machined into a single unit. The cone angle A of the large-angle cone is 30 to 90 degrees. Fluid enters from small flange 1 and exits from large flange 3, with the ratio of outlet area to inlet area being <12. For ease of installation and storage, auxiliary structures such as lifting rings and auxiliary supports can be installed.

[0041] Both small flange 1 and large flange 3 have double seals for the pipes at both ends: a low-temperature resistant silicone rubber VMQ sealing ring and a high-temperature resistant perfluoroether FFKM combined sealing ring, achieving a full-temperature range seal from low to high temperatures. The sealing pressure is not less than the maximum pressure of the gas in the pipeline. The rated temperature is greater than the maximum temperature of the gas in the pipeline. The rated pressure of commonly used subsonic and transonic wind tunnels is 2.5 MPa.

[0042] Aramid mesh 4 is a 0-200 mesh planar mesh woven from 0-3000D yarns. It is fixed at the inlet of the large-angle cone 2. Due to the airflow, it undergoes slight deformation to form a spherical surface, changing the airflow outlet angle and making the actual airflow angle smaller. Because aramid mesh 4 is lightweight, flexible, easy to replace, flame-retardant, and has excellent heat resistance, its tensile strength is 7 times that of steel. The aramid mesh composed of warp and weft yarns also has a microporous structure, which can achieve a certain degree of primary noise reduction. It can absorb oil stains and has the function of filtering impurities. For applications with less stringent requirements, it can be replaced by porous meshes such as carbon fiber mesh or metal mesh.

[0043] The conical sintered mesh plate 5 has a cone angle B ranging from 30 to 90 degrees, which is greater than the cone angle A of the large-angle cone, and BA ≤ 15 degrees. It is made of 20-200 mesh multi-layer porous stainless steel, which breaks down large vortices in the incoming airflow into smaller vortices, resulting in more uniform airflow and noise reduction of over 20 dB. Due to its extremely small pore size, the conical sintered mesh plate 5 can filter out excessively large impurities, ensuring the cleanliness of the downstream flow medium. The conical sintered mesh plate 5 can be machined with regularly arranged through holes or slots to ensure an appropriate opening (ratio of open area to total area). An excessively large opening may result in excessively high flow velocities through the openings, creating strong jets and noise, and potentially damaging the flow straightening device in the stable section. The opening selection should ensure that the flow velocity through the orifice remains Ma < 0.5. Attention should also be paid to the orifice distribution to ensure the most uniform airflow possible across the entire diffuser section cross-section.

[0044] Y-shaped support ribs 6 are used to fix the conical sintered mesh plate 5 and the large-angle cone 2, giving it impact resistance. Based on this, spring steel material can be selected for processing.

[0045] Manhole 7 is used for manual inspection of the overall operating status of the sintered mesh plate structure and for maintenance of the sensors in the large-angle diffusion section; the segmented sintered mesh plates can be installed by entering and exiting through the manhole.

[0046] Positioning ring 8 is used to fix the conical sintered mesh plate 5;

[0047] A certain number of triaxial vibration sensors 9 are arranged at the pointed tip of the conical sintered mesh plate 5 to monitor the structural vibration. They can be fixed using magnetic attraction or conventional threaded connection.

[0048] Two pulsating pressure sensors 10 are arranged at two points to monitor the noise reduction performance of the sintered mesh in real time. When the noise reduction is lower than 70% of the normal value, the metal mesh is removed, and ultrasonic cleaning technology and instruments are used to clean it to restore the normal noise reduction level before it is reinstalled and used.

[0049] Preferably, two pulse pressure sensors 10 are arranged at each placement point of the pulse pressure sensor 10, whether it is the placement point at the front end located on the side wall of the large-angle cone or the placement point at the outlet of the diffuser section at the rear, to provide redundancy. If both are effective, the average value is taken to improve accuracy. The distance between the two pulse pressure sensors 10 is a preset value L3. Figure 4 and Figure 6 As shown.

[0050] The conical sintered mesh plate and the large-angle cone are not limited to the shape of a cone. They can also be used for circular inlets and outlets; circular inlets and polygonal outlets; polygonal inlets and circular outlets; polygonal inlets and polygonal outlets, etc. When the generatrix of the profile is a continuous curved surface, the tangential angle of the same cross section of the large-angle cone and the cone inside the sintered mesh plate must be less than 7.5 degrees. It is also necessary to ensure that the profiles of the conical sintered mesh plate and the large-angle cone are consistent, and the ratio of the outlet area to the outlet area is <12.

[0051] like Figure 6 Another solution is proposed. When the conical sintered mesh plate 5 is used on one side of the small flange 1 of the large-angle cone 2, the aramid mesh is located at the gas outlet end, the large end of the conical sintered mesh plate is connected to the small flange 1 of the large-angle cone 2, the cone angle B of the conical sintered mesh plate is 30 degrees to 90 degrees, the cone angle B of the conical sintered mesh plate is smaller than the cone angle A of the large-angle cone, and AB≤15 degrees; to avoid flow separation.

[0052] When five or more conical sintered mesh plates are arranged, their axial spacing should be greater than 0.4 times the diameter of the large end of the conical sintered mesh plate. The optimal distance is to ensure that the airflow velocity at the outlet cross section is uniform.

[0053] The contents not described in detail in this specification are common knowledge to those skilled in the art.

Claims

1. A large-angle diffuser section noise reduction flow straightener, characterized in that It comprises: Small flange (1), large angle cone cylinder (2), large flange (3), aramid net (4), conical sintered mesh plate (5), Y type support rib (6), positioning ring (8), three direction vibration sensor (9) and pulsating pressure sensor (10); The small end and the large end of the large angle cone cylinder (2) are fixedly connected with the small flange (1) and the large flange (3) respectively, one end where the small flange (1) is located is the air inlet direction, and the large angle cone cylinder (2) is the entrance of the large angle diffusion section; The aramid net (4) is arranged on the small flange (1); The conical sintered mesh plate (5) is arranged in the large angle cone cylinder (2), the large end of the conical sintered mesh plate (5) is fixed on the large flange (3), and the conical sintered mesh plate (5) is supported and connected with the large angle cone cylinder (2) through the Y type support rib (6); A plurality of positioning rings (8) are sleeved on the conical sintered mesh plate (5) at intervals for preventing the conical sintered mesh plate (5) from deforming; A certain number of three direction vibration sensors (9) are arranged behind the sharp cone of the conical sintered mesh plate (5) for monitoring the vibration and dynamic load of the conical sintered mesh plate; The pulsating pressure sensor (10) is arranged at the entrance and the exit of the large angle diffusion section, and the pulsating pressure sensor (10) is flush with the inner wall surface of the position, for monitoring the noise reduction performance of the sintered mesh plate; The cone angle A of the large angle cone cylinder is 30 degrees to 90 degrees, the cone angle B of the conical sintered mesh plate is 45 degrees to 90 degrees, B>A and B-A≤15°, the airflow enters from the small end of the large angle cone cylinder and exits from the large end, and the ratio of the outlet area to the inlet area is less than 12; The tangential angle of the large angle cone cylinder and the inner cone of the conical sintered mesh plate at the same cross section is less than 7.5 degrees.

2. A device for reducing noise and stabilizing flow in a large-angle diffuser section according to claim 1, characterized in that: The aramid net (4) is formed by weaving 0-3000D silk into 0-200 mesh plane net, the aramid net (4) will be slightly deformed to form a spherical surface under the action of airflow, change the outlet angle of airflow, and the aramid net (4) is used for blocking oil stains and primary noise reduction.

3. A device for reducing noise and stabilizing flow in a large-angle diffuser section according to claim 1, characterized in that: It also includes a manhole (7) arranged on the side wall of the large angle cone cylinder (2) for checking the overall operation state of the conical sintered mesh plate structure and maintaining the sensor in the large angle diffusion section.

4. A device for reducing noise and stabilizing flow in a large-angle diffuser section according to claim 3, characterized in that: The material of the conical sintered mesh plate is 20-200 mesh multi-layer porous structure of metal stainless steel wire mesh sintered, which breaks the large vortex into small vortex, and the airflow is uniform after passing through the conical sintered mesh plate (5), realizing noise reduction; The thickness of the conical sintered mesh plate is 1 to 5 mm, which is welded integrally or segmented spliced; When segmented splicing, the segmented size is smaller than the size of the manhole, so that it can be replaced online quickly.

5. A flow straightener for use in a large angle diffuser section according to claim 1, characterized in that: The small flange (1) and the large flange (3) are sealed with two seals at both ends of the pipeline, which are low-temperature silicon rubber VMQ sealing ring and high-temperature perfluoroether FFKM combined sealing ring, realizing full temperature range sealing from low temperature to high temperature, the sealing pressure is not less than the maximum pressure of the pipeline gas, and the rated temperature is greater than the maximum temperature of the pipeline gas.

6. A flow straightener for use in a large angle diffuser section according to claim 4, characterized in that: The absolute value of the difference between the pulsating pressure sensors arranged at the inlet and outlet of the outer conical surface of the large-angle diffusion section is the noise reduction amount. When the noise reduction amount is lower than 70% of the normal value, the conical sintered mesh plate is removed, cleaned by ultrasonic cleaning, and reinstalled for use to restore the normal noise reduction level.

7. A flow straightener for use in a large angle diffuser section according to claim 1, characterized in that: When the conical sintered mesh plate is used at the small end of the large-angle conical cylinder, the aramid mesh is located at the air outlet end, the large end of the conical sintered mesh plate is connected to the small end of the large-angle conical cylinder, the conical angle B of the conical sintered mesh plate is 30 to 90 degrees, the conical angle B of the conical sintered mesh plate is smaller than the conical angle A of the large-angle conical cylinder, and A-B≤15 degrees; flow separation is avoided.

8. A flow straightener for use in a large angle diffuser section according to claim 1, characterized in that: When the conical sintered mesh plate is arranged in multiple layers, the axial spacing is greater than 0.4 times the diameter of the large end of the conical sintered mesh plate.

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