A wind channel, exhaust cabinet and vortex effect elimination method for eliminating vortex effect

Abstract

The application provides a kind of wind channel, exhaust cabinet and vortex effect elimination method for eliminating vortex effect, which can eliminate vortex on both sides of exhaust cabinet.Wind channel includes wind channel column, which contains column body and wind channel body, airflow channel is arranged inside wind channel body, and flow guide extension wall is arranged;Flow guide block is embedded in the joint gap of column inner wall and wind channel body, and first flow guide wing and second flow guide wing are arranged on it in ladder distribution;Airflow speed sensor is arranged in both channels of exhaust cabinet, and real-time airflow speed of both channels is collected by cooperating with central control device, and the cross-sectional area of channel is closed-loop controlled according to the ratio of airflow speed of both channels, so that the ratio of airflow speed is maintained in target interval.The application precisely suppresses vortex generation in two vortex zones on both sides of operation opening of exhaust cabinet by two-stage layered auxiliary airflow, stabilizes cabinet opening airflow field, improves uniformity of cabinet opening airflow speed, reduces risk of harmful gas overflow, and improves pollution isolation and protection performance of exhaust cabinet.

Description

Technical Field

[0001] This invention relates to the field of laboratory ventilation equipment technology, and in particular to an air duct, fume hood, and method for eliminating eddy current effects. Background Technology

[0002] When conducting experiments such as organic synthesis and reagent preparation in a chemical laboratory, volatile toxic and corrosive harmful gases are continuously released. If these harmful gases escape from the fume hood's operating vents, they will directly damage the respiratory system of laboratory personnel and pollute the overall laboratory environment. As a core pollutant isolation device in the laboratory, the fume hood relies on its internal air ducts to create a directional negative pressure airflow, centrally extracting and treating the waste gases generated during experiments.

[0003] Therefore, laboratories are often equipped with fume hoods as important contaminant control devices to perform hazardous chemical experiments within the fume hood's operating chamber. Existing conventional fume hoods have a significant airflow defect: when the cabinet door is raised and opened, two localized vortex stagnation zones easily form at the junction of the inner walls of the experimental operating ports on both sides of the cabinet and the side air ducts. These vortex areas create low-pressure eddies, continuously accumulating harmful gases on the side walls of the operating ports, significantly increasing the risk of contaminants escaping. Simultaneously, the vortices disrupt the main airflow field within the cabinet, reducing the uniformity of the fume hood's airflow. Summary of the Invention

[0004] This invention proposes an air duct, a fume hood, and a method for eliminating eddy current effects, in order to solve the technical problem that traditional fume hoods have difficulty in stabilizing the airflow on both sides of the cabinet when the cabinet door is open.

[0005] To solve the above problems, the technical solution adopted by the present invention is as follows: This invention provides an air duct for eliminating eddy current effects, comprising: Air duct support column, the air duct support column includes: The column body has an outer wall and an inner wall on its two sides. The inner surface of the inner wall facing away from the outer wall serves as an inner wall guide surface. The outer wall and the inner wall are connected to a duct body. The duct body has an airflow channel inside. A guide extension wall is provided at the connection between the duct body and the inner wall of the column. A flow guide block is embedded in the connection between the inner wall of the column and the main body of the air duct. The flow guide block includes: a first flow guide wing and a second flow guide wing distributed in a stepped manner. The second flow guide wing is connected between the end of the flow guide extension wall and the outer surface of the main body of the air duct. Multiple second branches are distributed at intervals between the second flow guide wing and the flow guide extension wall. One end of each second branch is connected to an airflow channel, and the other end of each second branch extends to the inner wall flow guide surface. The first flow guide wing is connected between the side of the second flow guide wing opposite to the flow guide extension wall and the outer surface of the main body of the air duct. Multiple first branches connected to airflow channels are distributed at intervals between the first flow guide wing and the second flow guide wing. The first adjustment mechanism is disposed inside the first guide vane and is used to adjust the flow cross-sectional area of ​​the first branch channel; The second adjustment mechanism is located inside the second guide vane and is used to adjust the flow cross-sectional area of ​​the second branch.

[0006] Preferably, the axial direction of the air duct column is the first direction Z, the inner wall of the column is a straight wall extending along the first direction Z, and the connection between the inner wall of the column and the air duct body is provided with a hollow notch extending along the first direction Z and matching the shape of the guide block; the guide extension wall extends along the first direction Z and is bent from the air duct body toward the outer wall of the column.

[0007] Preferably, the air duct body includes: a first air duct wall, connected between the corresponding ends of the outer wall and the inner wall of the column, wherein the connection between the first air duct wall and the inner wall of the column is provided with an air outlet extending along the first direction Z and facing the hollowed-out notch; a second air duct wall, connected to the connection between the outer wall of the column and the first air duct wall, and bent close to the inner wall of the column, wherein the outer surface of the second air duct wall serves as a first guide surface; and a third air duct wall, connected to the end of the second air duct wall, wherein the third air duct wall bends close to the inner wall of the column and is connected to the end of the inner wall of the column, wherein the outer surface of the third air duct wall serves as a second guide surface connected to the first guide surface. The flow guide extension wall is connected to the side of the first air duct wall away from the inner wall of the column at the air outlet opening; The hollowed-out notch is provided at the junction of the inner wall of the column and the third air duct wall. The guide block is embedded in and sealed at the hollowed-out notch. The first branch and the second branch are respectively connected to the air outlet notch. The first guide wing is sealed at the end of the hollowed-out notch facing the third air duct wall. The side of the first guide wing facing away from the second guide wing forms a third guide surface connected to the second guide surface. The second guide wing is sealed at the end of the guide extension wall. The side of the second guide wing facing away from the guide extension wall forms a fourth guide surface connected to the inner wall guide surface.

[0008] Preferably, the corresponding inner surfaces of the first air duct wall, the second air duct wall, and the third air duct wall are concentric arc surfaces, and the corresponding inner surfaces of the first air duct wall, the second air duct wall, and the third air duct wall form a cylindrical inner surface of the air duct body facing the airflow channel. The first guide surface is an arc surface concentric with the inner surface of the second air duct wall, and the second guide surface is an arc surface with a radius larger than that of the first guide surface.

[0009] Preferably, the fourth guiding surface includes a flat planar guiding area connected to the third guiding surface and a curved arc-shaped guiding area connected to the planar guiding area and connected to the inner wall guiding surface; The first branch includes a first transition cavity connected to the air outlet notch, and a first variable volume air passage connected to the first transition cavity. The first variable volume air passage passes through the end of the first guide vane away from the main body of the air passage. The second branch includes a second transition cavity connected to the air outlet notch, and a second variable volume air passage connected to the second transition cavity. The second variable volume air passage passes through the end of the second guide vane away from the main body of the air passage. The surface of the first guide vane facing the second guide vane serves as the first mating surface. Multiple first guide grooves are evenly spaced along the first direction Z. The bottom surface of the first guide groove is a plane parallel to the planar guide area. The first mating surface abuts against the planar flow guide area, and the planar flow guide area and the first guide groove form the first variable volume air passage.

[0010] Furthermore, the airflow guiding extension wall includes: an inclined extension section connected to the side of the first air duct wall away from the inner wall of the column corresponding to the air outlet notch; and a parallel extension section connected to the end of the inclined extension section and extending parallel to the inner wall airflow guiding surface. The second guide vane forms an inclined guide surface and a straight guide surface that are interconnected and respectively match the inclined extension section and the parallel extension section on the side facing the guide extension wall. The inclined guide surface is provided with a plurality of inclined guide grooves evenly spaced in the first direction Z. The bottom surface of the inclined guide groove is an arc surface that is concave relative to the inclined guide surface. The straight guide surface is provided with a plurality of second guide grooves that are connected to the inclined guide grooves evenly spaced in the first direction Z. The bottom surface of the second guide groove is a plane parallel to the parallel extension section. The inclined extension section and the inclined guide grooves form the second transition cavity. The side of the second guide vane facing away from the straight guide surface forms a frustum. The outer surface of the frustum is the arc surface guide area that connects the planar guide area and the inner wall guide surface. The guide block further includes: a mounting protrusion, which is mated to the straight guide surface and abuts against the parallel extension section, wherein the mounting protrusion and the second guide groove form the second variable volume air passage.

[0011] Preferably, the radial dimension of the first transition cavity is greater than the radial dimension of the first variable volume air passage, the radial dimension of the second transition cavity is greater than the radial dimension of the second variable volume air passage, the flow cross-sectional area of ​​the second variable volume air passage is greater than the flow cross-sectional area of ​​the first variable volume air passage, and the flow cross-sectional area of ​​the second transition cavity is greater than the flow cross-sectional area of ​​the first transition cavity. The bottom surface of the first guide channel is a first movable plate that can extend or retract towards or away from the planar guide area and is parallel to the planar guide area. The first adjustment mechanism is used to drive the first movable plate to extend or retract. The bottom surface of the second guide groove is a second movable plate that can extend or retract towards or away from the mounting protrusion and is parallel to the flat guide surface. The second adjustment mechanism is used to drive the second movable plate to extend or retract.

[0012] The present invention also provides a fume hood, which includes a cabinet body. The interior of the cabinet body forms an operating room. An experimental platform is provided at the bottom of the operating room. An experimental operating port that opens the operating room is provided on one side of the cabinet body. A lifting drive device is provided at the top of the cabinet body. The lifting drive device is used to drive the safety cabinet door to rise and fall at the experimental operating port to open and close the experimental operating port. A pair of air ducts for eliminating eddy current effects are provided on both sides of the experimental operating port. The bottom end of the air duct column is installed on the experimental platform, and the top end of the air duct column extends to the top of the cabinet body. The inner wall of the column faces the operating room. The exhaust fan also includes: The first wind speed sensor is located in the first branch channel; The second wind speed sensor is located in the second branch. The central control device is electrically connected to the first wind speed sensor, the second wind speed sensor, the first adjustment mechanism, and the second adjustment mechanism, respectively.

[0013] Furthermore, the top of the air duct body is provided with an air duct inlet, the guide block is spaced apart from the air duct inlet, and the airflow channel forms a static pressure chamber in the part between the air duct inlet and the guide block. The air duct also includes: A variable diameter adjusting component is provided in the airflow channel, extending along the airflow channel. The variable diameter adjusting component has an adjusting slope on the side facing the guide block. The distance between the adjusting slope and the guide block gradually decreases in the direction away from the air inlet of the air duct along the airflow channel. Several connecting pieces are connected between the adjusting inclined surface and the guide block; The exhaust fan also includes: A pair of pressure chambers are respectively located above a pair of air duct bodies, and the interior of each pressure chamber is provided with a transition flow channel connecting to the air inlet of the corresponding air duct. An air supply device is located at the top of the cabinet; A pair of rigid pipes are respectively connected between the gas supply device and a pair of transition channels, for conducting the airflow supplied by the gas supply device into the transition channels; A pair of regulating valves are respectively installed on a pair of rigid pipes to regulate the airflow speed in the corresponding rigid pipes.

[0014] The present invention also provides a method for eliminating eddy current effect, which utilizes the above-mentioned exhaust fan. The method for eliminating eddy current effect includes the following steps: S1: Simultaneously obtain the real-time wind speed W in the first branch and the real-time wind speed V in the second branch; S2: Calculate the ratio Z of real-time wind speed V to real-time wind speed W; S3: Determine if 0.667≤Z≤0.833; S4: If yes, return to S1; if no, adjust the flow cross-sectional area of ​​the first branch and / or the second branch, and return to S1.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The air duct, fume hood, and eddy effect elimination method provided by this invention enable stable control of the exhaust airflow on both sides of the fume hood when the safety cabinet door is open. This avoids eddy effects at the experimental operation ports on the inner walls of the operating room on both sides of the fume hood, reducing the risk of harmful gases escaping from both sides of the cabinet. The stepped first and second guide vanes can independently adjust the flow cross-sectional area of ​​the first and second branches to control the real-time wind speeds within the first and second branches to achieve a preset ratio, ensuring the simultaneous elimination of eddy effects in the first and second eddy zones at the junction of the first guide vane, the second guide vane, and the inner wall of the column. Attached Figure Description

[0016] To more clearly illustrate the technical solution proposed by this invention, the invention will be described in detail below with reference to embodiments and accompanying drawings. It should be understood that the embodiments and drawings described in the following detailed description and specification are merely some embodiments of this invention, and those skilled in the art can make changes to these drawings within the framework of this invention.

[0017] Figure 1 This is a three-dimensional structural schematic diagram of an embodiment of the air duct of the present invention, with partial guide blocks omitted. Figure 2 for Figure 1 A partially enlarged structural diagram of area A of the air duct column; Figure 3 A three-dimensional structural diagram of the guide block in an embodiment of the air duct of the present invention. Figure 1 ; Figure 4A three-dimensional structural diagram of the guide block in an embodiment of the air duct of the present invention. Figure 2 ; Figure 5 This is a schematic diagram of the main structure of the guide block in an embodiment of the air duct of the present invention; Figure 6 This is a cross-sectional view of the guide block in an embodiment of the air duct of the present invention. Figure 7 A schematic diagram of the three-dimensional assembly structure of the duct column and guide block in an embodiment of the present invention. Figure 1 ; Figure 8 A schematic diagram of the three-dimensional assembly structure of the duct column and guide block in an embodiment of the present invention. Figure 2 ; Figure 9 This is a schematic cross-sectional view of the assembly structure of the duct column and guide block in an embodiment of the duct of the present invention. Figure 10 for Figure 9 A partially enlarged structural diagram of region B of the air duct; Figure 11 This is a schematic diagram of the assembled three-dimensional structure of an embodiment of the exhaust fan of the present invention; Figure 12 This is a partial structural diagram of the pressure chamber and rigid piping of the fume hood; Figure 13 This is a three-dimensional structural diagram of the variable diameter adjustment component in an embodiment of the fume hood of the present invention.

[0018] The main markings in the attached figures are as follows: 1. Main body of the column; 11. Outer wall of the column; 12. Inner wall of the column; 121. Inner wall guide surface; 122. Hollowed-out notch; 13. Main body of the air duct; 131. First air duct wall; 1311. Air outlet notch; 132. Second air duct wall; 1321. First guide surface; 133. Third air duct wall; 1331. Second guide surface; 1332. First slot; 13321. Concave arc surface; 13322. Protruding corner surface; 134. Airflow channel; 135. Air inlet of the air duct; 14. Guide extension wall; 141. Inclined extension section; 142. Parallel extension section; 2. Guide block; 21. First guide vane; 211. First branch; 2111. First transition cavity; 2112. First variable volume air passage; 212. Third guide surface; 213. First mating surface; 2131. First guide groove; 214. First protrusion; 2141. Protruding arc surface; 2142. Concave corner surface; 22. Second guide vane; 221. Second branch; 2211. Second transition cavity; 2212. Second variable volume air passage; 222. Fourth guide surface; 2221. Planar guide area; 2222. Arc guide area; 223. Inclined guide surface; 2231. Inclined guide groove; 224. Straight guide surface ; 2241, Second guide groove; 225, Frustum; 23, Mounting protrusion; 231, Second protrusion; 3, Second slot; 4, Variable diameter adjustment component; 41, Adjustment component base; 42, Variable diameter extension; 421, Adjustment slope; 6, Connector; 5, Fume hood; 51, Cabinet body; 511, Operating room; 512, Experimental operating port; 52, Experimental platform; 53, Lifting drive device; 54, Safety cabinet door; 55, Pressure chamber; 551, Transition flow channel; 5511, First transition surface; 5512, Second transition surface; 56, Air supply device; 57, T-joint; 58, Rigid pipe; 59, Regulating valve.

[0019] Other markings in the diagram are as follows: C, First vortex region; D, Second vortex region; X, Second direction; Y, Third direction; Z, First direction. Detailed Implementation

[0020] To make the technical problem to be solved, the technical solution and the beneficial effects of the present invention clearer, the following description is provided in conjunction with the appendix. Figure 1-13 The present invention will be further described in detail below with reference to the embodiments.

[0021] Please refer to the following: Figure 1-10 The air duct for eliminating eddy current effect provided by the present invention includes: The duct support column has its axis in the first direction Z (vertical direction), its width in the second direction X, and its thickness in the third direction Y, with all three directions perpendicular to each other. The duct support column includes a support body 1, a duct body 13, and a flow-guiding extension wall 14.

[0022] The column body 1 has an outer wall 11 and an inner wall 12 on both sides in the width direction. The inner surface of the inner wall 12 facing away from the outer wall 11 serves as the inner wall guide surface 121, which is a straight wall surface extending along the first direction Z. A hollow notch 122 extending along the first direction Z is provided at the connection between the inner wall 12 and the air duct body 13 for embedding and installing the guide block 2.

[0023] The main body of the air duct 13 is connected to the same side of the outer wall 11 and the inner wall 12 of the column. The air duct main body 13 has an airflow channel 134 extending along the first direction Z inside. In this embodiment, the air duct main body 13 is formed by the first air duct wall 131, the second air duct wall 132 and the third air duct wall 133 connected end to end. The inner surfaces of the three are concentric arc surfaces, which together form a cylindrical airflow channel 134. It should be noted that the first air duct wall 131 connects the outer wall 11 and the inner wall 12 of the column, and an air outlet notch 1311 is opened at the junction of the first air duct wall 131 and the inner wall 12 of the column. It extends along the first direction Z and is directly opposite the hollow notch 122, connecting the airflow channel 134 with the outside. The second air duct wall 132 is connected at the junction of the outer wall 11 and the first air duct wall 131. It extends backward along the second direction X and bends towards the inner wall 12 of the column along the third direction Y. Its outer surface is the first guide surface 1321, which is concentric with the inner surface of the second air duct wall 132. The third air duct wall 133 is connected to the rear end of the second air duct wall 132. It bends towards the inner wall 12 of the column along the second direction X and the third direction Y, and is connected to the rear end of the inner wall 12 of the column. Its outer surface is the second guide surface 1331, which has a larger radius than the first guide surface 1321 and is smoothly connected to the first guide surface 1321.

[0024] The airflow extension wall 14 is connected to the side of the first air duct wall 131 corresponding to the air outlet 1311, away from the inner wall 12 of the column, extends along the first direction Z, and bends toward the outer wall 11 of the column.

[0025] The flow guide block 2 is a long strip-shaped structure extending along the first direction Z, which is embedded and sealed at the hollow notch 122. The whole includes the first flow guide wing 21, the second flow guide wing 22 and the mounting protrusion 23, which are integrally formed and distributed in a stepped manner.

[0026] The second guide wing 22 is connected between the end of the guide extension wall 14 and the outer surface of the air duct body 13. Multiple second branches 221 are distributed between the second guide wing 22 and the guide extension wall 14 along the height direction of the air duct column. One end of each second branch 221 is connected to the airflow channel 134, and the other end of each second branch 221 extends to the inner wall guide surface 121. The first guide wing 21 is connected between the side of the second guide wing 22 away from the guide extension wall 14 and the outer surface of the air duct body 13. Multiple first branches 211 are evenly distributed between the first guide wing 21 and the second guide wing 22 along the height direction of the air duct column, and each first branch 211 is connected to the airflow channel 134. Please refer to the following: Figure 1-27-8. In one embodiment of the duct for eliminating eddy current effect provided by the present invention, the axial direction of the duct column (i.e., the height direction of the duct column, which is also the length direction of the duct column) is the first direction Z. The inner wall 12 of the column is a straight wall extending along the first direction Z. The connection between the inner wall 12 of the column and the duct body 13 is provided with a hollow notch 122 extending along the first direction Z and matching the shape of the guide block 2. The hollow notch 122 serves as the mounting slot for the guide block 2. The guide extension wall 14 extends along the first direction Z and is bent from the duct body 13 toward the outer wall 11 of the column.

[0027] Please refer to the following: Figure 1-10 In a preferred embodiment of the ductwork for eliminating eddy current effects provided by the present invention, the cross-section of the duct body 13 is approximately rectangular, the first direction Z is vertical, the width direction of the duct column is a second direction X (i.e., the width direction) perpendicular to the first direction Z, and the thickness direction of the duct column is a third direction Y (i.e., the thickness direction) perpendicular to both the first direction Z and the second direction X. The duct body 13 is connected to the outer wall 11 and the inner wall 12 of the column on the same side in the second direction X. The outer wall 11 and the inner wall 12 of the column are connected to the other side in the second direction X by a frame structure. A hollow structure is formed between the outer wall 11, the inner wall 12 of the column and the frame structure, such as... Figure 1-2 As shown in Figures 7-10.

[0028] The main body of the air duct 13 includes: The first air duct wall 131 is connected between the corresponding ends of the outer wall 11 and the inner wall 12 of the column. At the junction of the first air duct wall 131 and the inner wall 12, there is an air outlet 1311 extending along the first direction Z and directly opposite the hollowed-out notch 122, so that the hollowed-out notch 122 can connect to the airflow channel 134 through the air outlet 1311. The second air duct wall 132 is connected at the junction of the outer wall 11 and the first air duct wall 131, and extends away from the first air duct along the second direction X. As the second air duct wall 132 extends, it bends towards the inner wall 12 of the column along the third direction Y. The outer surface of the second air duct wall 132 serves as the first guide surface 1321. The third air duct wall 133 is connected to the end of the second air duct wall 132. The third air duct wall 133 bends towards the inner wall 12 of the column along both the second direction X and the third direction Y and is connected to the end of the inner wall 12 of the column. The outer surface of the third air duct wall 133 serves as the second guide surface 1331 connected to the first guide surface 1321. Figure 1-2 As shown in Figures 7-10.

[0029] The guide extension wall 14 is connected to the side of the first air duct wall 131 away from the inner wall 12 of the column at the corresponding air outlet notch 1311, such as... Figure 1-2 As shown in Figures 7-10.

[0030] The connection between the inner wall 12 of the column and the third air duct wall 133 is provided with the aforementioned hollowed-out notch 122. That is, one end of the hollowed-out notch 122 in the second direction X is located at the end of the third air duct wall 133 in the second direction X, and the other end of the hollowed-out notch 122 in the second direction X is located at the inner wall 12 of the column. The guide block 2 is a long strip extending along the first direction Z and matching the hollowed-out notch 122. The guide block 2 is embedded in and seals the hollowed-out notch 122. The first branch 211 and the second branch 221 are respectively connected to the air outlet notch 1311, as shown below. Figure 1-2 As shown in Figures 7-10.

[0031] The first guide vane 21 is sealed at the end of the perforated notch 122 facing the third air duct wall 133. The side of the first guide vane 21 facing away from the second guide vane 22 forms a third guide surface 212 connected to the second guide surface 1331. The second guide vane 22 is sealed at the end of the guide extension wall 14 away from the first air duct wall 131. The side of the second guide vane 22 facing away from the guide extension wall 14 forms a fourth guide surface 222 connected to the inner wall guide surface 121. Figure 7-10 As shown.

[0032] Please refer to the following: Figure 1-2 8-10. In a preferred embodiment of the air duct for eliminating eddy current effect provided by the present invention, the corresponding inner surfaces of the first air duct wall 131, the second air duct wall 132 and the third air duct wall 133 are concentric arc surfaces, and the corresponding inner surfaces of the first air duct wall 131, the second air duct wall 132 and the third air duct wall 133 are connected end to end to form the cylindrical inner surface of the air duct body 13 facing the airflow channel 134.

[0033] The first guide surface 1321 is an arc surface concentric with the inner surface of the second air duct wall 132, and the second guide surface 1331 is an arc surface with a radius larger than that of the first guide surface 1321, such as... Figure 9-10 As shown.

[0034] Specifically, the ductwork for eliminating eddy current effects provided by this invention is used in the fume hood 5 as a supporting column on both sides of the experimental operation port 512 of the internal operating chamber 511 of the fume hood 5. The outer wall 11 of the column and the first guide surface 1321 are both located on the side of the fume hood 5 away from the experimental operation port 512, while the inner wall 12 of the column and the second guide surface 1331 are both located on the side of the fume hood 5 closer to the experimental operation port 512. The outer wall 11 of the column is smoothly connected to the first guide surface 1321, and the inner wall 12 of the column is smoothly connected to the second guide surface 1331. The outer wall 11, the first guide surface 1321, the second guide surface 1331, and the inner wall 12 of the column together constitute the outer surface structure of the ductwork column. Figure 1-2 As shown in Figures 8-10.

[0035] The first guide surface 1321 is an arc surface concentric with the inner surface of the second air duct wall 132, meaning the first guide surface 1321 and the airflow channel 134 form a concentric circle structure. The second guide surface 1331 is an arc surface with a radius larger than the first guide surface 1321, resulting in a thicker wall between the second guide surface 1331 and the airflow channel 134. This increased wall thickness improves the structural strength and support of the air duct column. Furthermore, since the guide block 2 needs to be installed on one side of the second guide surface 1331, the increased wall thickness provides sufficient installation strength for the guide block 2, preventing damage to the air duct column during installation. It also reduces the curvature of the second guide surface 1331, improving its ability to capture airflow on both sides of the experimental operating port 512, eliminating vortices generated inside the air duct column, and preventing harmful gases from escaping. Figure 9-10 As shown.

[0036] Please refer to the following: Figure 3-6 9-10. In a preferred embodiment of the air duct for eliminating eddy current effect provided by the present invention, the fourth guide surface 222 includes a planar guide area 2221 that is connected to the third guide surface 212 and is straight (parallel to the first direction Z and the second direction X, i.e., in a vertical posture), and an arc-shaped guide area 2222 that is connected to the planar guide area 2221 and connected to the inner wall guide surface 121 and is curved.

[0037] The first branch duct 211 includes a first transition cavity 2111 connected to the air outlet 1311, and a first variable-volume air duct 2112 connected to the first transition cavity 2111. The first variable-volume air duct 2112 penetrates the end of the first guide vane 21 away from the main body of the air duct 13, and the air outlet of the first variable-volume air duct 2112 is connected to the fourth guide surface 222. Figure 3-6 As shown in Figures 9-10.

[0038] The second branch duct 221 includes a second transition cavity 2211 connected to the air outlet 1311, and a second variable-volume air duct 2212 connected to the second transition cavity 2211. The second variable-volume air duct 2212 penetrates the end of the second guide vane 22 away from the main body of the air duct 13, and the air outlet of the second variable-volume air duct 2212 is connected to the inner wall guide surface 121. Figure 3-6 As shown in Figures 9-10.

[0039] The surface of the first guide vane 21 facing the second guide vane 22 serves as the first mating surface 213. Multiple first guide grooves 2131 are evenly spaced along the first direction Z. The bottom surface of each first guide groove 2131 is a plane parallel to the planar guide region 2221. Figure 3-6 As shown in Figures 9-10.

[0040] The first mating surface 213 abuts against the planar guide region 2221, and the planar guide region 2221 and the first guide groove 2131 form the first variable volume air passage 2112, such as Figure 9-10 As shown.

[0041] Please refer to the following: Figure 1-2 9-10, In a preferred embodiment of the air duct for eliminating eddy current effect provided by the present invention, the flow guiding extension wall 14 includes: An inclined extension section 141 is connected to the side of the first air duct wall 131 away from the inner wall 12 of the column at the air outlet 1311 corresponding to the air outlet 1311; a parallel extension section 142 is connected to the end of the inclined extension section 141 away from the first air duct wall 131 and extends parallel to the inner wall guide surface 121.

[0042] The second guide vane 22 forms an inclined guide surface 223 and a straight guide surface 224 on the side facing the guide extension wall 14, which are interconnected and respectively match the inclined extension section 141 and the parallel extension section 142. The inclined guide surface 223 has multiple inclined guide grooves 2231 evenly spaced along the first direction Z. The bottom surface of the inclined guide groove 2231 is an arc surface concave relative to the inclined guide surface 223. The straight guide surface 224 has multiple second guide grooves 2241 evenly spaced along the first direction Z, each connecting to one of the inclined guide grooves 2231. The bottom surface of the second guide groove 2241 is a plane parallel to the parallel extension section 142. Figure 9-10 As shown.

[0043] The inclined extension 141 abuts against the inclined guide surface 223 and forms a second transition cavity 2211 with the inclined guide groove 2231. The side of the second guide vane 22 facing away from the straight guide surface 224 forms a frustum 225. The outer surface of the frustum 225 is an arc-shaped guide area 2222 connecting the planar guide area 2221 and the inner wall guide surface 121, such as... Figure 9-10 As shown.

[0044] The flow guide block 2 also includes: The mounting protrusion 23 mates with the straight guide surface 224 and abuts against the parallel extension section 142. The mounting protrusion 23 and the second guide groove 2241 form the aforementioned second variable displacement air passage 2212. Figure 9-10 As shown.

[0045] Please refer to the following: Figure 9-10 In a preferred embodiment of the duct for eliminating eddy current effects provided by the present invention, a frustum 225 is disposed at the end of the second guide vane 22 away from the first guide vane 21. The frustum 225 protrudes towards the center of the experimental operation port 512, and the second guide vane 22 forms a streamlined structure on its surface through the frustum 225. The maximum thickness of the frustum 225 affects the airflow capture effect, and the maximum thickness range of the frustum 225 is preferably 4-6 mm. In this embodiment, the maximum thickness of the frustum 225 is selected as 5 mm.

[0046] Please refer to the following: Figure 9-10 In a preferred embodiment of the ductwork for eliminating eddy currents provided by the present invention, since the airflow on both sides of the experimental operation port 512 of the exhaust cabinet 5 is transported to the interior of the exhaust cabinet 5 in two stages, there is a certain angle between the first branch 211 and the second branch 221 to ensure a continuous and smooth transition of airflow. The second branch 221 is flush with the inner wall of the side of the experimental operation port 512 of the exhaust cabinet 5, ensuring that the airflow can move along the inner wall guide surface 121 and preventing airflow fluctuations within the experimental space. Therefore, when the apertures of the first branch 211 and the second branch 221 are both reasonable, only the angle of the first branch 211 needs to be designed. In this embodiment, the preferred angle range between the first branch 211 and the second branch 221 is 17-22°.

[0047] Please refer to the following: Figure 3-6 9-10. In a more preferred embodiment of the duct for eliminating eddy current effect provided by the present invention, the first guide vane 21, the second guide vane 22 and the mounting protrusion 23 are integrally formed, and a plurality of first branches 211 and a plurality of second branches 221 are evenly spaced along the first direction Z, and the first branches 211 and the second branches 221 are arranged in a manner similar to an accordion mouth.

[0048] Please refer to the following: Figure 1-2 9-10. In a preferred embodiment of the duct for eliminating eddy current effect provided by the present invention, the end of the third duct wall 133 away from the second duct wall 132 in the second direction X is provided with a first slot 1332, and the end of the first guide vane 21 connected to the third duct wall 133 in the second direction X is provided with a first protrusion 214 that cooperates with the first slot 1332.

[0049] A second groove 3 is formed between the connection between the inner wall 12 of the column, the hollow notch 122 and the parallel extension section 142. The mounting protrusion 23 has a second protrusion 231 that cooperates with the second groove 3 at one end facing the inner wall 12 of the column in the second direction X.

[0050] Please refer to the following: Figure 9-10 In a preferred embodiment of the air duct for eliminating eddy current effect provided by the present invention, the first protrusion 214 is provided with a protruding arc surface 2141 and a concave corner surface 2142 that are connected to each other, and correspondingly the first slot 1332 is provided with a concave arc surface 13321 and a protruding corner surface 13322 that are respectively matched with the protruding arc surface 2141 and the concave corner surface 2142.

[0051] When the first slot 1332 engages with the first protrusion 214, a sealing surface is formed. Especially at the junction of the arc-shaped protrusion and the concave arc surface 13321, the arc surface engagement increases the sealing area and sealing effect, preventing airflow from leaking out of the airflow channel 134 and interfering with the airflow on both sides of the experimental operation port 512 of the exhaust fan 5. This avoids the capture effect being affected by unstable airflow. Figure 9-10 As shown.

[0052] The second protrusion 231 is an elongated oval protrusion, and correspondingly, the second slot 3 is an elongated oval groove that matches the elongated oval protrusion. The second slot 3 is inclined towards the interior of the exhaust fan 5 (towards the inner wall 12 of the column), such as... Figure 9-10 As shown.

[0053] When the second slot 3 mates with the second protrusion 231, a sealing surface is formed. Especially at the junction of the elongated protrusion and the elongated groove, the inclined arrangement extends the mating length of the elongated protrusion and the elongated groove, thus increasing the sealing surface area and sealing effect. This prevents instability in the auxiliary airflow exiting the second branch 221 from the airflow channel 134 due to air leakage. Figure 9-10 As shown.

[0054] In summary, the engagement between the first protrusion 214 and the second slot 3 not only secures the guide block 2 but also prevents gas leakage from interfering with the airflow on both sides of the experimental operation port 512. The engagement between the second protrusion 231 and the second slot 3 prevents the unstable airflow from the second branch 221 in the airflow channel 134 from being unable to draw the auxiliary airflow from the second branch 221 and the airflow on both sides of the experimental operation port 512 into the fume hood 5.

[0055] Please refer to the following: Figure 9-10 In a preferred embodiment of the ductwork for eliminating eddy currents provided by the present invention, the second protrusion 231 engages with the second slot 3, making the mounting protrusion 23 flush with the inner side wall (i.e., the inner wall 12 of the column) of the experimental operation port 512 of the exhaust cabinet 5. Therefore, the direction of the second branch 221 is flush with the inner wall 12 of the column, ensuring that the auxiliary airflow flowing out of the second branch 221 adheres closely to the inner wall 12 of the column, thus improving airflow stability. Simultaneously, the guiding surfaces of the first guide vane 21 and the second guide vane 22 are streamlined, which on the one hand improves their guiding effect on the airflow, ensuring stable gas flow, and on the other hand enhances their airflow capture effect, preventing harmful gases from escaping.

[0056] Because the first guide vane 21 and the second guide vane 22 are arranged in a stepped manner, forming two layers of airflow branches, the first branch 211 and the second branch 221, the airflow on both sides of the experimental operation port 512 of the exhaust cabinet 5 can be transported a second time, avoiding turbulence on the outer arc surface of the air duct body 13. Figure 9-10 As shown.

[0057] Simultaneously, due to the stepped distribution of the first guide vane 21 and the second guide vane 22, two vortex regions are formed on one side of the first guide vane 21 and between the second guide vane 22 and the inner wall guide surface 121. These are the first vortex region C on one side of the first guide vane 21 and the second vortex region D between the second guide vane 22 and the inner wall guide surface 121. Both the first vortex region C and the second vortex region D are prone to generating vortices. The outlet of the first branch duct 211 is located directly above the first vortex region C, and the outlet of the second branch duct 221 is located directly below the second vortex region D. The auxiliary airflow from the first branch duct 211 and the second branch duct 221 can eliminate the first vortex region C and the second vortex region D. Figure 9-10 As shown.

[0058] Furthermore, because the auxiliary airflow velocity exiting the first branch 211 and the second branch 221 is relatively high, the pressure at the outlets of the first branch 211 and the second branch 221 (first vortex region C and second vortex region D) will be lower. This causes the auxiliary airflow exiting the first branch 211 to carry the airflow from the guide surface (third guide surface 212) of the first guide vane 21 to the guide surface (fourth guide surface 222) of the second guide vane 22, and through the auxiliary airflow from the first branch 211, drive the external airflow to move along the guide surface (fourth guide surface 222) of the second guide vane 22. Similarly, the auxiliary airflow exiting the second branch 221 will carry the airflow from the guide surface (fourth guide surface 222) of the second guide vane 22 to the inner side wall (inner wall guide surface 121) of the experimental operation port 512 of the exhaust cabinet 5, and move along the interior of the exhaust cabinet 5, such as... Figure 9-10 As shown.

[0059] Please refer to the following: Figure 6 , 9 -10. In a more preferred embodiment of the duct for eliminating eddy current effect provided by the present invention, the radial dimension of the first transition cavity 2111 is larger than the radial dimension of the first variable volume air passage 2112, the flow cross-sectional area of ​​the second variable volume air passage 2212 is larger than the flow cross-sectional area of ​​the first variable volume air passage 2112, the radial dimension of the second transition cavity 2211 is larger than the radial dimension of the second variable volume air passage 2212, and the flow cross-sectional area of ​​the second transition cavity 2211 is larger than the flow cross-sectional area of ​​the first transition cavity 2111, that is, the flow cross-sectional area of ​​the second branch passage 221 is larger than the flow cross-sectional area of ​​the first branch passage 211.

[0060] Because the cross-sectional area of ​​the second branch 221 is larger than that of the first branch 211, the auxiliary gas flow rate and velocity in the second branch 221 are larger. Due to Bernoulli's principle, the pressure is lower where the velocity is higher; that is, the pressure of the auxiliary gas flowing out of the second branch 221 is lower. This results in a lower local static pressure in the second branch 221 compared to the first branch 211. Consequently, the auxiliary gas flowing out of the first branch 211 carries the external airflow towards the outlet of the second branch 221, ultimately driving the airflow close to the inner wall of the experimental operating port 512 (inner wall guide surface 121). Figure 6 , 9 As shown in -10.

[0061] Please refer to the following: Figure 6 , 9 -10. In a preferred embodiment of the duct for eliminating eddy current effect provided by the present invention, in order to ensure that the auxiliary airflow coming out of the first branch 211 and the second branch 221 is stable, the length of the first branch 211 and the second branch 221 needs to be greater than 12mm. If the length is too short, the rectification effect of the first branch 211 and the second branch 221 on the auxiliary airflow will be poor, and the auxiliary airflow coming out of the first branch 211 and the second branch 221 will be unstable (the airflow will move downward and the airflow will interfere with each other, resulting in instability), which will cause turbulence in the airflow at the inner wall guide surface 121, which may cause harmful gases to overflow.

[0062] Because the radial dimension of the first transition cavity 2111 is larger than the radial dimension of the first variable volume air passage 2112, the flow cross-sectional area of ​​the second variable volume air passage 2212 is larger than the flow cross-sectional area of ​​the first variable volume air passage 2112, the radial dimension of the second transition cavity 2211 is larger than the radial dimension of the second variable volume air passage 2212, and the flow cross-sectional area of ​​the second transition cavity 2211 is larger than the flow cross-sectional area of ​​the first transition cavity 2111, when the auxiliary airflow enters the airflow channel 134, the auxiliary airflow can enter more into the first transition cavity 2111 of the first branch 211 and the second transition cavity 2211 of the second branch 221, improving the air intake effect of the first branch 211 and the second branch 221. Figure 6 , 9 As shown in -10.

[0063] Because the outer surface of the second transition cavity 2211 (i.e., the side of the second guide vane 22 facing the guide extension wall 14) is in contact with the inclined extension section 141, and the inner bottom surface of the second transition cavity 2211 (i.e., the bottom surface of the inclined guide groove 2231, which is an arc surface concave relative to the inclined guide surface 223) is streamlined, it smoothly transitions and connects with the second variable volume air passage 2212, improving the air intake guiding effect of the second branch 221, such as... Figure 9-10 As shown.

[0064] Since the parallel extension section 142 is connected to the end of the inclined extension section 141 away from the first air duct wall 131 and extends parallel to the inner wall guide surface 121, that is, the parallel extension section 142 and the inclined extension section 141 form an angle design, one end of the parallel extension section 142 in the second direction X is connected to the inclined extension section 141, and the other end of the parallel extension section 142 in the second direction X forms part of the second slot 3. The inclined extension section 141 and the parallel extension section 142 also extend axially along the first direction Z throughout the air duct column and meet the mounting protrusion 23 on the guide block 2 and the first... The two transition chambers 2211 are connected, thereby increasing the air intake of the second branch 221. Simultaneously, the lower dimension of the guide block 2 is increased so that it can connect to the parallel extension section 142. This allows the guide block 2 to block the cavity formed between the inner wall 12 of the column, the parallel extension section 142, and the airflow channel 134, preventing gas from entering the column, avoiding leakage, and preventing interference with the auxiliary airflow in the first and second branches 211. This ensures a stable and continuous airflow in the first and second branches 221. Figure 9-10 As shown.

[0065] Please refer to the following: Figure 11-13 The present invention also provides a fume hood 5, including a cabinet body 51, an operating room 511 formed inside the cabinet body 51, an experimental platform 52 at the bottom of the operating room 511, an experimental operating port 512 for opening the operating room 511 on one side of the cabinet body 51, a lifting drive device 53 at the top of the cabinet body 51, the lifting drive device 53 is used to drive the safety cabinet door 54 to rise and fall at the experimental operating port 512 to open and close the experimental operating port 512; a pair of air ducts for eliminating eddy current effect are respectively provided on both sides of the experimental operating port 512, the bottom end of the air duct column is installed on the experimental platform 52, the top end of the air duct column extends to the top of the cabinet body 51, and the inner wall 12 of the column faces the operating room 511.

[0066] The fume hood 5 also includes: The first wind speed sensor (not shown in the figure) is installed in the first branch channel 211; The second wind speed sensor (not shown in the figure) is located in the second branch 221.

[0067] Please refer to the following: Figure 11-12 In one embodiment of the exhaust fan 5 provided by the present invention, the top of the air duct body 13 is provided with an air duct inlet 135, the guide block 2 is spaced apart from the air duct inlet 135, and the airflow channel 134 forms a static pressure chamber in the part between the air duct inlet 135 and the guide block 2.

[0068] The air duct also includes: A variable diameter adjusting component 4 extends along the airflow channel 134 (along the first direction Z) and is disposed within the airflow channel 134. The variable diameter adjusting component 4 has an adjusting inclined surface 421 on the side facing the guide block 2. The distance between the adjusting inclined surface 421 and the guide block 2 gradually decreases along the direction away from the air inlet 135 of the airflow channel 134. Several connecting components 6 are disposed on the adjusting inclined surface 421 and abut against the guide block 2, such as... Figure 13 As shown.

[0069] Please refer to the following: Figure 7-8 11-12 In a preferred embodiment of the exhaust cabinet 5 provided by the present invention, the total length (height) of the guide block 2 embedded in the column body 1 is 500mm. During the experimental operation, the height of the safety cabinet door 54 of the exhaust cabinet 5 is generally set at a height of 450mm on the cabinet body 51. The overall height of the air duct column extends upward from the experimental platform 52 to the top of the cabinet body 51, and the overall height of the air duct column covers and is greater than the length (height) of the guide block 2.

[0070] Please see Figure 13 In a preferred embodiment of the exhaust fan 5 provided by the present invention, the variable diameter adjustment member 4 is wedge-shaped. The variable diameter adjustment member 4 includes a cylindrical adjustment member base 41 and a variable diameter extension 42 connected to the top of the adjustment member base 41. The radial dimension of the adjustment member base 41 matches the radial dimension of the airflow channel 134. The variable diameter extension 42 extends upward from the top of the adjustment member base 41 along the airflow channel 134 (along the first direction Z). The aforementioned adjustment slope 421 is provided on the side of the variable diameter extension 42 facing the guide block 2. That is, the variable diameter extension 42 is a cylindrical structure formed by cutting off part of the structure along the adjustment slope 421.

[0071] The adjusting base 41 is located at the bottom of the airflow channel 134 in the height direction corresponding to the air duct body 13, and blocks the bottom of the air duct body 13 in the height direction to prevent pressure from leaking from the bottom of the air duct body 13.

[0072] The variable diameter extension 42 and the adjusting base 41 constitute a variable diameter adjusting component 4, which is cylindrical in shape and partially wedge-shaped. Specifically, as the variable diameter extension 42 extends along the airflow channel 134 closer to the air inlet 135 (extending from bottom to top along the first direction Z), its adjusting slope 421 gradually moves away from the guide block 2 along the third direction Y, thereby gradually increasing the distance between the adjusting slope 421 and the guide block 2, that is, gradually decreasing the radial dimension of the variable diameter extension 42. In other words, in the direction along the airflow channel 134 away from the air inlet 135 (from top to bottom along the first direction Z), the radial dimension of the variable diameter extension 42 gradually increases.

[0073] This causes the distance between the inclined plane 421 and the guide block 2 to gradually decrease in the direction away from the air inlet 135 along the airflow channel 134 (from top to bottom along the first direction Z). When the auxiliary airflow flows away from the air inlet 135 along the airflow channel 134 (from top to bottom along the first direction Z) and passes through the guide block 2 embedded in the hollow notch 122 and the air outlet notch 1311, the auxiliary airflow gradually (in sequence) flows out from each of the first branch 211 and the second branch 221 from top to bottom. At this time, the pressure of the auxiliary airflow that continues to move downward gradually increases and the flow velocity gradually increases, thereby offsetting the airflow attenuation and maintaining a consistent flow velocity of the auxiliary airflow coming out from the upper and lower height parts of the guide block 2.

[0074] Therefore, through the diameter-changing effect of the wedge-shaped diameter-changing adjustment component 4, the radial dimension of the lower (bottom) of the airflow channel 134 is smaller than that of the upper (top) radial dimension, so as to offset the attenuation of the airflow pressure at the lower (bottom) of the airflow channel 134, so that the airflow pressure at the lower (bottom) of the airflow channel 134 can be kept within a certain range, thereby making the airflow velocity of the first branch 211 and the second branch 221 at the upper and lower height parts of the guide block 2 more uniform.

[0075] Please see Figure 2 and Figure 13 In a more preferred embodiment of the exhaust fan 5 provided by the present invention, the variable diameter extension 42 extends away from the top of the adjusting base 41 along the first direction Z to the middle of the height direction of the corresponding guide block 2 (i.e., the middle of the height direction of the hollow notch 122 and the air outlet notch 1311). The bottom end face of the adjusting base 41 is flush with the bottom end face of the air duct body 13. The arc-shaped outer wall of the long strip variable diameter extension 42 is closely attached to the inner wall of the airflow channel 134, so that the variable diameter adjusting member 4 enhances the structural strength of the air duct column.

[0076] Please see Figure 2 and Figure 13 In a preferred embodiment of the exhaust fan 5 provided by the present invention, due to the occurrence of head or partial bending of the elongated variable diameter adjustment component 4 during mass production, the arc-shaped outer wall of the elongated variable diameter extension 42 fails to completely fit the inner wall of the airflow channel 134, affecting the outlet air velocity of the guide block 2. Therefore, at least one of the aforementioned connecting components 6 is provided on the adjustment slope 421 of the variable diameter extension 42. The connecting component 6 is a connecting column, one end of which is fixedly connected to the adjustment slope 421, and the other end of which abuts against the inner wall of the guide block 2 facing the connecting component 6, and exerts a squeezing force on the variable diameter adjustment component 4, so that the arc-shaped outer wall of the variable diameter extension 42 fits tightly against the airflow channel 134, ensuring the outlet air velocity of the guide block 2.

[0077] Please see Figure 13In a more preferred embodiment of the exhaust fan 5 provided by the present invention, the connector 6 is disposed at a position that avoids each of the first branch 211 and the second branch 221 on the guide block 2.

[0078] In another embodiment of the exhaust fan 5 provided by the present invention, the connector 6 can also be fixedly connected to the inner wall of the guide block 2 facing the connector 6 and abut against the adjusting slope 421.

[0079] In other embodiments of the exhaust fan 5 provided by the present invention, the connecting member 6 can also be a connecting bolt instead of a connecting column. The connecting bolt passes through the guide block 2 from the outside and extends into the airflow channel 134, thereby generating a compressive force on the variable diameter adjusting member 4.

[0080] In a preferred embodiment of the exhaust fan 5 provided by the present invention, the exhaust fan 5 further includes: A pair of pressure chambers 55 are respectively located above a pair of air duct bodies 13. The pressure chambers 55 are provided with transition channels 551 that connect to the corresponding air duct inlets 135. An air supply device 56 is located on the top of the cabinet 51. A pair of rigid pipes 58 are respectively connected between the air supply device 56 and the pair of transition channels 551, and are used to conduct the airflow supplied by the air supply device 56 into the transition channels 551. A pair of regulating valves 59 are respectively located on the pair of rigid pipes 58, and are used to regulate the airflow speed in the corresponding rigid pipes 58.

[0081] In a more preferred embodiment of the exhaust fan 5 provided by the present invention, the outlet end of the air supply device 56 extends along the second direction X, and the outlet end of the air supply device 56 is connected to a pair of rigid pipes 58 respectively through a three-way connector 57. The pair of rigid pipes 58 extend in opposite directions along the third direction Y. The pressure chamber 55 extends along the second direction X, and the interior of the pressure chamber 55 is provided with the aforementioned transition channel 551 extending along the second direction X. One end of the transition channel 551 in the second direction X is connected to the corresponding rigid pipe 58. The opposite end of the air duct is sealed and connected to the air duct inlet 135 at the top of the air duct channel 134. The transition channel 551 forms a first transition surface 5511 and a second transition surface 5512 on the side of the third direction Y near the middle of the exhaust fan 5. Both the first transition surface 5511 and the second transition surface 5512 are arc surfaces. The first transition surface 5511 is smoothly connected to the rigid pipe 58, and the second transition surface 5512 is smoothly connected to the air duct inlet 135, so as to gradually guide the airflow from the transition channel 551 to the air duct channel 134.

[0082] Traditional air supply devices 56 are directly connected to airflow channels 134 via flexible hoses. However, the bends in the hoses reduce the airflow velocity, leading to unstable airflow and loss of airflow velocity in the airflow channels 134. Furthermore, the plug-in structure is prone to loosening due to vibration or other reasons during prolonged operation of the fume hood 5. In addition, the air outlet of one air supply device 56 is connected to the airflow channels 134 of the duct via flexible hoses, and the airflow distributed to the two airflow channels 134 usually has a different velocity, resulting in a velocity difference between the two sides of the cabinet 51 of the fume hood 5.

[0083] Therefore, the air duct adjusts the outlet air velocity of a pair of rigid pipes 58 through two regulating valves 59 to keep them consistent. Simultaneously, the first transition surface 5511 corresponding to the rigid pipe 58 is curved, which guides the airflow more smoothly, while the second transition surface 5512, also curved, smoothly guides the airflow in the transition channel 551 within the pressure chamber 55 to the airflow channel 134. Since both the rigid pipes 58 and the pressure chamber 55 are made of rigid materials, directly connecting the rigid pipes 58 and pressure chamber 55 to the airflow channel 134 reduces component vibration in the air duct. In summary, this makes the airflow in the airflow channel 134 more stable, reduces wind speed loss, and avoids a large wind speed difference on both sides of the exhaust cabinet 51.

[0084] It also includes a first regulating mechanism and a second regulating mechanism: The first adjustment mechanism (not shown in the figure) is used to adjust the flow cross-sectional area of ​​the first branch channel 211. For example, the bottom surface of the first guide groove 2131 is a retractable first movable plate, and the plate surface is parallel to the planar guide area 2221. The first adjustment mechanism is built into the first guide wing 21 and can use a micro electric push rod, piezoelectric ceramic actuator, etc. to drive the first movable plate to move closer to or away from the planar guide area 2221, thereby changing the height of the first variable volume air passage 2112 and realizing the adjustment of the flow cross-sectional area of ​​the first branch channel 211.

[0085] The second adjustment mechanism (not shown in the figure) is used to adjust the flow cross-sectional area of ​​the second branch channel 221. Similarly, for example, the bottom surface of the second guide groove 2241 is a retractable second movable plate with the plate surface parallel to the second guide groove 2241. The second adjustment mechanism is built into the second guide wing 22 and can be a miniature electric push rod, piezoelectric ceramic actuator, etc., to drive the second movable plate to move and realize the independent adjustment of the flow cross-sectional area of ​​the second branch channel 221.

[0086] The present invention also provides a method for eliminating eddy current effect, which utilizes the above-mentioned exhaust fan 5. The method for eliminating eddy current effect includes the following steps: S1: Simultaneously obtain the real-time wind speed W in the first branch 211 and the real-time wind speed V in the second branch 221; S2: Calculate the ratio Z of real-time wind speed V to real-time wind speed W; S3: Determine if 0.667≤Z≤0.833; S4: If yes, return to S1; if no, adjust the flow cross-sectional area of ​​the first branch 211 and / or the second branch 221. The adjustment instructions are as follows: When the ratio Z > 0.833 (the wind speed in the second branch 221 is too fast, and the wind speed in the first branch 211 is too slow). At this point, the proportion of wind speed V in the second branch channel is too high, and the suppression effect of the first vortex zone C is insufficient. Adjustment method: At the same time, reduce the cross-sectional area of ​​the second branch 221 and increase the cross-sectional area of ​​the first branch 211 until 0.667≤Z≤0.833.

[0087] When the ratio Z < 0.667 (the wind speed in the second branch 221 is too slow, and the wind speed in the first branch 211 is too fast). At this point, the wind speed W in the first branch channel is too high, and the suppression effect of the second vortex zone D is insufficient. Adjustment method: Simultaneously increase the cross-sectional area of ​​the second branch 221 and decrease the cross-sectional area of ​​the first branch 211 until 0.667≤Z≤0.833, then return to S1.

[0088] In one embodiment of the eddy current effect elimination method provided by the present invention, the real-time wind speed W in the first branch 211 and the real-time wind speed V in the second branch 221 are respectively obtained by the first wind speed sensor and the second wind speed sensor provided in the first branch 211 and the second branch 221.

[0089] In one embodiment of the eddy current effect elimination method provided by the present invention, the exhaust fan 5 further includes a central control device. The central control device is electrically connected to the first wind speed sensor and the second wind speed sensor respectively, receives the real-time wind speed signals collected by the two branches, calculates the ratio Z of the real-time wind speed V to the real-time wind speed W, and determines whether 0.667≤Z≤0.833 based on the ratio Z. The central control device is also electrically connected to the first adjustment mechanism and the second adjustment mechanism. After completing the wind speed ratio calculation, the central control device outputs a control signal and controls the first adjustment mechanism and the second adjustment mechanism to adjust the flow cross-sectional area of ​​the first branch 211 and the second branch 221 respectively according to the judgment result.

[0090] If the radial dimension of the second branch 221 of the guide block 2 is set to be smaller than that of the first branch 211, in fact, due to the existence of the second branch 221, when the radial dimension of the second branch 221 is smaller than that of the first branch 211, more gas inside the airflow channel 134 will be discharged from the first branch 211, resulting in less airflow and lower wind speed discharged from the second branch 221, which is not effective in eliminating the vortex effect of the second vortex region D.

[0091] To this end, the present invention uses a first wind speed sensor and a second wind speed sensor installed in the first branch 211 and the second branch 221 to obtain the real-time wind speed W in the first branch 211 and the real-time wind speed V in the second branch 221, respectively. The ratio Z of the real-time wind speed V to the real-time wind speed W is calculated. Then, based on the ratio Z, the first adjustment mechanism and the second adjustment mechanism are used to adjust the flow cross-sectional area of ​​the first branch 211 and the second branch 221, respectively, until the ratio Z satisfies 0.667≤Z≤0.833, thereby simultaneously eliminating the vortex effect of the first vortex region C and the second vortex region D.

[0092] To verify the effect of the airflow guiding structure of the present invention on the suppression of airflow and vortices at the exhaust fan opening, airflow velocity tests were conducted at the opening for different air duct size schemes. The airflow velocity data at the test points are shown in the table below. The test results show that after adjusting the air duct flow cross section, the uniformity of airflow velocity at the opening is significantly improved, which can effectively suppress the generation of vortices on both sides.

[0093] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Those skilled in the art should understand that any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A duct for eliminating eddy current effects, characterized in that, include: Air duct support column, the air duct support column includes: The column body (1) has an outer wall (11) and an inner wall (12) on both sides. The inner surface of the inner wall (12) facing away from the outer wall (11) serves as an inner wall guide surface (121). The outer wall (11) and the inner wall (12) are connected by a duct body (13). The duct body (13) has an airflow channel (134) inside. The connection between the duct body (13) and the inner wall (12) is provided with a guide extension wall (14). A flow guide block (2) is embedded in the connection between the inner wall (12) of the column and the main body of the air duct (13). The flow guide block (2) includes: a first flow guide wing (21) and a second flow guide wing (22) distributed in a stepped manner. The second flow guide wing (22) is connected between the end of the flow guide extension wall (14) and the outer surface of the main body of the air duct (13). A plurality of second branches (221) are distributed between the second flow guide wing (22) and the flow guide extension wall (14). One end of each second branch (221) is connected to the airflow channel (134), and the other end of each second branch (221) extends to the inner wall flow guide surface (121). The first flow guide wing (21) is connected between the side of the second flow guide wing (22) facing away from the flow guide extension wall (14) and the outer surface of the main body of the air duct (13). A plurality of first branches (211) connected to the airflow channel (134) are distributed between the first flow guide wing (21) and the second flow guide wing (22). The first adjustment mechanism is located inside the first guide vane (21) and is used to adjust the flow cross-sectional area of ​​the first branch channel (211); The second adjustment mechanism is located inside the second guide vane (22) and is used to adjust the flow cross-sectional area of ​​the second branch (221).

2. The air duct for eliminating eddy current effect as described in claim 1, characterized in that, The axial direction of the air duct column is the first direction Z. The inner wall (12) of the column is a straight wall extending along the first direction Z. The connection between the inner wall (12) of the column and the air duct body (13) is provided with a hollow notch (122) extending along the first direction Z and matching the shape of the guide block (2). The guide extension wall (14) extends along the first direction Z and is bent from the air duct body (13) toward the outer wall (11) of the column.

3. The air duct for eliminating eddy current effect as described in claim 2, characterized in that, The main body of the air duct (13) includes: a first air duct wall (131), connected between the corresponding ends of the outer wall (11) and the inner wall (12) of the column, wherein the connection between the first air duct wall (131) and the inner wall (12) of the column is provided with an air outlet (1311) extending along the first direction Z and facing the hollowed-out notch (122); and a second air duct wall (132), connected between the outer wall (11) of the column and the first air duct wall (131), and The second air duct wall (132) bends near the inner wall (12) of the column, and its outer surface serves as the first guide surface (1321); the third air duct wall (133) is connected to the end of the second air duct wall (132), and its outer surface serves as the second guide surface (1331) connected to the first guide surface (1321). The flow-guiding extension wall (14) is connected to the side of the first air duct wall (131) away from the inner wall (12) of the column at the air outlet (1311); The inner wall (12) of the column and the third air duct wall (133) are provided with the hollowed-out notch (122). The guide block (2) is embedded and sealed in the hollowed-out notch (122). The first branch (211) and the second branch (221) are respectively connected to the air outlet notch (1311). The first guide wing (21) is sealed at the end of the hollowed-out notch (122) facing the third air duct wall (133). The side of the first guide wing (21) facing away from the second guide wing (22) forms a third guide surface (212) connected to the second guide surface (1331). The second guide wing (22) is sealed at the end of the guide extension wall (14). The side of the second guide wing (22) facing away from the guide extension wall (14) forms a fourth guide surface (222) connected to the inner wall guide surface (121).

4. The air duct for eliminating eddy current effect as described in claim 3, characterized in that, The corresponding inner surfaces of the first air duct wall (131), the second air duct wall (132) and the third air duct wall (133) are concentric arc surfaces, and the corresponding inner surfaces of the first air duct wall (131), the second air duct wall (132) and the third air duct wall (133) form the cylindrical inner surface of the air duct body (13) facing the airflow channel (134); The first guide surface (1321) is an arc surface concentric with the inner surface of the second air duct wall (132), and the second guide surface (1331) is an arc surface with a radius greater than that of the first guide surface (1321).

5. The air duct for eliminating eddy current effect as described in claim 4, characterized in that, The fourth guide surface (222) includes a flat planar guide area (2221) connected to the third guide surface (212) and a curved arc guide area (2222) connected to the planar guide area (2221) and connected to the inner wall guide surface (121). The first branch (211) includes a first transition cavity (2111) connected to the air outlet (1311) and a first variable volume air passage (2112) connected to the first transition cavity (2111). The first variable volume air passage (2112) passes through the end of the first guide vane (21) away from the main body of the air passage (13). The second branch (221) includes a second transition cavity (2211) connected to the air outlet (1311) and a second variable volume air duct (2212) connected to the second transition cavity (2211). The second variable volume air duct (2212) passes through the end of the second guide vane (22) away from the main body of the air duct (13). The side surface of the first guide vane (21) facing the second guide vane (22) serves as the first mating surface (213). The first mating surface (213) is provided with a plurality of first guide grooves (2131) evenly spaced in the first direction Z. The bottom surface of the first guide groove (2131) is a plane parallel to the planar guide area (2221). The first mating surface (213) abuts against the planar guide area (2221), and the planar guide area (2221) and the first guide groove (2131) form the first variable volume air passage (2112).

6. The air duct for eliminating eddy current effect as described in claim 5, characterized in that, The flow-guiding extension wall (14) includes: an inclined extension section (141) connected to the side of the first air duct wall (131) away from the inner wall (12) of the column at the air outlet (1311); and a parallel extension section (142) connected to the end of the inclined extension section (141) and extending parallel to the inner wall flow-guiding surface (121). The second guide vane (22) forms an inclined guide surface (223) and a straight guide surface (224) that are connected to and respectively match the inclined extension section (141) and the parallel extension section (142) on the side facing the guide extension wall (14). The inclined guide surface (223) is provided with a plurality of inclined guide grooves (2231) evenly spaced in the first direction Z. The bottom surface of the inclined guide groove (2231) is an arc surface that is concave relative to the inclined guide surface (223). The straight guide surface (224) is provided with a plurality of inclined guide grooves (2231) that are connected to the inclined extension section (141) and the parallel extension section (142) respectively on the first direction Z. The second guide groove (2241) of the inclined guide groove (2231) has a bottom surface that is parallel to the plane of the parallel extension section (142); the inclined extension section (141) and the inclined guide groove (2231) form the second transition cavity (2211); the second guide wing (22) forms a frustum (225) on the side facing away from the straight guide surface (224), and the outer surface of the frustum (225) is the arc-shaped guide area (2222) connecting the planar guide area (2221) and the inner wall guide surface (121). The guide block (2) further includes: a mounting protrusion (23) that mates with the straight guide surface (224) and abuts against the parallel extension section (142), wherein the mounting protrusion (23) and the second guide groove (2241) form the second variable volume air passage (2212).

7. The air duct for eliminating eddy current effect as described in claim 6, characterized in that, The radial dimension of the first transition cavity (2111) is greater than the radial dimension of the first variable volume air passage (2112), the radial dimension of the second transition cavity (2211) is greater than the radial dimension of the second variable volume air passage (2212), the flow cross-sectional area of ​​the second variable volume air passage (2212) is greater than the flow cross-sectional area of ​​the first variable volume air passage (2112), and the flow cross-sectional area of ​​the second transition cavity (2211) is greater than the flow cross-sectional area of ​​the first transition cavity (2111). The bottom surface of the first guide groove (2131) is a first movable plate that can extend or retract toward the planar guide area (2221) and is parallel to the planar guide area (2221). The first adjustment mechanism is used to drive the first movable plate to extend or retract. The bottom surface of the second guide groove (2241) is a second movable plate that can extend or retract toward the mounting protrusion (23) and is parallel to the flat guide surface (224). The second adjustment mechanism is used to drive the second movable plate to extend or retract.

8. A fume hood, employing the ductwork for eliminating eddy current effects as described in any one of claims 1-7, characterized in that, It also includes a cabinet (51), the interior of which forms an operating room (511). The bottom of the operating room (511) is provided with an experimental platform (52). One side of the cabinet (51) is provided with an experimental operating port (512) that opens the operating room (511). The top of the cabinet (51) is provided with a lifting drive device (53). The lifting drive device (53) is used to drive the safety cabinet door (54) to rise and fall at the experimental operating port (512) to open and close the experimental operating port (512). On both sides of the experimental operating port (512), there is a pair of air ducts for eliminating eddy current effect. The bottom end of the air duct column is installed on the experimental platform (52), and the top end of the air duct column extends to the top of the cabinet (51). The inner wall (12) of the column faces the operating room (511). The exhaust fan also includes: The first wind speed sensor is located in the first branch (211); The second wind speed sensor is located in the second branch (221); The central control device is electrically connected to the first wind speed sensor, the second wind speed sensor, the first adjustment mechanism, and the second adjustment mechanism, respectively.

9. The exhaust fan as described in claim 8, characterized in that, The top of the air duct body (13) is provided with an air duct inlet (135), the guide block (2) is spaced apart from the air duct inlet (135), and the airflow channel (134) forms a static pressure chamber in the part between the air duct inlet (135) and the guide block (2). The air duct also includes: A variable diameter adjustment component (4) is provided in the airflow channel (134) extending along the airflow channel (134). The variable diameter adjustment component (4) has an adjustment slope (421) on the side facing the guide block (2). In the direction away from the air inlet (135) of the airflow channel (134), the distance between the adjustment slope (421) and the guide block (2) gradually decreases. Several connectors (6) are connected between the adjusting inclined surface (421) and the guide block (2); The exhaust fan also includes: A pair of pressure chambers (55) are respectively located above a pair of air duct bodies (13), and the pressure chambers (55) are provided with transition channels (551) that connect to the corresponding air duct inlets (135). An air supply device (56) is located on the top of the cabinet (51); A pair of rigid pipes (58) are respectively connected between the gas supply device (56) and a pair of transition channels (551) for transmitting the airflow supplied by the gas supply device (56) into the transition channels (551); A pair of regulating valves (59) are respectively provided on a pair of rigid pipes (58) for regulating the airflow speed in the corresponding rigid pipes (58).

10. A method for eliminating eddy current effects, employing the fume hood as described in claim 8, characterized in that, The method for eliminating eddy current effects includes the following steps: S1: Simultaneously obtain the real-time wind speed W in the first branch (211) and the real-time wind speed V in the second branch (221); S2: Calculate the ratio Z of real-time wind speed V to real-time wind speed W; S3: Determine if 0.667≤Z≤0.833; S4: If yes, return to S1; if no, adjust the flow cross-sectional area of ​​the first branch (211) and / or the second branch (221) and return to S1.

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