A fume hood stand column capable of eliminating vortex effect

Abstract

The application discloses a kind of exhaust cabinet stand column that can eliminate vortex effect, technical field of laboratory equipment, two sides of exhaust cabinet are symmetrically arranged with stand column assembly, two stand column assemblies are experimental operation port in middle, the stand column assembly includes flow guide block, flow guide block includes first wind guide wing and second wind guide wing in ladder distribution, first wind guide wing and second wind guide wing are equipped with first air passage spaced distribution between, second wind guide wing and experimental operation port inner wall surface are equipped with second air passage spaced distribution between.The flow guide block on stand column assembly can send the airflow on the side of the experimental operation port of exhaust cabinet to the inside of exhaust cabinet body smoothly, prevent harmful gas from overflowing from the two sides of exhaust cabinet, first wind guide wing and second wind guide wing on flow guide block will be sent to the exhaust cabinet body with airflow two-stage processing, simultaneously, through first air passage and second air passage, vortex effect between first wind guide wing and second wind guide wing is eliminated, so that harmful gas cannot overflow in vortex zone.

Description

Technical Field

[0001] This invention relates to a laboratory fume hood structure, and more specifically, to a fume hood column that can eliminate eddy current effects. Background Technology

[0002] Fume hoods are crucial contaminant control devices in laboratories. Chemical experiments often involve the generation of harmful gases. These gases, released into the air, can impact the health of laboratory personnel. Hazardous chemical experiments are primarily conducted within fume hoods; if the fume hood's contaminant control performance is unstable, the risk of harmful gas spills increases significantly. Therefore, minimizing fume hood leakage is essential for ensuring laboratory safety. However, existing fume hoods often fail to achieve stable airflow control and zero leakage even with the door open.

[0003] For example, Chinese Patent Publication No. CN215466926U, published on January 11, 2022, entitled "A Makeup Air Type Exhaust Cabinet," discloses an exhaust cabinet structure including a cabinet body with an opening on the front side. The bottom of the cabinet body has a downwardly inclined air intake component for upward exhaust and an upwardly inclined air intake component for downward exhaust. This design creates an air curtain at the exhaust cabinet door vent, isolating harmful gases inside the cabinet and improving safety. However, it still carries the risk of harmful gas leakage. Conversely, at the location of the air curtain, due to the higher flow rate and lower pressure, harmful gases are more likely to move towards the exhaust cabinet door, increasing the risk of leakage. Summary of the Invention

[0004] This invention overcomes the risk of harmful gas leakage during experimental operations of existing fume hoods and provides a fume hood column that can eliminate eddy current effects. This solution can smoothly transport the airflow outside the fume hood into the cabinet, prevent harmful gas from overflowing, eliminate eddy currents generated inside the column, and achieve zero leakage.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: a fume hood column that can eliminate eddy current effects. Column assemblies are symmetrically arranged on both sides of the fume hood, with an experimental operation port between the two column assemblies. Each column assembly includes a guide block, which includes a first guide vane and a second guide vane arranged in a stepped manner. A first air passage is spaced apart between the first and second guide vanes, and a second air passage is spaced apart between the second guide vane and the inner wall surface of the experimental operation port. The guide block on the column assembly can smoothly transport the airflow from the side of the experimental operation port of the fume hood towards the interior of the fume hood, eliminating eddies generated inside the column and preventing harmful gases from overflowing from both sides of the fume hood. The first and second guide vanes on the guide block process the airflow in two stages and transport it into the fume hood interior. Simultaneously, the first and second air passages eliminate the eddy current effect between the first and second guide vanes, ensuring a smooth airflow without fluctuations and reducing the possibility of harmful gases overflowing in the eddy current zone.

[0006] Preferably, both the first and second guide vanes are streamlined, with a frustum at the end of the second guide vane. The streamlined design of the first and second guide vanes, based on aerodynamic principles, facilitates airflow along their surfaces, preventing the leakage of harmful gases. The frustum structure on the second guide vane enhances its airflow capture effect, allowing airflow to flow along its surface.

[0007] Preferably, the column assembly includes a column body with a gas channel inside. The gas channel connects to the first air duct and the second air duct. The column body is a hollow column with a gas channel inside. The gas channel is used to introduce auxiliary airflow and is connected to both the first and second air ducts. This allows the auxiliary airflow to enter the first and second air ducts. When the auxiliary airflow exits the first and second air ducts, its velocity is faster than the airflow velocity at the first and second guide vanes. This causes the airflow at the first and second guide vanes to move towards the interior of the cabinet, while also eliminating vortices in the vortex zone between the first and second guide vanes and between the second guide vane and the inner wall surface of the experimental operation port. This allows the external airflow to enter the cabinet more smoothly.

[0008] Preferably, a transition cavity is provided between the gas channel and the first air passage, and between the gas channel and the second air passage. The transition cavity serves to be larger than the air passage orifice diameter of the first and second air passages, so that when the auxiliary airflow enters the airflow channel, more of the auxiliary airflow can enter the air inlet positions of the first and second air passages.

[0009] Preferably, the column body includes a first cylindrical surface and a second cylindrical surface, which are transitionally connected, and the second cylindrical surface is transitionally connected to the first air guide vane. The first and second cylindrical surfaces are located on the front surface of the column, which can improve the airflow capture effect of the fume hood opening. The second cylindrical surface, closer to the experimental operation port of the fume hood, smoothly transitions with the surface of the first air guide vane, and the radius of the second cylindrical surface is larger than that of the first cylindrical surface.

[0010] Preferably, the column body is provided with a mounting groove, and the guide block is provided in the mounting groove. The guide block and the column body are detachable, and the guide block is embedded in the mounting groove, which is beneficial for the maintenance and repair of the fume hood equipment.

[0011] Preferably, the angle between the first and second air ducts is 17° to 23°, and the second air duct is flush with the inner wall surface of the experimental operation port. The flow direction of the second air duct being flush with the inner wall surface of the experimental operation port allows the auxiliary airflow exiting the second air duct to flow close to the inner wall surface of the experimental operation port, thus guiding the inlet airflow at the second guide vane towards the inner wall surface of the experimental operation port. Similarly, the first and second air ducts are arranged at a certain angle, and the outer surface of the first air duct is flush with the second guide vane, allowing the auxiliary airflow exiting the first air duct to flow close to the surface of the second guide vane, thus guiding the inlet airflow at the first guide vane to the surface of the second guide vane. This achieves airflow on both sides of the experimental operation port of the fume hood flush with the surface of the column. The two-stage guide vane design also ensures very smooth gas flow, avoiding the generation of eddies and turbulence.

[0012] Preferably, the diameter of the first airway is larger than that of the second airway. The diameter of the first airway needs to be designed to be larger than that of the second airway, so that the flow velocity of the auxiliary airflow from the second airway is greater than that from the first airway. Since the auxiliary airflow at the second airway has a faster flow velocity and lower pressure, the auxiliary airflow at the first airway will move closer to the airflow at the second airway and flow close to the inner sidewall of the experimental operating port, which improves the airflow capture effect and reduces the leakage of harmful gases.

[0013] Preferably, the column body is also provided with an air inlet, which is connected to the gas channel. A static pressure chamber is provided between the air inlet and the guide block. The air inlet is used to introduce auxiliary airflow. The auxiliary airflow is provided by the air intake system. After the airflow enters the air inlet, it cannot immediately form a relatively stable airflow. Therefore, a static pressure chamber is also provided inside the column body. After rectification by the static pressure chamber, the auxiliary airflow from the gas channel is more stable before entering the first and second air channels in the guide block.

[0014] Preferably, a wedge-shaped block is also provided within the gas channel. The wedge-shaped block is located on the side of the gas channel away from the air inlet, and the diameter of the gas channel corresponding to the wedge-shaped block gradually decreases from top to bottom. The wedge-shaped block on the side of the gas channel away from the air inlet alters the space within the gas channel, thereby changing the internal gas pressure. This ensures that all the first and second air channels on the guide block maintain the same flow velocity, resulting in uniform flow velocity throughout the column body and improving the stability and uniformity of gas flow within the gas channel.

[0015] Compared with the prior art, the beneficial effects of the present invention are: (1) the dual-channel auxiliary airflow technology is used to capture the airflow entering the cabinet from both sides, eliminating the vortex effect at the edge and preventing harmful gases from being rolled out and causing leakage during the experimental operation; (2) the column body adopts an arc-shaped structure, and the airflow is guided by two layers of air guides in stages, which enhances the effect of the airflow adhering to the inner wall of the exhaust cabinet; (3) the auxiliary airflow is stable up and down and horizontally distributed, the airflow blown out in the air duct is stable, and the interference between the airflows up and down is minimal; (4) the air duct components are further set on the column body, which, together with the original structural design, achieve zero leakage of experimental gases. Attached Figure Description

[0016] Figure 1 This is an isometric view of the present invention.

[0017] Figure 2 This is a front view of the column assembly of the present invention.

[0018] Figure 3 This is an isometric view of the column assembly of the present invention.

[0019] Figure 4 This is an isometric view of the main column of the present invention.

[0020] Figure 5 This is an isometric view of the flow guide block of the present invention.

[0021] Figure 6 This is an isometric view of the flow guide block of the present invention from another perspective.

[0022] Figure 7 This is a cross-sectional view of the flow guide block of the present invention.

[0023] Figure 8 This is a cross-sectional view of the main body of the column of the present invention at the section containing the first and second air passages at the guide block. Figure 2 A cross-sectional view along the AA direction.

[0024] Figure 9 This is a schematic diagram of the wedge block of the present invention.

[0025] Figure 10 This is a schematic diagram showing the fit between the wedge-shaped block and the main column of the present invention.

[0026] In the diagram: 1. Column assembly, 2. Experimental operation port, 3. Guide block, 4. First guide vane, 5. Second guide vane, 6. First air passage, 7. Second air passage, 8. Frustum, 9. Column body, 9.1. Inner wall, 9.2. Outer wall, 10. Gas passage, 11. Transition cavity, 11.1. First transition cavity, 11.2. Second transition cavity, 12. Second cylindrical surface, 13. Second cylindrical surface, 14. Mounting groove, 15. Air inlet, 16. Static pressure cavity, 17. Wedge block, 18. Safety door, 19. Front panel, 20. First slot, 21. Second slot, 22. First protrusion, 22.1. Arc-shaped protrusion surface, 22.2. Concave corner surface, 23. Second protrusion, 24. Mounting block, 25. Mounting surface, 26. Support plate, 27. Locking block. Detailed Implementation

[0027] The technical solution of the present invention will be further described in detail below through specific embodiments and in conjunction with the accompanying drawings.

[0028] Example 1: As Figure 1 The diagram shows a fume hood support column designed to eliminate eddy current effects. The front of the fume hood has an experimental operation port 2, and a support column assembly 1 is arranged on each side of the experimental operation port 2 to support the safety door 18 and the fume hood. Figures 2 to 8 As shown, the structure of the column assembly 1 of the fume hood is shown. The column assembly 1 includes a column body 9 and a flow guide block 3. The bottom of the column body 9 abuts against the bottom of the experimental platform inside the fume hood, and the top of the column body 9 extends to the top of the fume hood.

[0029] like Figure 3 or Figure 8 and combined Figure 1 As shown, the main body of the column 9 is a hollow column structure, and the front side of the main body of the column 9 ( Figure 8The structure shown in the lower diagram has a cylindrical gas channel 10 inside, which runs through the entire axial direction of the column body 9. The front side of the column body 9 is formed by two continuous cylindrical surfaces. Specifically, the cylindrical surfaces include a first cylindrical surface 12 and a second cylindrical surface 13. The first cylindrical surface 12 is located on the side of the fume hood away from the experimental operation port 2, and the second cylindrical surface 13 is located on the side of the fume hood closer to the experimental operation port 2. The column body 9 also has an inner sidewall 9.1 and an outer sidewall 9.2. The outer sidewall 9.2 is smoothly connected to the first cylindrical surface 12, and the inner sidewall 9.1 is smoothly connected to the second cylindrical surface 13. The cylindrical surfaces and the inner and outer sidewalls together form the outer surface structure of the column body 9. The first cylindrical surface 12 and the gas channel 10 are concentric circles. The radius of the second cylindrical surface 13 is larger than that of the first cylindrical surface 12, resulting in a thicker wall between the second cylindrical surface 13 and the gas channel 10. This increased wall thickness enhances the structural strength of the column body 9 and improves its support effect. Furthermore, since the guide block 3 needs to be installed on one side of the second cylindrical surface 13, the increased wall thickness of the second cylindrical surface 13 provides sufficient installation strength for the guide block 3, preventing damage to the column body 9 during installation. It also reduces the curvature of the second cylindrical surface 13, resulting in better airflow capture on both sides of the exhaust fan's experimental operation port 2, eliminating eddies generated inside the column, and preventing harmful gases from escaping.

[0030] An air inlet 15 is provided on the upper side of the column body 9. The air inlet 15 is located at the position corresponding to the front panel 19 of the exhaust fan. Specifically, the air inlet 15 is located at the connection between the second cylindrical surface 12 and the inner side wall 9.1. On the one hand, the air inlet 15 penetrates the second cylindrical surface 13 to connect the gas channel 10. On the other hand, the air inlet 15 also penetrates the inner side wall 9.1, thereby increasing the size of the air inlet 15 and increasing the air intake effect. The main column 9 also supports the front panel 19, and the front end of the front panel 19 is flush with the front side of the second cylindrical surface 13, so that the air inlet 15 is located on the rear side of the front panel 19. The front panel 19 shields the air inlet 15. In the specific implementation, the air supply system adopts a vortex fan (not shown in the figure). The vortex fan can also be arranged on the rear side of the front panel 19, thereby improving the overall aesthetics of the exhaust cabinet. The vortex fan can provide auxiliary airflow into the air inlet 15. Specifically, a flexible hose can be used to connect the air inlet 15 and the air outlet of the vortex fan to ensure that the airflow enters the gas channel 10 as much as possible.

[0031] like Figures 4 to 8 and combined Figure 1As shown, a mounting groove 14 is also provided on the lower side of the column body 9. The mounting groove 14 is fitted with a flow guide block 3 and is connected to the gas channel 10. Specifically, at the location of the mounting groove 14, the second cylindrical surface 13 is hollowed out, so that the mounting groove 14 is connected to the gas channel 10. One end of the mounting groove 14 is located in the axial hollowed-out inner section of the second cylindrical surface 13, and the other end of the mounting groove 14 is located on the inner side wall 9.1. A first slot 20 is provided in the axial hollowed-out inner section of the second cylindrical surface 13, and a second slot 21 is provided in the inner side wall 9.1. The guide block 3 is elongated and fits into the slot of the mounting groove 14. A first protrusion 22 and a second protrusion 23 are provided along the width of the guide block 3, respectively located at both ends of the width direction. The second protrusion 23 is mounted on the mounting block 24 of the guide block 3. The first protrusion 22 engages with the first slot 20, and the second protrusion 23 engages with the second slot 21. The first protrusion 22 has an arc-shaped raised surface 22.1 and a concave corner surface 22.2, corresponding to the concave arc surface and raised corner surface on the first slot 20. When the first slot 20 and the first protrusion 22 are connected... A sealing surface is formed, especially at the location of the arc-shaped protrusion 22.1. The arc surface increases the sealing area and sealing effect, preventing the airflow in the gas channel 10 from leaking to the outside of the second cylindrical surface 13, interfering with the airflow on both sides of the experimental operation port 2 of the fume hood, causing airflow instability and affecting the capture effect. Similarly, the second protrusion 23 is provided with an elongated oval protrusion, corresponding to an elongated oval groove on the second slot 21. The second slot 21 is inclined towards the inside of the fume hood, and the length of the elongated oval is increased by the inclined arrangement, thereby increasing the sealing surface and sealing effect, preventing airflow leakage at this point from causing instability in the auxiliary airflow in the second air channel 7. The first protrusion 22 and the second slot 21 not only serve to fix the guide block 3, but also seal to prevent gas leakage from interfering with the airflow on both sides of the experimental operation port 2. The second protrusion 23 and the second slot 21 prevent the airflow at the second air channel 10 from being unstable, thus preventing the auxiliary airflow at the first air channel 6 and the airflow on both sides of the experimental operation port 2 from being brought into the fume hood.

[0032] The guide block 3 includes a first guide vane 4 and a second guide vane 5, which are arranged in a stepped manner. The first guide vane 4, the second guide vane 5 and the mounting block 24 are integrally formed. Several first air channels 6 are provided between the first guide vane 4 and the second guide vane 5. The first air channels 6 are evenly distributed and have a rectangular hole structure. The interval between the first air channels 6 (the wall thickness between the first air channels 6) is 2 mm. The dimension in the width direction (the arrangement direction of the first air channels 6) is also 2 mm. The distance between the first guide vane 4 and the second guide vane 5 (that is, another dimension of the first air channel 6) is 1.5 mm. The interval between the first air channels 6 (the wall thickness between the first air channels 6) cannot be less than 2 mm. The second air guide wing 5 and the mounting block 24 have several second air channels 7 formed by intervals. The second air channels 7 are evenly distributed and have a rectangular hole structure. The interval between the second air channels 7 (the wall thickness between the second air channels 7) is 2 mm. The dimension in the width direction of the second air channels 7 (the arrangement direction of the second air channels 7) is also 2 mm. The distance between the second air guide wing 5 and the mounting block 24 (that is, another dimension of the second air channel 7) is 1 mm.

[0033] Because the second protrusion 23 on the mounting block 24 engages with the second slot 21 on the mounting groove 14, the mounting block 24 is flush with the inner side wall of the experimental operation port 2 of the fume hood (i.e., the inner side wall 9.1 of the column body 9). This means the direction of the second air duct 7 is flush with the inner side wall of the experimental operation port 2 of the fume hood, allowing the auxiliary airflow from the second air duct 7 to adhere closely to the inner side wall of the experimental operation port 2 of the fume hood, thus improving airflow stability. The airflow guiding surfaces of the first guide vane 4 and the second guide vane 5 are streamlined, which on the one hand helps improve the airflow guiding effect, ensuring stable gas flow, and on the other hand, improves the airflow capture effect, preventing harmful gases from escaping.

[0034] Since the first guide vane 4 and the second guide vane 5 are arranged in a stepped manner, forming two layers of air channels, the first air channel 6 and the second air channel 7, the airflow on both sides of the exhaust fan experimental operation port 2 can be transported in a secondary manner, avoiding the airflow from generating turbulence on the arc surface of the column body 9. Meanwhile, due to the stepped distribution of the first guide vane 4 and the second guide vane 5, a vortex zone will be formed between the first guide vane 4 and the second guide vane 5, and between the second guide vane 5 and the inner sidewall 9.1. Vortexes are also easily generated here. The outlets of the first air passage 6 and the second air passage 7 are located in the vortex zone. The auxiliary airflow from the first air passage 6 and the second air passage 7 can eliminate the vortex zone. At the same time, since the auxiliary airflow from the first air passage 6 and the second air passage 7 has a higher flow velocity, the pressure at the outlets (vortex zone) of the first air passage 6 and the second air passage 7 will be lower. As a result, the auxiliary airflow from the first air passage 6 will carry the airflow from the guide surface of the first guide vane 4 to the guide surface of the second guide vane 5. The auxiliary airflow from the first air passage 6 will drive the external airflow to move along the guide surface of the second guide vane 5. Similarly, the auxiliary airflow from the second air passage 7 will carry the airflow from the guide surface of the second guide vane 5 to the inner side wall of the experimental operation port 2 of the exhaust cabinet, and move along the inside of the exhaust cabinet.

[0035] It should be noted that the aperture of the second airway 7 is smaller than that of the first airway 6, so the auxiliary airflow velocity flowing out of the second airway 7 is faster, that is, the pressure of the auxiliary airflow flowing out of the second airway 7 is lower, while the pressure of the auxiliary airflow flowing out of the first airway 6 is greater. This causes the auxiliary airflow flowing out of the first airway 6 to carry the external airflow together towards the outlet of the second airway 7, and finally causes the airflow to move close to the inner wall of the side of the experimental operation port 2.

[0036] In order to ensure that the auxiliary airflow from the first air passage 6 and the second air passage 7 is stable, the length of the first air passage 6 and the second air passage 7 needs to be greater than 12mm. If the length is too short, the rectification effect of the first air passage 6 and the second air passage 7 on the auxiliary airflow will be poor, and the auxiliary airflow from the first air passage 6 and the second air passage 7 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 on the surface of the column body 9, which may lead to the leakage of harmful gases.

[0037] In the specific design process of the first airway 6 and the second airway 7 in this scheme, a smoke machine was used to generate smoke on one side of the experimental operation port 2 (where the first cylindrical surface 12 is located) to observe the specific airflow effect, as shown in Tables 1 and 2 below (only part of the data of the first airway is shown).

[0038]

[0039] Table 1

[0040]

[0041] Table 2

[0042] As shown in Tables 1 and 2 above, if the spacing between the first air passages 6 (the wall thickness between the first air passages 6) is too small, it will cause the airflow between adjacent first air passages 6 to interfere with each other and generate turbulence. If it is too large, it will cause the airflow to be uneven and affect the airflow capture effect. The same applies to the second air passage 7. The appropriate range for the spacing between the first air passages 6 (the wall thickness between the first air passages 6) and the spacing between the second air passages 7 (the wall thickness between the second air passages 7) is 2mm to 4.5mm. The length of the first air passages 6 and the second air passages 7 needs to be greater than 12mm. If the length is too short, the rectification effect of the first air passages 6 and the second air passages 7 on the auxiliary airflow will be poor, and the auxiliary airflow from the first air passages 6 and the second air passages 7 will be unstable.

[0043] A frustum 8 is provided at the end of the second guide vane 5 away from the first guide vane 4. The frustum 8 protrudes towards the middle of the experimental operation port 2. The second guide vane 5 forms a streamlined structure on its surface through the frustum 8 structure, wherein the maximum thickness of the frustum 8 is ( Figure 8 The maximum distance between the left and right sides of the truncated cone 8 shown will also affect the airflow capture effect. The maximum thickness of the truncated cone 8 is 4 to 6 mm. In this embodiment, the maximum thickness of the truncated cone 8 is 5 mm.

[0044] Since the airflow on both sides of the fume hood's experimental operating port 2 is delivered to the inside of the fume hood in two stages, there is a certain angle between the first air duct 6 and the second air duct 7 to ensure a continuous and smooth transition of airflow. The second air duct 7 is flush with the inner wall of the fume hood's experimental operating port 2 to ensure that the airflow can move along the inner wall and prevent airflow fluctuations within the experimental space. Therefore, assuming that the orifice diameters of the first air duct 6 and the second air duct 7 are both reasonable, only the angle of the first air duct 6 needs to be designed. According to the experimental test data in Table 3 (partial experimental data), the angle between the first air duct 6 and the second air duct 7 can be selected as 17° to 22°.

[0045]

[0046] Table 3

[0047] As shown in Table 3 above, and in conjunction with... Figure 8As shown, when the angle between the first air duct 6 and the second air duct 7 is too small, that is, when the angle between the first guide vane 4 and the side wall of the experimental operation port 2 is small, the smoke at the location of the first cylindrical surface 12 and the second cylindrical surface 13 is difficult to move along the guide surface of the first guide vane 4, and a vortex will be formed in area A, so that only part of the smoke will enter the fume hood, reducing the airflow capture effect at the second cylindrical surface 13, resulting in less smoke at the outlet of the first air duct 6 and the outlet of the second air duct 7 (some smoke will overflow); while when the angle between the first air duct 6 and the second air duct 7 is too large, although the smoke at the location of the second cylindrical surface 13 can move better along the guide surface of the first guide vane 4, the vertical distance between the first air duct 6 and the second air duct 7 increases, and a vortex will be generated at the location of area B. The smoke is difficult to be carried by the auxiliary airflow from the second air duct 7 to the location close to the side wall. Therefore, the capture effect of the airflow at the second air duct 7 is reduced, which will also increase the possibility of harmful gas overflow. In this embodiment, region A is the area between the first cylindrical surface 13 and the first guide vane 4, and region B is the area of ​​the frustum 8 near the outlet of the second air duct 7. The included angle between the first air duct 6 and the second air duct 7 is 20°.

[0048] Since the mounting groove 14 is connected to the gas channel 10, and the guide block 3 is installed on the mounting groove 14, the gas channel 10 is also connected to the first air passage 6 and the second air passage 7 inside the guide block 3. The mating surfaces of the first air passage 6 and the second air passage 7 with the gas channel 10 are adapted arc surfaces. A mounting surface 25 that fits with the mounting block 24 is provided on the mounting groove 14. A second transition cavity 11.2 is formed between the mounting surface 25 and the second air guide 5. A first transition cavity 11.1 is also formed on the side of the first air guide 4 near the mounting groove 14 and the side of the second air guide 5 near the mounting groove 14. Both the first transition cavity 11.1 and the second transition cavity 11.2 are larger than the aperture of the first air passage 6 and the second air passage 7. When the auxiliary airflow enters the interior of the gas channel 10, the auxiliary airflow can enter more into the first transition cavity 11.1 of the first air passage 6 and the second transition cavity 11.2 of the second air passage 7, thereby improving the air intake effect of the first air passage and the second air passage.

[0049] The upper sidewall of the second transition cavity 11.2 is streamlined, smoothly transitioning and connecting with the second air passage 7, improving the air intake and guiding effect of the second air passage 7. The lower sidewall of the second transition cavity 11.2 fits snugly against the mounting surface 25. Figure 4As shown, a support plate 26 is also provided in the inner wall 9.1 of the column body 9. The support plate 26 is designed with an angle. One side of the support plate 26 is connected to the outer wall of the gas channel 10, and the other side of the support plate 26 forms part of the second slot 21. The support plate 26 also extends axially to the entire column body 9. At the location of the mounting slot 14, the support plate 26 is also the mounting surface 25 on the mounting slot 14, which is used to connect with the mounting block 24 of the guide block 3 and the second transition cavity 11.2. The second transition cavity 11.2 not only increases the air intake of the second air passage 7, but also increases the size of the guide block 3 below to match the support plate, so that the guide block 3 itself can block the cavity formed by the inner wall 9.1, the support plate 26 and the side wall of the gas channel 10, preventing the gas in this place from entering the guide block 3 and interfering with the auxiliary airflow of the first air passage 6 and the second air passage 7 in the axial direction, so that the first air passage 6 and the second air passage 7 cannot generate a stable and continuous airflow.

[0050] In this design, the total length of the guide block 3 on the main column 9 is 500mm. During the operation of the fume hood experiment, the height of the safety door 18 is generally set at 450mm. The overall length of the main column 9 is above the fume hood experimental platform. Therefore, a static pressure chamber 16 is formed in the gas channel 10 on the upper part of the main column 9 (excluding the guide block 3). The vortex fan introduces auxiliary airflow into the air inlet 15. After the auxiliary airflow enters the air inlet 15, it cannot immediately form a relatively stable airflow. Therefore, a static pressure chamber 16 is also set inside the main column 9. After rectification by the static pressure chamber 16, the auxiliary airflow in the gas channel 10 becomes more stable before entering the first air passage 6 and the second air passage 7 in the guide block 3.

[0051] like Figure 9 and Figure 10 and combined Figure 1 As shown, a wedge-shaped block 17 structure is provided at the bottom of the column body 9. Specifically, the bottom of the wedge-shaped block 17 is cylindrical and is adapted to the diameter of the gas channel 10. A latch is provided at the bottom of the gas channel 10, and a latching block 27 that cooperates with the latch is provided at the bottom of the wedge-shaped block 17. The upper side of the wedge-shaped block 17 is a wedge-shaped structure with a cylindrical surface. The size of the wedge-shaped block 17 gradually increases from top to bottom, so that the diameter of the gas channel 10 gradually decreases from top to bottom. When the auxiliary airflow flows from top to bottom, after passing through the guide block 3 at the mounting groove 14, the auxiliary airflow gradually flows out from the first air passage 6 and the second air passage 7, which will cause the pressure of the auxiliary airflow that continues to move downward to decrease and the flow rate to slow down. This will cause the flow rate of the auxiliary airflow coming out of the guide block 3 to be inconsistent. Therefore, through the diameter change effect of the wedge-shaped block 17, the airflow pressure at the bottom of the gas channel 10 can be kept within a certain range, so that the flow rate of the airflow blown out of the first air passage 6 and the second air passage 7 is uniform.

[0052] It should be noted that the top of the wedge block 17 structure is located in the middle of the guide block 3, while the bottom of the wedge block 17 is flush with the lower end face of the column body 9. The wedge block 17 also plays a role in structural reinforcement of the column body 9 to a certain extent, and at the same time blocks the lower end face of the gas channel 10 to prevent pressure leakage.

Claims

1. A fume hood column capable of eliminating eddy current effects, wherein column assemblies are symmetrically arranged on both sides of the fume hood, and an experimental operation port is located between the two column assemblies, characterized in that, The column assembly includes a guide block and a column body. The guide block includes a first guide vane and a second guide vane arranged in a stepped manner. A first air passage is provided between the first guide vane and the second guide vane, and a second air passage is provided between the second guide vane and the inner sidewall surface of the experimental operation port. A gas channel is provided inside the column body, and the gas channel is connected to both the first and second air passages. An installation groove is provided on the column body, and a guide block is provided in the installation groove. The installation groove is connected to the gas channel. The column body is formed by the transition between two continuous first and second cylindrical surfaces. The first cylindrical surface and the gas channel inside the column body are concentric circles, and the radius of the second cylindrical surface is larger than the radius of the first cylindrical surface. The airflow coming out of the second air passage closely adheres to the inner sidewall of the experimental operation port, causing the airflow coming out of the first air passage to drive the external airflow together towards the outlet of the second air passage.

2. The exhaust fan column for eliminating eddy current effects according to claim 1, characterized in that, Both the first and second wind guide vanes are streamlined. The end of the second wind guide vane away from the first wind guide vane is provided with a frustum, which protrudes towards the center of the experimental operation port.

3. The exhaust fan column for eliminating eddy current effects according to claim 2, characterized in that, The first cylindrical surface is located on the side of the fume hood away from the experimental operation port, and the second cylindrical surface is located on the side of the fume hood closer to the experimental operation port. The guide block is installed on one side of the second cylindrical surface.

4. The exhaust fan column for eliminating eddy current effects according to claim 3, characterized in that, A transition cavity is provided between the gas channel and the first air passage, and between the gas channel and the second air passage.

5. A fume hood column for eliminating eddy current effects according to claim 3, characterized in that, The main body of the column includes a first cylindrical surface and a second cylindrical surface, which are connected in transition, and the second cylindrical surface is connected in transition to the first wind guide vane.

6. A fume hood column capable of eliminating eddy current effects according to any one of claims 3 to 5, characterized in that, The gas channel runs through the entire axis of the column body.

7. A fume hood column capable of eliminating eddy current effects according to claim 1, characterized in that, The angle between the first airway and the second airway is 17° to 22°, and the second airway is flush with the inner sidewall surface of the experimental operation port.

8. The exhaust fan column for eliminating eddy current effect according to claim 1, characterized in that, The diameter of the first airway is larger than the diameter of the second airway.

9. A fume hood column for eliminating eddy current effects according to claim 6, characterized in that, The column body is also provided with an air inlet, which is connected to the gas channel, and a static pressure chamber is provided between the air inlet and the guide block.

10. A fume hood column capable of eliminating eddy current effects according to claim 9, characterized in that, A wedge-shaped block is also provided in the gas channel. The wedge-shaped block is located on the side of the gas channel away from the air inlet. The diameter of the gas channel corresponding to the wedge-shaped block gradually decreases from top to bottom.

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