A centrifugal pump sealing detection device and a detection method thereof

Abstract

The application relates to the technical field of valve detection, and discloses a centrifugal pump sealing property detection device and a detection method thereof, which comprises a water tank and a support installed on the back of the water tank, the front of the support is provided with a slidable support column, the inside of the support is provided with a lifting device for driving the support column to move up and down, a platform for storing the centrifugal pump is connected to the support column, the platform is driven by the support column to be immersed in the water tank, and the sealing property of the centrifugal pump is detected through bubbles. The water tank is designed in layers of a high-temperature zone, a convection zone and a low-temperature zone, when the low-temperature zone is detected, the leakage bubbles rise to the high-temperature zone along with the liquid, the gas is expanded in volume by heat, the tiny bubbles generated by tiny leakage can be amplified, the problem that tiny bubbles are difficult to observe in traditional detection is solved, meanwhile, the high-temperature zone can clean the interference bubbles attached to the surface of the centrifugal pump in advance, the convection zone further promotes the bubbles to be separated, and the interference of the initial attached bubbles on the detection result is avoided.

Description

Technical Field

[0001] This invention relates to the field of valve testing technology, specifically to a centrifugal pump sealing performance testing device and its testing method. Background Technology

[0002] Centrifugal pumps are widely used fluid transport equipment in industrial production, and their sealing performance directly affects operational stability, efficiency, and safe production. Currently, the field of centrifugal pump sealing performance testing faces numerous technical challenges that urgently need to be addressed.

[0003] Limited detection accuracy is a major problem in existing technologies. Traditional detection methods, such as simple air pressure testing, judge the sealing of centrifugal pumps by observing whether the air pressure decreases, which is difficult to detect minute leaks. In contrast, the immersion method has become the mainstream detection technology in the industry due to its advantages such as simple operation, intuitive test results, and low equipment investment cost. Its core principle is to immerse the centrifugal pump under test in water and pressurize the pump body with a certain pressure through an air pressure device. If there is a sealing defect in the pump body, the gas will escape from the leak point and form bubbles. The tester judges the sealing status of the centrifugal pump by observing the formation of bubbles in the water.

[0004] However, in actual testing, for the common micro-leakage of centrifugal pumps, the microbubbles generated by the leak are easily dissolved in the test water, causing the leakage signal to be masked and unable to be effectively captured, thus leading to the problem of missed detection. To address this, the present invention provides a centrifugal pump sealing test device and its test method. Summary of the Invention

[0005] To address the aforementioned shortcomings of existing technologies, this invention provides a centrifugal pump sealing performance testing device and method. Through a layered design of a high-temperature zone, a convection zone, and a low-temperature zone, the device utilizes temperature gradients to amplify microbubbles and enhance the observation of bubbles.

[0006] The present invention provides the following technical solution: a centrifugal pump sealing performance testing device, including a water tank and a support installed on the back of the water tank. The front of the support is provided with a slidable support column, and the inside of the support is provided with a lifting device for driving the support column to move up and down. A platform for storing the centrifugal pump is connected to the support column. The platform is driven by the support column to be immersed in the water tank, and the sealing performance of the centrifugal pump is detected by air bubbles.

[0007] Furthermore, one port of the centrifugal pump is sealed by an end plate, and the other port of the centrifugal pump is connected to a pneumatic system, which performs inflation testing on the centrifugal chamber of the pump body.

[0008] The water tank is divided into an upper high-temperature zone, a middle convection zone, and a bottom low-temperature zone. The centrifugal pump passes through the high-temperature zone, where the high temperature cleans the air bubbles attached to the surface of the centrifugal pump. The convection zone allows the air bubbles on the surface of the centrifugal pump to detach and remove them. The centrifugal pump undergoes a sealing test in the low-temperature zone. When the air bubbles rise from the bottom low-temperature zone to the high-temperature zone, the gas volume expands, which detects tiny bubbles caused by minor leaks and accelerates the rising speed of the bubbles.

[0009] The water tank is equipped with a convection suppression structure in the low-temperature zone. The magnet array of the convection suppression structure suppresses hot and cold convection through Lorentz force, thereby reducing the hot and cold convection phenomenon in the convection zone.

[0010] An electric field structure is installed in the low-temperature zone of the water tank. The electric field structure forms a non-uniform electric field, which creates a weak field region in the center, driving the bubbles to gather towards the center, making them easier to observe and preventing the bubbles from moving towards the inner wall of the water tank and attaching to it.

[0011] An alternating magnetic field is installed in the convection zone outside the water tank. The eddy current induced by the alternating magnetic field will generate a reverse Lorentz force, and an upward magnetic levitation force will be formed in the hot and cold interface zone to counteract the natural convection disturbance, reduce the flow intensity driven by the temperature gradient, and prevent the bubbles from breaking.

[0012] Preferably, the convection suppression structure includes a mesh frame installed at the bottom of the inner side of the water tank, and the four corners of the mesh frame are separated from the bottom of the inner side of the water tank by connecting posts, and magnets are installed at the intersections of the mesh frame, and the magnets are distributed in a rectangular array.

[0013] Preferably, all magnets on the grid frame are arranged in an alternating N-pole and S-pole array. The Lorentz force and magnetophoretic force work together to suppress hot and cold convection. If the liquid is conductive, the vertical magnetic field interacts with the convection velocity to generate a reverse Lorentz force that directly counteracts the buoyancy-driven flow caused by thermal rise and cooling. The magnetic field gradient drives magnetic particles to migrate to the high field strength region, indirectly interfering with the fluid eddy structure, disrupting convection stability, reducing convection shear force, and delaying bubble merging or rupture. However, it should be noted that a strong magnetic field may hinder the buoyancy of the bubbles.

[0014] Preferably, the electric field structure includes electrode plates installed on the four sides of the low-temperature zone of the water tank, so that a strong electric field region is formed near the inner wall of the low-temperature zone of the water tank. The negative permittivity pushes the bubbles from the wall to the middle region of the weak electric field region, while the bubbles gather towards the center of the tank.

[0015] Preferably, the alternating magnetic field includes several sets of electromagnets installed on both sides of the convection zone of the water tank, and the magnetic poles of the electromagnets are alternately and equally distributed. The alternating magnetophore force is generated by the periodic magnetic field gradient reversal, which causes the adsorbed bubbles to be oscillated and impacted and detached. At the same time, microscale Lorentz vortices are generated to counteract turbulent energy, counteract horizontal disturbance energy, and form a magnetic field channel pointing towards the center of the tank.

[0016] Preferably, a heat-conducting sheet is embedded in the low-temperature zone at the bottom of the water tank, and a semiconductor cooling chip is attached to the bottom of the heat-conducting sheet. The semiconductor cooling chip cools the heat-conducting sheet, and the heat-conducting sheet cools the liquid in the water tank.

[0017] Preferably, the high-temperature zone of the water tank is fitted with inwardly inclined glass covers on both sides, and infrared radiation lamps are installed on the inclined upper part of the glass covers. The light from the infrared radiation lamps heats the liquid in the high-temperature zone of the water tank at an angle from the upper side, avoiding contact between the light and the convection zone. At the same time, the liquid is heated while it is still, which avoids the liquid flowing during heating and reduces the disturbance of the convection zone.

[0018] Preferably, the pneumatic system includes a flange plate installed at another port of the centrifugal pump and a pneumatic control valve installed on the flange plate. The pneumatic control valve is connected to the air-filling device through a pipe into the support, so that high-pressure gas is introduced into the centrifugal chamber of the centrifugal pump. The sealing performance is checked by detecting whether air bubbles exist after the centrifugal pump is immersed in water through a water tank.

[0019] A method for testing the sealing performance of a centrifugal pump, characterized by employing a centrifugal pump sealing test device as described in any one of the claims, and specifically operating as follows:

[0020] S1. Place the centrifugal pump to be tested on the platform, ensure the pump body is stable, seal the port of the centrifugal pump with the end plate and the air pressure system, and introduce high pressure gas into the centrifugal chamber of the centrifugal pump.

[0021] S2. Start the internal lifting device of the support to drive the support column to slowly lower the platform, so that the centrifugal pump passes through the high temperature zone, convection zone and low temperature zone, and is immersed in water in sequence, and finally stays in the middle of the low temperature zone and remains stable.

[0022] S3. Activate the convection suppression structure to suppress hot and cold convection through the synergistic effect of Lorentz force and magnetophoresis force, thereby reducing disturbance in the convection zone. Activate the electric field structure to energize the four electrode plates in the low-temperature zone, forming a non-uniform electric field. Utilize the negative permittivity force to push the bubbles from the tank wall to the central weak field region for easier observation. Activate the alternating magnetic field to start the electromagnets with alternating magnetic poles on both sides of the convection zone. The alternating magnetophoresis force is generated through the periodic reversal of the magnetic field gradient, causing the adsorbed bubbles to fall off. At the same time, Lorentz vortices are generated to counteract turbulence and prevent the bubbles from breaking.

[0023] S4. Continuously observe the rising of bubbles in the high-temperature zone to determine the sealing performance of the centrifugal pump.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] (1) The water tank adopts a layered design of high temperature zone, convection zone and low temperature zone. When the low temperature zone is detected, the leaked bubbles rise with the liquid to the high temperature zone. The gas expands in volume when heated, which can magnify the tiny bubbles generated by the tiny leak, solving the problem that tiny bubbles are difficult to observe in traditional detection. At the same time, the high temperature zone can clean the interfering bubbles attached to the surface of the centrifugal pump in advance, and the convection zone further promotes the bubbles to detach, avoiding the interference of the initial attached bubbles on the detection results and greatly reducing the risk of misjudgment.

[0026] (2) The low-temperature region suppresses convection through an array of magnets with alternating N and S poles. The Lorentz force directly counteracts the buoyancy-driven flow caused by thermal rise and cooling. At the same time, the magnetic force interferes with the fluid vortex structure, destroys the convection stability, reduces the influence of convection shear force on the bubbles, delays bubble merging or rupture, and ensures that the leaking bubbles rise in an independent form, making it easier to accurately determine the location and extent of the leak.

[0027] (3) The alternating magnetic field in the convection zone generates alternating magnetophoretic force through the periodic magnetic field gradient reversal, which causes the bubbles adsorbed on the pump body or tank wall to fall off. At the same time, microscale Lorentz vortices are generated to counteract turbulent energy, avoid horizontal disturbances that cause bubble breakage, and further ensure the integrity of the bubbles during the rising process, providing a reliable basis for detection.

[0028] (4) The electric field structure in the low temperature zone generates negative permittivity through a non-uniform electric field, which pushes the bubbles from the tank wall to the central weak field area to gather, avoiding the bubbles from adhering to the inner wall of the water tank and being unable to be observed. Operators can focus on observing the central area, which significantly improves the bubble identification efficiency and detection accuracy. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0030] Figure 2 This is a schematic diagram of the support structure of the present invention;

[0031] Figure 3 This is a schematic diagram of the convection suppression structure of the present invention;

[0032] Figure 4 This is a schematic diagram of the installation position of the heat-conducting sheet of the present invention;

[0033] Figure 5 This is a schematic diagram of the electric field structure of the present invention;

[0034] Figure 6 This is a schematic diagram of the glass cover structure of the present invention.

[0035] In the diagram: 1. Water tank; 2. Support; 3. Support column; 4. Platform; 5. Convection suppression structure; 6. Electric field structure; 7. Alternating magnetic field; 11. High temperature zone; 12. Convection zone; 13. Low temperature zone; 51. Frame; 52. Magnet; 8. Glass cover; 9. Infrared radiation lamp; 10. Heat-conducting plate; 21. Flange plate; 22. Pressure control valve. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of the embodiments of this disclosure clearer, the technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. In order to keep the following description of the embodiments of this disclosure clear and concise, detailed descriptions of known functions and known components are omitted to avoid unnecessarily obscuring the concept of the present invention.

[0037] Please see Figure 1 The interior of the water tank 1 is divided into three parts along the vertical direction: a high-temperature zone 11, a convection zone 12, and a low-temperature zone 13, with the height ratio of each zone being 1:2:3.

[0038] High-temperature zone 11: Responsible for the heating, expansion, and cleaning of bubbles.

[0039] See Figure 6 The inner walls of both sides of the high-temperature zone 11 in the water tank 1 are inlaid with inwardly inclined quartz glass covers 8. The inclination angle can be finely adjusted by bolts. Multiple sets of infrared radiation lamps 9 are installed diagonally above the glass covers 8. The light shines on the liquid in the high-temperature zone along the inclination direction of the glass covers, avoiding direct illumination of the convection zone 12. The infrared radiation lamps 9 are regulated by a thermostat to stabilize the liquid temperature in the high-temperature zone at 50-60℃. At this temperature, the volume of the tiny bubbles can expand by 1.2-1.5 times, and at the same time, it can melt the tiny water vapor film attached to the surface of the centrifugal pump, preventing the bubbles from remaining on the pump body surface due to "film adsorption".

[0040] Convection Zone 12: Buffers hot and cold convection and bubble desorption.

[0041] An alternating magnetic field 7, consisting of multiple sets of electromagnets, is installed on the outer wall of the convection zone 12. These electromagnets are distributed alternately and equidistantly along the length of the water tank, with their poles arranged in an alternating "NSNS" pattern. Driven by a frequency converter with a frequency adjustment range of 5-20Hz, a periodically changing magnetic field gradient is generated. The alternating magnetic field induces eddy currents in the liquid, which in turn generate a reverse Lorentz force. This creates an upward magnetic levitation force in the hot-cold interface zone, counteracting the natural convection caused by the liquid's "heat rise and cold fall," reducing the intensity of convection disturbance, and preventing bubbles from breaking up due to turbulence during their ascent.

[0042] Low temperature zone 13: Core sealing test area.

[0043] See Figure 4In the low-temperature zone 13, a heat-conducting plate 10 made of high thermal conductivity is embedded at the bottom of the water tank. Multiple sets of semiconductor cooling chips are fully attached to the bottom of the heat-conducting plate 10. The cooling chips are controlled by a temperature control module to stabilize the liquid temperature in the low-temperature zone at 5-10℃. Due to the low temperature and high density of the liquid in the low-temperature zone, the rising speed of bubbles can be slowed down. At the same time, in conjunction with the convection suppression structure 5 and the electric field structure 6, stable capture and aggregation of bubbles are achieved.

[0044] The support 2 is welded into an L-shaped structure and fixed at the center of the back of the water tank 1. Its front is provided with symmetrical T-shaped slide rails along the vertical direction. The support column 3 is slidably connected to the slide rails by a slider to ensure that the support column moves only in the vertical direction.

[0045] The support 2 is equipped with a lifting device, specifically a servo motor and ball screw drive structure. The servo motor is connected to the ball screw via a coupling, and the ball screw nut is fixed to the bottom of the support column 3. The motor is controlled by a PLC controller, which can realize the adjustment of the lifting speed and high-precision positioning of the support column 3. This ensures that the centrifugal pump can slowly and smoothly immerse itself in the high-temperature zone 11, the convection zone 12, and finally stop in the middle of the low-temperature zone 13, avoiding turbulent bubbles caused by excessive immersion speed, which would interfere with the test results.

[0046] The top of the support column 3 is bolted to the platform 4 via a flange. The surface of the platform 4 has multiple sets of oblong holes for installing adjustable limit blocks. The position of the limit blocks is adjusted according to the size of the centrifugal pump base to achieve stable fixation for common flow and diameter ranges of different models of centrifugal pumps, preventing the pump body from shifting due to buoyancy or convection after immersion in liquid. At the same time, the oblong holes also facilitate the passage of liquid.

[0047] See Figure 3 The convection suppression structure 5 is installed at the bottom of the inner side of the water tank in the low temperature zone 13. It includes a mesh frame 51 and a magnet 52. The size of the mesh frame 51 matches the bottom of the low temperature zone. Its four corners are separated from the bottom of the water tank by connecting columns to ensure that the liquid under the mesh frame can flow normally and avoid local stagnant water.

[0048] At the intersection of the longitudinal and transverse ribs of the frame 51, magnets 52 are fixedly installed by countersunk bolts. The magnets are distributed in a rectangular array, and the N poles and S poles of all magnets are arranged alternately in the longitudinal and transverse directions, such as "NSN" and "SNS".

[0049] During operation, the magnetic field generated by magnet 52 interacts with the liquid in the low-temperature zone, which contains trace amounts of electrolytes, exhibiting weak conductivity. The vertical magnetic field and the convective flow velocity form a Lorentz force, directly counteracting the buoyancy-driven flow caused by thermal rise and cooling. Simultaneously, the magnetic field gradient generates a magnetophore force, driving tiny impurities in the liquid to migrate towards the high-field region, indirectly disrupting the convective vortex structure. Under this dual effect, the convective intensity of the liquid in the low-temperature zone is significantly reduced. This not only prevents bubble coalescence and breakage caused by convective shear forces but also allows water molecules to align orderly along magnetic field lines through the magnetic field, increasing the apparent viscosity of the water, slowing bubble rise, and providing time for the capture of tiny leaking bubbles.

[0050] See Figure 5 The electric field structure 6 consists of multiple electrode plates, which are installed on the inner walls of the four sides of the low-temperature zone 13 through insulating brackets. The electrode plates maintain a certain distance from the water tank wall and bottom to avoid interference with other components.

[0051] The electrode plates are powered by a high-voltage DC power supply with an output voltage of 0-500V and a current of 0-10mA. The electrode plates on adjacent sides are connected to the positive and negative terminals respectively, forming a non-uniform electric field in the low-temperature region. The electric field strength is high near the inner wall of the water tank and low in the central region. Because the dielectric constant of air bubbles is much smaller than that of water, they are subjected to negative permittivity and accumulate from the high-field-strength water tank wall to the low-field-strength central region. This effectively avoids bubbles adhering to the inner wall of the water tank and being difficult to observe. At the same time, the bubbles that accumulate in the central region are more easily captured by the naked eye or image acquisition equipment, improving the detection rate of minute leaks.

[0052] See Figure 2 The pneumatic system is used to introduce high-pressure gas into the centrifugal chamber of the centrifugal pump to simulate the sealing state under actual working pressure. Specifically, it includes flange plate 21, pneumatic control valve 22, and air charging equipment. Flange plate 21 adopts a standard flange that matches the port of the centrifugal pump. It is sealed by fitting the gasket to the port of the pump body and tightening the bolts. The other port of the centrifugal pump is completely sealed by the end plate to ensure that the centrifugal chamber of the pump body forms a closed space.

[0053] An air passage interface is provided on the flange plate 21, and a high-pressure hose is connected to the air pressure control valve 22. The other end of the air pressure control valve passes through a pipe into the support 2 and is connected to the air filling equipment such as an air compressor and an air tank.

[0054] Before testing, the inflation pressure is set to 0.1-1.0 MPa using the air pressure control valve 22 according to the rated working pressure of the centrifugal pump. The inflation device slowly inflates the centrifugal chamber. After the pressure stabilizes, the centrifugal pump is then immersed in the water tank to avoid pump deformation or false bubbles caused by sudden pressure changes.

[0055] S1: Centrifugal pump positioning and sealing inflation

[0056] According to the base size of the centrifugal pump to be tested, adjust the position of the upper limit block of platform 4, place the centrifugal pump stably in the center of platform 4, and ensure that the pump body is in close contact with the limit block.

[0057] Seal one port of the centrifugal pump with an end plate, tighten the bolts evenly to prevent the gasket from shifting, and connect the other port to the pneumatic system through flange plate 21. Check the gasket for damage and ensure there is no leakage at the interface.

[0058] Start the inflation equipment and slowly introduce high-pressure gas into the centrifugal pump chamber through the air pressure control valve 22. After the pressure gauge shows that the pressure has stabilized at the set value, close the inflation equipment and the air pressure control valve, and maintain the pressure for 5 minutes. If there is no obvious large leakage in the pump body, it is determined that the pump is unqualified. If the pressure drops suddenly, it is directly determined to be unqualified.

[0059] S2: Centrifugal pump stepwise immersion

[0060] Start the lifting device inside the support 2, set the descent speed of the support column 3 through the PLC controller, and drive the platform 4 to drive the centrifugal pump to descend slowly;

[0061] When the bottom of the centrifugal pump enters the high-temperature zone 11, the platform 4 triggers the proximity switch, pauses the descent for 30 seconds, and uses the liquid in the high-temperature zone to remove the tiny bubbles and water vapor film attached to the surface of the pump body.

[0062] As it continues to descend, the centrifugal pump passes through convection zone 12 in sequence, buffering the hot and cold convection to prevent sudden temperature changes from causing pump body deformation. Finally, it stops in the middle of low temperature zone 13, triggering the proximity switch again. The lifting device stops working, maintaining the centrifugal pump in a stable immersion state.

[0063] S3: Magnetoelectric coordinated field control, optimizing the detection environment.

[0064] Activate the convection suppression structure 5. Magnet 52 naturally forms a stable magnetic field. Through the combined action of Lorentz force and magnetophoresis force, liquid convection in the low-temperature region is suppressed. After observing that there is no obvious disturbance on the liquid surface, proceed to the next step.

[0065] Turn on the electric field structure 6, energize the four electrode plates of the low temperature zone 13, adjust the high voltage DC power supply to the set voltage, and after the electric field stabilizes, you can observe the bubbles gathering towards the center of the water tank.

[0066] Turn on the alternating magnetic field 7, start the electromagnets on both sides of the convection zone 12, set the magnetic field frequency through the frequency converter, and use the alternating magnetophoretic force generated by the periodic magnetic field gradient reversal to cause the bubbles adsorbed on the pump body surface to fall off. At the same time, the Lorentz vortex cancels out the turbulence and prevents the bubbles from breaking.

[0067] S4: Bubble Observation and Sealing Assessment

[0068] The upward movement of bubbles in the high-temperature zone 11 can be continuously observed and recorded in real time with a high-definition camera. The observation time is usually set to 5-10 minutes according to the detection requirements.

[0069] Judgment criteria: If no bubbles are generated in the high-temperature zone or only a very small number of irregular tiny bubbles are generated, it is determined that the gas is dissolved in the water and the centrifugal pump is qualified for sealing.

[0070] If regular bubbles continue to be generated in the high-temperature zone, such as rising from the pump body sealing surface or interface, it is determined that there is a leak. Based on the frequency and size of the bubble generation, the leak level is further determined, such as minor leak or serious leak.

[0071] S5: Finalization after inspection

[0072] After the test is completed, first shut off the electric field structure 6 and the alternating magnetic field 7, then open the air pressure control valve 22 to release the high-pressure gas in the centrifugal pump chamber, start the lifting device to lift the centrifugal pump outside the water tank, remove the end plate and flange plate, clean the water on the surface of the pump body, and the test is completed.

[0073] The above embodiments are merely exemplary embodiments of the present invention and are not intended to limit the present invention. The scope of protection of the present invention is defined by the claims. Those skilled in the art can make various modifications or equivalent substitutions to the present invention within its spirit and scope of protection, and such modifications or equivalent substitutions should also be considered to fall within the scope of protection of the present invention.

Claims

1. A centrifugal pump sealing performance testing device, characterized in that: Includes a water tank (1) and a support (2) installed on the back of the water tank. The front of the support (2) is provided with a sliding support column (3). The inside of the support (2) is provided with a lifting device for driving the support column (3) to move up and down. A platform (4) for storing a centrifugal pump is connected to the support column (3). The platform (4) is driven by the support column (3) to be immersed in the water tank (1). The sealing performance of the centrifugal pump is detected by air bubbles. Furthermore, one port of the centrifugal pump is sealed by an end plate, and the other port of the centrifugal pump is connected to a pneumatic system, which performs air filling and testing on the centrifugal chamber of the pump body. The water tank (1) is divided into an upper high-temperature zone (11), a middle convection zone (12), and a bottom low-temperature zone (13). The centrifugal pump passes through the high-temperature zone (11) to clean the bubbles attached to the surface of the centrifugal pump through high temperature. The convection zone (12) can remove the bubbles from the surface of the centrifugal pump and remove the bubbles. The centrifugal pump is tested for sealing in the low-temperature zone (13). When the bubbles rise from the bottom low-temperature zone (13) to the high-temperature zone (11), the gas volume expands, which detects the tiny bubbles generated by the tiny leaks and accelerates the rising speed of the bubbles. The water tank (1) has a convection suppression structure (5) in the low temperature zone (13). The magnet array of the convection suppression structure (5) suppresses hot and cold convection through Lorentz force, thereby reducing the hot and cold convection phenomenon in the convection zone (12). An electric field structure (6) is installed in the low-temperature zone (13) of the water tank (1). A non-uniform electric field is formed through the electric field structure (6). The electric field will form a weak field area in the center, driving the bubbles to gather towards the center, which is convenient for observation and prevents the bubbles from moving towards the inner wall of the water tank (1) and attaching to it. An alternating magnetic field (7) is installed in the convection zone (12) outside the water tank (1). The eddy current induced by the alternating magnetic field will generate a reverse Lorentz force, and an upward magnetic levitation force will be formed in the cold and hot junction zone to counteract the natural convection disturbance, reduce the flow intensity driven by the temperature gradient, and avoid bubble breakage.

2. The centrifugal pump sealing performance testing device according to claim 1, characterized in that: The convection suppression structure (5) includes a mesh frame (51) installed at the bottom of the inner side of the water tank (1), and the four corners of the mesh frame (51) are separated from the bottom of the inner side of the water tank (1) by connecting columns, and magnets (52) are installed at the intersection of the mesh frame (51) and the magnets (52) are distributed in a rectangular array.

3. The centrifugal pump sealing performance testing device according to claim 2, characterized in that: The N and S poles of all magnets (52) on the frame (51) are arranged in an alternating array. The hot and cold convection is suppressed by the Lorentz force and the magnetophoretic force. If the liquid is conductive, the vertical magnetic field interacts with the convection velocity to generate a reverse Lorentz force that directly counteracts the buoyancy driving flow caused by the rise in temperature and the fall in temperature. The magnetic field gradient drives the magnetic particles to migrate to the high field strength region, which indirectly interferes with the fluid eddy structure, destroys the convection stability, reduces the convection shear force, and delays the merging or rupture of bubbles. However, it should be noted that the strong magnetic field may hinder the buoyancy of the bubbles.

4. The centrifugal pump sealing performance testing device according to claim 1, characterized in that: The electric field structure (6) includes electrode plates installed on the four sides of the low temperature zone (13) of the water tank (1), so that a strong electric field region is formed near the inner wall of the low temperature zone (13) of the water tank (1), and the negative permittivity pushes the bubbles from the wall to the middle area of ​​the weak electric field region, while the bubbles gather towards the center of the tank.

5. The centrifugal pump sealing performance testing device according to claim 1, characterized in that: The alternating magnetic field (7) includes several sets of electromagnets installed on both sides of the convection zone (12) of the water tank (1), and the magnetic poles of the electromagnets are distributed alternately and equally. The alternating magnetic force is generated by the periodic magnetic field gradient reversal, which causes the adsorbed bubbles to be oscillated and impacted and fall off. At the same time, microscale Lorentz vortices are generated to counteract turbulent energy, counteract horizontal disturbance energy, and form a magnetic field channel pointing to the center of the tank.

6. The centrifugal pump sealing performance testing device according to claim 1, characterized in that: The low-temperature zone (13) at the bottom of the water tank (1) is inlaid with a heat-conducting plate (10), and a semiconductor cooling plate is attached to the bottom of the heat-conducting plate (10). The heat-conducting plate (10) is cooled by the semiconductor cooling plate, and the heat-conducting plate (10) cools the liquid in the water tank (1).

7. The centrifugal pump sealing performance testing device according to claim 1, characterized in that: The high-temperature zone (11) of the water tank (1) is inlaid with inwardly inclined glass covers (8) on both sides, and an infrared radiation lamp (9) is installed on the upper side of the glass cover (8). The light from the infrared radiation lamp (9) heats the liquid in the high-temperature zone (11) of the water tank (1) at an angle to the upper side, avoiding contact between the light and the convection zone (12). At the same time, the liquid is heated while it is still, avoiding the liquid from flowing during heating and reducing the disturbance of the convection zone (12).

8. The centrifugal pump sealing performance testing device according to claim 1, characterized in that: The pneumatic system includes a flange plate (21) installed on another port of the centrifugal pump and a pneumatic control valve (22) installed on the flange plate (21). The pneumatic control valve (22) is connected to the air-filling device through a pipe into the support (2) so that high-pressure gas is introduced into the centrifugal chamber of the centrifugal pump. The sealing performance is detected by checking whether there are air bubbles after the centrifugal pump is immersed in water through a water tank (1).

9. A method for testing the sealing performance of a centrifugal pump, characterized in that, The centrifugal pump sealing performance testing device according to any one of claims 1-8 is operated as follows: S1. Place the centrifugal pump to be tested on the platform (4) to ensure the pump body is stable, seal the port of the centrifugal pump with the end plate and the air pressure system, and introduce high pressure gas into the centrifugal chamber of the centrifugal pump. S2. Start the internal lifting device of the support (2), drive the support column (3) to drive the platform (4) to slowly descend, so that the centrifugal pump passes through the high temperature zone (11), the convection zone (12) and the low temperature zone (13), and is immersed in water in sequence, and finally stays in the middle of the low temperature zone (13) to remain stable; S3. Activate the convection suppression structure (5) to suppress hot and cold convection through the synergistic effect of Lorentz force and magnetophoresis force, thereby reducing the disturbance in the convection zone (12). Activate the electric field structure (6) to energize the electrode plates on the four sides of the low temperature zone (13) to form a non-uniform electric field. Use negative permittivity to push the bubbles from the tank wall to the central weak field zone for easy observation. Activate the alternating magnetic field (7) to start the electromagnets with alternating magnetic poles on both sides of the convection zone (12). The alternating magnetophoresis force is generated through the periodic magnetic field gradient reversal, which causes the adsorbed bubbles to fall off. At the same time, Lorentz vortices are generated to counteract turbulence and prevent the bubbles from breaking. S4. Continuously observe the rising of bubbles in the high-temperature zone (11) and judge the sealing performance of the centrifugal pump by observing the bubble situation.

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