Vertical pump cavitation testing device and system

Abstract

The utility model discloses a vertical pump cavitation testing device and system, the device comprises an upper component, a partition plate, a to-be-tested impeller assembly with a lower shaft, and a lower component, the upper component comprises a driving assembly and an upper shaft driven by the driving assembly to rotate; the partition plate is arranged between the upper component and the lower component, a liquid inlet area is formed on the lower side of the partition plate, and a liquid outlet area is formed on the upper side of the partition plate; the lower shaft of the impeller assembly to be tested is connected with the upper shaft of the upper component through a coupling; a communication hole is formed in the middle of the partition plate, the lower shaft is arranged in the communication hole in a penetrating mode, and an impeller of the impeller assembly to be tested can drive liquid to enter the liquid outlet area from the liquid inlet area through the communication hole. The cavitation performance measuring device has the advantages of being high in cavitation performance measuring accuracy, simplifying the test process, saving the test time and saving the test cost.

Description

Technical Field

[0001] This utility model relates to the technical field of pump testing devices, and in particular to a vertical pump cavitation testing device and system. Background Technology

[0002] In cavitation tests of vertical pumps (especially VS6 pumps in the API standard), measuring the cavitation performance of the first-stage impeller presents significant technical challenges. In practical testing applications, to compensate for insufficient net positive suction head (NPSHa) during field use, these pumps employ a submerged impeller mounting structure, increasing the impeller insertion depth to improve the actual NPSHA during operation. However, this design results in a relatively high actual NPSHA for the first-stage impeller.

[0003] Since the required net positive suction head (NPSHr, NPSHa when cavitation begins to occur in the first-stage impeller) is typically only about 1 m, theoretically, as long as it is below the mounting surface, conventional test methods cannot measure cavitation. Current technology uses a vacuum pump to adjust the suction head (hgs) to control test conditions, but this is limited by the actual capacity of the vacuum pump, making it difficult to meet the testing requirements of this type of pump.

[0004] To address these issues, industry professionals typically employ a solution involving the design of a dedicated test fixture shaft. This involves raising the position of the first-stage impeller and reducing the insertion depth to decrease the suction height (Zs value), then combining this with a system vacuum operation to measure NPSHr. However, this approach has significant drawbacks: First, due to the original pump design, the Zs value remains relatively high, meaning that even with an increased impeller position, cavitation performance cannot be accurately measured. Second, dedicated fixture shafts are often custom-made for single orders, resulting in high manufacturing costs. Third, testing requires disassembling the original pump assembly and reassembling it after testing, consuming considerable time and potentially leading to efficiency losses during the manufacturing process.

[0005] Therefore, existing methods for testing the cavitation of the first-stage impeller of vertical pumps suffer from problems such as insufficient measurement accuracy, high cost, and cumbersome procedures. Utility Model Content

[0006] The purpose of this invention is to provide a vertical pump cavitation testing device and system, which at least solves the problem of low accuracy in cavitation performance measurement due to the high Zs value in existing vertical pump first-stage impeller cavitation tests.

[0007] The above-mentioned objectives of this utility model can be achieved by the following technical solutions:

[0008] This utility model provides a vertical pump cavitation testing device, including an upper component, a partition plate, a test impeller assembly with a lower shaft, and a lower component. The upper component includes a drive assembly and an upper shaft driven to rotate by the drive assembly. The partition plate is disposed between the upper component and the lower component, forming an inlet area on the lower side of the partition plate and an outlet area on the upper side of the partition plate. The lower shaft of the test impeller assembly is connected to the upper shaft of the upper component via a coupling. A connecting hole is provided in the middle of the partition plate, through which the lower shaft passes. The impeller of the test impeller assembly can drive liquid from the inlet area through the connecting hole into the outlet area.

[0009] Preferably, the lower component further includes a liquid inlet cylinder and a mounting bracket. The liquid inlet cylinder is mounted on the mounting bracket, and the interior of the liquid inlet cylinder forms the liquid inlet area. The bottom of the mounting bracket forms a mounting plane, and the reference plane of the impeller of the impeller assembly to be tested is at least 0.5 meters higher than the mounting plane. The liquid inlet cylinder has a liquid inlet on its horizontal side, and the bottom surface of the liquid inlet cylinder is higher than the mounting plane. The upper component further includes a liquid outlet cylinder, the interior of which forms the liquid outlet area, and the liquid outlet cylinder has a liquid outlet on its horizontal side.

[0010] Preferably, the connection between the upper shaft and the lower shaft is located inside the liquid outlet cylinder, and the impeller assembly to be tested includes a middle section for supporting the impeller assembly to be tested. The liquid outlet cylinder, the liquid inlet cylinder, and the middle section of the impeller assembly to be tested are all detachably connected to the partition plate.

[0011] Preferably, the upper shaft and the lower shaft are coaxially connected at their adjacent ends, and the coupling includes two limiting half-rings symmetrically arranged about the connecting section and a fixing ring sleeved on the two limiting half-rings. The inner wall of the limiting half-rings forms a limiting groove, and the side walls of the two connecting sections are circumferentially formed with limiting protrusions that abut against the limiting grooves. The fixing ring includes two fixing half-rings, and the two ends of the two fixing half-rings are respectively fixedly connected to limit the relative movement of the two limiting half-rings and the connecting section.

[0012] Preferably, one of the two fixing half-rings is provided with a mounting hole, and the other of the two fixing half-rings is provided with a threaded hole that mates with the mounting hole. The two ends of the two fixing half-rings are fixedly connected by a threaded connection.

[0013] Preferably, the impeller assembly to be tested further includes an intake horn, an intake cover, an impeller, and a guide vane, which are sequentially assembled from bottom to top outside the lower shaft. The guide vane is fitted with the middle section. A lower bearing sleeve and a lower bearing bushing are connected radially outward between the lower shaft and the intake horn. A lower guide bearing is connected between the lower end of the lower bearing bushing and the lower bearing sleeve.

[0014] Preferably, the drive assembly includes a motor, an output coupling, and a bearing housing, with the upper shaft passing through the bearing housing and connected to the output shaft of the motor via the output coupling.

[0015] Preferably, the lower shaft has multiple stepped shaft diameters with different diameters to test impeller assemblies of different sizes.

[0016] Preferably, the length of the lower shaft is 300mm to 400mm.

[0017] Another objective of this invention is to provide a vertical pump cavitation testing system, comprising: the vertical pump cavitation testing device as described above; a test conduit, wherein the inlet pipe of the test conduit is connected to the liquid outlet area, and the outlet pipe of the test conduit is connected to the liquid inlet area, thereby forming a closed test loop.

[0018] The features and advantages of this utility model are as follows: The vertical pump cavitation testing device provided by this utility model achieves the positioning and connection of the upper component, lower component, and impeller assembly under test through a partition plate, and realizes the power transmission between the drive assembly and the impeller assembly under test through the transmission connection of the upper and lower shafts. This eliminates the installation space occupied by the guide pipe in the traditional cavitation test scheme, reduces the distance between the installation plane and the impeller suction center line, thereby reducing the Zs value and improving the accuracy of cavitation performance measurement. Furthermore, the upper component, lower component, and impeller assembly under test adopt an integrated modular design. For vertical pumps of different orders, only the different impeller assemblies under test need to be replaced to quickly enter the cavitation test of different vertical pumps. This solves the problems of the prior art, which requires disassembling the original assembly of the pump body and restoring it after testing, resulting in time and labor costs, and the high cost caused by the tooling shaft usually only being available for a single order. This utility model has the advantages of simplifying the test process, saving test time and test costs. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the vertical pump cavitation testing device provided in the embodiment of this utility model.

[0021] Figure 2 This is an exploded view of the connection between the upper and lower shafts in the vertical pump cavitation testing device provided in this embodiment of the present invention.

[0022] Figure 3 This is a schematic diagram showing the connection between the lower component and the impeller assembly to be tested in the vertical pump cavitation testing device provided in this embodiment of the present invention.

[0023] Explanation of icon numbers:

[0024] 1. Upper assembly; 11. Drive assembly; 111. Motor; 112. Output coupling; 113. Bearing housing; 12. Liquid outlet cylinder; 121. Liquid outlet; 13. Upper shaft; 131. Upper connecting section; 132. Upper limit ring; 14. Motor bracket; 15. Connecting parts; 16. Seals;

[0025] 2. Divider plate; 21. Connecting hole;

[0026] 3. Impeller assembly to be tested; 31. Lower shaft; 311. Lower connecting section; 312. Lower limit ring; 32. Suction nozzle; 33. Suction cover; 34. Impeller; 35. Guide vane; 36. Intermediate section; 37. Lower bearing sleeve; 38. Lower bearing bushing; 39. Lower guide bearing;

[0027] 4. Lower component; 41. Liquid inlet cylinder; 411. Liquid inlet; 42. Mounting bracket; 421. Mounting surface;

[0028] 5. Coupling; 51. Limiting half ring; 511. Limiting groove; 52. Fixing half ring. Detailed Implementation

[0029] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0030] like Figures 1 to 3As shown, this utility model provides a vertical pump cavitation testing device, including an upper component 1, a partition plate 2, a test impeller assembly 3 with a lower shaft 31, and a lower component 4 with an inlet cylinder 41. The upper component 1 includes a drive assembly 11, an outlet cylinder 12 connected to the lower part of the drive assembly 11, and an upper shaft 13 that is drively connected to the drive assembly 11. The lower component 4 is connected to the upper component 1 through the partition plate 2, and an inlet area is formed between the inlet cylinder 41 and the partition plate 2, separating the pump. A liquid outlet area is formed between plate 2 and liquid outlet cylinder 12; the impeller assembly 3 to be tested is located in the liquid inlet area, and the impeller assembly 3 to be tested is connected to the upper shaft 13 through the lower shaft 31; the middle part of the partition plate 2 is provided with a connecting hole 21, the lower shaft 31 passes through the connecting hole 21, and the annular space between the connecting hole 21 and the lower shaft 31 is used to connect the fluid channel of the impeller assembly 3 to be tested and the liquid outlet area. The impeller 34 of the impeller assembly 3 to be tested can drive the liquid from the liquid inlet area to the liquid outlet area through the connecting hole 21.

[0031] For example, the partition plate 2 can be a flat plate structure with a predetermined thickness, having an upper surface and a lower surface opposite each other along the thickness direction. The outer contour of the lower surface of the partition plate 2 can cover the opening end of the liquid inlet cylinder 41, and the lower surface of the partition plate 2 is sealed to the opening end of the liquid inlet cylinder 41 to form a liquid inlet area. The outer contour of the upper surface of the partition plate 2 can cover the opening end of the liquid outlet cylinder 12, and the upper surface of the partition plate 2 is sealed to the opening end of the liquid outlet cylinder 12 to form a liquid outlet area.

[0032] API 610, version 12, clause 8.3.4.3.2 specifies the testing requirements for pump net positive suction head (NPSHr): The NPSHr test should determine the NPSH3 value at each test point 2, 5, 6, 7, and 8 (as described in 8.3.3.4.1) based on a 3% drop in head for a single-stage pump or a 3% drop in head for the first stage of a two- or multi-stage pump. If possible, the first stage head of a two- or multi-stage pump should be measured using a separate connection to the first-stage discharge port, or only the first stage should be tested. Therefore, for vertical pumps, the requirements for testing only the first-stage impeller (first-stage impeller) are typically only required.

[0033] During cavitation testing, the vertical pump cavitation testing device is mounted on the test bench via the mounting plane 421 of the lower component 4 and connected to the closed test loop. Following standard cavitation testing procedures, the required net positive suction head (NPSHr) of the vertical pump using the impeller assembly 3 under test as the first-stage impeller can be verified. In the cavitation test, water flows through the closed test loop into the inlet cylinder 41, then through the fluid channel of the impeller assembly 3 under test, and finally into the outlet cylinder 12 via the connecting port. From there, water flows back into the closed test loop, forming a circulating flow.

[0034] The vertical pump cavitation testing device provided by this utility model uses a partition plate 2 to position and connect the upper component 1, lower component 4, and impeller assembly 3 under test. The drive assembly 11 and impeller assembly 3 under test are connected via a transmission link between the upper shaft 13 and the lower shaft 31. This eliminates the installation space occupied by the guide pipe in traditional cavitation testing schemes, reduces the distance between the mounting plane 421 and the suction center line of the impeller 34, thereby lowering the Zs value and improving the accuracy of cavitation performance measurement. Furthermore, the upper component 1, lower component 4, and impeller assembly 3 under test adopt an integrated modular design. For vertical pumps from different orders, only the impeller assembly 3 under test needs to be replaced to quickly begin cavitation testing on different vertical pumps. This solves the problems of existing technologies that require disassembling the original pump body assembly and reassembling it after testing, which is time-consuming and labor-intensive, and the high cost caused by tooling shafts typically only being usable for a single order. This utility model has the advantages of simplifying the testing process, saving testing time, and reducing testing costs.

[0035] According to one embodiment of the present invention, such as Figure 1 As shown, the lower component 4 also includes a mounting bracket 42. The inlet cylinder 41 is mounted on the mounting bracket 42. The bottom of the mounting bracket 42 forms a mounting plane 421. The bottom surface of the inlet cylinder 41 is higher than the mounting plane 421, and the reference plane of the impeller 34 of the impeller assembly 3 to be tested is more than 0.5 meters higher than the mounting plane 421 to facilitate cavitation. Specifically, according to the requirements of GB3216-2016 and ANSI / HI14.6-2011, NPSHa=hsa-hvp=hatm+hs-hvp=hatm+(hgs+hvs+Zs)-hvp, where hsa is the absolute suction head, hs is the suction inlet head, hatm is the atmospheric head, hgs is the suction measurement head (i.e., the apparent head), hvs is the suction velocity head, Zs is the vertical height difference between the pump suction centerline and the mounting plane 421, and hvp is the absolute vapor pressure of the liquid at the pump head. In this embodiment, Zs is positive when the mounting plane 421 is above the pump suction centerline, and negative otherwise. In this embodiment, the mounting plane 421 is located below the base surface of the impeller 34, making Zs negative. During the cavitation test, NPSHA can be reduced simply by controlling the valve opening, causing the impeller assembly 3 under test to reach a cavitation state, thus allowing for more accurate determination of its performance parameters such as net positive suction head (NPSH).

[0036] According to one embodiment of the present invention, such as Figure 1 and Figure 3As shown, the connection between the upper shaft 13 and the lower shaft 31 is located within the liquid outlet area. The impeller assembly 3 under test includes a middle section 36 for supporting the impeller 34. The liquid outlet cylinder 12, the liquid inlet cylinder 41, and the middle section 36 of the impeller assembly 3 under test are all detachably connected to the partition plate 2. This facilitates the quick replacement of different impeller assemblies 3 under test. For example, a through hole is provided in the middle of the cylinder wall of the liquid outlet cylinder 12 away from the partition plate 2 (i.e., the closed end of the liquid outlet cylinder 12). The upper shaft 13 is sealed and passes through this through hole and is connected to the lower shaft 31 within the liquid outlet area.

[0037] According to one embodiment of this utility model, the upper shaft 13 and the lower shaft 31 are coaxially connected at their adjacent ends, and the two connecting sections abut against each other and are connected by a coupling 5. Specifically, as shown... Figure 2 As shown, the lower part of the upper shaft 13 forms an upper connecting section 131, and the upper part of the lower shaft 31 forms a lower connecting section 311. The upper connecting section 131 and the lower connecting section 311 are aligned and abutted together and are fixedly connected by the coupling 5 to stably and efficiently transmit the output power of the drive assembly 11 to the impeller assembly 3 under test.

[0038] According to one embodiment of this utility model, the coupling 5 includes two limiting semi-rings 51 symmetrically arranged about the connecting section and a fixing ring sleeved on the two limiting semi-rings 51. The inner wall of the limiting semi-rings 51 forms a limiting groove 511, and the side walls of the two connecting sections have limiting protrusions that abut against the limiting grooves 511 along the circumferential direction. The fixing ring includes two fixing semi-rings 52, the two ends of which are fixedly connected to limit the relative movement of the two limiting semi-rings 51 and the connecting section. Specifically, as shown... Figure 2 As shown, the free end of the upper connecting section 131 extends radially outward to form an upper limit convex ring 132, and the free end of the lower connecting section 311 extends radially outward to form a lower limit convex ring 312. The limiting groove 511 is a U-shaped groove, and the two groove arms of the limiting groove 511 abut against the upper limit convex ring 132 and the lower limit convex ring 312 respectively to axially limit the upper shaft 13 and the lower shaft 31. Two fixed half-rings 52 are arranged around the limiting half-rings 51, and the two ends of the two fixed half-rings 52 are fixedly connected to press the two limiting half-rings 51, thereby completely restricting the relative movement of the upper shaft 13 and the lower shaft 31, so as to realize the stable and efficient transmission of the output power of the drive assembly 11.

[0039] According to one embodiment of the present invention, such as Figure 2 As shown, one of the two fixed half-rings 52 has a mounting hole, and the other of the two fixed half-rings 52 has a threaded hole that mates with the mounting hole. The two ends of the two fixed half-rings 52 are fixedly connected by a threaded connection. This facilitates quick assembly and disassembly of the impeller assembly 3 to be tested from the upper component 1.

[0040] According to one embodiment of the present invention, such as Figure 3As shown, the impeller assembly 3 under test also includes, from bottom to top, an intake bell 32, an intake cover 33, an impeller 34, and a guide vane 35, all assembled outside the lower shaft 31. A middle section 36 is fitted over the guide vane 35. A lower bearing sleeve 37 and a lower bearing bushing 38 are connected radially outward between the lower shaft 31 and the intake bell 32. A lower guide bearing 39 is connected between the lower end of the lower bearing bushing 38 and the lower bearing sleeve 37. The impeller assembly 3 under test is connected to the partition plate 2 via the middle section 36. The middle section 36 and the partition plate 2 can be assembled by a mating plug-in structure designed at their closest points. In the cavitation test, after the water enters the inlet cylinder 41, it flows sequentially through the intake bell 32, impeller 34, guide vane 35, and the flow channel formed between the connecting hole 21 and the lower shaft 31, before flowing out of the outlet cylinder 12. The specific flow direction is shown in [reference needed]. Figure 3 As indicated by the hollow arrow.

[0041] According to one embodiment of the present invention, the drive assembly 11 includes a motor 111, an output coupling 112, and a bearing housing 113. The upper shaft 13 passes through the bearing housing 113 and is connected to the output shaft of the motor 111 via the output coupling 112. Specifically, as shown... Figure 1 As shown, the motor 111 is detachably connected to the bearing housing 113 via the motor bracket 14. The bearing housing 113 is detachably connected to the liquid outlet cylinder 12 via a connector 15 at its lower end, balancing connection reliability and operational flexibility. The upper shaft 13 passes through the bearing housing 113 and is connected to the output shaft of the motor 111 via the output coupling 112 for stable and efficient power transmission. A seal 16 is provided between the portion of the upper shaft 13 extending downwards from the bearing housing 113 and the bearing housing 113 to seal the bearing housing 113.

[0042] According to one embodiment of this utility model, there are multiple impeller assemblies 3 to be tested, and these multiple impeller assemblies 3 are applied to vertical pumps with different performance characteristics. Specifically, when conducting cavitation tests on vertical pumps with different performance characteristics, firstly, a suitable lower shaft 31 is selected, the connection between the partition plate 2 and the upper component 1 and the lower component 4 is loosened, the upper component 1 is lifted, and then the lower shaft 31 is fixed to the upper shaft 13 with two limiting half-rings 51 and connected and tightened by two fixing half-rings 52. Then, the partition plate 2, the middle section 36, the guide vane 35, the impeller 34, the suction cover 33, the lower bearing sleeve 37, the lower bearing bushing 38, the lower guide bearing 39, and the suction bell mouth 32 are installed in sequence. Finally, the entire assembly is lowered onto the liquid inlet cylinder 41, and the liquid inlet cylinder 41 and the partition plate 2 are connected and tightened. The device is connected to a closed test circuit. After inspection according to the standard test procedure, the cavitation test can be carried out. After the test is completed, it is only necessary to reverse the above steps to remove and reinstall the new impeller assembly 3 to be tested. The new impeller assembly 3 to be tested differs from the current impeller assembly 3 to be tested in that the impeller 34 and the lower shaft 31 are different. That is, only the impeller 34 and the lower shaft 31 need to be replaced to reinstall and start a new round of cavitation test.

[0043] According to one embodiment of this utility model, the length of the lower shaft is 300mm~400mm, which is beneficial for saving disassembly and assembly time and miniaturizing the design of the middle section and the liquid outlet cylinder.

[0044] According to one embodiment of this invention, the lower shaft has multiple stepped shaft diameters with different diameters to test impeller assemblies of different sizes. Thus, when performing cavitation tests on vertical pumps with different performance characteristics, only the impeller needs to be replaced.

[0045] It should be noted that in the test impeller assembly 3 with a one-to-one configuration of impeller 34 and lower shaft 31, the length of the lower shaft is generally designed to be 300mm~400mm; in the test impeller assembly 3 with a multiple-to-one configuration of impeller 34 and lower shaft 31, since the lower shaft 31 has multiple stepped shaft diameters with different diameters to test impellers 34 of different sizes in different test impeller assemblies 3, the length of the lower shaft 31 is not limited to 300mm~400mm.

[0046] Based on the above, the vertical pump cavitation testing device provided in this embodiment of the present invention has the following beneficial effects:

[0047] The vertical pump cavitation testing device provided in this embodiment uses a partition plate 2 to position and connect the upper component 1, lower component 4, and impeller assembly 3 under test. Power transmission between the drive assembly 11 and the impeller assembly 3 is achieved through the transmission connection between the upper shaft 13 and the lower shaft 31. This eliminates the installation space occupied by the guide pipe in traditional cavitation testing schemes, reduces the distance between the mounting plane 421 and the suction center line of the impeller 34, thereby lowering the Zs value and improving the accuracy of cavitation performance measurement. Furthermore, the upper component 1, lower component 4, and impeller assembly 3 under test adopt an integrated modular design, allowing for the replacement of different impeller assemblies for different orders. The impeller assembly 3 can quickly enter the cavitation test of different vertical pumps, which solves the problems of the prior art, which requires disassembling the original pump body assembly and restoring it after the test, resulting in time and labor costs, and the tooling shaft usually only being available for a single order, resulting in high costs. This utility model has the advantages of simplifying the test process, saving test time and test costs. In addition, the mounting plane 421 of the mounting bracket 42 in the lower component 4 is located below the base surface where the impeller 34 is located, so that Zs is negative. In the cavitation test, NPSHa can be reduced by simply controlling the valve opening, so that the impeller assembly 3 under test reaches the cavitation state, thereby more accurately measuring its cavitation margin and other performance parameters.

[0048] Another objective of this utility model is to provide a vertical pump cavitation testing system, comprising: the vertical pump cavitation testing device as described above; a test conduit, the inlet pipe of which is connected to the outlet cylinder 12, and the outlet pipe of which is connected to the inlet cylinder 41, thereby forming a closed test loop. Wherein, as... Figure 1 and Figure 3 As shown, the liquid outlet cylinder 12 has a liquid outlet 121 on its horizontal side for connecting to the inlet pipe of the test conduit, and the liquid inlet cylinder 41 has a liquid inlet 411 on its horizontal side for connecting to the outlet pipe of the test conduit, thus forming a circulating liquid supply.

[0049] The vertical pump cavitation testing system provided by this utility model can achieve the technical effects of the above-mentioned vertical pump cavitation testing device by setting up the vertical pump cavitation testing device. For details, please refer to the specific description of the above-mentioned embodiments, which will not be repeated here.

[0050] The above descriptions are merely a few embodiments of this utility model. Those skilled in the art can make various modifications or variations to the embodiments of this utility model based on the content disclosed in the application documents without departing from the spirit and scope of this utility model.

Claims

1. A vertical pump cavitation testing device, characterized in that, It includes an upper assembly, a partition plate, a test impeller assembly with a lower shaft, and a lower assembly, wherein the upper assembly includes a drive assembly and an upper shaft driven to rotate by the drive assembly; The partition plate is disposed between the upper component and the lower component, and a liquid inlet area is formed on the lower side of the partition plate, and a liquid outlet area is formed on the upper side of the partition plate; The lower shaft of the impeller assembly under test is connected to the upper shaft of the upper component via a coupling; The partition plate has a connecting hole in the middle, and the lower shaft passes through the connecting hole. The impeller of the impeller assembly to be tested can drive liquid from the inlet area through the connecting hole into the outlet area.

2. The vertical pump cavitation testing device according to claim 1, characterized in that, The lower component also includes a liquid inlet cylinder and a mounting bracket. The liquid inlet cylinder is mounted on the mounting bracket. The liquid inlet area is formed inside the liquid inlet cylinder. The bottom of the mounting bracket forms a mounting plane. The reference plane of the impeller of the impeller assembly to be tested is more than 0.5 meters higher than the mounting plane. The liquid inlet is provided on the horizontal side of the liquid inlet cylinder, and the bottom surface of the liquid inlet cylinder is higher than the mounting plane; The upper component also includes a liquid outlet cylinder, the liquid outlet area is formed inside the liquid outlet cylinder, and a liquid outlet is provided on the horizontal side of the liquid outlet cylinder.

3. The vertical pump cavitation testing device according to claim 2, characterized in that, The connection between the upper shaft and the lower shaft is located inside the liquid outlet cylinder. The impeller assembly to be tested includes a middle section for supporting the impeller assembly to be tested. The liquid outlet cylinder, the liquid inlet cylinder, and the middle section of the impeller assembly to be tested are all detachably connected to the partition plate.

4. The vertical pump cavitation testing device according to claim 1, characterized in that, The upper shaft and the lower shaft are coaxially connected at their adjacent ends. The coupling includes two limiting semi-rings symmetrically arranged about the connecting section and a fixing ring sleeved on the two limiting semi-rings. The inner wall of the limiting semi-rings forms a limiting groove. The side walls of the two connecting sections are circumferentially formed with limiting protrusions that abut against the limiting grooves. The fixing ring includes two fixing semi-rings, and the two ends of the two fixing semi-rings are respectively fixedly connected to limit the relative movement of the two limiting semi-rings and the connecting section.

5. The vertical pump cavitation testing device according to claim 4, characterized in that, One of the two fixed half-rings is provided with a mounting hole, and the other of the two fixed half-rings is provided with a threaded hole that mates with the mounting hole. The two ends of the two fixed half-rings are fixedly connected by a threaded connection.

6. The vertical pump cavitation testing device according to claim 3, characterized in that, The impeller assembly to be tested also includes an intake horn, an intake cover, an impeller, and a guide vane, which are assembled sequentially from bottom to top outside the lower shaft. The guide vane is fitted with the middle section. A lower bearing sleeve and a lower bearing bushing are connected radially outward between the lower shaft and the intake horn. A lower guide bearing is connected between the lower end of the lower bearing bushing and the lower bearing sleeve.

7. The vertical pump cavitation testing device according to claim 1, characterized in that, The drive assembly includes a motor, an output coupling, and a bearing housing. The upper shaft passes through the bearing housing and is connected to the output shaft of the motor via the output coupling.

8. The vertical pump cavitation testing device according to claim 1, characterized in that, The lower shaft has multiple stepped shaft diameters with different diameters, used to test the impeller assemblies of different sizes.

9. The vertical pump cavitation testing device according to claim 1, characterized in that, The length of the lower shaft is 300mm~400mm.

10. A vertical pump cavitation testing system, characterized in that, include: The vertical pump cavitation testing device as described in any one of claims 1-9; The test conduit has an inlet tube connected to the outlet area and an outlet tube connected to the inlet area, thereby forming a closed test loop.

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