Observation Device and Observation Method for Cavitation Condition of Water Pump Impeller Based on Hollow Sphere

Abstract

The present invention discloses an observation device for the cavitation condition of a water pump impeller based on hollow balls, including a water pump and auxiliary devices. The water pump includes an inlet section (1), a pump casing (2), an outlet section (3), an impeller (4) and a main shaft (5). The auxiliary devices include an inlet pipe (6), an outlet pipe (12), an opening pipe (7), a container (8), a gate valve (9), hollow small iron balls (10) and water (11). The present invention also discloses an observation method for the cavitation condition of a water pump impeller based on hollow balls, including steps of connecting the water pump and auxiliary devices to a pump performance test station, adjusting the pump performance test station, gradually releasing the hollow small iron balls (10) and water (11) in the container (8) into the inlet pipe (6) through a circular opening (71) on the opening pipe (7), then stopping the water pump test and disassembling the impeller (4) to take pictures and observe to obtain the adsorption condition of the hollow small iron balls (10) on the impeller (4), etc. The observation device disclosed by the present invention has a simple structure, is convenient to manufacture and has a low cost. The corresponding observation method is simple to operate, intuitive and reliable, and the obtained results have high precision and rich information.

Description

Technical Field

[0001] The present invention relates to the field of water pumps, and in particular to an observation device and an observation method for the cavitation condition of a water pump impeller based on hollow spheres. Background Art

[0002] Water pumps are widely used in various fields of industrial and agricultural production and residential life, playing the role of fluid transportation and pressurization. Cavitation may occur during the operation of a water pump, and the impeller is the most vulnerable part to cavitation. When water with a relatively low pressure is sucked into the water pump from the inlet, the water velocity increases under the action of the impeller and the pressure at the wall surface of some positions of the impeller slightly decreases. When the pressure of the water is lower than the vaporization pressure at the corresponding temperature, the water will vaporize and turn into bubbles containing water vapor and generate from the wall surface of the impeller, resulting in cavitation at some parts of the impeller; and when the bubbles containing water vapor move to the high-pressure area in the impeller flow channel, they will compress and collapse. The cavitation performance of a water pump is related to the design and manufacturing factors of the water pump. In order to enhance the cavitation resistance of the water pump, in addition to testing the cavitation performance curve of the water pump, the most important thing is to understand the cavitation condition of the water pump impeller, that is, to obtain the generation position and generation amount of bubbles on the surface of the water pump impeller. On this basis, the structure and process of the water pump are optimized and designed.

[0003] Currently, the well-known method for obtaining the generation situation of bubbles on the surface of a water pump impeller is to use plexiglass to make a transparent water pump housing, and then conduct high-speed photography observation during the water pump test, and analyze the generation position and generation amount of bubbles on the surface of the impeller during the cavitation process according to the images. However, this method has three significant disadvantages: First, due to the high production cost of the plexiglass pump housing and its poor structural strength and pressure-bearing capacity, it is generally only applicable to the research of small experimental pumps in the laboratory and is not applicable to actual industrial pumps with large sizes, high pressure-bearing capacity, and large vibrations; Second, the photography method can only observe the generation situation of bubbles at some positions of the impeller at the front end of the field of view, and it is not easy to observe the sheltered positions; Third, the photography method can only obtain two-dimensional images, and the observation results are not clear, intuitive, and vivid enough.

[0004] Therefore, in view of the deficiencies of the existing well-known technical solutions, according to the needs of water pump cavitation resistance research and design, it is necessary to develop an observation device and an observation method for the cavitation condition of a water pump impeller that meet industrial requirements, and obtain intuitive, reliable, high-precision, and information-rich observation results. Summary of the Invention

[0005] In order to solve the above technical problems, the present invention provides an observation device for the cavitation condition of a water pump impeller based on hollow spheres, and provides an observation method.

[0006] According to one aspect of the present invention, the technical solution for solving the above problems is: an observation device for the cavitation condition of a water pump impeller based on hollow balls, including a water pump and auxiliary devices. The water pump includes an inlet section, a pump casing, an outlet section, an impeller, and a main shaft. The auxiliary devices include an inlet pipe connected to the inlet section of the water pump, an outlet pipe connected to the outlet section of the water pump, an opening pipe vertically inserted into the inlet pipe from the outside of the inlet pipe, a container located outside the inlet pipe and connected to the opening pipe, a gate valve located at the connection between the opening pipe and the container, a number of hollow small iron balls and water located in the container.

[0007] For the above observation device for the cavitation condition of a water pump impeller based on hollow balls, the diameter of the hollow small iron balls is between 1 mm and 5 mm, and the volumetric density of the hollow small iron balls is equal to the density of water so that the hollow small iron balls can suspend in water.

[0008] For the above observation device for the cavitation condition of a water pump impeller based on hollow balls, a number of circular openings are provided on the pipe wall of the part of the opening pipe located inside the inlet pipe, and the sizes and mutual spacings of all the openings are the same. The diameter of the openings is 1.5 to 3 times the diameter of the hollow small iron balls.

[0009] For the above observation device for the cavitation condition of a water pump impeller based on hollow balls, the material of the impeller is magnetic and can attract ferromagnetic materials through magnetic force. The material of the main shaft is not ferromagnetic, and an interference fit relationship exists between the impeller and the main shaft.

[0010] According to another aspect of the present invention, an observation method using the above observation device for the cavitation condition of a water pump impeller based on hollow balls is provided, including the following steps:

[0011] Step S1: Keep the gate valve in the closed state and connect the water pump and auxiliary devices to the pump performance test station.

[0012] Step S2: Adjust the pump performance test station to make the water pump operate at the rotation speed, flow rate, and inlet pressure to be observed.

[0013] Step S3: Open the gate valve to allow the hollow small iron balls and water in the container to gradually be released into the inlet pipe through the circular openings on the opening pipe.

[0014] Step S4: After all the hollow small iron balls in the container are released, close the gate valve, wait for 1 to 5 minutes, and then stop the water pump test.

[0015] Step S5: Disassemble the impeller of the water pump for photographing and observation to obtain the adsorption condition of the hollow small iron balls on the impeller.

[0016] For the above-mentioned method for observing the cavitation condition of the water pump impeller based on hollow spheres, during the water pump test, the pressure in the container can be adjusted by pressurizing or depressurizing the container to ensure that the pressure in the container is 1000 Pa to 5000 Pa higher than the pressure at the position of the opening pipe in the inlet pipe.

[0017] The beneficial effects of the present invention are as follows:

[0018] 1. The observation device provided by the present invention has a simple structure, is easy to manufacture, and has a low cost. Among them, the water pump can be obtained by simply replacing parts or processing the process on the basis of existing industrial water pumps, including magnetizing the impeller to make it magnetic, and replacing the main shaft with a non-ferromagnetic material to avoid the main shaft being magnetized and attracting hollow small iron balls; the auxiliary device includes an inlet pipe communicating with the inlet section of the water pump, an outlet pipe communicating with the outlet section of the water pump, an opening pipe vertically inserted into the inlet pipe from the outside of the inlet pipe, a container located outside the inlet pipe and communicating with the opening pipe, a gate valve located at the connection between the opening pipe and the container, hollow small iron balls and water located in the container, and can all be obtained by conventional materials and processing and assembly processes.

[0019] 2. The corresponding observation method of the present invention is simple to operate and highly reliable. During the process of using a pump performance test station to conduct a conventional test on the water pump, only the link of opening the gate valve to release the hollow small iron balls is added, which does not affect the existing test process. The hollow small iron balls suspended in the water are uniformly released into the inlet pipe through the circular openings uniformly arranged on the opening pipe together with the water, and flow into the area near the impeller along with the water flow. At this time, in the area where more bubbles are generated on the surface of the impeller, since the impeller wall is covered with bubbles and bubbles are constantly emerging, it is difficult for the hollow small iron balls to be adsorbed by the magnetic impeller wall; while in the area where no bubbles or fewer bubbles are generated on the surface of the impeller, the hollow small iron balls are easily adsorbed by the magnetic impeller wall. Finally, when the test stops and the impeller is disassembled, the distribution density of the hollow small iron balls on each part of the impeller surface is inconsistent: in the area with more serious cavitation, more and larger bubbles are generated, and fewer hollow small iron balls are adsorbed; on the contrary, in the area where cavitation is not obvious or there is no cavitation, fewer and smaller bubbles are generated, and more hollow small iron balls are adsorbed, thereby realizing the observation of the cavitation condition of the impeller.

[0020] 3. The corresponding observation method of the present invention is intuitive and reliable, and the obtained results are highly accurate and rich in information. Compared with the existing image photography method, not only does it not require an expensive and fragile plexiglass pump shell, but also the observer can observe the adsorption of hollow small iron balls in each area of the impeller from multiple angles and at close range, which can obtain a better and more intuitive observation experience and observation effect, and can also provide more abundant, accurate information for the design and optimization of the water pump's cavitation resistance performance. Description of the Drawings

[0021] Figure 1 It is a schematic structural diagram in an embodiment of the present invention. Detailed implementation mode

[0022] The present invention will be further described below in conjunction with the drawings and embodiments.

[0023] As Figure 1 shown, an observation device for the cavitation condition of a water pump impeller based on hollow balls includes a water pump and auxiliary devices. The water pump includes an inlet section 1, a pump casing 2, an outlet section 3, an impeller 4, and a main shaft 5. The auxiliary devices include an inlet pipe 6 connected to the inlet section 1 of the water pump, an outlet pipe 12 connected to the outlet section 3 of the water pump, an opening pipe 7 vertically inserted into the inlet pipe 6 from the outside of the inlet pipe 6, a container 8 located outside the inlet pipe 6 and connected to the opening pipe 7, a gate valve 9 located at the connection between the opening pipe 7 and the container 8, a number of hollow small iron balls 10 and water 11 located in the container 8.

[0024] For the above-mentioned observation device for the cavitation condition of a water pump impeller based on hollow balls, the diameter of the hollow small iron balls 10 is between 1 mm and 5 mm, and the volumetric density of the hollow small iron balls 10 is equal to the density of water so that the hollow small iron balls 10 can suspend in water.

[0025] For the above-mentioned observation device for the cavitation condition of a water pump impeller based on hollow balls, a number of circular openings 71 are provided on the pipe wall of the part of the opening pipe 7 located inside the inlet pipe 6, and the sizes and mutual distances of all the openings 71 are the same. The diameter of the openings 71 is 1.5 to 3 times the diameter of the hollow small iron balls 10.

[0026] For the above-mentioned observation device for the cavitation condition of a water pump impeller based on hollow balls, the material of the impeller 4 is magnetic and can attract ferromagnetic materials through magnetic force. The material of the main shaft 5 is not ferromagnetic, and an interference fit relationship exists between the impeller 4 and the main shaft 5.

[0027] An observation method applied to the above-mentioned observation device for the cavitation condition of a water pump impeller based on hollow balls includes the following steps:

[0028] Step S1: Keep the gate valve 9 in a closed state, and connect the water pump and auxiliary devices to the pump performance test station;

[0029] Step S2: Adjust the pump performance test station to make the water pump operate at the required rotational speed, flow rate, and inlet pressure for observation;

[0030] Step S3: Open the gate valve 9 to allow the hollow small iron balls 10 and water 11 in the container 8 to pass through the circular openings 71 on the opening pipe 7 and be gradually released into the inlet pipe 6;

[0031] Step S4: After all the hollow small iron balls 10 in the container 8 are released, close the gate valve 9, wait for 1 to 5 minutes, and then stop the water pump test;

[0032] Step S5: Disassemble the impeller 4 of the water pump for photographing and observation to obtain the adsorption condition of the hollow small iron balls 10 on the impeller 4.

[0033] In the above observation method of the cavitation condition of the water pump impeller based on hollow balls, during the water pump test, the pressure in the container 8 can be adjusted by pressurizing or depressurizing the container 8 to ensure that the pressure in the container 8 is 1000 Pa to 5000 Pa higher than the pressure at the position of the inlet pipe 6 where the perforated pipe 7 is located.

[0034] Embodiment

[0035] A certain water pump, driven by an electric motor, with a rated flow rate, rated head and rated speed of 600 m 3 / h, 100 m and 1480 r / min respectively. First, it is necessary to observe the cavitation condition of the impeller of this water pump at the rated flow rate and speed, and when the absolute inlet pressure is 0.97 times the atmospheric pressure.

[0036] In the observation device, the impeller 4 is made of magnetic steel and can attract iron materials through magnetic force. The main shaft 5 is made of copper that does not attract magnetic materials. The diameter of the hollow small iron balls 10 is 1.5 mm and they can suspend in water. Three evenly distributed circular openings 71 with a diameter of 3 mm are provided on the pipe wall of the part of the perforated pipe 7 inside the inlet pipe 6. The container 8 is connected to the perforated pipe 7 through a gate valve 9. There are 1000 hollow small iron balls 10 and water 11 in the container 8, and the hollow small iron balls 10 are suspended in the water 11.

[0037] During the observation, the following steps are taken:

[0038] Step S1: Keep the gate valve 9 closed and connect the water pump and its accessories to the pump performance test station;

[0039] Step S2: Adjust the pipeline valves and motor speed of the pump performance test station to make the water pump operate at the required speed, flow rate and inlet pressure, that is, the flow rate is 600 m 3 / h, the speed is 1480 r / min, and the inlet pressure is 0.97 times the atmospheric pressure;

[0040] Step S3: Open the gate valve 9 to allow the hollow small iron balls 10 and water 11 in the container 8 to pass through the circular openings 71 on the perforated pipe 7 and be gradually released into the inlet pipe 6;

[0041] Step S4: After all the hollow small iron balls 10 in the container 8 are released, close the gate valve 9, wait for 2 minutes, and then stop the water pump test;

[0042] Step S5: Disassemble the impeller 4 of the water pump for photographing and observation to obtain the adsorption condition of the hollow small iron balls 10 on the impeller 4.

[0043] In this embodiment, it is finally found that the densities of the hollow small iron balls 10 adsorbed on the surfaces of various parts of the impeller 4 are different. The number of hollow small iron balls 10 on the back of the blade near the front cover plate at the blade inlet is small, indicating that the cavitation condition at this position is more serious than that at other positions.

[0044] It should be noted that in this embodiment, the absolute pressure at the inlet of the water pump required during the water pump test process is 0.97 times the atmospheric pressure. In this case, the container 8 can be directly opened to communicate with the atmosphere to ensure that the pressure in the container 8 is 1000 Pa to 5000 Pa higher than the pressure at the position of the inlet pipe 6 where the orifice pipe 7 is located; if the absolute pressure at the inlet of the water pump differs greatly from the atmospheric pressure, at this time, a method of pressurizing or depressurizing the container 8 should be adopted to ensure that the pressure in the container 8 is 1000 Pa to 5000 Pa higher than the pressure at the position of the inlet pipe 6 where the orifice pipe 7 is located, so as to facilitate the release of the hollow small iron balls 10 into the inlet pipe 6.

[0045] In addition, if necessary, the pump performance test station can be manually controlled to make the water pump operate at the required rotational speed and flow rate, but sufficient inlet pressure is given to the water pump so that no cavitation occurs. Under this operating condition, the hollow small iron balls 10 are released and the adsorption situation of the hollow small iron balls 10 on the impeller 4 is observed. Finally, the adsorption situations of the hollow small iron balls 10 on the impeller 4 in the cases of no cavitation and cavitation are compared, so as to better observe and study the cavitation condition of the impeller.

[0046] The observation device provided in this embodiment has a simple structure, is easy to manufacture, and has a low cost. Among them, the water pump can be obtained by simply replacing parts or processing the existing industrial water pump, including magnetizing the impeller to make it magnetic, and replacing the main shaft with a non-ferromagnetic material to prevent the main shaft from being magnetized and attracting the hollow small iron balls; the auxiliary devices include an inlet pipe connected to the inlet section of the water pump, an outlet pipe connected to the outlet section of the water pump, an opening pipe vertically inserted into the inlet pipe from the outside of the inlet pipe, a container located outside the inlet pipe and connected to the opening pipe, a gate valve located at the connection between the opening pipe and the container, the hollow small iron balls and water in the container, and can all be obtained by conventional materials and processing and assembly processes. The observation method provided in this embodiment is simple to operate and has high reliability. During the process of using a pump performance test station to conduct a conventional test on the water pump, only the link of opening the gate valve to release the hollow small iron balls is added, which does not affect the existing test process. The hollow small iron balls suspended in the water are uniformly released into the inlet pipe through the circular openings uniformly arranged on the opening pipe together with the water, and flow into the area near the impeller along with the water flow. At this time, in the area where more bubbles are generated on the surface of the impeller, since the impeller wall is covered with bubbles and bubbles are constantly emerging, it is difficult for the hollow small iron balls to be adsorbed by the magnetic impeller wall; while in the area where no bubbles or fewer bubbles are generated on the surface of the impeller, the hollow small iron balls are easily adsorbed by the magnetic impeller wall. Finally, when the test stops and the impeller is disassembled, the distribution density of the hollow small iron balls on each part of the impeller surface is inconsistent: in the area with more serious cavitation, more and larger bubbles are generated, and fewer hollow small iron balls are adsorbed; on the contrary, in the area where cavitation is not obvious or there is no cavitation, fewer and smaller bubbles are generated, and more hollow small iron balls are adsorbed, thus realizing the observation of the cavitation condition of the impeller. The observation method provided in this embodiment is intuitive and reliable, and the obtained results have high accuracy and rich information. Compared with the existing image photography method, it not only does not require an expensive and fragile plexiglass pump housing, but also the observer can observe the adsorption situation of the hollow small iron balls in each area of the impeller from multiple angles and at close range, can obtain a better and more intuitive observation experience and observation effect, and can also provide more rich, accurate information for the design optimization of the cavitation resistance performance of the water pump.

Claims

1. Observation device for cavitation condition of water pump impeller based on hollow sphere, characterized in that It includes a water pump and auxiliary devices. The water pump includes an inlet section (1), a pump casing (2), an outlet section (3), an impeller (4) and a main shaft (5). The auxiliary devices include an inlet pipe (6) connected to the inlet section (1) of the water pump, an outlet pipe (12) connected to the outlet section (3) of the water pump, an opening pipe (7) vertically inserted into the inlet pipe (6) from the outside of the inlet pipe (6), a container (8) located outside the inlet pipe (6) and connected to the opening pipe (7), a gate valve (9) located at the connection of the opening pipe (7) and the container (8), several hollow small iron balls (10) and water (11) located in the container (8); The volume density of the hollow small iron balls (10) is equal to the density of water so that the hollow small iron balls (10) can suspend in water; The material of the impeller (4) is magnetic and can attract each other with ferromagnetic materials through magnetic force, and the material of the main shaft (5) is non-ferromagnetic.

2. The observation device for the cavitation condition of the water pump impeller based on hollow balls according to claim 1, characterized in that, The diameter of the hollow small iron balls (10) is between 1 mm and 5 mm.

3. The observation device for the cavitation condition of the water pump impeller based on hollow spheres according to claim 1, characterized in that, Several circular openings (71) are provided on the pipe wall of the part of the opening pipe (7) located inside the inlet pipe (6), and the sizes and mutual spacings of all the openings (71) are the same. The diameter of the openings (71) is 1.5 to 3 times the diameter of the hollow small iron balls (10).

4. The observation device for the cavitation condition of the water pump impeller based on hollow spheres according to claim 1, characterized in that, An interference fit relationship exists between the impeller (4) and the main shaft (5).

5. Observation method applied to the observation device for the cavitation condition of the hollow-sphere-based water pump impeller described in any one of claims 1 to 4, characterized in that, It includes the following steps: Step S1: Keep the gate valve (9) in the closed state and connect the water pump and auxiliary devices to the pump performance test station; Step S2: Adjust the pump performance test station to make the water pump operate at the required rotational speed, flow rate and inlet pressure for observation; Step S3: Open the gate valve (9) to allow the hollow small iron balls (10) and water (11) in the container (8) to gradually be released into the inlet pipe (6) through the circular openings (71) on the opening pipe (7); Step S4: After all the hollow small iron balls (10) in the container (8) are released, close the gate valve (9), wait for 1 to 5 minutes, and then stop the water pump test; Step S5: Disassemble the impeller (4) of the water pump for photographing and observation to obtain the adsorption condition of the hollow small iron balls (10) on the impeller (4).

6. The method for observing the cavitation condition of the water pump impeller based on hollow balls according to claim 5, characterized in that, During the water pump test, the pressure in the container (8) can be adjusted by pressurizing or decompressing the container (8) to ensure that the pressure in the container (8) is 1000 Pa to 5000 Pa higher than the pressure at the position of the inlet pipe (6) where the opening pipe (7) is located.

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