A device for measuring the cavitation pressure of water

Abstract

The present invention provides a water body cavitation pressure measuring device in the field of cavitation experiment technology, which includes a box body. Inside the box body, there is a measuring cylinder body with a piston cavity. A connecting rod is connected to the box body directly above the measuring cylinder body. The lower end of the connecting rod is connected to a dynamometer. The dynamometer is connected with a piston that extends downward into the piston cavity and can move up and down in the piston cavity. A connecting pipe that extends out of the box body is connected to the measuring cylinder body below the piston. A switching valve is provided on the connecting pipe. A camera is connected to the bottom of the box body, and the camera can take pictures of the piston cavity. A drain pipe that extends out of the box body is also provided on the measuring cylinder body. The invention has low cost, small floor area, good cavitation experiment effect, and can realize the visual teaching work of cavitation pressure testing.

Description

Technical Field

[0001] The present invention belongs to the technical field of cavitation experiments, and particularly relates to a device for measuring the cavitation pressure of water bodies. Background Art

[0002] Cavitation is a unique kinetic phenomenon of liquids, which occurs in liquid regions where the local pressure is lower than the saturated vapor pressure at that temperature. The operation of equipment such as the blades of hydraulic turbines, pumps, and ship propeller thrusters is troubled by cavitation erosion. Cavitation is one of the main problems affecting the service life and performance of fluid machinery, which can lead to a decrease in mechanical efficiency, an increase in noise and vibration, and even cause material erosion and structural damage of the blade.

[0003] In the existing cavitation experimental devices, generally large-scale equipment such as a circular water tunnel is required. A high-power pump is used to realize liquid circulation, and a vacuum pump is used to reduce the water pressure to finally form cavitation. Such experimental equipment has many problems. The entire device occupies a large area, has a high investment cost, high usage and maintenance costs, and the experimental equipment and structure are complex, it is difficult to replace the flowing medium, it is impossible to visually observe, and it affects the cavitation experimental effect.

[0004] In the energy and power courses, cavitation is a common phenomenon in hydraulic machinery and has a significant impact on the safe and stable operation of hydraulic machinery. Currently, for the research on cavitation, whether it is numerical calculation or experimental research, the cavitation pressure is the core parameter. Therefore, there is an urgent need for a cavitation pressure measurement experimental device that reduces the cost of experimental equipment, is safe and effective, and is convenient for teachers to conduct in-class experimental demonstrations. Summary of the Invention

[0005] Aiming at the defects in the prior art, the purpose of the present invention is to solve the deficiencies in the prior art, solve the technical problems of high cost, large floor area, and poor cavitation experimental effect in the prior art, and provide a device for measuring the cavitation pressure of water bodies, which has low cost, small floor area, and good cavitation experimental effect.

[0006] The purpose of the present invention is realized as follows: A device for measuring the cavitation pressure of water bodies includes a box body. A measuring cylinder with a piston cavity is arranged inside the box body. A connecting rod is connected to the box body directly above the measuring cylinder. The lower end of the connecting rod is connected to a dynamometer. A piston that extends downward into the piston cavity and can move up and down in the piston cavity is connected to the dynamometer. A connecting pipe that extends outside the box body is connected to the measuring cylinder below the piston. A switching valve is arranged on the connecting pipe. A camera is connected to the bottom of the box body, and the camera can take pictures of the piston cavity. A drain pipe that extends outside the box body is also arranged on the measuring cylinder.

[0007] When the present invention works, the switch valve is opened, and water flows into the measuring cylinder from the water inlet pipe. After reaching the set liquid level, the switch valve is closed, and the camera is turned on to start video recording. The connecting rod moves upward, pulling the dynamometer, and the dynamometer pulls the piston to move upward along the inner wall of the measuring cylinder. The pressure in the measuring cylinder gradually decreases. When the pressure decreases to a certain value, cavitation occurs in the water to generate bubbles. At this time, the camera records the cavitation generation process and captures the cavitation phenomenon. When the camera captures the cavitation phenomenon, the connecting rod stops moving, and the pulling force value on the dynamometer at this time is recorded. The incipient cavitation pressure value of the water can be calculated through the pulling force value, realizing the pressure measurement and teaching work of water body cavitation. After the experiment, the tested water is discharged through the drain pipe; in the present invention, the setting of the measuring cylinder and the piston can effectively simulate the cavitation environment, with low cost, small floor area, and good cavitation experiment effect; the setting of the camera can realize visual teaching, record the cavitation phenomenon in real time, is easy to use, and has good observation effect; the setting of the dynamometer can calculate the incipient cavitation pressure value by measuring the pulling force value, is easy to use, and has high working efficiency; it can be applied to the visual teaching work of cavitation pressure testing.

[0008] In order to facilitate tracking the generated bubbles and observing and recording, an extension connecting rod is provided on the connecting rod above the measuring cylinder, a sliding rod is vertically provided on the extension connecting rod, a mounting plate is provided on the sliding rod, the mounting plate is below the piston, a laser and a convex lens are connected to the mounting plate, the convex lens is between the laser and the measuring cylinder, and the lens of the laser just aligns with the center of the convex lens.

[0009] In order to facilitate the camera to record, a hollow upper bottom plate and a lower bottom plate are provided at the bottom of the box body, a transparent plate is provided between the upper bottom plate and the lower bottom plate, the transparent plate is directly below the piston, the measuring cylinder is connected to the upper bottom plate, a connecting seat is connected to the bottom of the box body directly below the measuring cylinder, and the camera is installed on the connecting seat, and the lens of the camera is directly below the transparent plate.

[0010] In order to facilitate the camera to record, a transparent bottom plate is provided at the bottom of the box body, the measuring cylinder is connected to the transparent bottom plate, a connecting seat is connected to the lower side of the transparent bottom plate, and the camera is installed on the connecting seat, and the lens of the camera is directly below the piston.

[0011] In order to remove the dissolved gas in the water and improve the detection accuracy, a support frame is provided on one side of the box body, a heating cylinder is provided on the support frame, a water inlet pipe and an exhaust pipe are provided at the upper end of the heating cylinder, a water inlet valve is provided on the water inlet pipe, an exhaust valve is provided on the exhaust pipe, an opening is provided at the bottom of the heating cylinder, the connecting pipe is connected to the heating cylinder through the opening, at least one heater is provided on the inner wall of the heating cylinder, and a thermometer extending into the heating cylinder is further connected to the upper end of the heating cylinder.

[0012] As a further improvement of the present invention, an upper cover is connected to the upper end of the box body. A connection port is opened on the upper cover. An installation seat is provided at the upper end of the upper cover. A linear driver is provided on the installation seat. A lifting rod that can reciprocate in the height direction is provided on the linear driver. The connecting rod extends out of the measuring cylinder through the connection port and is connected to the lifting rod. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 is a schematic structural diagram of the present invention.

[0014] Figure 2 is Figure 1 a partial enlarged view of part A in

[0015] Figure 3 is a schematic structural diagram of Embodiment 2 of the present invention.

[0016] Wherein, 1 is the box body, 101 is the upper bottom plate, 102 is the lower bottom plate, 103 is the upper cover, 103a is the connection port, 104 is the installation seat, 2 is the measuring cylinder, 3 is the connecting rod, 4 is the dynamometer, 5 is the piston, 6 is the connecting pipe, 7 is the transparent plate, 8 is the connecting rod, 801 is the sliding rod, 9 is the mounting plate, 10 is the laser, 11 is the convex lens, 12 is the support frame, 13 is the heating cylinder, 1301 is the water inlet pipe, 1302 is the exhaust pipe, 14 is the heater, 15 is the thermometer, 16 is the linear driver, 1601 is the lifting rod, 17 is the drain pipe, 18 is the drain valve, 19 is the switching valve, 20 is the display, 21 is the connecting seat, 22 is the transparent bottom plate, 23 is the camera. DETAILED DESCRIPTION OF THE INVENTION

[0017] The present invention will be further described below with reference to the accompanying drawings.

[0018] Such as Figures 1 - 2A water cavitation pressure measuring device shown in the figure includes a box body 1. Inside the box body 1, there is a measuring cylinder body 2 with a piston 5 cavity. The upper end of the box body 1 is connected with an upper cover 103. There is a connection port 103a on the upper cover 103. An installation seat 104 is provided at the upper end of the upper cover 103. A linear driver 16 is provided on the installation seat 104. An elevating rod 1601 that can reciprocate in the height direction is provided on the linear driver 16. A connecting rod 3 is connected to the box body 1 directly above the measuring cylinder body 2. The connecting rod 3 extends out of the measuring cylinder body 2 through the connection port 103a and is connected to the elevating rod 1601. A force measuring instrument 4 is connected to the lower end of the connecting rod 3. A piston 5 that extends downward into the piston 5 cavity and can move up and down in the piston 5 cavity is connected to the force measuring instrument 4. A connecting pipe 6 that extends out of the box body 1 is connected to the measuring cylinder body 2 below the piston 5. A switch valve 19 is provided on the connecting pipe 6. A camera 23 is connected to the bottom of the box body 1. A display 20 is also provided. The camera 23 is electrically connected to the display 20. The camera 23 can take pictures of the piston 5 cavity. A drain pipe 17 that extends out of the box body 1 is also provided on the measuring cylinder body 2. A drain valve 18 is provided on the drain pipe 17. An extension rod 8 that extends outward is provided on the connecting rod 3 above the measuring cylinder body 2. A sliding rod 801 is vertically provided on the extension rod 8. A mounting plate 9 is provided on the sliding rod 801. The mounting plate 9 is below the piston 5. A laser 10 and a convex lens 11 are connected to the mounting plate 9. The convex lens 11 is between the laser 10 and the measuring cylinder body 2. The lens of the laser 10 just aligns with the center of the convex lens 11. A hollow upper bottom plate 101 and a lower bottom plate 102 are provided at the bottom of the box body 1. A transparent plate 7 is provided between the upper bottom plate 101 and the lower bottom plate 102. The transparent plate 7 is directly below the piston 5. The measuring cylinder body 2 is connected to the upper bottom plate 101. A connecting seat 21 is connected to the bottom of the box body 1 directly below the measuring cylinder body 2. The camera 23 is installed on the connecting seat 21. The lens of the camera 23 is directly below the transparent plate 7. A support frame 12 is provided on one side of the box body 1. A heating cylinder 13 is provided on the support frame 12. A water inlet pipe 1301 and an exhaust pipe 1302 are provided at the upper end of the heating cylinder 13. A water inlet valve is provided on the water inlet pipe 1301. An exhaust valve is provided on the exhaust pipe 1302. An opening is provided at the bottom of the heating cylinder 13. The connecting pipe 6 is connected to the heating cylinder 13 through the opening. At least one heater 14 is provided on the inner wall of the heating cylinder 13. A thermometer 15 that extends into the heating cylinder 13 is also connected to the upper end of the heating cylinder 13.

[0019] In the present invention, the material of the measuring cylinder body 2 is preferably made of plexiglass. Before the operation of this device, the switching valve 19 is in the closed state, the water inlet valve is in the open state, the exhaust valve is in the open state, and the drain valve 18 is in the closed state. When this device is operating, the water to be measured is injected into the heating cylinder 13 through the water inlet pipe 1301. The heater 14 heats the water to be measured, and the dissolved gas in the water can be removed. The gas is discharged from the exhaust valve. Observe the reading of the thermometer 15. When it reaches a certain value, it indicates that the heating is completed. Then, close the exhaust valve and the water inlet valve, and let the water to be measured cool naturally. Observe the thermometer 15. After the water temperature drops to the required temperature, open the switching valve 19. The water to be measured enters the measuring cylinder body 2 through the connecting pipe 6 to reach the set water level. Turn on the dynamometer 4 and zero it. At the same time, start the camera 23 to start video recording. The lifting rod 1601 of the linear actuator 16 moves upward. The lifting rod 1601 drives the connecting rod 3 to move upward. The connecting rod 3 pulls the dynamometer 4. The dynamometer 4 pulls the piston 5 to move upward along the inner wall of the measuring cylinder body 2. The pressure inside the measuring cylinder body 2 gradually decreases. When the pressure drops to a certain value, cavitation occurs in the water to generate bubbles. At the same time, the movement of the connecting rod 3 drives the infrared beam emitted by the laser 10 to irradiate the water to be measured in the measuring cylinder body 2 through the convex lens 11, tracking the generated bubbles for easy observation and recording. At this time, the camera 23 records the cavitation generation process and captures the cavitation phenomenon. People can observe the cavitation phenomenon from the display 20. Immediately stop the operation of the linear actuator 16 and record the pulling force value on the dynamometer 4 at this time. The incipient cavitation pressure value of the water can be calculated through the pulling force value, realizing the pressure measurement of water cavitation and teaching work. When a large number of bubbles continuously appear in the water to be measured, it represents the end of this test. After the measurement, open the drain valve 18, and the tested water is discharged from the drain pipe 17. Turn off the camera 23. At the same time, start the linear actuator 16 to make the piston 5 return to the initial position for the next measurement experiment. In the present invention, the settings of the measuring cylinder body 2 and the piston 5 can effectively simulate the cavitation environment, with low cost, small floor area, and good cavitation experiment effect. The settings of the camera 23 and the display 20 can achieve visual teaching, record the cavitation phenomenon in real time, are convenient to use, and have good observation effect. The setting of the dynamometer 4 can calculate the incipient cavitation pressure value by measuring the pulling force value, is convenient to use, and has high working efficiency. It can be applied to the visual teaching work of cavitation pressure testing.

[0020] Embodiment 2

[0021] As Figure 3 shown in a water body cavitation pressure measuring device, the difference between this embodiment and Embodiment 1 is that a transparent bottom plate 22 is provided at the bottom of the box body 1. The measuring cylinder body 2 is connected to the transparent bottom plate 22. A connecting seat 21 is connected to the lower side of the transparent bottom plate 22. The camera 23 is installed on the connecting seat 21, and the lens of the camera 23 is directly below the piston 5.

[0022] This invention patent is not limited to the above examples. Based on the technical solutions disclosed in this invention patent, those skilled in the art can make some substitutions and deformations to some of the technical features without creative labor according to the disclosed technical content, and these substitutions and deformations are all within the protection scope of this invention patent.

Claims

1. A water body cavitation pressure measuring device, comprising a box body. A measuring cylinder with a piston chamber is arranged inside the box body. A connecting rod is connected to the box body directly above the measuring cylinder. The lower end of the connecting rod is connected to a dynamometer. A piston that extends downward into the piston chamber and can move up and down in the piston chamber is connected to the dynamometer. A connecting pipe that extends outside the box body is connected to the measuring cylinder below the piston. A switching valve is arranged on the connecting pipe. A camera is connected to the bottom of the box body, and the camera can take pictures of the piston chamber. A drain pipe that extends outside the box body is also arranged on the measuring cylinder. An extension connecting rod that extends outward is arranged on the connecting rod above the measuring cylinder. A sliding rod is vertically arranged on the connecting rod. A mounting plate is arranged on the sliding rod, and the mounting plate is below the piston. A laser and a convex lens are connected to the mounting plate. The convex lens is between the laser and the measuring cylinder, and the lens of the laser just aims at the center of the convex lens. A support frame is arranged on one side of the box body. A heating cylinder is arranged on the support frame. A water inlet pipe and an exhaust pipe are arranged at the upper end of the heating cylinder. A water inlet valve is arranged on the water inlet pipe. An exhaust valve is arranged on the exhaust pipe. An opening is arranged at the bottom of the heating cylinder. The connecting pipe is connected to the heating cylinder through the opening. At least one heater is arranged on the inner wall of the heating cylinder. A thermometer that extends into the heating cylinder is also connected to the upper end of the heating cylinder. An upper cover is connected to the upper end of the box body. A connection port is opened on the upper cover. A mounting seat is arranged at the upper end of the upper cover. A linear actuator is arranged on the mounting seat. A lifting rod that can reciprocate in the height direction is arranged on the linear actuator. The connecting rod extends out of the measuring cylinder through the connection port and is connected to the lifting rod.

2. The water body cavitation pressure measuring device according to claim 1, wherein: The bottom of the box body is provided with a hollow upper bottom plate and a lower bottom plate. A transparent plate is arranged between the upper bottom plate and the lower bottom plate. The transparent plate is directly below the piston. The measuring cylinder body is connected to the upper bottom plate. A connecting seat is connected to the bottom of the box body directly below the measuring cylinder body. The camera is installed on the connecting seat, and the lens of the camera is directly below the transparent plate.

3. The water body cavitation pressure measuring device according to claim 1, wherein: The bottom of the box body is provided with a transparent bottom plate. The measuring cylinder body is connected to the transparent bottom plate. A connecting seat is connected to the lower side of the transparent bottom plate. The camera is installed on the connecting seat, and the lens of the camera is directly below the piston.

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