A novel magnetic alternating cavitation experimental device and method

Abstract

The invention discloses a novel magnetic alternating cavitation experimental device and method. A through cavitation generating chamber is arranged in the middle of a cavitation generator, and a magnetic driver is arranged at each end. Each magnetic driver has a piston cylinder and an energized coil shell. A piston, a permanent magnet and a spring connected in sequence are arranged inside each piston cylinder. An electromagnet is arranged inside each energized coil shell. A coil is wound around each electromagnet. The magnetic force magnitude and period of the two coils are changed. The two pistons reciprocate under the action of an alternating magnetic field and a spring, and cavitation is generated by alternating positive and negative pressures. A high-speed camera shoots the shape, size and period of the cavitation cloud in the process of cavitation generation, development and collapse of cavitation bubbles inside the cavitation generating chamber. A pressure sensor and a temperature sensor respectively detect the pressure change and temperature change of liquid in the cavitation generating chamber, and explores the relationship between the volume alternating cavitation process parameters and the severity of cavitation and the strength of the cavitation field.

Description

Technical Field

[0001] The invention relates to the technical field of cavitation experiments, in particular to a cavitation generating device with alternating magnetic forces, which is used for studying the cavitation generating mechanism and cavitation phenomenon. Background Art

[0002] Cavitation refers to the phenomenon of vaporization and liquefaction caused by the pressure in a local area of ​​a liquid decreasing and increasing successively. According to the factors causing cavitation, cavitation is usually divided into ultrasonic cavitation, laser-induced cavitation and hydraulic cavitation. Cavitation is widely found in hydraulic machinery, high-speed water tunnels, underwater weapons and other occasions. The vibration and noise caused by cavitation will corrode the surface of these devices, leading to equipment failure. However, the energy released by cavitation can be used to strengthen and modify the surface of parts. Therefore, the study of cavitation is the basis for mastering the phenomenon of strengthening and modifying the surface of parts.

[0003] At present, ultrasonic cavitation can only generate cavitation bubbles near the ultrasonic vibration head, laser cavitation can only generate a single cavitation bubble, and hydraulic jet has problems such as strong disturbance during oscillation, complex equipment structure, and inconvenient installation and disassembly. The document with Chinese patent publication number CN113120990A discloses a hydraulic cavitation generating device and method, which immerses a wheel in water, drives the wheel to rotate with a driving mechanism, and introduces water flow at a set pressure into the water inlet pipe. When the wheel rotates to align the set flow channel with the water inlet pipe, the water in the set flow channel changes from static to flowing at a set speed, thereby generating cavitation bubbles. However, the cavitation bubbles generated by this method are not easy to observe, and the pressure and temperature changes when cavitation occurs cannot be obtained, and the process and strength of the cavitation phenomenon cannot be known. Summary of the invention

[0004] The purpose of the present invention is to provide a novel magnetic alternating cavitation experimental device and an experimental method thereof, which are convenient for observing cavitation bubbles, can learn the cavitation phenomenon in different fluid media, and study the cavitation mechanism.

[0005] To achieve the above-mentioned purpose, the technical solution adopted by the novel magnetic alternating cavitation experimental device of the present invention is as follows: a through cavitation generating chamber is arranged in the middle of the cavitation generator, a liquid supply circulation system injects liquid into the cavitation generator, the cavitation generator is made of transparent material, and a magnetic driver is provided at each end, the two magnetic drivers have the same structure and are symmetrical relative to the center of the cavitation generating chamber, each magnetic driver has a piston cylinder and a powered coil housing, the piston cylinder is fixedly connected between the powered coil housing and the cavitation generator, and the central axes of the three are collinear; each piston cylinder is provided with a piston, a permanent magnet and a spring connected in sequence, and the piston On the side close to the cavitation chamber, the central axes of the piston, permanent magnet and spring are collinear with the central axis of the piston cylinder; the two permanent magnets are magnetized along the central axis and the magnetization directions are opposite; an electromagnet is provided inside each of the energized coil shells, and a coil is wound around each of the electromagnets, and the central axes of the electromagnet and the coil are collinear with the central axis of the permanent magnet; there is a closed chamber between the two pistons and the cavitation chamber; opposite currents are simultaneously passed through the two coils to drive the corresponding two permanent magnets and pistons to move away from or close to the cavitation chamber; a temperature sensor and a pressure sensor are arranged on the inner wall of the cavitation chamber.

[0006] Furthermore, the cavitation chamber is a cylindrical step through hole, with a section with a smaller inner diameter in the middle, and the temperature sensor and the pressure sensor are arranged on the inner wall of the section with a smaller inner diameter.

[0007] Furthermore, the two coils are connected to a computer via corresponding control circuits, and the temperature sensor and the pressure sensor are connected to the computer via signal lines.

[0008] The technical solution adopted by the experimental method of the novel magnetic alternating cavitation experimental device is:

[0009] By changing the magnetic force and period of the two coils, the two pistons reciprocate under the action of the alternating magnetic field and the spring, the volume of the closed cavity is changed, and cavitation is generated by alternating positive and negative pressures;

[0010] A high-speed camera is placed outside the cavitation generator, facing the middle section of the cavitation chamber, to capture the shape, size and period of the cavitation cloud during the generation, development and collapse of cavitation bubbles inside the cavitation chamber.

[0011] The pressure sensor and the temperature sensor detect the pressure change and temperature change of the liquid in the cavitation chamber respectively;

[0012] The cavitation collapse mechanism is analyzed based on the pressure changes, temperature changes, cavitation cloud shape, size and period, and the magnetic force of the coil and period.

[0013] Furthermore, the reciprocating time of the two pistons for one cycle is greater than the single cycle time of cavitation initiation, development and collapse.

[0014] Furthermore, when the pressure sensor measures the maximum pressure, the distance between the two pistons is the shortest and the space in the closed cavity is the smallest. When the pressure sensor measures the minimum pressure, the distance between the two pistons is the farthest and the space in the closed cavity is the smallest. The volume change rate and action time are determined.

[0015] Furthermore, when the aperture size and the shape of the cavity cross section of the cavitation chamber are changed, the strength of the current passed through the two coils and the current direction are periodically changed to change the movement frequency and stroke of the two pistons, and the influence of the aperture size and the cavity cross section shape in the cavitation chamber on the volumetric alternating cavitation process parameters is obtained.

[0016] Abrasive particles are added into the cavitation chamber. The temperature sensor and pressure sensor detect the temperature change and pressure change between the cavitation bubble and the abrasive particles. The high-speed camera captures the mutual cloud diagram, cycle and action area between the cavitation bubble and the abrasive particles.

[0017] The present invention has the following beneficial effects:

[0018] (1) The volume of the cavitation chamber is periodically changed by controlling the movement of the two pistons through alternating magnetic force, so as to achieve cavitation by alternating positive and negative pressures. This method is different from the current ultrasonic cavitation, laser cavitation and hydraulic cavitation. It is innovative in the way of inducing cavitation, has a simple experimental device structure and a better cavitation effect.

[0019] (2) By introducing different types of liquids, we can explore the effects of different liquid types on the generation, collapse and erosion mechanisms of cavitation under the same conditions, and study the cavitation phenomenon in different fluid media.

[0020] (3) By shooting with a high-speed camera, the generation, development, and collapse of cavitation bubbles can be recorded in detail and clearly. The temperature sensor and pressure sensor installed on the cavitation generator can detect the pressure and temperature generated when the cavitation bubble collapses, which is convenient for analyzing the cavitation collapse mechanism.

[0021] (4) By changing the strength of the electric current to change the strength of the magnetic field, the movement frequency and stroke of the piston can be controlled. The relationship between the volumetric alternating cavitation process parameters (piston reciprocating frequency, volume change rate, action time) and the severity of cavitation and the strength of the cavitation field can be further explored. The influence of the process parameters on the dynamic evolution of the cavitation cloud in the water medium in the cavitation chamber and the concentrated collapse of the cavitation bubbles can be further analyzed, which helps to clarify the occurrence mechanism of volumetric alternating cavitation.

[0022] (5) By changing the aperture size and the shape of the cavity cross section of the cavitation generator, we can explore the effects of the aperture size and the shape of the cavity cross section on the volumetric alternating cavitation process parameters (piston reciprocating frequency, volume change rate, action time), thereby achieving the effect of actively regulating the severity of cavitation and the strength of the cavitation field. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a structural schematic diagram of a novel magnetic alternating cavitation experimental device according to the present invention;

[0024] Figure 2 for Figure 1 Enlarged left view of the cavitation generator;

[0025] Figure 3 for Figure 1 A magnified view of the cavitation generator;

[0026] Figure 4 for Figure 1 Schematic diagram of the magnetic drive driving the piston away from the cavitation generator;

[0027] Figure 5 for Figure 1 Schematic diagram of a magnetic drive driving a piston close to a cavitation generator.

[0028] In the figure: 1. liquid inlet; 2. liquid storage tank; 3. first throttle valve; 4. plunger pump; 5. infusion tube; 6. pressure gauge; 7. flow meter; 8. first buffer plate; 9. liquid inlet hole; 10. first sealing cover; 11. second throttle valve; 12. computer; 13. cavitation generator; 14. second sealing ring; 15. second buffer plate; 16. right piston cylinder; 17. right piston; 18. second permanent magnet; 19. right spring; 20. second coil; 21. second energized coil housing; 22. Second electromagnet; 23. Right support seat; 24. Third buffer plate; 25. Drain hole; 26. Second sealing cover; 27. Third throttle valve; 28. Pressure sensor; 29. ​​Temperature sensor; 30. Cavitation chamber; 31. First sealing ring; 32. Fourth buffer plate; 33. Left piston; 34. Left piston cylinder; 35. Left support seat; 36. First permanent magnet; 37. Left spring; 38. First energized coil housing; 39. First electromagnet; 40. First coil; 41. Drain pipe; 42. Drain port; 43. Liquid; 44. First threaded hole; 45. Second threaded hole; 46. Third threaded hole; 47. Fourth threaded hole; 48. Sealing ring groove. DETAILED DESCRIPTION

[0029] like Figure 1As shown, the novel magnetic alternating cavitation experimental device of the present invention comprises a cavitation generator 13, a liquid supply circulation system and a magnetic driver. In the middle of the cavitation generator 13 is a cavitation generating chamber 30 that passes through both ends of the cavitation generator 13. The cavitation generator 13 is provided with a liquid inlet hole 9 and a liquid outlet hole 25, which are connected to the cavitation generating chamber 30.

[0030] The liquid supply circulation system provides liquid 43 to the inside of the cavitation generator 13, and the liquid 43 is supplied to the cavitation generating chamber 30. After the cavitation generating chamber 30 ends, the liquid 43 flows back to the liquid supply circulation system, thus realizing circulation. The liquid supply circulation system includes a liquid storage tank 2, a plunger pump 4, an infusion pipe 5 and a discharge pipe 41. The plunger pump 4 is arranged on the infusion pipe 5. The liquid 43 is stored in the liquid storage tank 2. The liquid storage tank 2 is connected to the liquid inlet 9 through the infusion pipe 5, and the first sealing cover 10 is used to seal the orifice of the liquid inlet 9. Under the action of the plunger pump 4, the liquid 43 enters the cavitation generating chamber 30. The bottom of the liquid storage tank 2 is provided with a liquid inlet 1 and a discharge port 42, which are used for the liquid inlet and discharge of the liquid storage tank 2 respectively.

[0031] The first throttle valve 3, the pressure gauge 6, the flow meter 7 and the second throttle valve 11 are also arranged on the infusion pipe 5. The first throttle valve 3 is at the input end of the plunger pump 4 to control the flow rate entering the plunger pump 4. The pressure gauge 6, the flow meter 7 and the second throttle valve 11 are installed on the infusion pipe 5 between the plunger pump 4 and the liquid inlet hole 9. The pressure gauge 6 is used to display the pressure of the liquid 43 entering the cavitation chamber 30, the flow meter 7 displays the flow rate of the liquid 43 entering the cavitation chamber 30, and the second throttle valve 11 is used to control the liquid 43 in the liquid storage tank 2 to enter the cavitation chamber 30.

[0032] The liquid storage tank 2 is connected to the liquid discharge hole 25 through a liquid discharge pipe 41, and the opening of the liquid discharge hole 25 is sealed by a second sealing cover 26. A third throttle valve 27 is installed on the liquid discharge pipe 41. When the third throttle valve 27 is opened, the liquid in the cavitation chamber 30 flows back into the liquid storage tank 2.

[0033] The first throttle valve 3, the second throttle valve 11 and the third throttle valve 27 are respectively connected to the computer 12 via corresponding control lines, and the flow rate of the liquid 43 entering and exiting the cavitation generator 13 can be regulated at any time by the computer 12.

[0034] When the liquid supply circulation system is working, different types of liquids 43 can be selected according to the different research objects, so as to explore the influence of different types of liquids 43 on the generation, collapse and erosion mechanism of cavitation phenomenon under the same conditions. The computer 12 controls the plunger pump 4, the first throttle valve 3 and the second throttle valve 11 to open at the same time, and the liquid 43 in the liquid storage tank 2 is injected into the cavitation chamber 30. When the liquid level is about 10 cm away from the top of the cavitation chamber 30, it is considered that the liquid 43 is sufficient. At this time, the computer 12 controls the plunger pump 4 to stop working and close the first throttle valve 3 and the second throttle valve 11. The injection amount of liquid 43 can also be adjusted according to actual conditions. The temperature of the liquid 43 in the liquid storage tank 2 is 20-30°C, which ensures that the liquid 43 is more likely to generate cavitation bubbles.

[0035] A magnetic driver is provided at each of the two ends of the cavitation generator 13 . The two magnetic drivers have the same structure and are symmetrically arranged relative to the center of the cavitation generating chamber 30 . Figure 1 As shown, two magnetic drivers are arranged at the left and right ends of the cavitation generator 13 respectively. Each magnetic driver has a piston cylinder and a powered coil housing. The piston cylinder is fixedly connected between the powered coil housing and the cavitation generator 13, and the central axes of the three are collinear. Each piston cylinder is provided with a piston, a permanent magnet and a spring connected in sequence. The central axes of the piston, the permanent magnet and the spring are collinear. The piston is sealed and movably connected to the inner wall of the piston cylinder, and can move back and forth along the central axis direction of the piston cylinder, relative to the side of the permanent magnet close to the cavitation chamber 30; each powered coil housing is provided with an electromagnet, and each electromagnet is wound with a coil, and the central axes of the electromagnet, the coil and the piston and the permanent magnet are collinear. The details are as follows:

[0036] The piston cylinders of the two magnetic actuators are the left piston cylinder 34 and the right piston cylinder 16. The left piston cylinder 34 and the right piston cylinder 16 have the same structure and are symmetrically arranged relative to the center of the cavitation chamber 30, and the central axis is collinear with the central axis of the cavitation chamber 30. The bottom of the left piston cylinder 34 is supported by the left support seat 35, and the bottom of the right piston cylinder 16 is supported by the right support seat 23. The left support seat 35 and the right support seat 23 have the same height, so that the left piston cylinder 34 and the right piston cylinder 16 are at the same height.

[0037] Inside the two piston cylinders are the left piston 33 and the right piston 17, respectively. The left piston 33 and the right piston 17 have the same structure and are arranged symmetrically relative to the center of the cavitation chamber 30. The cavitation chamber 30 is connected to the left piston 33 and the right piston 17, that is, the inner cavity of the piston cylinder formed by the cavitation generator 13 and the left piston 33 and the right piston 17 is connected to the cavitation chamber 30. The left piston 33 and the right piston 17 are at both ends of the cavitation chamber 30, facing the cavitation chamber 30, so a closed cavity is formed between the cavitation chamber 30 and the left piston cylinder 34, the right piston cylinder 16, the left piston 33, and the right piston 17. When the left piston 33 and the right piston 17 are closer to the cavitation chamber 30, the volume of the closed chamber becomes smaller, the pressure in the closed chamber rises, and cavitation bubbles begin to form; when the left piston 33 and the right piston 17 are farther away from the cavitation chamber 30, the volume of the closed chamber becomes larger, the pressure in the closed chamber decreases, and when the pressure reduces the cavitation bubble collapse pressure, the cavitation bubble will release energy and emit light and heat when it collapses.

[0038] The left piston 33 and the right piston 17 are each fixedly connected to a permanent magnet in the middle of the side away from the cavitation chamber 30, which are the first permanent magnet 36 and the second permanent magnet 18. The first permanent magnet 36 and the second permanent magnet 18 are both cylinders with the same structure, and the central axis is collinear with the central axis of the cavitation chamber 30, and are arranged symmetrically relative to the center of the cavitation chamber 30. One end of the first permanent magnet 36 is fixedly connected to the left piston 33, and the other end is fixedly connected to the left spring 37. One end of the second permanent magnet 18 is fixedly connected to the right piston 17, and the other end is fixedly connected to the right spring 19. When the left piston 33 and the right piston 17 move in the direction away from the cavitation chamber 30, the left spring 37 and the right spring 19 contact the inner walls of the corresponding left piston cylinder 34 and the right piston cylinder 16 and are gradually compressed, so that the left spring 37 and the right spring 19 generate a rebound force.

[0039] Outside each piston cylinder, directly opposite to the spring, there is a power coil housing, and inside each power coil housing is an electromagnet with a coil wound around it. The first power coil housing 38 is fixedly connected to the left piston cylinder 34, and inside the first power coil housing 38 is fixed a first electromagnet 39, which is cylindrical and has a first coil 40 wound around it. The second power coil housing 21 is fixedly connected to the right piston cylinder 16, and inside the second power coil housing 21 is fixed a second electromagnet 22, which is cylindrical and has a second coil 20 wound around it. The central axes of the first electromagnet 39 and the second electromagnet 22 are collinear with the central axes of the left piston cylinder 34, the right piston cylinder 16, and the cavitation chamber 30.

[0040] The first coil 40 and the second coil 20 are both connected to the computer 12 via corresponding control circuits. The computer 12 energizes the first coil 40 and the second coil 20 via the control circuit. When the first coil 40 and the second coil 20 are energized, the first electromagnet 39 and the second electromagnet 22 generate a magnetic field, which acts on the first permanent magnet 36 and the second permanent magnet 18, thereby driving the left piston 33 and the right piston 17 to reciprocate.

[0041] See also Figure 2 Four threaded holes are evenly distributed on the two end surfaces of the cavitation generator 13, namely the first threaded hole 44, the second threaded hole 45, the third threaded hole 46 and the fourth threaded hole 47, and a sealing ring groove 48 is also opened respectively for installing sealing rings, namely the first sealing ring 31 and the second sealing ring 14, for sealing to prevent liquid leakage in the cavitation chamber 30.

[0042] See also Figure 3 The cavitation chamber 30 is a cylindrical step through hole. The inner diameter of the middle section of the cavitation chamber 30 is smaller, and the cavitation effect is enhanced here. The inner diameter of the cavitation chamber 30 is 5 to 15 mm. The liquid inlet hole 9 and the liquid discharge hole 25 are connected to the side walls of the two ends of the cavitation chamber 30, and the diameters of the liquid inlet hole 9 and the liquid discharge hole 25 are both 3 mm.

[0043] A temperature sensor 29 and a pressure sensor 28 are arranged on the inner wall of the cavitation chamber 30. The temperature sensor 29 and the pressure sensor 28 are installed on the middle section of the inner wall where the inner diameter of the cavitation chamber 30 is smaller. The temperature sensor 29 and the pressure sensor 28 are connected to an external computer 12 through a signal line to detect the pressure and temperature when the cavitation bubble is generated, developed, and collapsed.

[0044] Outside the cavitation generator 13, a high-speed camera is placed facing the middle section of the cavitation chamber 30 ( Figure 1The high-speed camera is omitted), and the high-speed camera is connected to the computer 12. The axis of the high-speed camera and the axis of the cavitation chamber 30 are in the same horizontal plane. The cavitation generator 13 is made of a transparent acrylic glass plate, and the high-speed camera can be used to clearly record the generation, development, and collapse process of the cavitation bubble inside the cavitation chamber 30. Different liquids have significantly different physical properties. When it is necessary to analyze the cavitation collapse mechanism of a certain liquid under a certain water pressure, the pressure sensor 28 detects the pressure change of the liquid in the cavitation chamber 30, and the temperature sensor 29 detects the temperature change of the liquid in the cavitation chamber 30. The cavitation releases local high temperature during the collapse process, and the temperature reaches the highest value. Combined with the shape, size and periodicity of the cavitation cloud captured by the high-speed camera, the pressure, cavitation cloud shape and cavitation collapse area of ​​the liquid at the best cavitation collapse are judged. The computer 12 changes the magnetic force size and period of the first coil 40 and the first coil 40 according to the temperature and pressure signals transmitted by the temperature sensor 29 and the pressure sensor 28, so that the space and pressure formed by the left piston cylinder 34 and the right piston cylinder 16 change periodically, thereby analyzing the cavitation collapse mechanism of a certain liquid.

[0045] See also Figure 4 , the magnetization directions of the first permanent magnet 36 and the second permanent magnet 18 are along the direction of their central axis, and the magnetization directions of the first permanent magnet 36 and the second permanent magnet 18 are opposite. For example, the end of the first permanent magnet 36 connected to the left piston cylinder 34 is the S pole, and the end close to the first electromagnet 39 is the N pole. Similarly, the end of the second permanent magnet 18 connected to the right piston 17 is the S pole, and the end close to the second electromagnet 22 is the N pole. When the first coil 40 and the second coil 20 are energized at the same time, the energized currents are opposite to each other, the first coil 40 is fed with counterclockwise current, and the second coil 20 is fed with clockwise current (viewed from left to right), the first electromagnet 39 and the second electromagnet 22 respectively generate corresponding magnetic fields, the first electromagnet 39 and the second electromagnet 22 form S poles at the end close to the left piston 33 and the right piston 17, and form N poles at the end away from the left piston 33 and the right piston 17, attracting the corresponding first permanent magnet 36 and the second permanent magnet 18, driving the first permanent magnet 36 and the second permanent magnet 18 to move, therefore, the left piston 33 and the right piston 17 move in the direction away from the cavitation chamber 30 under the action of the magnetic field generated by the first coil 40 and the second coil 20, thereby increasing the volume of the closed chamber formed between the left piston cylinder 34, the right piston cylinder 16 and the left piston 33, the right piston 17 and the cavitation chamber 30, and reducing the pressure in the closed chamber. During the movement of the left piston 33 and the right piston 17, the left spring 37 and the right spring 19 will be compressed to store elastic potential energy.

[0046] See also Figure 5 ,and Figure 4On the contrary, when the direction of the current in the first coil 40 and the second coil 20 is changed, that is, the first coil 40 is supplied with clockwise current and the second coil 20 is supplied with counterclockwise current, and the current is reversed, the first coil 40 and the second coil 20 generate a magnetic field, and the first electromagnet 39 and the second electromagnet 22 form an N pole at the end close to the left piston 33 and the right piston 17 and form an S pole at the end away from the left piston 33 and the right piston 17. Under the action of the magnetic field and the elastic force of the left spring 37 and the right spring 19, the left piston 33 and the right piston 17 move toward the cavitation chamber 30, thereby reducing the volume of the closed chamber and increasing the pressure in the closed chamber.

[0047] Buffer plates are installed on the inner walls of the left piston cylinder 34 and the right piston cylinder 16, and close to the two ends of the cavitation chamber 30. The first buffer plate 8 and the fourth buffer plate 32 are installed on the inner wall of the left piston cylinder 34, and the second buffer plate 15 and the third buffer plate 24 are installed on the inner wall of the right piston cylinder 16. The buffer plates are fixed to the inner walls of the piston cylinders by vacuum oxygen ion technology, and can play a certain buffering role when the left piston 33 and the right piston 17 reciprocate.

[0048] An alternating magnetic field is generated by controlling the strength of the current in the first coil 40 and the second coil 20 and periodically changing the direction of the current. The left piston 33 and the right piston 17 can reciprocate under the action of the alternating magnetic field and the elastic force of the left spring 37 and the right spring 17. The movement of the left piston 33 and the right piston 17 is then controlled by alternating magnetic force to periodically change the volume of the cavitation generator 13, so as to achieve cavitation by alternating positive and negative pressures.

[0049] When the first coil 40 and the second coil 20 are connected with an enhanced current and the direction of the current is changed quickly, the movement frequency of the left piston 33 and the right piston 17 will be accelerated, the stroke will be longer, and the volume change rate of the closed cavity formed between the left piston cylinder 34, the right piston cylinder 16 and the left piston 33, the right piston 17 and the cavitation chamber 30 will also increase. The amount of cavitation cloud can be observed by adjusting the brightness and contrast of the high-speed camera, and the pressure and temperature when the cavitation collapses can be obtained by the computer 12 connected to the temperature sensor 29 and the pressure sensor 28. When it is necessary to analyze the piston reciprocating frequency of the volume alternating cavitation process parameters, the highest temperature detected by the temperature sensor 29 is the temperature when the cavitation collapses in a single cycle. At this time, the pressure when the cavitation collapses detected by the pressure sensor 28 is combined with the cavitation cloud map taken by the high-speed camera, and the computer 12 determines the single cycle time of cavitation initiation, development, and collapse. The original position of the left piston cylinder 34 and the right piston cylinder 16 is the start time of the cycle, the space is compressed, the pressure rises, and the cavitation is nurtured. Then the two pistons move away, the space becomes larger, the pressure drops, the cavitation develops and collapses, and the position of the piston is the end position of a cycle. The piston reciprocates for a cycle longer than a single cycle of cavitation initiation, development, and collapse, ensuring that the entire cycle of cavitation is complete. In a single cycle of cavitation initiation, development, and collapse, when the pressure sensor 28 measures the maximum pressure, it is the closest distance between the left piston 33 and the right piston 17, and the space in the closed cavity is the smallest. When the pressure sensor 28 measures the minimum pressure, it is the farthest distance between the left piston 33 and the right piston 17, and the space in the closed cavity is the largest. The computer 12 determines the volume change rate and action time through the positions of the left piston 33 and the right piston 17, and the computer determines the intensity of cavitation based on the high-speed camera shooting of the cavitation cloud area. Therefore, the relationship between the volume alternating cavitation process parameters (piston reciprocating frequency, volume change rate and action time) and the severity of cavitation and the strength of the cavitation field is analyzed through pressure, temperature, cavitation cloud shape, size and period, and the positions of the left piston 33 and the right piston 17, as well as their influence on the dynamic evolution of the water medium cavitation cloud and the concentrated collapse of cavitation bubbles in the cavitation chamber 30, so as to provide theoretical and experimental basis for clarifying the influence mechanism of volume alternating cavitation.

[0050] After changing the aperture size and the shape of the aperture cross section of the cavitation chamber 30 in the cavitation generator 13, by controlling the strength of the current passed through the first coil 40 and the second coil 20 and periodically changing the direction of the current to change the movement frequency and stroke of the left piston 33 and the right piston 17, the influence of the aperture size and the aperture cross section shape in the cavitation chamber 30 on the volumetric alternating cavitation process parameters (piston reciprocating frequency, volume change rate, action time) can be explored, thereby providing guidance for actively controlling the severity of cavitation and the strength of the cavitation field under different conditions.

[0051] By adding abrasive particles into the liquid inlet 9 of the cavitation generator 13, the abrasive particles are added into the cavitation generating chamber 30. By the same principle, the temperature and pressure changes of the interaction between the cavitation bubbles and the abrasive particles are detected and recorded by the temperature sensor 29 and the pressure sensor 28, and the mutual cloud diagram, cycle and action area between the cavitation bubbles and the abrasive particles are photographed by a high-speed camera. When it is necessary to process different areas of the micro-cavity, different shapes of cavitation cavities are formed by different positions of the left and right pistons, and the areas where the cavitation bubbles collapse are controlled to process different areas of the micro-cavity, thereby obtaining a new method for polishing the micro-cavity by the synergistic effect of volume alternating cavitation and abrasive particles.

[0052] When the cavitation bubbles in the cavitation chamber 30 collapse, the computer 12 cuts off the power to the first coil 40 and the second coil 20 , opens the third throttle valve 27 , and the liquid in the cavitation chamber 30 flows back to the liquid storage tank 2 .

[0053] The embodiments are preferred implementations of the present invention, but the present invention is not limited to the above-mentioned implementations. Any obvious improvements, substitutions or modifications that can be made by those skilled in the art without departing from the essential content of the present invention belong to the protection scope of the present invention.

Claims

1. A novel magnetic alternating cavitation experimental device, comprising a cavitation generator (13) and a liquid supply circulation system; wherein: The middle of the cavitation generator (13) is a through cavitation chamber (30), and a liquid supply circulation system injects liquid into the cavitation generator (13); the characteristics are: the cavitation generator (13) is made of transparent material, and a magnetic driver is provided at each end, the two magnetic drivers have the same structure and are symmetrical relative to the center of the cavitation chamber (30), each magnetic driver has a piston cylinder and a power coil housing, the piston cylinder is fixedly connected between the power coil housing and the cavitation generator (13), and the central axes of the three are collinear; each piston cylinder is provided with a piston, a permanent magnet and a spring connected in sequence, and the piston is close to the side of the cavitation chamber (30). , the central axes of the piston, the permanent magnet, and the spring are collinear with the central axis of the piston cylinder; the two permanent magnets are magnetized along the central axis direction and in opposite directions; each of the energized coil housings is provided with an electromagnet, each of the electromagnets is wound with a coil, and the central axes of the electromagnet and the coil are collinear with the central axis of the permanent magnet; a closed cavity is formed between the two pistons and the cavitation chamber (30); opposite currents are simultaneously passed through the two coils to drive the corresponding two permanent magnets and the pistons to move away from or toward the cavitation chamber (30); a temperature sensor (29) and a pressure sensor (28) are arranged on the inner wall of the cavitation chamber (30); The cavitation generating chamber (30) is a cylindrical stepped through hole, with a section with a reduced inner diameter in the middle, and the temperature sensor (29) and the pressure sensor (28) are arranged on the inner wall of the section with a reduced inner diameter; The cavitation generator (13) is provided with a liquid inlet hole (9) and a liquid discharge hole (25). The liquid supply circulation system comprises a liquid storage tank (2), a plunger pump (4), a liquid infusion pipe (5) and a liquid discharge pipe (41). The liquid storage tank (2) is connected to the liquid inlet hole (9) via the liquid infusion pipe (5), and is connected to the liquid discharge hole (25) via the liquid discharge pipe (41). The liquid infusion pipe (5) is provided with a first throttle valve (3), a plunger pump (4), a pressure gauge (6), a flow meter (7) and a second throttle valve (11).

2. A novel magnetic alternating cavitation experimental device according to claim 1, characterized in that: The two coils are connected to the computer (12) via corresponding control circuits, and the temperature sensor (29) and the pressure sensor (28) are connected to the computer (12) via signal lines.

3. A novel magnetic alternating cavitation experimental device according to claim 1, characterized in that: Buffer sheets are provided on the inner walls of the two piston cylinders, close to the two ends of the cavitation generating chamber (30).

4. A cavitation test method using the novel magnetic alternating cavitation test device according to claim 1, characterized in that The following steps are involved: By changing the magnetic force and period of the two coils, the two pistons reciprocate under the action of the alternating magnetic field and the spring, the volume of the closed cavity is changed, and cavitation is generated by alternating positive and negative pressures; A high-speed camera is placed outside the cavitation generator (13) facing the middle section of the cavitation chamber (30) to photograph the shape, size and period of the cavitation cloud during the generation, development and collapse of cavitation bubbles inside the cavitation chamber (30); The pressure sensor (28) and the temperature sensor (29) respectively detect the pressure change and temperature change of the liquid in the cavitation generating chamber (30); The cavitation collapse mechanism is analyzed based on the pressure changes, temperature changes, cavitation cloud shape, size and period, and the magnetic force of the coil and period.

5. The cavitation test method according to claim 4, characterized in that: The reciprocating time of the two pistons is longer than the single cycle time of cavitation generation, development and collapse.

6. The cavitation test method according to claim 4, characterized in that: When the pressure sensor (28) measures the maximum pressure, the distance between the two pistons is the shortest and the space in the closed chamber is the smallest. When the pressure sensor (28) measures the minimum pressure, the distance between the two pistons is the farthest and the space in the closed chamber is the smallest. The volume change rate and action time are determined.

7. The cavitation experiment method according to claim 4, characterized in that: When the aperture size and the shape of the aperture cross section of the cavitation chamber (30) are changed, the intensity of the current passed through the two coils and the direction of the current are periodically changed to change the movement frequency and stroke of the two pistons, and the influence of the aperture size and the shape of the aperture cross section in the cavitation chamber (30) on the volumetric alternating cavitation process parameters is obtained.

8. The cavitation test method according to claim 4, characterized in that: Abrasive particles are added to the cavitation generating chamber 30, and the temperature sensor (29) and the pressure sensor (28) detect the temperature change and pressure change between the cavitation bubbles and the abrasive particles. The high-speed camera captures the mutual cloud diagram, cycle and action area between the cavitation bubbles and the abrasive particles.

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