Test system and method for weakening cavitation damage by using preset bubbles

Abstract

The invention discloses a test system and method for weakening cavitation damage by using preset bubbles. The method comprises a preparation stage and an experiment stage, the preparation stage comprises the steps that plasma water is injected into the transparent water tank, and the liquid level of the plasma water is located on the side, away from the bottom face, of the flat plate; adjusting the position of a high-speed camera, wherein a shot picture of the high-speed camera at least comprises an area between the flat plate and the electrode; the experimental stage comprises the following steps: starting a peristaltic pump, and injecting air bubbles with a preset volume into one side, close to the bottom surface, of a flat plate by the peristaltic pump according to a preset gas injection rate and preset injection time; moving the hose out of the transparent water tank; and adjusting the position of the electrode, and sequentially controlling the charging switch and the control switch for testing. Air bubbles are injected into the side, close to the electrode, of the flat plate through the peristaltic pump, the influence of the air bubbles on the cavitation bubbles is tested when the cavitation bubbles are excited by the electrode, and therefore the influence of the air bubbles on the cavitation damage is tested, and a new thought is provided for controlling or weakening the cavitation damage degree.

Description

Technical Field

[0001] The invention relates to the technical field of cavitation damage experiments, and more specifically, to a testing system and method for reducing cavitation damage by using preset bubbles. Background Art

[0002] In applications such as water pumps and rotating control valves in power plant generation, and propellers and impellers in marine shipping, the dynamic interaction of high-speed rotating mechanical parts with water often triggers a special phenomenon, namely cavitation. Cavitation is the process of vapor bubbles forming in a liquid, which is particularly prominent when high-speed moving mechanical parts come into contact with liquid.

[0003] During the cavitation process, the rapid generation, expansion and collapse of bubbles will produce strong impact force on the wall of the flow channel, resulting in erosion and damage of the wall material. This erosion and damage not only affects the aesthetics and durability of the flow channel wall, but may also affect its structure and safety. Therefore, research on controlling or reducing the degree of cavitation damage is of great significance.

[0004] In the prior art, the patent document with application publication number CN117723477A discloses a spark-induced cavitation generation and measurement device and method, which forms a discharge loop from the input end of the energy storage capacitor to the output end of the energy storage capacitor by controlling the discharge of the switch, generates a pulse voltage, and applies it to the underwater electrode to stimulate cavitation. When the control switch is closed, the high-voltage DC power supply sends a pulse signal to the synchronizer through the control switch, and the synchronizer outputs a signal to the high-speed camera and the oscilloscope. The high-speed camera synchronously photographs the cavitation phenomenon of the underwater electrode, and the oscilloscope records the voltage and current waveforms during the discharge process measured by the high-voltage probe and the Rogowski coil. In other words, the prior art already has a device that generates cavitation through spark excitation and accurately records the process from the generation to the collapse of cavitation when cavitation is generated, but the device cannot control or reduce the degree of cavitation damage, nor can it conduct research on controlling or reducing the degree of cavitation damage.

[0005] Therefore, there is an urgent need to provide a test system and method for reducing cavitation damage by using pre-set bubbles to study and control the degree of cavitation damage so as to reduce the degree of damage to the solid surface caused by cavitation collapse. Summary of the invention

[0006] In view of this, the present invention provides a testing system and method for reducing cavitation damage by using pre-set bubbles.

[0007] In one aspect, the present invention provides a test system for reducing cavitation damage by using pre-set bubbles, comprising: an impulse current generator, a camera device, an unloading device, a plate, a peristaltic pump and a moving device, wherein:

[0008] The impulse current generator comprises an energy storage capacitor, a first resistor, a diode, an adjustable high-voltage direct current power supply and a charging switch connected in sequence; the impulse current generator also comprises an electrode placed in a transparent water tank, the positive electrode of the electrode is connected to the input end of the energy storage capacitor, and the negative electrode of the electrode is connected to the output end of the energy storage capacitor; the impulse current generator also comprises a voltmeter, the positive electrode of the voltmeter is connected to the input end of the energy storage capacitor, and the negative electrode of the voltmeter is connected to the output end of the energy storage capacitor; the impulse current generator also comprises a control switch, the output end of the control switch is connected to the input end of the energy storage capacitor, and the input end of the control switch is connected to an external power supply;

[0009] The camera device comprises a high-speed camera, a second resistor, a synchronizer and a third resistor connected in sequence, wherein the third resistor is connected to the control switch;

[0010] The unloading device comprises a heat releasing resistor and an unloading switch connected to each other, the input end of the heat releasing resistor is connected to the output end of the energy storage capacitor, and the output end of the unloading switch is connected to the input end of the energy storage capacitor;

[0011] The flat plate is fixed in the transparent water tank and is located on a side of the electrode away from the bottom surface of the transparent water tank;

[0012] The peristaltic pump comprises a main body and a hose connected to each other, wherein an end of the hose away from the main body is located between the plate and the electrode in a direction perpendicular to the bottom surface;

[0013] The movable device comprises a transverse slide rail group extending in the transverse direction, the transverse slide rail group is located at a side of the flat plate away from the bottom surface, the transverse slide rail group comprises a left transverse slide rail and a right transverse slide rail arranged opposite to each other in the longitudinal direction, the left transverse slide rail is connected to at least one left support on the side close to the bottom surface, and the right transverse slide rail is connected to at least one right support on the side close to the bottom surface, the transverse direction, the longitudinal direction and the direction perpendicular to the bottom surface are perpendicular to each other; the movable device also comprises a longitudinal slide rail extending in the longitudinal direction, one end of the longitudinal slide rail is slidably connected to the left transverse slide rail along the transverse direction, and the other end is slidably connected to the right transverse slide rail along the transverse direction; the movable device also comprises a telescopic rod extending in a direction perpendicular to the bottom surface, one end of the telescopic rod is slidably connected to the side of the longitudinal slide rail close to the bottom surface along the longitudinal direction, and the other end is connected to a clamp, and the clamp clamps the flat plate.

[0014] Optionally, one end of the left support away from the left transverse slide rail and one end of the right support away from the right transverse slide rail both abut against the ground.

[0015] Optionally, one end of the left support away from the left transverse slide rail and one end of the right support away from the right transverse slide rail are both connected to the transparent water tank.

[0016] Optionally, it also includes:

[0017] The monitoring and recording system includes an oscilloscope and a fourth resistor connected to each other, wherein the fourth resistor is connected to the synchronizer; the monitoring and recording system also includes a high-voltage probe and a Rogowski coil connected to the oscilloscope, wherein the probe of the high-voltage probe is connected to the circuit connecting the energy storage capacitor and the positive electrode of the electrode, and the Rogowski coil is sleeved outside the circuit connecting the energy storage capacitor and the positive electrode of the electrode.

[0018] On the other hand, the present invention also provides a test method for reducing cavitation damage by using preset bubbles, which is applied to any of the above test systems for reducing cavitation damage by using preset bubbles, and includes a preparation stage and an experimental stage;

[0019] The preparation stage includes: injecting plasma water into the transparent water tank, wherein the liquid level of the plasma water is located on the side of the plate away from the bottom surface; adjusting the position of the high-speed camera, wherein the shooting picture of the high-speed camera at least includes the area between the plate and the electrode;

[0020] The experimental stage includes: turning on the peristaltic pump, and the peristaltic pump injects a preset volume of air bubbles on the side of the flat plate close to the bottom surface according to a preset gas injection rate and a preset injection time; moving the hose out of the transparent water tank; adjusting the position of the electrode, and controlling the charging switch and the control switch in turn to perform the test.

[0021] Optionally, adjusting the position of the electrode and sequentially controlling the charging switch and the control switch to perform the test includes:

[0022] Adjusting the position of the electrode so that the center of the electrode overlaps with the center of the air bubble in a direction perpendicular to the bottom surface;

[0023] The charging switch is closed for a preset time period, and the adjustable high-voltage DC power supply charges the energy storage capacitor; the charging switch is closed for the preset time period and then disconnected, and the voltmeter measures whether the voltage across the energy storage capacitor is a preset voltage; if it is the preset voltage, the control switch is closed for a preset time, and the energy storage capacitor discharges to generate cavitation, and the camera device records test data at the same time;

[0024] The control switch is closed for the preset time and then disconnected, the camera device outputs the test data, and the unloading device unloads the residual voltage of the energy storage capacitor after discharge.

[0025] Optionally, adjusting the position of the electrode and sequentially controlling the charging switch and the control switch to perform the test includes:

[0026] Adjusting the position of the electrode so that the center of the electrode overlaps with the center of the air bubble in a direction perpendicular to the bottom surface;

[0027] Multiple tests are performed, each with a different preset voltage and the same preset duration. During any test, the charging switch is closed for a preset time period, and the adjustable high-voltage DC power supply charges the energy storage capacitor; the charging switch is disconnected after being closed for the preset time period, and the voltmeter measures whether the voltage across the energy storage capacitor is the preset voltage; if it is the preset voltage, the control switch is closed for the preset time period, the energy storage capacitor discharges to produce cavitation, and the camera device records test data; the control switch is disconnected after being closed for the preset time period, the camera device outputs the test data, and the unloading device unloads the residual voltage of the energy storage capacitor after discharge.

[0028] Optionally, adjusting the position of the electrode and sequentially controlling the charging switch and the control switch to perform the test includes:

[0029] Perform multiple tests, each test has a different preset distance, the same preset voltage, and the same preset duration. During any test, adjust the position of the electrode so that the center of the electrode overlaps with the center of the air bubble in a direction perpendicular to the bottom surface, and the distance between the center of the electrode and the center of the air bubble is the preset distance.

[0030] The charging switch is closed for a preset time period, and the adjustable high-voltage DC power supply charges the energy storage capacitor; the charging switch is closed for the preset time period and then disconnected, and the voltmeter measures whether the voltage across the energy storage capacitor is the preset voltage; if it is the preset voltage, the control switch is closed for the preset time period, the energy storage capacitor discharges to generate cavitation, and the camera device records test data; the control switch is closed for the preset time period and then disconnected, the camera device outputs the test data, and the unloading device unloads the residual voltage of the energy storage capacitor after discharge.

[0031] Optionally, after the unloading device unloads the residual voltage after the energy storage capacitor is discharged, it also includes:

[0032] Using the voltmeter to measure whether the voltage across the energy storage capacitor is zero;

[0033] If it is zero, end the current test;

[0034] If it is not zero, the voltage across the energy storage capacitor is measured using the voltmeter at preset intervals, and when the voltage across the energy storage capacitor is zero, the current test is terminated.

[0035] Compared with the prior art, the testing system and method for reducing cavitation damage by using pre-placed bubbles provided by the present invention achieve at least the following beneficial effects:

[0036] 1. The present invention provides a testing system and method for reducing cavitation damage by using pre-set bubbles. A flat plate is fixed in a transparent water tank and is located on the side of the bottom surface of the transparent water tank away from the electrode. By setting the flat plate, the influence of cavitation bubbles on the wall of the flow channel can be studied.

[0037] 2. The present invention provides a test system and method for reducing cavitation damage by using preset bubbles. The peristaltic pump includes a main body and a hose connected to each other. The end of the hose away from the main body is located between the plate and the electrode in a direction perpendicular to the bottom surface. Air bubbles are injected into the side of the plate close to the electrode through the peristaltic pump. When the electrode excites the generation of cavitation bubbles, the influence of the air bubbles on the cavitation bubbles is tested, thereby testing the influence of the air bubbles on the cavitation damage, providing a new idea for controlling or reducing the degree of cavitation damage.

[0038] 3. The test system and method for reducing cavitation damage by using preset bubbles provided by the present invention, in multiple tests, adjusts the preset working conditions or preset distances to further explore the influence of air bubbles on controlling or reducing the degree of cavitation damage.

[0039] Of course, any product implementing the present invention does not necessarily need to achieve all of the technical effects described above at the same time.

[0040] Further features and advantages of the present invention will become apparent from the following detailed description of exemplary embodiments of the present invention with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

[0042] Figure 1 It is a structural schematic diagram of a test system for reducing cavitation damage by using pre-set bubbles provided by the present invention;

[0043] Figure 2 It is a structural schematic diagram of a mobile device;

[0044] Figure 3 It is a flow chart of a test method for reducing cavitation damage by using pre-set bubbles provided by the present invention;

[0045] Figure 4 It is a flow chart of a test;

[0046] Figure 5 This is a comparison chart with and without preset air bubbles.

[0047] In the figure: 1. impulse current generator; 2. energy storage capacitor; 3. first resistor; 4. diode; 5. adjustable high-voltage DC power supply; 6. charging switch; 7. transparent water tank; 8. electrode; 9. voltmeter; 10. control switch; 11. camera device; 12. high-speed camera; 13. second resistor; 14. synchronizer; 15. third resistor; 16. unloading device; 17. exothermic resistor; 18. unloading switch; 19. plate; 20. peristaltic pump; 21. main body; 22. hose; 23. moving device; 24. transverse slide rail group; 25. left transverse slide rail; 26. right transverse slide rail; 27. left support; 28. right support; 29. ​​longitudinal slide rail; 30. telescopic rod; 31. fixture; 32. monitoring and recording system; 33. oscilloscope; 34. fourth resistor; 35. high-voltage probe; 36. Rogowski coil; X, horizontal direction; Y, vertical direction; Z, direction perpendicular to the bottom surface. DETAILED DESCRIPTION

[0048] Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that the relative arrangement of components and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present invention unless otherwise specifically stated.

[0049] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses.

[0050] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered as part of the specification.

[0051] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0052] It should be noted that like reference numerals and letters refer to similar items in the following figures, and therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0053] Combination Figure 1 , Figure 1 1 is a structural schematic diagram of a test system for reducing cavitation damage by using preset bubbles provided by the present invention, to illustrate a specific embodiment of the test system for reducing cavitation damage by using preset bubbles provided by the present invention, including:

[0054] The impulse current generator 1 includes an energy storage capacitor 2, a first resistor 3, a diode 4, an adjustable high-voltage direct current power supply 5 and a charging switch 6 connected in sequence; the impulse current generator 1 also includes an electrode 8 placed in a transparent water tank 7, the positive electrode of the electrode 8 is connected to the input end of the energy storage capacitor 2, and the negative electrode of the electrode 8 is connected to the output end of the energy storage capacitor 2; the impulse current generator 1 also includes a voltmeter 9, the positive electrode of the voltmeter 9 is connected to the input end of the energy storage capacitor 2, and the negative electrode of the voltmeter 9 is connected to the output end of the energy storage capacitor 2; the impulse current generator 1 also includes a control switch 10, the output end of the control switch 10 is connected to the input end of the energy storage capacitor 2, and the input end of the control switch 10 is externally connected to a power supply;

[0055] The camera device 11 includes a high-speed camera 12, a second resistor 13, a synchronizer 14 and a third resistor 15 connected in sequence, and the third resistor 15 is connected to the control switch 10;

[0056] The unloading device 16 includes a heat releasing resistor 17 and an unloading switch 18 connected to each other, wherein the input end of the heat releasing resistor 17 is connected to the output end of the energy storage capacitor 2, and the output end of the unloading switch 18 is connected to the input end of the energy storage capacitor 2;

[0057] The flat plate 19 is fixed in the transparent water tank 7 and is located on the side of the electrode 8 away from the bottom surface of the transparent water tank 7;

[0058] The peristaltic pump 20 includes a main body 21 and a hose 22 connected to each other. Along a direction Z perpendicular to the bottom surface, an end of the hose 22 away from the main body 21 is located between the plate 19 and the electrode 8 .

[0059] It should be noted that the input end of the energy storage capacitor 2 is connected to the output end of the first resistor 3, the input end of the first resistor 3 is connected to the output end of the diode 4, the input end of the diode 4 is connected to the output end of the adjustable high-voltage DC power supply 5, the input end of the adjustable high-voltage DC power supply 5 is connected to the output end of the charging switch 6, and the input end of the charging switch 6 is connected to the output end of the energy storage capacitor 2. The input end of the third resistor 15 is connected to the output end of the control switch 10, the output end of the third resistor 15 is connected to the input end of the synchronizer 14, the output end of the synchronizer 14 is connected to the input end of the second resistor 13, and the output end of the second resistor 13 is connected to the high-speed camera 12.

[0060] Specifically, this embodiment provides a circuit parameter of the impulse current generator 1, which can be referred to in Table 1:

[0061] Table 1. Circuit parameters of impulse current generator

[0062]

[0063] This embodiment also provides a parameter of the peristaltic pump 20, which can be referred to Table 2:

[0064] Table 2. Peristaltic pump parameters

[0065]

[0066] It can be understood that the flat plate 19 is fixed on the side of the electrode 8 away from the bottom surface to simulate the flow channel wall. The material and shape of the flat plate 19 can be set according to actual needs. This embodiment does not make specific restrictions on this. In this embodiment, the material of the flat plate 19 is polymethyl methacrylate (PMMA).

[0067] By controlling the switch 10 to discharge, a discharge loop is formed from the input end of the energy storage capacitor 2 to the output end of the energy storage capacitor 2, a pulse voltage is generated and applied to the underwater electrode 8, and the electrode 8 excites cavitation. At the same time, the high-voltage DC power supply sends a pulse signal to the synchronizer 14 through the control switch 10, and the synchronizer 14 outputs a signal to the high-speed camera 12. The high-speed camera 12 synchronously shoots the cavitation phenomenon of the underwater electrode 8. By setting the flat plate 19, the influence of cavitation bubbles on the wall of the flow channel can be studied. If air bubbles are injected into the side of the flat plate 19 close to the electrode 8 by the peristaltic pump 20 before the cavitation is excited, when the electrode 8 excites the cavitation, the influence of air bubbles on cavitation can be tested, thereby testing the influence of air bubbles on cavitation damage, providing a new idea for controlling or reducing the degree of cavitation damage.

[0068] In some optional embodiments, referring to Figure 1 and Figure 2 , Figure 2 is a structural schematic diagram of a mobile device. The test system for reducing cavitation damage by using preset bubbles provided in this embodiment also includes:

[0069] The moving device 23 includes a transverse rail group 24 extending along the transverse direction X. The transverse rail group 24 is located on the side of the flat plate 19 away from the bottom surface. The transverse rail group 24 includes a left transverse rail 25 and a right transverse rail 26 that are arranged opposite to each other along the longitudinal direction Y. The side of the left transverse rail 25 close to the bottom surface is connected to at least one left support 27. The side of the right transverse rail 26 close to the bottom surface is connected to at least one right support 28. The transverse direction X, the longitudinal direction Y and the direction Z perpendicular to the bottom surface are perpendicular to each other.

[0070] The moving device 23 further includes a longitudinal slide rail 29 extending along the longitudinal direction Y, one end of the longitudinal slide rail 29 is slidably connected to the left transverse slide rail 25 along the transverse direction X, and the other end is slidably connected to the right transverse slide rail 26 along the transverse direction X;

[0071] The moving device 23 also includes a telescopic rod 30 extending in a direction Z perpendicular to the bottom surface. One end of the telescopic rod 30 is slidably connected to the side of the longitudinal slide rail 29 close to the bottom surface along the longitudinal direction Y, and the other end is connected to a clamp 31 that clamps the flat plate 19.

[0072] It is understandable that the flat plate 19 is located in the transparent water tank 7. During the experiment, plasma water is injected into the transparent water tank 7, and the liquid level of the plasma water is located on the side of the flat plate 19 away from the bottom surface of the transparent water tank 7. The flat plate 19 cannot be fixed by itself, so a clamp 31 is provided to clamp the flat plate 19 to fix the position of the flat plate 19. By moving the longitudinal slide rail 29 and the telescopic rod 30, adjusting the length of the telescopic rod 30, and adjusting the position of the clamp 31, the flat plate 19 is fixed at a preset position.

[0073] In some optional embodiments, continue to refer to Figure 1 and Figure 2 The end of the left support 27 away from the left transverse slide rail 25 and the end of the right support 28 away from the right transverse slide rail 26 are both in contact with the ground.

[0074] It is understandable that the moving device 23 is not integrated with the transparent water tank 7, which is convenient for movement and transportation, and the adjustment flexibility of the position of the flat plate 19 is higher.

[0075] In some optional embodiments, continue to refer to Figure 1 and Figure 2 One end of the left support 27 away from the left transverse slide rail 25 and one end of the right support 28 away from the right transverse slide rail 26 are both connected to the transparent water tank 7.

[0076] It can be understood that the moving device 23 and the transparent water tank 7 are integrated, and the relative position of the clamp 31 and the transparent water tank 7 is more accurate, which helps to fix the plate 19 at a preset position.

[0077] In some optional embodiments, continue to refer to Figure 1 The test system for reducing cavitation damage by using preset bubbles provided in this embodiment further includes:

[0078] The monitoring and recording system 32 includes an oscilloscope 33 and a fourth resistor 34 connected to each other, and the fourth resistor 34 is connected to the synchronizer 14; the monitoring and recording system 32 also includes a high-voltage probe 35 and a Rogowski coil 36 connected to the oscilloscope 33, the probe of the high-voltage probe 35 is connected to the circuit connecting the energy storage capacitor 2 and the positive electrode of the electrode 8, and the Rogowski coil 36 is set outside the circuit connecting the energy storage capacitor 2 and the positive electrode of the electrode 8.

[0079] It should be noted that the input end of the fourth resistor 34 is connected to the output end of the synchronizer 14 , and the output end of the fourth resistor 34 is connected to the input end of the oscilloscope 33 .

[0080] It can be understood that when the electrode 8 excites cavitation, the synchronizer 14 outputs signals to the high-speed camera 12 and the oscilloscope 33. The high-speed camera 12 synchronously captures the cavitation phenomenon occurring in the underwater electrode 8. The oscilloscope 33 records the voltage and current waveforms during the discharge process measured by the high-voltage probe 35 and the Rogowski coil 36. Setting up the monitoring and recording system 32 can realize the simultaneous recording of multiple measurement data.

[0081] Specifically, in this embodiment, a list of main components of a test system for reducing cavitation damage by using preset bubbles is provided, which can be referred to Table 3:

[0082] Table 3. List of main components

[0083]

[0084] Based on the same invention idea, refer to Figure 1 and Figure 3 , Figure 3 1 is a flow chart of a test method for reducing cavitation damage by using preset bubbles provided by the present invention. The present invention also provides a test method for reducing cavitation damage by using preset bubbles, which is applied to a test system for reducing cavitation damage by using preset bubbles in any one of the above embodiments, and includes S1, a preparation phase and S2, an experimental phase;

[0085] S1, the preparation stage includes: injecting plasma water into the transparent water tank 7, the liquid level of the plasma water is located on the side of the plate 19 away from the bottom surface; adjusting the position of the high-speed camera 12, and the shooting picture of the high-speed camera 12 includes the area between the plate 19 and the electrode 8;

[0086] S2, the experimental stage includes: turning on the peristaltic pump 20, the peristaltic pump 20 injects a preset volume of air bubbles on the side of the flat plate 19 close to the bottom surface according to a preset gas injection rate and a preset injection time; moving the hose 22 out of the transparent water tank 7; adjusting the position of the electrode 8, and controlling the charging switch 6 and the control switch 10 in turn to perform the test.

[0087] It is understandable that the collapse of cavitation will generate a high-speed jet, and the jet speed can even reach hundreds of meters per second. This high-speed jet can cause damage to the surface of almost any material, which is also an important factor in the damage caused by cavitation. A preset volume of air bubbles is injected into the side of the flat plate 19 close to the bottom surface, the position of the electrode 8 is adjusted, and the charging switch 6 and the control switch 10 are controlled in turn for testing. After the test, it is found that the cavitation will be repelled by the free surface of the air bubble during the collapse process, generating a beam of liquid jet away from the free surface, and the cavitation gradually leaves the free surface. Therefore, the jet generated by the collapse of the cavitation has a weakened damaging effect on the flat plate 19, that is, the preset air bubbles can weaken the damage effect of cavitation.

[0088] In some optional embodiments, referring to Figure 1 , Figure 4 and Figure 5 , Figure 4 This is a flow chart of a test. Figure 5 It is a comparison diagram of preset air bubbles and no preset air bubbles. The position of the electrode 8 is adjusted, and the charging switch 6 and the control switch 10 are controlled in sequence to perform the test, including:

[0089] Adjust the position of the electrode 8 so that the center of the electrode 8 overlaps with the center of the air bubble in the direction Z perpendicular to the bottom surface;

[0090] The charging switch 6 is closed for a preset time period, and the adjustable high-voltage DC power supply 5 charges the energy storage capacitor 2; the charging switch 6 is disconnected after being closed for a preset time period, and the voltmeter 9 measures whether the voltage across the energy storage capacitor 2 is a preset voltage; if it is a preset voltage, the control switch 10 is closed for a preset time, and the energy storage capacitor 2 discharges to generate cavitation, and the camera device 11 starts to record test data;

[0091] The control switch 10 is closed for a preset time and then disconnected, the camera device 11 outputs test data, and the unloading device 16 unloads the residual voltage of the energy storage capacitor 2 after discharge.

[0092] It is understandable that, referring to Figure 5 , -3mm represents that the length of the line segment shown is equivalent to the actual ground length of 3mm, 0.23ms represents the 0.23ms since the control switch 10 is closed, 0.40ms represents the 0.40ms since the control switch 10 is closed, 0.63ms represents the 0.63ms since the control switch 10 is closed, 0.67ms represents the 0.67ms since the control switch 10 is closed, 0.83ms represents the 0.83ms since the control switch 10 is closed, 0.87ms represents the 0.87ms since the control switch 10 is closed, 0.97ms represents the 0.97ms since the control switch 10 is closed, 1.06ms represents the 1.06ms since the control switch 10 is closed, and 1.33ms represents the 1.33ms since the control switch 10 is closed. Figure 5 (a) is a set of high-speed camera images of cavitation when there is no preset air bubble on the side of the plate 19 close to the electrode 8. Figure 5 (b) is a set of high-speed camera images of cavitation when air bubbles are pre-placed on the side of the plate 19 close to the electrode 8. Figure 5 It can be seen that when there is no pre-set air bubble, the destructive jet generated during the cavitation collapse is directed toward the flat plate 19; after the air bubble is pre-set, the cavitation rebounds in the direction of the jet and moves away from the wall, so the pre-set air bubble has a certain weakening effect on cavitation damage.

[0093] In some optional embodiments, adjusting the position of the electrode 8 and sequentially controlling the charging switch 6 and the control switch 10 to perform the test includes:

[0094] Adjust the position of the electrode 8 so that the center of the electrode 8 overlaps with the center of the air bubble in the direction Z perpendicular to the bottom surface;

[0095] Multiple tests are performed, each with a different preset voltage and the same preset duration. During any test, the charging switch 6 is closed for a preset time period, and the adjustable high-voltage DC power supply 5 charges the energy storage capacitor 2; the charging switch 6 is disconnected after being closed for a preset time period, and the voltmeter 9 measures whether the voltage across the energy storage capacitor 2 is the preset voltage; if it is the preset voltage, the control switch 10 is closed for a preset time period, the energy storage capacitor 2 discharges to produce cavitation, and the camera device 11 starts to record test data; the control switch 10 is disconnected after being closed for a preset time period, the camera device 11 outputs the test data, and the unloading device 16 unloads the residual voltage of the energy storage capacitor 2 after discharge.

[0096] It is understandable that through multiple tests, in which the variable of each test is only the preset voltage, the effect of cavitation of different intensities on the damage effect of the flat plate 19 can be explored, and the effect of preset air bubbles on the cavitation damage effect can be further studied.

[0097] In some optional embodiments, adjusting the position of the electrode 8 and sequentially controlling the charging switch 6 and the control switch 10 to perform the test includes:

[0098] Perform multiple tests, each with a different preset distance, the same preset voltage, and the same preset duration. During any test, adjust the position of the electrode 8 so that the center of the electrode 8 overlaps with the center of the air bubble in the direction Z perpendicular to the bottom surface, and the distance between the center of the electrode 8 and the center of the air bubble is the preset distance.

[0099] The charging switch 6 is closed for a preset time period, and the adjustable high-voltage DC power supply 5 charges the energy storage capacitor 2; the charging switch 6 is closed for a preset time period and then disconnected, and the voltmeter 9 measures whether the voltage across the energy storage capacitor 2 is a preset voltage; if it is a preset voltage, the control switch 10 is closed for a preset time period, the energy storage capacitor 2 discharges to produce cavitation, and the camera device 11 starts to record test data; the control switch 10 is closed for a preset time period and then disconnected, the camera device 11 outputs test data, and the unloading device 16 unloads the residual voltage of the energy storage capacitor 2 after discharge.

[0100] It is understandable that through multiple tests, the variable of each test is only the preset distance, which can explore the influence of different relative positions of air bubbles and cavitation bubbles on the damage effect of the plate 19, and further study the influence of preset air bubbles on the cavitation damage effect. Of course, the variable can also be controlled to be different in size of the air bubble each time, and this embodiment is not limited to this. Different variables can be adjusted according to needs, and this embodiment will not be described in detail here.

[0101] In some optional embodiments, after the unloading device 16 unloads the residual voltage after the energy storage capacitor 2 is discharged, it also includes:

[0102] Use a voltmeter 9 to measure whether the voltage across the energy storage capacitor 2 is zero;

[0103] If it is zero, end the current test;

[0104] If it is not zero, the voltage across the energy storage capacitor 2 is measured by a voltmeter 9 at preset intervals. When the voltage across the energy storage capacitor 2 is zero, the current test is terminated.

[0105] It is understandable that at the end of each test, it is necessary to ensure that the residual voltage in the circuit of the impulse current generator 1 is completely released, so as to ensure the safety of the next test.

[0106] It can be seen from the above embodiments that the testing system and method for reducing cavitation damage by using pre-placed bubbles provided by the present invention achieve at least the following beneficial effects:

[0107] 1. The present invention provides a testing system and method for reducing cavitation damage by using pre-set bubbles. A flat plate is fixed in a transparent water tank and is located on the side of the bottom surface of the transparent water tank away from the electrode. By setting the flat plate, the influence of cavitation bubbles on the wall of the flow channel can be studied.

[0108] 2. The present invention provides a test system and method for reducing cavitation damage by using preset bubbles. The peristaltic pump includes a main body and a hose connected to each other. The end of the hose away from the main body is located between the plate and the electrode in a direction perpendicular to the bottom surface. Air bubbles are injected into the side of the plate close to the electrode through the peristaltic pump. When the electrode excites the generation of cavitation bubbles, the influence of the air bubbles on the cavitation bubbles is tested, thereby testing the influence of the air bubbles on the cavitation damage, providing a new idea for controlling or reducing the degree of cavitation damage.

[0109] 3. The test system and method for reducing cavitation damage by using preset bubbles provided by the present invention, in multiple tests, adjusts the preset working conditions or preset distances to further explore the influence of air bubbles on controlling or reducing the degree of cavitation damage.

[0110] Although some specific embodiments of the present invention have been described in detail by way of example, it will be appreciated by those skilled in the art that the above examples are for illustration only and are not intended to limit the scope of the present invention. It will be appreciated by those skilled in the art that the above embodiments may be modified without departing from the scope and spirit of the present invention. The scope of the present invention is defined by the appended claims.

Claims

1. A test system for reducing cavitation damage using pre-placed bubbles, characterized in that: include: An impulse current generator, a camera device, an unloading device, a plate, a peristaltic pump and a moving device, wherein: The impulse current generator comprises an energy storage capacitor, a first resistor, a diode, an adjustable high-voltage direct current power supply and a charging switch connected in sequence; the impulse current generator also comprises an electrode placed in a transparent water tank, the positive electrode of the electrode is connected to the input end of the energy storage capacitor, and the negative electrode of the electrode is connected to the output end of the energy storage capacitor; the impulse current generator also comprises a voltmeter, the positive electrode of the voltmeter is connected to the input end of the energy storage capacitor, and the negative electrode of the voltmeter is connected to the output end of the energy storage capacitor; the impulse current generator also comprises a control switch, the output end of the control switch is connected to the input end of the energy storage capacitor, and the input end of the control switch is connected to an external power supply; The camera device comprises a high-speed camera, a second resistor, a synchronizer and a third resistor connected in sequence, wherein the third resistor is connected to the control switch; The unloading device comprises a heat releasing resistor and an unloading switch connected to each other, the input end of the heat releasing resistor is connected to the output end of the energy storage capacitor, and the output end of the unloading switch is connected to the input end of the energy storage capacitor; The flat plate is fixed in the transparent water tank and is located on a side of the electrode away from the bottom surface of the transparent water tank; The peristaltic pump comprises a main body and a hose connected to each other, wherein an end of the hose away from the main body is located between the plate and the electrode in a direction perpendicular to the bottom surface; The movable device comprises a transverse slide rail group extending in the transverse direction, the transverse slide rail group is located at a side of the flat plate away from the bottom surface, the transverse slide rail group comprises a left transverse slide rail and a right transverse slide rail arranged opposite to each other in the longitudinal direction, the left transverse slide rail is connected to at least one left support on the side close to the bottom surface, and the right transverse slide rail is connected to at least one right support on the side close to the bottom surface, the transverse direction, the longitudinal direction and the direction perpendicular to the bottom surface are perpendicular to each other; the movable device also comprises a longitudinal slide rail extending in the longitudinal direction, one end of the longitudinal slide rail is slidably connected to the left transverse slide rail along the transverse direction, and the other end is slidably connected to the right transverse slide rail along the transverse direction; the movable device also comprises a telescopic rod extending in a direction perpendicular to the bottom surface, one end of the telescopic rod is slidably connected to the side of the longitudinal slide rail close to the bottom surface along the longitudinal direction, and the other end is connected to a clamp, and the clamp clamps the flat plate.

2. The test system for reducing cavitation damage by using pre-placed bubbles according to claim 1, characterized in that: One end of the left support away from the left transverse slide rail and one end of the right support away from the right transverse slide rail are both in contact with the ground.

3. The test system for reducing cavitation damage by using pre-placed bubbles according to claim 1, characterized in that: One end of the left support away from the left transverse slide rail and one end of the right support away from the right transverse slide rail are both connected to the transparent water tank.

4. The testing system for reducing cavitation damage by using pre-placed bubbles according to claim 1, characterized in that: Also includes: The monitoring and recording system includes an oscilloscope and a fourth resistor connected to each other, wherein the fourth resistor is connected to the synchronizer; the monitoring and recording system also includes a high-voltage probe and a Rogowski coil connected to the oscilloscope, wherein the probe of the high-voltage probe is connected to the circuit connecting the energy storage capacitor and the positive electrode of the electrode, and the Rogowski coil is sleeved outside the circuit connecting the energy storage capacitor and the positive electrode of the electrode.

5. A test method for reducing cavitation damage by using pre-placed bubbles, applied to the test system for reducing cavitation damage by using pre-placed bubbles as claimed in any one of claims 1 to 4, characterized in that: It includes the preparation phase and the experimental phase; The preparation stage includes: injecting plasma water into the transparent water tank, wherein the liquid level of the plasma water is located on the side of the plate away from the bottom surface; adjusting the position of the high-speed camera, wherein the shooting picture of the high-speed camera at least includes the area between the plate and the electrode; The experimental stage includes: turning on the peristaltic pump, and the peristaltic pump injects a preset volume of air bubbles on the side of the flat plate close to the bottom surface according to a preset gas injection rate and a preset injection time; moving the hose out of the transparent water tank; adjusting the position of the electrode, and controlling the charging switch and the control switch in turn to perform the test.

6. The test method for reducing cavitation damage by using pre-placed bubbles according to claim 5, characterized in that: Adjusting the position of the electrode and sequentially controlling the charging switch and the control switch to perform a test includes: Adjusting the position of the electrode so that the center of the electrode overlaps with the center of the air bubble in a direction perpendicular to the bottom surface; The charging switch is closed for a preset time period, and the adjustable high-voltage DC power supply charges the energy storage capacitor; the charging switch is closed for the preset time period and then disconnected, and the voltmeter measures whether the voltage across the energy storage capacitor is a preset voltage; if it is the preset voltage, the control switch is closed for a preset time, and the energy storage capacitor discharges to generate cavitation, and the camera device records test data at the same time; The control switch is closed for the preset time and then disconnected, the camera device outputs the test data, and the unloading device unloads the residual voltage of the energy storage capacitor after discharge.

7. The test method for reducing cavitation damage by using pre-placed bubbles according to claim 5, characterized in that: Adjusting the position of the electrode and sequentially controlling the charging switch and the control switch to perform a test includes: Adjusting the position of the electrode so that the center of the electrode overlaps with the center of the air bubble in a direction perpendicular to the bottom surface; Multiple tests are performed, each with a different preset voltage and the same preset duration. During any test, the charging switch is closed for a preset time period, and the adjustable high-voltage DC power supply charges the energy storage capacitor; the charging switch is disconnected after being closed for the preset time period, and the voltmeter measures whether the voltage across the energy storage capacitor is the preset voltage; if it is the preset voltage, the control switch is closed for the preset time period, the energy storage capacitor discharges to produce cavitation, and the camera device records test data; the control switch is disconnected after being closed for the preset time period, the camera device outputs the test data, and the unloading device unloads the residual voltage of the energy storage capacitor after discharge.

8. The test method for reducing cavitation damage by using pre-placed bubbles according to claim 5, characterized in that: Adjusting the position of the electrode and sequentially controlling the charging switch and the control switch to perform a test includes: Perform multiple tests, each test has a different preset distance, the same preset voltage, and the same preset duration. During any test, adjust the position of the electrode so that the center of the electrode overlaps with the center of the air bubble in a direction perpendicular to the bottom surface, and the distance between the center of the electrode and the center of the air bubble is the preset distance. The charging switch is closed for a preset time period, and the adjustable high-voltage DC power supply charges the energy storage capacitor; the charging switch is closed for the preset time period and then disconnected, and the voltmeter measures whether the voltage across the energy storage capacitor is the preset voltage; if it is the preset voltage, the control switch is closed for the preset time period, the energy storage capacitor discharges to generate cavitation, and the camera device records test data; the control switch is closed for the preset time period and then disconnected, the camera device outputs the test data, and the unloading device unloads the residual voltage of the energy storage capacitor after discharge.

9. The test method for reducing cavitation damage by using pre-placed bubbles according to claim 6, characterized in that: After the unloading device unloads the residual voltage after the energy storage capacitor is discharged, it also includes: Using the voltmeter to measure whether the voltage across the energy storage capacitor is zero; If it is zero, end the current test; If it is not zero, the voltage across the energy storage capacitor is measured using the voltmeter at preset intervals, and when the voltage across the energy storage capacitor is zero, the current test is terminated.

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