A method and system for generating high-repetition-rate shock waves based on long-pulse (DC) liquid-phase discharge.

Abstract

This invention discloses a method and system for generating high-repetition-rate shock waves based on long-pulse (DC) liquid-phase discharge. The method includes the following steps: 1) Charging an energy storage capacitor using a charging module until the voltage across the capacitor reaches a set value; closing a solid-state switch, allowing the energy storage capacitor to discharge to a discharge electrode, thereby transmitting a pulsed shock wave to the target discharge region; 2) After a time Δt, opening the solid-state switch, monitoring the number and duration of voltage pulses generated by the discharge electrode; if the number and duration of the pulsed shock waves are less than a preset threshold, returning to step 2); otherwise, ending the discharge. The system includes a high-voltage pulse power supply module, a discharge module, and a measurement module. This invention proposes a method for generating high-repetition-rate shock waves based on long-pulse (DC) liquid-phase discharge, which can control the frequency and intensity of the shock wave by adjusting the discharge parameters, and has advantages such as simple structure and low cost compared to traditional high-voltage pulse generators.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of liquid phase discharge, in particular to a heavy frequency shock wave generation method and system based on long pulse (direct current) liquid phase discharge. BACKGROUND

[0002] High-voltage pulse liquid phase discharge can generate shock waves with strong mechanical effects. The phenomenon of converting electrical energy into mechanical energy through high-voltage pulse discharge is called "liquid-electric effect". The strong shock wave generated has wide applications in industrial and civil fields, such as rock breaking, liquid-electric cleaning, and oil production increase, etc.

[0003] During high-voltage pulse liquid phase discharge, the liquid-gas-plasma transition is completed in a very short time, forming a high-temperature and dense plasma channel. The initial plasma channel has very high temperature and pressure, which will expand rapidly outward, thereby realizing high-speed conversion from electrical energy to mechanical energy. Due to the weak compressibility of the liquid around the plasma channel, the mechanical energy is mainly released in the form of waves, and the high-energy wave is called shock wave.

[0004] In the application of traditional "liquid-electric effect", a single shock wave is generally generated by a single pulse. If multiple shock waves are to be generated continuously, multiple continuous pulses are usually required, and the traditional high-voltage heavy frequency pulse source has the problems of complex structure and high cost. SUMMARY

[0005] The purpose of the present application is to provide a heavy frequency shock wave generation method based on long pulse (direct current) liquid phase discharge, comprising the following steps:

[0006] 1) injecting a liquid medium into a discharge adjusting device; placing a pair of discharge electrodes in the liquid medium and adjusting the immersion depth until the discharge electrodes are immersed in the liquid medium;

[0007] 2) presetting the on-off times of the solid-state switch and the pulse width, setting the liquid conductivity, the energy storage capacitor value, and the current limiting resistance value;

[0008] 3) charging the energy storage capacitor using a charging module until the voltage across the energy storage capacitor reaches the set voltage value; closing the solid-state switch, and discharging the energy storage capacitor to the discharge electrodes, thereby transmitting a pulse shock wave to the discharge target area;

[0009] 4) after Δt time, the solid-state switch is opened, the number and duration of voltage pulses generated by the discharge electrode are monitored, if the number and duration of pulse shock waves are less than the preset threshold, return to step 3), otherwise end the discharge.

[0010] Further, the liquid medium includes water, oil, alcohol, and ester.

[0011] Further, the discharge time of the energy storage capacitor is greater than the bubble pulsation period, so that the discharge electrode generates a repetitive frequency pulse shock wave.

[0012] The bubble pulsation period is the time from bubble formation to collapse; the principle of bubble formation is that after a high voltage is applied to the two ends of the electrode, the liquid medium is broken down and a plasma channel is formed, and the continuous action of the discharge current causes the liquid in the plasma channel region to evaporate, forming a bubble.

[0013] Further, in step 3), the energy storage capacitor discharges the discharge electrode through the current-limiting resistor.

[0014] Further, the energy storage capacitor C≥100uF, the current-limiting resistor R≤1kΩ; the discharge electrode spacing d≤5mm.

[0015] Further, the material of the discharge electrode includes tungsten copper, tungsten, and stainless steel; the electrode form includes needle-needle, needle-plate, and ball-ball forms.

[0016] The system applying the repetitive frequency shock wave generation method based on long pulse (direct current) liquid phase discharge includes a high-voltage pulse power supply module, a discharge module, and a measurement module.

[0017] The high-voltage pulse power supply module includes a dry test transformer, a rectifier unit, and an energy storage capacitor.

[0018] The dry test transformer converts a certain grade of AC voltage into another grade of AC voltage of the same frequency, and then outputs a DC voltage through the rectifier unit to charge the energy storage capacitor.

[0019] The discharge module includes a current-limiting resistor, a solid-state switch, a discharge electrode, and a discharge adjustment device.

[0020] The discharge adjustment device is filled with a liquid medium.

[0021] The discharge electrode is located in the liquid medium,

[0022] When the solid-state switch is off, the energy storage capacitor is in a charged state.

[0023] When the solid-state switch is on, the energy storage capacitor discharges the discharge electrode through the current-limiting resistor.

[0024] The measurement module includes a high-voltage probe, a current probe, a shock wave probe, and an oscilloscope.

[0025] The high-voltage probe and the current probe are used to monitor the voltage and current of the discharge electrode, respectively, and are displayed in the oscilloscope.

[0026] The shock wave probe is used to monitor the number and duration of voltage pulses of the discharge electrode and is displayed in the oscilloscope.

[0027] Further, the insulated cable is further included;

[0028] The insulated cable is used for connecting the energy storage capacitor, the current limiting resistor, the solid state switch and the discharge electrode in series.

[0029] The technical effect of the present application is self-evident, the present application proposes a long pulse (direct current) liquid phase discharge based frequency shock wave generation method, the frequency, intensity and the like of the shock wave can be controlled by adjusting the discharge parameters, and the long pulse (direct current) liquid phase discharge based frequency shock wave generation method has the advantages of simple structure, low cost and the like compared with the traditional high voltage pulse generation device. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 The long pulse (direct current) liquid phase discharge frequency shock wave generation system;

[0031] Figure 2 The long pulse (direct current) liquid phase discharge frequency shock wave system in water;

[0032] Figure 3 The long pulse (direct current) liquid phase discharge frequency shock wave waveform in water;

[0033] Figure 4 The long pulse (direct current) liquid phase discharge frequency shock wave flow chart. DETAILED DESCRIPTION

[0034] The present application will be further described below in conjunction with the embodiments, but should not be understood as limiting the above-mentioned subject matter of the present application to only the following embodiments. According to ordinary technical knowledge and conventional means in the art, various substitutions and modifications can be made without departing from the above-mentioned technical idea of the present application, and all of them should be included in the protection scope of the present application.

[0035] Example 1:

[0036] Referring to Figures 1 to 4 , the long pulse (direct current) liquid phase discharge based frequency shock wave generation method includes the following steps:

[0037] 1) injecting a liquid medium in the discharge adjusting device, and adjusting the liquid level, so that the height of the liquid medium is greater than the length of the discharge electrode to be placed; placing a pair of discharge electrodes in the liquid medium, and adjusting the immersion depth until the discharge electrodes are immersed in the liquid medium;

[0038] 2) presetting the on-off times of the solid state switch and the pulse width, setting the liquid conductivity, the energy storage capacitor value and the current limiting resistor value;

[0039] 3) charging the energy storage capacitor by using the charging module until the voltage across the energy storage capacitor reaches the set voltage value; the solid state switch is closed, the energy storage capacitor discharges the discharge electrode, and then the discharge electrode transmits the pulse shock wave to the discharge target area;

[0040] 4) After Δt time, the solid-state switch is turned off, the number and duration of voltage pulses generated by the discharge electrode are monitored, if the number and duration of pulse shock waves are less than the preset threshold, return to step 3), otherwise end the discharge.

[0041] The liquid medium includes water, oil, alcohol, and ester.

[0042] The discharge time of the energy storage capacitor is greater than the bubble pulsation period, so that the discharge electrode generates a repetitive pulse shock wave;

[0043] The bubble pulsation period is the time from bubble formation to shrinkage and collapse. The principle of bubble formation is that after a high voltage is applied between the electrodes, the liquid medium is broken down and a plasma channel is formed. The continuous action of the discharge current causes the liquid in the plasma channel to evaporate, forming a bubble.

[0044] In step 3), the energy storage capacitor discharges the discharge electrode through the current-limiting resistor.

[0045] The energy storage capacitor C is greater than or equal to 100uF, and the current-limiting resistor R is less than or equal to 1kΩ; the discharge electrode spacing d is less than or equal to 5mm.

[0046] The material of the discharge electrode includes tungsten copper, tungsten, and stainless steel; the electrode form includes needle-needle, needle-plate, and ball-ball forms.

[0047] The system applying the repetitive shock wave generation method based on long pulse (direct current) liquid phase discharge includes a high-voltage pulse power supply module, a discharge module, and a measurement module.

[0048] The high-voltage pulse power supply module includes a dry test transformer, a rectifier unit, and an energy storage capacitor.

[0049] The dry test transformer converts a certain level of AC voltage into another level of AC voltage of the same frequency, and then outputs a DC voltage through the rectifier unit to charge the energy storage capacitor.

[0050] The discharge module includes a current-limiting resistor, a solid-state switch, a discharge electrode, and a discharge adjustment device.

[0051] The discharge adjustment device is injected with a liquid medium;

[0052] The discharge electrode is located in the liquid medium,

[0053] When the solid-state switch is turned off, the energy storage capacitor is in a charged state;

[0054] When the solid-state switch is turned on, the energy storage capacitor discharges the discharge electrode through the current-limiting resistor;

[0055] The measurement module includes a high-voltage probe, a current probe, a shock wave probe, and an oscilloscope.

[0056] The high-voltage probe and the current probe are respectively used for monitoring the voltage and the current of the discharge electrode and displaying in an oscilloscope.

[0057] The shock wave probe is used for monitoring the number and duration of voltage pulses of the discharge electrode and displaying in an oscilloscope.

[0058] The insulated cable is further included.

[0059] The insulated cable is used for connecting the energy storage capacitor, the current limiting resistor, the solid-state switch and the discharge electrode in series.

[0060] Embodiment 2:

[0061] The method for generating the repetitive shock wave based on the long-pulse (direct current) liquid-phase discharge comprises the following contents.

[0062] The present application uses liquid (water, oil, alcohol, ester, etc.) as the discharge medium, and a high voltage is applied between the electrodes. After the liquid medium is broken down and a plasma channel is formed, the plasma channel expands rapidly and squeezes the surrounding liquid to radiate a primary shock wave. The continuous action of the discharge current causes the liquid around the channel to evaporate, forming a low-brightness vapor sheath (bubble). The bubble continues to absorb energy and expand outward, and then shrinks and collapses. When the bubble shrinks to the smallest volume, the internal energy rapidly compresses the surrounding liquid, forming a secondary shock wave. If a long pulse (direct current) is set, the duration of the applied voltage is greater than the bubble pulsation period, and when the energy is continuously injected, the bubble will experience a periodic pulsation process, thereby forming a repetitive pulse shock wave.

[0063] The discharge parameters will affect the energy deposited by the plasma channel, and at the same time, the bubble pulsation characteristics are affected by the deposited energy. For example, different electrode spacing, energy storage capacitor and voltage amplitude will affect the bubble pulsation period, thereby regulating the shock wave frequency and intensity. Therefore, the present application controls the shock wave characteristics by adjusting the discharge parameters.

[0064] The key to generating a repetitive pulse shock wave lies in: (1) the periodic change of arc impedance R1 in the RC discharge circuit; (2) the capacitance value of the discharge capacitor is large enough to make the time constant τ of the RC discharge circuit reach sub-second level or above to meet the direct current condition. The specific selection can refer to C≥100uF and R≤1kΩ; (3) the electrode spacing d should not be too long, so that the plasma channel is roughly point-shaped rather than long strip-shaped (the length-width ratio of the arc is less than 5), so as to ensure that the internal physicochemical properties of the plasma channel are relatively uniform, and the expansion and contraction of each part of the arc are basically synchronized to generate regular repetitive pulse shock waves.

[0065] The long pulse (direct current) liquid discharge repetitive frequency shock wave generating system mainly comprises a high-voltage pulse power module, an insulation cable, a discharge module and a measuring module. The high-voltage pulse power module comprises a dry test transformer, a rectifier unit and an energy storage capacitor, and the insulation cable is used for energy transmission. The discharge module comprises a current-limiting resistor, a solid-state switch, a discharge electrode and an adjusting device, the solid-state switch is a device capable of controlling the on-off of the main circuit, the material of the discharge electrode is tungsten copper (tungsten, stainless steel and other metals), the electrode forms include needle-needle, needle-plate, ball-ball, etc., the electrode geometry parameters can be adjusted, and the adjusting device comprises electrode gap distance, electrode immersion depth in liquid, liquid height and the like adjustment. The measuring module comprises a high-voltage probe, a current probe and a shock wave probe. The discharge main circuit is composed of a current-limiting resistor, a solid-state switch and a discharge electrode in series, and the series order is not limited, and the device has universality.

[0066] Figure 2 is an example of a long pulse (direct current) liquid discharge repetitive frequency shock wave system in water, the energy storage capacitor is 135 μF, the current-limiting resistor is 0.45 kΩ, and the solid-state switch adopts BEHLKE HTS651-03-LC model. The charging unit in the high-voltage pulse power module charges the energy storage capacitor, and after reaching the specified voltage, the solid-state switch is controlled to be closed, at this time the main discharge circuit is turned on, and the capacitor discharges to the water gap. A tungsten copper needle-needle electrode is used, the needle electrode tip radius is 1 mm, the gap distance is 1 mm, and the water solution conductivity is 100 μs / cm. In the measuring module, the gap voltage and current signals are collected by a high-voltage probe (Tektronix P6015A) and a current probe (Cybertek CP8050A) respectively, and the shock wave signal is collected by a shock wave probe (RHSA-10) and stored in a high-resolution oscilloscope (Lecroy HDO6054A).

[0067] The operating steps of the long pulse (direct current) liquid discharge repetitive frequency shock wave are as follows:

[0068] (1) Pour a certain amount of liquid medium into the discharge observation box, adjust the liquid level, place two discharge electrodes in the liquid medium, and adjust the immersion depth until the target area is reached.

[0069] (2) Pre-set the on-off times and pulse width of the solid-state switch, set the liquid conductivity, energy storage capacitor value (≥100 uF), current-limiting resistor value (≤1 kΩ), electrode gap distance (≤5 mm).

[0070] (3) The solid-state switch is closed at time t1, and is opened at time t2, and the pulse voltage duration Δt = t2-t1. The energy storage capacitor is charged by the charging module until the set voltage value (≥5kV) is reached. The solid-state switch is closed, the main discharge circuit is connected, and the discharge is triggered. When the pulse voltage duration Δt = pulse width, the solid-state switch is opened, and the high voltage, current and shock wave probe collect signals and display them on the oscilloscope. The number and duration of the generated voltage pulses are analyzed and judged to see if they meet the preset values. If the number and duration of the pulses are lower than the preset values, the capacitor is charged again to the preset voltage, the solid-state switch is closed, and the discharge is repeated multiple times. Otherwise, the discharge is ended.

[0071] Example 3

[0072] The method for generating repetitive shock waves based on long pulse (direct current) liquid discharge includes the following steps:

[0073] 1) The liquid medium is injected into the discharge adjustment device; a pair of discharge electrodes are placed in the liquid medium, and the immersion depth is adjusted until the discharge electrodes are immersed in the liquid medium.

[0074] 2) The number of times of opening and closing of the solid-state switch and the pulse width are preset, and the liquid conductivity, the energy storage capacitor value, and the current limiting resistor value are set;

[0075] 3) The energy storage capacitor is charged by the charging module until the voltage across the energy storage capacitor reaches the set voltage value; the solid-state switch is closed, the energy storage capacitor discharges the discharge electrodes, and then the discharge electrodes transmit the pulse shock wave to the discharge target area;

[0076] 4) After Δt time, the solid-state switch is opened, the number and duration of the voltage pulses generated by the discharge electrodes are monitored, and if the number and duration of the pulse shock waves are less than the preset threshold, step 3) is returned, otherwise the discharge is ended.

[0077] Example 4

[0078] The method for generating repetitive shock waves based on long pulse (direct current) liquid discharge, the main content is seen in example 3, wherein the liquid medium includes water, oil, alcohol, and ester.

[0079] Example 5

[0080] The method for generating repetitive shock waves based on long pulse (direct current) liquid discharge, the main content is seen in example 3, wherein the discharge time of the energy storage capacitor is greater than the bubble pulsation period, so that the discharge electrodes generate repetitive pulse shock waves;

[0081] The bubble pulsation period is the time from bubble formation to shrinkage and collapse. The principle of bubble formation is that after a high voltage is applied across the electrodes, the liquid medium is broken down and a plasma channel is formed. The continuous action of the discharge current causes the liquid in the region where the plasma channel is located to evaporate, forming a bubble.

[0082] Embodiment 6:

[0083] The repetitive frequency shock wave generation method based on long pulse (direct current) liquid phase discharge, the main content is seen in embodiment 3, wherein, in step 3), the energy storage capacitor discharges the discharge electrode through the current limiting resistor.

[0084] Embodiment 7:

[0085] The repetitive frequency shock wave generation method based on long pulse (direct current) liquid phase discharge, the main content is seen in embodiment 3, wherein, the energy storage capacitor C≥100uF, the current limiting resistor R≤1kΩ; the discharge electrode spacing d≤5mm.

[0086] Embodiment 8:

[0087] The repetitive frequency shock wave generation method based on long pulse (direct current) liquid phase discharge, the main content is seen in embodiment 3, wherein, the material of the discharge electrode includes but is not limited to tungsten copper, tungsten, stainless steel; the electrode form includes but is not limited to needle-needle, needle-plate, ball-ball form.

[0088] Embodiment 9:

[0089] The system applying the repetitive frequency shock wave generation method based on long pulse (direct current) liquid phase discharge, including high voltage pulse power supply module, discharge module and measurement module;

[0090] The high voltage pulse power supply module includes dry type test transformer, rectifier unit and energy storage capacitor;

[0091] The dry type test transformer converts a certain grade of alternating voltage into another grade of alternating voltage of the same frequency, and then outputs direct current voltage through the rectifier unit to charge the energy storage capacitor;

[0092] The discharge module includes current limiting resistor, solid state switch, discharge electrode and discharge adjusting device;

[0093] The discharge adjusting device is injected with liquid medium;

[0094] The discharge electrode is located in the liquid medium,

[0095] When the solid state switch is off, the energy storage capacitor is in the charging state;

[0096] When the solid state switch is on, the energy storage capacitor discharges the discharge electrode through the current limiting resistor;

[0097] The measurement module includes high voltage probe, current probe, shock wave probe and oscilloscope;

[0098] The high voltage probe and the current probe are respectively used for monitoring the voltage and current of the discharge electrode, and are displayed in the oscilloscope;

[0099] The shock wave probe is used for monitoring the number and duration of voltage pulses of the discharge electrode and displaying in an oscilloscope.

[0100] Example 10:

[0101] The system applying the burst shock wave generation method based on long pulse (direct current) liquid discharge, the main content is seen in example 9, wherein, further comprising an insulated cable;

[0102] The insulated cable is used for connecting in series the energy storage capacitor, the current limiting resistor, the solid state switch and the discharge electrode.

Claims

1. A method of long-pulse liquid-discharge-based repetitive shockwave generation, characterized in that, The method comprises the following steps: 1) injecting a liquid medium into a discharge adjusting device; placing a pair of discharge electrodes in the liquid medium and adjusting the immersion depth until the discharge electrodes are immersed in the liquid medium; 2) presetting the on-off times and pulse width of a solid-state switch, setting the liquid conductivity, energy storage capacitor value, and current limiting resistor value; 3) charging the energy storage capacitor using a charging module until the voltage across the energy storage capacitor reaches the set voltage value; closing the solid-state switch, and the energy storage capacitor discharges the discharge electrodes, thereby transmitting a pulse shock wave to the discharge target area; 4) after Δt time, the solid-state switch is opened, and the number and duration of voltage pulses generated by the discharge electrodes are monitored; if the number and duration of the pulse shock wave are less than the preset threshold, return to step 3), otherwise end the discharge; The discharge time of the energy storage capacitor is greater than the bubble pulsation period, so that the discharge electrodes generate a heavy frequency pulse shock wave; The bubble pulsation period is the time from bubble formation to shrinkage and collapse; the principle of bubble formation is that after a high voltage is applied across the electrodes, the liquid medium breaks down and forms a plasma channel, and the continuous action of the discharge current causes the liquid in the region where the plasma channel is located to evaporate, forming a bubble; In step 3), the energy storage capacitor discharges the discharge electrodes through the current limiting resistor; The energy storage capacitor C is greater than or equal to 100 uF, and the current limiting resistor R is less than or equal to 1 kΩ; the discharge electrode spacing d is less than or equal to 5 mm.

2. The long-pulse liquid-discharge-based repetitive shockwave generation method of claim 1, wherein, The liquid medium comprises water, oil, alcohol, and ester.

3. The long-pulse liquid-discharge-based repetitive shockwave generation method of claim 1, wherein, The material of the discharge electrode comprises tungsten copper, tungsten, and stainless steel; the electrode form comprises needle-needle, needle-plate, and ball-ball.

4. System for applying the method for generating repetitive shock waves based on long-pulse liquid discharge according to any one of claims 1 to 3, characterized in that, It comprises a high-voltage pulse power supply module, a discharge module, and a measurement module; The high-voltage pulse power supply module comprises a dry test transformer, a rectifier unit, and an energy storage capacitor; The dry test transformer converts a certain grade of AC voltage into another grade of AC voltage of the same frequency, and then outputs a DC voltage through the rectifier unit to charge the energy storage capacitor; The discharge module comprises a current limiting resistor, a solid-state switch, a discharge electrode, and a discharge adjusting device; The discharge adjusting device is injected with a liquid medium; The discharge electrode is located in the liquid medium, When the solid-state switch is opened, the energy storage capacitor is in a charging state; When the solid-state switch is turned on, the energy storage capacitor discharges the discharge electrode through the current limiting resistor; The measurement module comprises a high-voltage probe, a current probe, a shock wave probe, and an oscilloscope; The high-voltage probe and the current probe are used to monitor the voltage and current of the discharge electrode, respectively, and display them on the oscilloscope; The shock wave probe is used to monitor the number and duration of voltage pulses generated by the discharge electrode and display them on the oscilloscope.

5. The system for the method of generating repetitive shock waves based on long-pulse liquid-discharge according to claim 4, characterized in that, It also comprises an insulated cable; The insulated cable is used to connect the energy storage capacitor, the current limiting resistor, the solid-state switch, and the discharge electrode in series.

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