A method for suppressing combustion oscillation by synergistically suppressing combustion oscillation of central plasma and side plasma in sliding arc discharge
Through the synergistic effect of the central plasma of the sliding arc discharge and the side plasma, the coupling of flame heat release rate and pressure pulsation is destroyed, and the combustion oscillation is significantly suppressed, which solves the problems of insufficient frequency and mechanical losses in the prior art, and provides them in harsh environments. Stable and uniform discharge effect.
Patent Information
- Application Number
- CN202211337225.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2022-10-28
- Publication Date
- 2024-12-06
- Estimated Expiration
- 2042-10-28
AI Technical Summary
The existing combustion oscillation suppression methods have problems such as insufficient operating frequency, large delay in operating time and mechanical losses, and DBD discharge is unstable and easy to damage in harsh environments such as gas turbines and aircraft engines.
By adopting the method of synergistically suppressing combustion oscillation between the sliding arc discharge center plasma and the side plasma, a two-dimensional knife-type sliding arc and a three-phase rotary sliding arc are generated by installing an inclined first electrode and a second electrode with uniform circumferential direction in the combustion chamber. Discharge, forming a uniformly distributed plasma, destroying the coupling relationship between flame unstable heat release and sound waves, and adjusting the discharge frequency and intensity to suppress combustion oscillation.
It significantly reduces the pressure oscillation amplitude of combustion oscillation, improves the operating frequency and electrode life, adapts to harsh environments such as gas turbines and aircraft engines, has low energy consumption and high frequency operation characteristics, and solves the frequency deficiency and mechanical losses of traditional active control. question.
Smart Images
Figure CN115604900B_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of energy and power technology, and relates to a method for suppressing combustion oscillation by using plasma, and in particular to a method for suppressing combustion oscillation by cooperatively using central plasma and side plasma of sliding arc discharge. Background Art
[0002] The increasingly stringent emission requirements have forced modern aircraft engines and gas turbines to generally adopt lean premixed combustion technology. This combustion technology can significantly reduce the emission of pollutants such as NOx and soot, but this combustion technology is often accompanied by combustion oscillation in engineering applications. Combustion oscillation, also known as "thermoacoustic oscillation" or "combustion instability", is a periodic phenomenon caused by the coupling between the heat release rate pulsation of the flame and the inherent acoustic characteristics in the combustion chamber. The "Rayleigh criterion" is widely used to judge and analyze combustion oscillation. The Rayleigh criterion points out that there are heat release rate pulsation and pressure pulsation in the combustion chamber at the same time. When the phase difference between the pressure and heat release rate in the combustion zone is less than 90°, the heat released by unstable combustion will be transferred to the pressure pulsation. If this part of energy is greater than the total energy dissipated by the sound pressure at each boundary, the pressure pulsation will be continuously strengthened until it reaches equilibrium, causing combustion oscillation; on the contrary, when the phase difference between the heat release and pressure pulsation in the combustion zone is greater than 90°, combustion oscillation is impossible. When combustion oscillation occurs, the combustion heat release rate and pressure will pulsate periodically and release high-decibel noise. This change in heat release rate will lead to local high temperatures and incomplete combustion, which will increase pollutant emissions. In addition, high-intensity pressure pulsations may also damage the combustion chamber structure. Therefore, in order to avoid this phenomenon, it is necessary to control the combustion oscillation phenomenon of the combustion system.
[0003] At present, the control methods of combustion oscillation mainly include active control and passive control. Passive control refers to the avoidance or suppression of thermoacoustic oscillations by adding fixed structural parts in the combustion device and changing the acoustic or flow structure of the combustion system. Common types of acoustic components, such as quarter-wavelength tubes or Helmholtz resonators, are used to increase the damping and dissipation of sound waves of specific frequencies, thereby suppressing oscillations. However, these acoustic components are large in size and only work on specific oscillation conditions of specific equipment, and often fail in low-frequency areas. In addition, passive control technology is only developed for a certain type of specific burner, resulting in a series of problems such as long development cycle and high development costs. Active control mainly modulates the air flow or fuel flow of the combustion system by adding artificial actuators to destroy the coupling relationship between sound waves and unsteady heat release during self-excited oscillations. It has the advantages of good system feedback, good control effect, and strong adaptability; but at the same time, the actuator also has problems such as insufficient actuation frequency (usually less than 100Hz), actuation time delay, and mechanical loss.
[0004] In view of the technical problems of insufficient actuation frequency, large actuation time delay and mechanical loss in the current methods for suppressing combustion pressure pulsation, existing patents such as 201811639692.9, 201811635818.5, 201811635817.0, etc., adopt a solution of using central plasma or side plasma or both in coordination as a dynamic and active way to regulate the pressure pulsation state of the combustion system during the combustion process. However, all of them use the dielectric barrier discharge (DBD) method to generate plasma. Although this method can produce a large area of low-temperature plasma, this method also has the problems of uneven discharge and its dielectric layer is very easy to rupture due to uneven heating, and the electrode is damaged. In addition, the working environment of the combustion chambers of gas turbines, aircraft engines, etc. is harsh, which makes their dielectric layers more easily damaged. Therefore, DBD discharge is not convenient for application in these combustion chambers. Summary of the invention
[0005] In order to overcome the shortcomings of the above-mentioned prior art, the purpose of the present invention is to provide a method for cooperatively suppressing combustion oscillations by the central plasma and the side plasma of sliding arc discharge. The first purpose is to solve the problems of insufficient actuation frequency, delayed actuation time and mechanical loss in the method of actively controlling combustion oscillations; the second purpose is to solve the problems of uneven discharge, extremely easy rupture of the dielectric layer due to uneven heating, damage to the electrode, and inability to adapt to the harsh working environment of the combustion chamber of gas turbines and aircraft engines in the method of DBD discharge generating plasma to suppress pressure pulsation.
[0006] In order to achieve the above object, the technical solution adopted by the present invention is:
[0007] A method for cooperatively suppressing combustion oscillation by central plasma and side plasma of a sliding arc discharge, comprising:
[0008] In the combustion chamber, two inclined first electrodes are symmetrically installed along the axis thereof, and the distance between the two first electrodes at one end close to the combustion chamber outlet is greater than the distance between the two first electrodes at one end away from the combustion chamber outlet; one first electrode is connected to a first power source, and the other first electrode is grounded;
[0009] In the combustion chamber head, three second electrodes are evenly installed along the circumferential direction, and the three second electrodes are respectively connected to a second power source A, a second power source B, and a second power source C; the second power source A, the second power source B, and the second power source C are sinusoidal AC power sources with phase difference in output;
[0010] A combustible premixed gas is injected into the combustion chamber and ignited. When combustion oscillation occurs in the combustion chamber and is accompanied by pressure and heat release rate fluctuations of a certain amplitude, the first power supply and each second power supply are turned on. In the combustion chamber, a two-dimensional knife-shaped sliding arc discharge arc is generated at the minimum distance between the two first electrodes. The two-dimensional knife-shaped sliding arc discharge arc slides downstream under the impetus of the combustible premixed gas to form a uniformly distributed spatial discharge, and the generated plasma acts on both sides of the flame; at the head of the combustion chamber, a three-phase rotating sliding arc discharge arc is generated by the change of the potential difference between the three second electrodes with different phases and in coordination with the swirling airflow. The three-phase rotating sliding arc discharge arc rotates and slides between the three second electrodes to form plasma and acts on the root of the flame; the two plasmas work synergistically to destroy the coupling relationship between the unstable heat release of the flame and the sound wave, and suppress the combustion oscillation of the combustion chamber.
[0011] In one embodiment, the discharge frequencies of the two plasmas are adjusted to be integer multiples of the main frequency of the flame pressure pulsation, and the discharge intensity of the plasma is adjusted at the same time to cause the suspended flame to be adsorbed near the first electrode and the second electrode.
[0012] In one embodiment, for the plasma applied to both sides of the flame, the discharge intensity of the plasma is adjusted so that the flame is adsorbed near the first electrode, thereby causing the phase difference between the combustion heat release rate and the pressure pulsation to fail to meet the Rayleigh criterion; for the plasma applied to the root of the flame, the discharge frequency is adjusted to an integer multiple of the main frequency of the flame pressure pulsation, thereby affecting the phase and frequency of the flame heat release rate.
[0013] In one embodiment, the first electrode is an L-shaped structure with an inclined vertical portion, a top end located near the outlet end face of the combustion chamber, and a horizontal portion located near the root of the flame, extending out of the combustion chamber and connected to a first power source or ground.
[0014] In one embodiment, the top ends of the two first electrodes lean against the inner wall of the outlet end of the combustion chamber, and the distance between the bottom ends of the two first electrodes is equal to the outlet diameter of the head of the combustion chamber.
[0015] In one embodiment, the three second electrodes are all located in the middle of the upper and lower end walls of the burner head.
[0016] In one embodiment, a swirler is installed in the combustion chamber head upstream of the three second electrodes, and an axial bluff body is installed on a side of the swirler facing the combustion chamber.
[0017] In one embodiment, the second power supply A, the second power supply B and the second power supply C are connected to the output end of the three-phase voltage regulator, and the three-phase voltage regulator is connected to the output end of the phase sequence controller. By inputting the phase sequence into the phase sequence controller and adjusting the three-phase voltage regulator, the voltage sinusoidal wave phase and voltage amplitude at the output end of the second power supply A, the second power supply B and the second power supply C are adjusted.
[0018] In one embodiment, the second power source A, the second power source B and the second power source C are sinusoidal AC power sources with consistent output amplitudes and a phase difference of 120°.
[0019] In one embodiment, the output of at least one of the second power supply A, the second power supply B and the second power supply C is a sinusoidal high voltage alternating waveform.
[0020] In one embodiment, the first power supply is a nanosecond pulse power supply, a high frequency AC power supply, or a DC-AC coupled power supply.
[0021] The present invention applies sliding arc plasma discharge to the root and both sides of a flame in a combustion chamber where combustion oscillation occurs, which can significantly change the heat release law of the flame, thereby breaking the formation conditions of the heat release rate and pressure of the flame in the combustion chamber that meet the combustion oscillation, achieving the mitigation of heat release pulsation and pressure pulsation, and suppressing the combustion oscillation. Experiments have found that the amplitude of pressure oscillation can be reduced to about 2% of the previous value, with a very significant effect.
[0022] Compared with the traditional active control method, the present invention uses sliding arc discharge plasma as a new type of active control method, which has obvious advantages: lower energy consumption, fast start-up, no moving parts or other complex structures, easy adjustment of excitation parameters, high excitation efficiency of active particles, and its own high-frequency actuation characteristics of thousands of hertz and small delay, thus solving the problems of insufficient actuation frequency, delayed actuation time and mechanical loss in traditional active control. In addition, the two-dimensional knife-shaped sliding arc and the three-phase rotating sliding arc can produce large-volume low-temperature plasma, stable and uniform discharge, small electrode ablation, long electrode life, and the electrode structure is relatively simple, which is convenient for installation and adjustment in the combustion chamber, thus solving the problems of uneven DBD discharge, uneven heating of the dielectric layer and rupture, electrode damage, and inability to adapt to the harsh working environment of the combustion chamber of gas turbines and aircraft engines. From the effect point of view, when the rotating sliding arc discharge plasma is started, it can be seen that the flame is obviously adsorbed near the first electrode and the second electrode, the flame structure is stable, and is less affected by airflow disturbance. In addition, by connecting different power supplies and adjusting different parameters, a series of results with different degrees of suppression of combustion oscillation in the combustion chamber can be obtained. For the combustion oscillation of a dynamic combustion chamber, there are better feedback adjustment implementation conditions. By changing various relevant parameters, the best effect of suppressing the combustion oscillation of the combustion chamber can be finally achieved. BRIEF DESCRIPTION OF THE DRAWINGS
[0023] Figure 1 It is a schematic diagram of a method for cooperatively suppressing combustion oscillations by central plasma and side plasma of a sliding arc discharge according to the present invention.
[0024] Figure 2 for Figure 1 Schematic diagram of two-dimensional knife-shaped electrode sliding arc discharge.
[0025] Figure 3 for Figure 1 Schematic diagram of three-phase rotating sliding arc discharge.
[0026] Figure 4 These are the combustion oscillation data of a combustion chamber without sliding arc discharge plasma effect and a combustion chamber with sliding arc discharge plasma effect whose first power supply is a nanosecond pulse power supply.
[0027] Figure 5 These are the combustion oscillation data of a combustion chamber without the action of sliding arc discharge plasma and a combustion chamber with the action of sliding arc discharge plasma whose first power source is a high-frequency AC power source.
[0028] Figure 6 These are the combustion oscillation data of a combustion chamber without gliding arc discharge plasma action and a combustion chamber with gliding arc discharge plasma action whose first power supply is a DC-AC coupled power supply. DETAILED DESCRIPTION
[0029] The embodiments of the present invention are described in detail below with reference to the accompanying drawings and examples.
[0030] like Figure 1 , Figure 2 and Figure 3 As shown, the present invention provides a method for suppressing combustion oscillation by synergistically suppressing combustion oscillation by central plasma and side plasma of sliding arc discharge, comprising the following steps:
[0031] In the combustion chamber 10, two first electrodes 3 are installed. The main body of the first electrode 3 is a vertical structure with a certain inclination angle. In order to produce a regular effect, the two first electrodes 3 should preferably be installed symmetrically along the axis of the combustion chamber 10, but the two may not be strictly symmetrical. However, on the whole, the spacing between the two first electrodes 3 at the head and tail ends should be different. Specifically, the spacing at the tail end, that is, the spacing at the end close to the outlet of the combustion chamber 10, should be greater than the spacing at the head end, that is, the spacing at the end away from the outlet of the combustion chamber 10. In order to form a discharge circuit, it is obvious that the two first electrodes 3 should be connected to the first power supply 1 and the ground wire respectively. According to the function, the first electrode 3 can be called a two-dimensional knife-shaped sliding arc discharge electrode.
[0032] In the combustion chamber head 9, three second electrodes 4 are installed, and each second electrode 4 is located on the same horizontal plane. In order to produce a regular effect, the three second electrodes 4 should preferably be evenly distributed along the circumference, but they may not be strictly uniform. In order to form a discharge circuit, the three second electrodes 4 are connected to the second power supply 2, and the second power supply 2 is a sinusoidal AC power supply. Specifically, there are three second power supplies 2, namely, the second power supply A2-1, the second power supply B2-2 and the second power supply C2-3, which are respectively connected to the three second electrodes 4, and the outputs of the second power supply A2-1, the second power supply B2-2 and the second power supply C2-3 should have a phase difference. According to the function, the second electrode 4 can be called a three-phase rotating sliding arc discharge electrode.
[0033] In the present invention, “head” and “tail” refer to the flow direction of the combustible premixed gas 5 , that is, the combustion chamber head 9 is a component connected to the upstream of the combustion chamber 10 .
[0034] During operation, the combustible premixed gas 5 is injected into the combustion chamber 10 and ignited. When the combustion chamber 10 undergoes combustion oscillation accompanied by pressure and heat release rate fluctuations of a certain amplitude, the first power source 1 and the second power source 2 are turned on, and the two-dimensional knife-shaped sliding arc plasma and the three-phase rotating sliding arc plasma are used in a coordinated manner as a dynamic and active way to regulate the combustion oscillation phenomenon in the combustion chamber. The specific process is as follows:
[0035] In the combustion chamber 10, a two-dimensional knife-shaped sliding arc discharge arc 12 is generated at the minimum distance between the two first electrodes 3. The two-dimensional knife-shaped sliding arc discharge arc 12 slides downstream under the push of the combustible premixed gas 5 to form a uniformly distributed spatial discharge, and the generated plasma acts on both sides of the flame 11.
[0036] In the combustion chamber head 9, a three-phase rotating sliding arc discharge arc 13 is generated by changing the potential difference between the three second electrodes 4 of different phases and coordinating with the swirling airflow. The three-phase rotating sliding arc discharge arc 13 rotates and slides between the three second electrodes 4 to form a spatially distributed large-volume low-temperature plasma and act on the root of the flame 11.
[0037] Thus, the two plasmas act on both sides and the root of the flame 11 respectively and synergistically affect the flame 11, and adjust the discharge frequency of the plasma to an integral multiple of the main frequency of the pressure pulsation of the flame 11, and adjust the discharge intensity of the plasma at the same time, so as to cause the suspended flame 11 to be adsorbed near the first electrode 3 and the second electrode 4. The synergistic effect of the two plasmas will destroy the coupling relationship between the unstable heat release of the flame 11 and the sound wave, and suppress the combustion oscillation of the combustion chamber 10.
[0038] Specifically, considering that the main frequency of the combustion oscillation in the combustion chamber 10 is in the range of 100 Hz to 500 Hz, the discharge frequency of the plasma is adjusted to be an integer multiple of the main frequency when the flame undergoes combustion oscillation, that is, 500 Hz to 100 kHz.
[0039] For the plasma applied to both sides of the flame 11, by adjusting the input energy, that is, by adjusting the discharge intensity of the plasma, the distance between the main heat release area of the flame and the combustion chamber outlet is changed, so that the flame 11 is adsorbed near the first electrode 3, and then the path length of the pressure pulsation in the combustion chamber reflected from the combustion chamber outlet is changed, so that the phase difference between the combustion heat release rate and the pressure pulsation cannot meet the Rayleigh criterion.
[0040] For the plasma applied to the root of the flame 11, the discharge frequency is adjusted to an integer multiple of the main frequency of the pressure pulsation of the flame 11, which produces local heat release. The high-temperature area formed will affect the phase and frequency of the heat release rate of the flame, and then the flame's response to the airflow disturbance in the combustion chamber will change. Finally, by adjusting the frequency, voltage or current amplitude of the two plasma excitation power supplies and the energy input ratio of the two, the purpose of suppressing the combustion oscillation of the combustion chamber can be achieved.
[0041] In one embodiment of the present invention, the first electrode 3 can be called a two-dimensional knife-shaped sliding arc discharge electrode, which can be made of brass and installed on the wall of the combustion chamber 10. It is in the shape of a knife-shaped screw, or an L-shaped structure, and the vertical portion is inclined, that is, the aforementioned "vertical structure with a certain inclination angle", and is installed near both sides of the flame 11 in a relative arrangement. The top of the vertical portion is located near the outlet end face of the combustion chamber 10, and for example, it can be connected to or lean against the inner wall of the outlet end of the combustion chamber 10, and its horizontal portion is located near the root of the flame 11 and extends out of the combustion chamber 10 to be externally connected to the first power source 1 or the ground wire. In this embodiment, the head spacing of the first electrode 3, that is, the spacing of its bottom end, is equal to the outlet diameter of the combustion chamber head 9.
[0042] In one embodiment of the present invention, the wall of the combustion chamber 10 is made of high temperature resistant quartz glass to meet the requirements of high temperature combustion conditions. A mounting hole for the horizontal portion of the first electrode 3 is reserved at the bottom thereof, the horizontal portion of the first electrode 3 passes through the bottom of the combustion chamber 10, and the top of the vertical portion rests on the inner wall of the combustion chamber 10 outlet end.
[0043] In one embodiment of the present invention, the combustion chamber head 9 is made by 3D ceramic printing technology, and the side wall of the combustion chamber head 9 is chiseled with three installation channels for the second electrode 4. The second electrode 4 is a copper wire and is installed in the reserved channel of the combustion chamber head 9. The premixing section 6 can be further connected to the upstream of the combustion chamber head 9, and the swirler 7 is installed at the junction of the premixing section 6 and the combustion chamber head 9. The axial blunt body 8 is installed in the combustion chamber head 9. The blunt body 8 is coaxial with the swirler 7 and can be installed as an integral structure with the swirler 7. The swirler 7 can promote the better formation of the three-phase rotating sliding arc discharge arc 13, and the central reflow zone generated by the blunt body 8 can effectively stabilize the flame 11.
[0044] In one embodiment of the present invention, the three second electrodes 4 are evenly distributed on the side wall of the combustion chamber head 9 in the circumferential direction, and are all located in the middle of the upper and lower end walls of the burner head 9 in the horizontal direction.
[0045] In one embodiment of the present invention, the second power supply 2 is composed of a second power supply A2-1, a second power supply B2-2, a second power supply C2-3, a three-phase voltage regulator 2-4, and a phase sequence controller 2-5. The second power supply A2-1, the second power supply B2-2, and the second power supply C2-3 are all sinusoidal AC power supplies, and the output of at least one sinusoidal AC power supply is a sinusoidal high-voltage alternating waveform. The three second electrodes 4 are respectively connected to the output ends of the three sinusoidal AC power supplies, and the three sinusoidal AC power supplies are also simultaneously connected to the output end of the three-phase voltage regulator 2-4, and the three-phase voltage regulator 2-4 is connected to the output end of the phase sequence controller 2-5.
[0046] In this embodiment, during operation, the phase sequence is input into the phase sequence controller 2-5, and the three-phase voltage regulator 2-4 is adjusted, thereby adjusting the voltage sinusoidal wave phase and voltage amplitude at the output ends of the three sinusoidal AC power supplies. The sinusoidal AC high voltage output by the three sinusoidal AC power supplies is also applied to the three second electrodes 4.
[0047] When the three second electrodes 4 are evenly distributed, the second power source A2-1, the second power source B2-2 and the second power source C2-3 are preferably sinusoidal AC power sources with consistent output amplitudes and a phase difference of 120°.
[0048] In the present invention, the first power supply 1 can be a nanosecond pulse power supply, a high-frequency AC power supply or a DC-AC coupled power supply. The present invention is verified by the following test:
[0049] Test 1: The first power source 1 is a nanosecond pulse power source.
[0050] In this experiment, after a combustion oscillation of a certain intensity is induced in the combustion chamber 10, the first power supply 1 is turned on to generate a two-dimensional knife-shaped sliding arc discharge arc 12 at the minimum distance between the two first electrodes 3. The two-dimensional knife-shaped sliding arc discharge arc 12 slides downstream under the impetus of the combustible premixed gas 5 to form a uniformly distributed spatial discharge, and the generated plasma acts on both sides of the flame 11; the second power supply 2 is turned on, and a sinusoidal AC high voltage with a consistent amplitude and a phase difference of 120° is output at the high-voltage output end of the second power supply 2 connected to the three second electrodes 4. Through the change of the potential difference between the electrodes of three different phases and the coordination of the swirling airflow, the three-phase rotating sliding arc discharge arc 13 is driven to rotate and slide at high speed between the three electrodes, forming a large-volume low-temperature plasma distributed in space, and acting on the root of the flame 11. The frequencies of the two plasmas are adjusted to be integer multiples of the main frequency of the flame 11 when combustion oscillation occurs. At this time, the thermal effect, activation effect (dynamic aspect) and transport effect (aerodynamic aspect) of the plasma act on the flame 11 to reduce the influence of the disturbance of the combustible premixed gas 5 on the flame 11, and the heat release stability is improved; and the flame heat release law is adjusted to reduce the amplification degree of the pulsating energy in the burner, that is, the process in which the velocity pulsation affects the pulsation of the flame heat release rate is blocked, thereby achieving the suppression of combustion oscillations in the combustion chamber 10.
[0051] like Figure 4 As shown, when the pressure pulsation frequency is consistent, in the absence of the two-dimensional knife-shaped sliding arc and the three-phase rotating sliding arc discharge plasma, the pressure pulsation amplitude of the flame 11 in the combustion chamber 10 is 613Pa, and under the synergistic effect of the two-dimensional knife-shaped sliding arc and the three-phase rotating sliding arc discharge plasma, the pressure pulsation amplitude of the flame is 11.2Pa. It can be seen that in this embodiment, the first power supply adopts a nanosecond pulse power supply, the second power supply adopts a sinusoidal AC power supply, and the two-dimensional knife-shaped sliding arc and the three-phase rotating sliding arc plasma act on the two sides and the root of the flame 11 to significantly suppress the combustion oscillation. At the same time, it is found in practice that the method provided by the present invention for the coordinated suppression of combustion oscillation by the central plasma of the sliding arc discharge and the side plasma has a significant effect of suppressing the combustion oscillation for single swirl flames, stratified swirl flames, combustible premixed gases and combustible premixed liquids, etc., and has good versatility. In addition, the method designed by the present invention for the coordinated suppression of combustion oscillation by the central plasma of the sliding arc discharge and the side plasma is suitable for common working ranges, such as the range of equivalence ratio 0.50 to 0.90, and can significantly suppress the combustion oscillation.
[0052] Test 2: The first power source 1 is a high-frequency AC power source.
[0053] like Figure 5As shown, when the pressure pulsation frequency is consistent, in the absence of the two-dimensional knife-shaped sliding arc and the three-phase rotating sliding arc discharge plasma, the pressure pulsation amplitude of the flame 11 in the combustion chamber 10 is 613 Pa, while under the synergistic effect of the two-dimensional knife-shaped sliding arc and the three-phase rotating sliding arc discharge plasma, the pressure pulsation amplitude of the flame is 14.1 Pa. It can be seen that in this embodiment, the first power supply adopts a high-frequency AC power supply, the second power supply adopts a sinusoidal AC power supply, and the two-dimensional knife-shaped sliding arc and the three-phase rotating sliding arc plasma act on both sides and the root of the flame 11, which can significantly suppress the combustion oscillation.
[0054] Test 3: The first power supply 1 is a DC-AC coupled power supply.
[0055] like Figure 6 As shown, when the pressure pulsation frequency is consistent, in the absence of the two-dimensional knife-shaped sliding arc and the three-phase rotating sliding arc discharge plasma, the pressure pulsation amplitude of the flame 11 in the combustion chamber 10 is 613 Pa, while under the synergistic effect of the two-dimensional knife-shaped sliding arc and the three-phase rotating sliding arc discharge plasma, the pressure pulsation amplitude of the flame is 14.7 Pa. It can be seen that in this embodiment, the first power supply adopts a DC-AC coupled power supply, the second power supply adopts a sinusoidal AC power supply, and the two-dimensional knife-shaped sliding arc and the three-phase rotating sliding arc plasma act on both sides and the root of the flame 11, which can significantly suppress the combustion oscillation.
[0056] Finally, it should be noted that the above experiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned experiments, a person of ordinary skill in the art should understand that the technical solutions described in the aforementioned experiments can still be modified, or some of the technical features can be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.
Claims
1. A method for suppressing combustion oscillation by synergistically suppressing combustion oscillation by central plasma and side plasma of sliding arc discharge. It is characterized in that include: In a combustion chamber (10), two inclined first electrodes (3) are symmetrically installed along the axial direction thereof, and the distance between the two first electrodes (3) at one end close to the combustion chamber (10) outlet is greater than the distance between the two first electrodes (3) at one end away from the combustion chamber (10) outlet; one first electrode (3) is connected to a first power source (1), and the other first electrode (3) is grounded; In the combustion chamber head (9), three second electrodes (4) are evenly distributed along the circumferential direction, and the three second electrodes (4) are respectively connected to a second power source A (2-1), a second power source B (2-2) and a second power source C (2-3); the second power source A (2-1), the second power source B (2-2) and the second power source C (2-3) are sinusoidal alternating current power sources that output a phase difference; A combustible premixed gas (5) is injected into a combustion chamber (10) and ignited. When the combustion chamber (10) undergoes combustion oscillation accompanied by pressure and heat release rate fluctuations of a certain amplitude, the first power source (1) and each second power source are turned on. In the combustion chamber (10), a two-dimensional knife-shaped sliding arc discharge arc (12) is generated at the minimum distance between the two first electrodes (3). The two-dimensional knife-shaped sliding arc discharge arc (12) slides downstream under the impetus of the combustible premixed gas (5) to form a uniformly distributed spatial discharge, and the generated plasma acts on both sides of the flame (11). At the head (9) of the combustion chamber, a three-phase rotating sliding arc discharge arc (13) is generated by the change of the potential difference between the three second electrodes (4) of different phases and in coordination with the swirling airflow. The three-phase rotating sliding arc discharge arc (13) rotates and slides between the three second electrodes (4) to form plasma and acts on the root of the flame (11). The two plasmas work together to destroy the coupling relationship between the unstable heat release of the flame (11) and the sound wave, thereby suppressing the combustion oscillation of the combustion chamber (10).
2. The method for cooperatively suppressing combustion oscillation by central plasma and side plasma of sliding arc discharge according to claim 1, It is characterized in that The discharge frequencies of the two plasmas are adjusted to be integer multiples of the main frequency of the pressure pulsation of the flame (11), and the discharge intensity of the plasma is adjusted at the same time, so as to cause the suspended flame to be adsorbed near the first electrode (3) and the second electrode (4).
3. The method for cooperatively suppressing combustion oscillation by central plasma and side plasma of sliding arc discharge according to claim 1, It is characterized in that For the plasma applied to both sides of the flame (11), the discharge intensity of the plasma is adjusted so that the flame is adsorbed near the first electrode (3), thereby causing the phase difference between the combustion heat release rate and the pressure pulsation to fail to meet the Rayleigh criterion; for the plasma applied to the root of the flame (11), the discharge frequency is adjusted to an integer multiple of the main frequency of the pressure pulsation of the flame (11), thereby affecting the phase and frequency of the heat release rate of the flame.
4. The method for cooperatively suppressing combustion oscillation by central plasma and side plasma of sliding arc discharge according to claim 1, It is characterized in that The first electrode (3) is an L-shaped structure, and the vertical part is inclined, the top end is located near the outlet end face of the combustion chamber (10), the horizontal part is located near the root of the flame (11), and it extends outward from the combustion chamber (10) and is connected to the first power supply (1) or the ground. The three second electrodes (4) are all located in the middle of the upper and lower end walls of the burner head (9).
5. The method for cooperatively suppressing combustion oscillation by central plasma and side plasma of a sliding arc discharge according to claim 1 or 4, It is characterized in that The top ends of the two first electrodes (3) are against the inner wall of the outlet end of the combustion chamber (10), and the distance between the bottom ends of the two first electrodes (3) is equal to the outlet diameter of the combustion chamber head (9).
6. The method for cooperatively suppressing combustion oscillation by central plasma and side plasma of sliding arc discharge according to claim 1, It is characterized in that A swirler (7) is installed in the combustion chamber head (9) upstream of the three second electrodes (4), and an axial blunt body (8) is installed on the side of the swirler (7) facing the combustion chamber (10).
7. The method for cooperatively suppressing combustion oscillation by central plasma and side plasma of a sliding arc discharge according to claim 1, It is characterized in that The second power supply A (2-1), the second power supply B (2-2) and the second power supply C (2-3) are connected to the output end of a three-phase voltage regulator (2-4), and the three-phase voltage regulator (2-4) is connected to the output end of a phase sequence controller (2-5). By inputting a phase sequence into the phase sequence controller (2-5) and adjusting the three-phase voltage regulator (2-4), the voltage sinusoidal wave phase and voltage amplitude at the output ends of the second power supply A (2-1), the second power supply B (2-2) and the second power supply C (2-3) are adjusted.
8. The method for cooperatively suppressing combustion oscillation by central plasma and side plasma of a sliding arc discharge according to claim 1 or 7, It is characterized in that The second power supply A (2-1), the second power supply B (2-2) and the second power supply C (2-3) are sinusoidal AC power supplies with consistent output amplitudes and a phase difference of 120°.
9. The method for cooperatively suppressing combustion oscillation by central plasma and side plasma of sliding arc discharge according to claim 8, It is characterized in that At least one of the second power supply A (2-1), the second power supply B (2-2) and the second power supply C (2-3) has an output of a sinusoidal high voltage alternating waveform.
10. The method for cooperatively suppressing combustion oscillation by central plasma and side plasma of a sliding arc discharge according to claim 1, It is characterized in that The first power source (1) is a nanosecond pulse power source, a high-frequency AC power source, or a DC-AC coupled power source.