CN109361154B - Self-excitation type jet flow spark igniter - Google Patents

Self-excitation type jet flow spark igniter Download PDF

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Publication number
CN109361154B
CN109361154B CN201811328320.4A CN201811328320A CN109361154B CN 109361154 B CN109361154 B CN 109361154B CN 201811328320 A CN201811328320 A CN 201811328320A CN 109361154 B CN109361154 B CN 109361154B
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electrode
discharge
voltage
insulator
jet
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CN109361154A (en
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张志波
吴云
金迪
宋慧敏
贾敏
梁华
崔巍
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Air Force Engineering University of PLA
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Air Force Engineering University of PLA
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01T—SPARK GAPS; OVERVOLTAGE ARRESTERS USING SPARK GAPS; SPARKING PLUGS; CORONA DEVICES; GENERATING IONS TO BE INTRODUCED INTO NON-ENCLOSED GASES
    • H01T13/00—Sparking plugs
    • H01T13/20—Sparking plugs characterised by features of the electrodes or insulation
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02C—GAS-TURBINE PLANTS; AIR INTAKES FOR JET-PROPULSION PLANTS; CONTROLLING FUEL SUPPLY IN AIR-BREATHING JET-PROPULSION PLANTS
    • F02C7/00—Features, components parts, details or accessories, not provided for in, or of interest apart form groups F02C1/00 - F02C6/00; Air intakes for jet-propulsion plants
    • F02C7/26—Starting; Ignition
    • F02C7/264—Ignition
    • F02C7/266—Electric
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01T—SPARK GAPS; OVERVOLTAGE ARRESTERS USING SPARK GAPS; SPARKING PLUGS; CORONA DEVICES; GENERATING IONS TO BE INTRODUCED INTO NON-ENCLOSED GASES
    • H01T13/00—Sparking plugs
    • H01T13/02—Details
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01T—SPARK GAPS; OVERVOLTAGE ARRESTERS USING SPARK GAPS; SPARKING PLUGS; CORONA DEVICES; GENERATING IONS TO BE INTRODUCED INTO NON-ENCLOSED GASES
    • H01T13/00—Sparking plugs
    • H01T13/02—Details
    • H01T13/04—Means providing electrical connection to sparking plugs
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01T—SPARK GAPS; OVERVOLTAGE ARRESTERS USING SPARK GAPS; SPARKING PLUGS; CORONA DEVICES; GENERATING IONS TO BE INTRODUCED INTO NON-ENCLOSED GASES
    • H01T13/00—Sparking plugs
    • H01T13/20—Sparking plugs characterised by features of the electrodes or insulation
    • H01T13/22—Sparking plugs characterised by features of the electrodes or insulation having two or more electrodes embedded in insulation
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01T—SPARK GAPS; OVERVOLTAGE ARRESTERS USING SPARK GAPS; SPARKING PLUGS; CORONA DEVICES; GENERATING IONS TO BE INTRODUCED INTO NON-ENCLOSED GASES
    • H01T13/00—Sparking plugs
    • H01T13/20—Sparking plugs characterised by features of the electrodes or insulation
    • H01T13/34—Sparking plugs characterised by features of the electrodes or insulation characterised by the mounting of electrodes in insulation, e.g. by embedding
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01T—SPARK GAPS; OVERVOLTAGE ARRESTERS USING SPARK GAPS; SPARKING PLUGS; CORONA DEVICES; GENERATING IONS TO BE INTRODUCED INTO NON-ENCLOSED GASES
    • H01T13/00—Sparking plugs
    • H01T13/20—Sparking plugs characterised by features of the electrodes or insulation
    • H01T13/39—Selection of materials for electrodes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01T—SPARK GAPS; OVERVOLTAGE ARRESTERS USING SPARK GAPS; SPARKING PLUGS; CORONA DEVICES; GENERATING IONS TO BE INTRODUCED INTO NON-ENCLOSED GASES
    • H01T13/00—Sparking plugs
    • H01T13/40—Sparking plugs structurally combined with other devices

Abstract

A self-exciting jet spark igniter is provided, which has the same shape as a conventional igniter and is composed of a metal shell (201), an insulator (202), discharge electrodes including an outer discharge electrode pair (203) and an inner electrode pair (301), a lead wire (204) and a jet hole (205). The igniter can effectively improve the reliability of secondary ignition in the combustion chamber under the extreme high altitude condition. Compared with the conventional electric spark discharge ignition, the jet spark igniter can generate stable strong penetrating jet sparks to form a large-area heating area, effectively increases an initial ignition core, improves the penetration depth of sparks, improves the ignition capability, and provides a strong penetrating jet spark igniter without an air source for aviation secondary ignition.

Description

Self-excitation type jet flow spark igniter
Technical Field
The invention belongs to the field of design of aero-engine combustion chambers, and particularly relates to a self-excitation type jet spark igniter which is suitable for reliable ignition in an aero-engine combustion chamber under high altitude extreme conditions.
Background
When the flying height of the military aircraft exceeds 11km, the engine is exposed to the atmospheric conditions of low temperature, low pressure and low density; meanwhile, the flying mach number of the unmanned aerial vehicle during high-altitude long-endurance is reduced, so that the air flow passing through the engine is reduced. These special flight conditions have a number of adverse effects on engine operation, such as reduced compressor surge margin, poor fuel nozzle atomization, and the like, which in turn results in poor engine stability. However, in order to keep the stability of the height and the meter speed of the unmanned aerial vehicle, the engine must be frequently operated, so that the engine is very easy to have a high-altitude flameout problem.
After high-altitude flameout, the working capacity of the air compressor is weakened, the inflow supercharging and temperature increasing are weakened, and the temperature of the inflow air is reduced, so that the temperature reduction of the combustion chamber is accelerated. These changes cause a number of problems, such as reduced air flow resulting in reduced oxygen content in the combustion chamber, reduced fuel temperature and increased viscosity resulting in a deterioration of fuel nozzle atomization. These factors result in a flame tube with velocity and concentration fields that deviate from the design, a reduced mixture area at chemically correct ratios, a reduced rate of chemical reaction of the fuel, increased minimum ignition energy, and difficult flame propagation, placing higher demands on igniter performance. However, in the conventional spark discharge ignition currently used, the spark discharge is concentrated in one arc channel between the central high-voltage electrode and the outer edge low-voltage electrode, the area of a heating area is small, and the ignition initial fire core is small. As the air pressure is reduced, the energy released by spark discharge is reduced, the penetration capability of a fire core is weakened, and the performance of the igniter is not increased but reduced. The increase of the requirement of the ignition capability and the reduction of the supply of the ignition capability cause the shortage of the high-altitude ignition capability of the igniter of the aircraft engine. Under the extreme conditions of high altitude, low temperature and low pressure, after an engine is flamed out, the conventional electric spark igniter is difficult to realize effective ignition.
Disclosure of Invention
In order to improve the reliability of high-altitude secondary ignition of an aircraft engine and overcome the defects of conventional electric spark discharge ignition, the invention provides a self-excitation type jet flow spark igniter, which is hereinafter referred to as an 'igniter', the shape of the self-excitation type jet flow spark igniter is the same as that of the conventional igniter, and the self-excitation type jet flow spark igniter is composed of a metal shell 201, an insulator 202, a discharge electrode, an external discharge electrode pair 203, an internal electrode pair 301, a lead 204 and a jet hole 205; wherein
The igniter is in a flashlight shape, and the lead 204 is positioned at the tail part of the igniter; the metal shell 201 is positioned at the front half part of the igniter and is in a hollow cylindrical shape; the insulator 202 is cylindrical, is positioned in the metal shell, the outer circumference of the insulator is tightly contacted with the inside of the metal shell 201, and grooves and holes are machined in the insulator, are used as a jet hole 205 and a discharge cavity 302, and are used for installing an external discharge electrode pair 203 and an internal electrode pair 301; the external discharge electrode pair 203 and the jet hole 205 are both located on the same diameter of the insulator 202, wherein the jet hole 205 is located at the center of the insulator 202, and the external discharge electrode pair 203 is symmetrically located about the symmetry axis AA with the jet hole 205 as the center; the jet hole 205 is arranged in the center of the insulator 202, penetrates through the insulator 202 and leads to the discharge chamber 302; the outer discharge electrode pair 203 penetrates the insulator 202, and one end of the outer discharge electrode pair is positioned inside the insulator 202 and connected with a lead 204; the other end opens to the outside of the insulator 202; the discharge chamber 302 is positioned in the insulator 202 and is adjacent to the jet hole 205, and two internal discharge electrode pairs 301 are arranged at two ends; one electrode of the external discharge electrode pair 203 is connected to the low-voltage terminal of the ignition power supply, the other electrode is connected to one electrode of the internal discharge electrode pair and then connected to the low-voltage terminal of the ignition power supply by connecting a capacitor in series, and the other electrode of the internal discharge electrode pair is connected to the high-voltage terminal of the ignition power supply.
In one embodiment of the present invention, the pair of outer discharge electrodes 203 protrude 0.2 to 2mm from the end surface of the insulator 202; the external discharge electrode pair 203 consists of two sub-electrodes, the shape of each sub-electrode is the same, each sub-electrode is of a cylindrical structure, the diameter of each sub-electrode is 0.5-2 mm, and the distance between the electrodes is matched with the diameter of the jet hole and is 1-3 mm; adopting tungsten or molybdenum as a metal material; the jet hole 205 is circular, the diameter is 0.5-2 mm, and the depth is 0.5-2 mm; the internal electrode pair 301 is composed of two sub-electrodes, the shape of each sub-electrode is the same, each sub-electrode is of a long-strip cylindrical structure, the diameter of each sub-electrode is 0.5-2 mm, the electrode distance is matched with the length of the discharge cavity and is 1-3 mm, and the height of the electrode protruding out of the discharge cavity is 0.5-2 mm; the discharge cavity 302 is cylindrical, the diameter is 0.5-2 mm, and the length is 1.5-3 mm.
In one embodiment of the present invention, the pair of outer discharge electrodes 203 protrudes 1mm from the end face of the insulator 202; the diameter of the external discharge electrode pair 203 is 1.5mm, and the electrode spacing is 2 mm; adopting tungsten as a metal material; the diameter of the jet hole 205 is 1mm, and the depth is 1 mm; the diameter of the internal electrode pair 301 is 1.5mm, the electrode spacing is 2mm, and the height of the electrode protruding out of the discharge cavity is 1 mm; the discharge chamber 302 has a diameter of 1mm and a length of 2 mm.
In one embodiment of the present invention, the insulator 202 is wrapped by the metal shell 201 and tightly fitted in a nested manner, and the material is selected from a high temperature resistant ceramic insulator.
In one particular embodiment of the present invention, the insulator 202 is an alumina ceramic.
In an embodiment of the present invention, in order to fix the metal casing 201 to the outer wall of the combustion chamber, the middle section of the outer part of the metal casing 201 has a bolt structure, and the specific thread parameters are based on the installation joint of the outer wall of the combustion chamber; the thread close to the wire end is used for connecting with the aviation cable, and the specific thread parameters are based on the installation joint of the aviation cable.
In an embodiment of the present invention, the external leads 205 are three independent high-voltage-resistant electromagnetic shielding wires, each external lead corresponding to a discharge electrode; wherein, one electrode in the external discharge electrode pair 203 is connected with any electrode in the internal electrode pair 301 to be used as a discharge sub-electrode, and is directly connected with the voltage-dividing capacitor C after being connected with a lead01Connecting; the other internal discharge electrode is connected with the high-voltage end of the power supply through the second of the three lead wires, and the other external discharge electrode is connected with the low-voltage end of the power supply; the metallic conductive portion of the lead wire is in contact with a discharge electrode built in the insulator 202.
The working process of the self-excitation type jet flow spark igniter is as follows:
impedance adjustment voltage division capacitor C is added after electrode discharge gap01The separation of the high-voltage breakdown and the capacitor discharge process is realized; the self-excited fluidic igniter includes a 2-stage electrode gap; first-stage electrode gap and voltage-dividing capacitor C01After being connected in series, the low-voltage end is connected with the high-voltage end; second electrode gap and voltage-dividing capacitor C01Parallel connection; the first-stage electrode gap can be regarded as a capacitor before breakdown, and the capacitance value of the capacitor is about 1 pF; voltage dividing capacitor C01The capacitance range is 50-500 pF; according to the voltage division law of the series capacitor, firstly, most of high voltage from a high-voltage end is loaded to two ends of a first-stage electrode gap; when the first-stage electrode gap is broken down, air between the gaps is changed into a conductor from an insulator; at the moment, the whole circuit becomes a voltage-dividing capacitor C through a discharge channel01Charging; voltage dividing capacitor C01Connected in parallel with the second electrode gap, thus dividing the voltage of the capacitor C01The voltage of the two ends of the second-stage electrode gap is the same as that of the two ends of the second-stage electrode gap; the breakdown voltage of the electrode gap is far less than that of the voltage-dividing capacitor C01The voltage resistance value, the second electrode gap with low voltage resistance value is firstly broken down; at the moment, the power supply releases energy through a discharge loop formed by breakdown; in the whole discharging loop, except for a spark channel formed by discharging, only a connected wire is used, and no energy consumption elements such as extra resistors are introduced, so that the discharging efficiency is high.
In one embodiment of the present invention, the voltage dividing capacitor C01The capacitance value is 100 pF.
In one embodiment of the present invention, the discharge chamber 302 and the jet hole 205 are designed at the igniter head; when the ignition power supply works, air between the strip-shaped inner electrode pairs 301 is broken down, and the discharge releases energy to heat gas in the discharge cavity; the gas in the discharge chamber is heated to the temperature and the pressure to be rapidly increased, and is ejected out of the jet hole 205 under the action of the pressure difference to form jet flow; after the jet flow is sprayed out, the jet flow directly acts on sparks generated by the external discharge electrode pair 203, the discharge spark form can be changed, and jet flow sparks are formed, so that the penetration depth of the sparks is improved, and the size of a fire core is increased.
The self-excitation type jet flow spark igniter can effectively improve the reliability of secondary ignition in the combustion chamber under the extreme high altitude condition. Compared with the conventional electric spark discharge ignition, the device can generate stable strong penetrating jet spark to form a large-area heating area, effectively increases an initial ignition core, improves the penetration depth of the spark, improves the ignition capability, and provides a strong penetrating jet spark igniter without an air source for aviation secondary ignition.
Drawings
FIG. 1 is a schematic structural view of a self-igniting jet spark igniter of the invention, wherein FIG. 1(a) is a perspective view of a three-dimensional external shape of the igniter and FIG. 1(b) is a cross-sectional view of a critical portion of the igniter head tip;
FIG. 2 is a discharge principle circuit of the self-exciting jet spark igniter of the invention;
FIG. 3 is a schematic diagram of the operation and actual operation of the fluidic spark produced by the self-exciting fluidic spark igniter of the invention, wherein FIG. 3(a) is a schematic diagram of the operation and FIG. 3(b) is an image of the spark produced during the operation;
FIG. 4 is a spark image of a commercial igniter operating;
fig. 5 is a schematic diagram of the power supply circuit for the self-exciting jet spark igniter of the invention.
Reference numerals:
C01-a voltage-dividing capacitor for dividing the voltage,
C1-a capacitance between the first electrodes,
C2-a capacitance between the second electrodes,
201-metal shell of the igniter,
202-an insulator body which is provided with a plurality of holes,
203-an outer discharge electrode,
204-an igniter lead wire,
205-a jet hole, wherein the jet hole,
301-internal discharge electrodes,
302-internal discharge Chamber
Detailed Description
The invention will now be further described with reference to the accompanying figures 1 to 3.
The invention provides a self-excited jet spark igniter. When in ignition, the device can realize two-channel high-energy spark discharge. Meanwhile, energy can be reasonably distributed, and the unique geometric design of the igniter is combined, so that the energy of one channel can be effectively converted into mechanical energy to form synthetic jet. The synthetic jet flow acts on the discharge spark of the other channel, so that the discharge form can be effectively changed, and the penetration depth and the initial fire core size of the spark are enhanced.
As shown in fig. 1, a self-excited jet spark igniter (hereinafter, simply referred to as "igniter") has the same outer shape as a conventional igniter and is mainly composed of a metal shell 201, an insulator 202, discharge electrodes (an outer discharge electrode pair 203 and an inner discharge electrode pair 301), a lead wire 204, and a jet hole 205. As shown in fig. 1(a), the igniter is in the shape of a flashlight with a wire 204 at the end of the igniter. The metal shell 201 is in the shape of a hollow cylinder in the front half of the igniter. The insulator 202 is cylindrical, is positioned inside the metal shell, has an outer circumference in close contact with the inside of the metal shell 201, is internally provided with a groove and a circular hole, serves as a jet hole 205 and a discharge chamber 302, and is used for mounting the outer discharge electrode pair 203 and the inner electrode pair 301. The outer discharge electrode pair 203 and the jet hole 205 are located on the same diameter of the insulator 202, wherein the jet hole 205 is located at the center of the insulator 202, and the outer discharge electrode pair 203 is located symmetrically about the axis of symmetry AA with the jet hole 205 as the center. The jet hole 205 is centrally disposed in the insulator 202 and penetrates the insulator 202 to open into the discharge chamber 302. The outer discharge electrode pair 203 may be a cylindrical electrode penetrating the insulator 202, and one end of the cylindrical electrode is located inside the insulator 202 and connected to the lead 204; and the other end opens to the outside of the insulator 202. One electrode of the external discharge electrode pair 203 is connected to the low-voltage terminal of the ignition power supply, the other electrode is connected to one electrode of the internal discharge electrode pair and then connected to the low-voltage terminal of the ignition power supply by connecting a capacitor in series, and the other electrode of the internal discharge electrode pair is connected to the high-voltage terminal of the ignition power supply.
The present invention is characterized in that the discharge chamber 302 and the jet hole 205 are designed at the head of the igniter unlike the conventional igniter in order to efficiently convert a part of discharge energy into mechanical energy to form a jet. The discharge chamber 302 is located inside the insulator 202 with two elongated pairs of inner electrodes 301 disposed at either end. When the ignition power supply works, air between the elongated inner electrode pair 301 breaks down, and the discharge releases energy to heat the gas in the discharge chamber. The gas in the discharge chamber is heated to a temperature and a pressure which are rapidly increased, and is ejected out of the jet hole 205 under the action of the pressure difference to form jet flow. After the jet flow is sprayed out, the jet flow directly acts on sparks generated by the external discharge electrode pair 203, the discharge spark form can be changed, and jet flow sparks are formed, so that the penetration depth of the sparks is improved, and the size of a fire core is increased.
The principle circuit of discharge is shown in fig. 2, and the basic principle is that impedance is added after the electrode discharge gap to adjust the voltage-dividing capacitor, so that the separation of the high-voltage breakdown and the capacitor discharge is realized. As shown in fig. 2, the self-exciting jet igniter includes a 2-stage electrode gap; first-stage electrode gap and voltage-dividing capacitor C01After being connected in series, the low-voltage end is connected with the high-voltage end; second stage electrode gap and minuteVoltage capacitor C01And (4) connecting in parallel. The first stage electrode gap, which was not broken down, was considered to be a capacitor having a capacitance of about 1pF as measured by an impedance analyzer. Selected voltage-dividing capacitor C01The capacitance range is 50-500 pF, preferably 100 pF. According to the voltage division law of the series capacitance, firstly, most of the high voltage from the high voltage terminal is applied across the first-stage electrode gap. When the first electrode gap breaks down, the air between the gaps changes from an insulator to a conductor. At the moment, the whole circuit becomes a voltage-dividing capacitor C through a discharge channel01And (6) charging. Voltage dividing capacitor C01Connected in parallel with the second electrode gap, thus dividing the voltage of the capacitor C01The voltage across the second-stage electrode gap is the same. The breakdown voltage of the electrode gap is far less than that of the voltage-dividing capacitor C01The withstand voltage value, the second stage electrode gap with low withstand voltage value is broken down first. At this time, the power supply discharges energy through a discharge loop formed by breakdown. In the whole discharging loop, except for a spark channel formed by discharging, only a connected wire is used, and no energy consumption elements such as extra resistors are introduced, so that the discharging efficiency is high.
In one embodiment of the present invention, the pair of outer discharge electrodes 203 (exposed on the surface of the insulator 202) protrude from the end surface of the insulator 202 by about 0.2 to 2mm, preferably 1 mm. The external discharge electrode pair 203 consists of two sub-electrodes, the shape of each sub-electrode is the same, the sub-electrodes are of cylindrical structures, the diameter is 0.5-2 mm, preferably 1.5mm, the electrode distance is matched with the diameter of the jet hole and is about 1-3 mm, preferably 2 mm; the metal material with high temperature resistance and good conductivity, such as tungsten, molybdenum and the like, is adopted, and the metal tungsten is preferred. The jet hole 205 is circular, and has a diameter of about 0.5-2 mm, preferably 1mm, and a depth of 0.5-2 mm, preferably 1 mm. The internal electrode pair 301 is composed of two sub-electrodes, each sub-electrode is the same in shape and is of a long-strip cylindrical structure, the diameter of each sub-electrode is 0.5-2 mm, the optimal diameter of each sub-electrode is 1.5mm, the electrode distance is matched with the length of the discharge cavity and is about 1-3 mm, the optimal diameter of each sub-electrode is 2mm, and the height of the electrode protruding out of the discharge cavity is about 0.5-2 mm, and is preferably 1 mm. The discharge cavity 302 is cylindrical, and has a diameter of 0.5-2 mm, preferably 1mm, and a length of 1.5-3 mm, preferably 2 mm.
The insulator 202 is used for effectively insulating the discharge electrode from the metal shell 201 to ensure that discharge operates according to a designed mode; second, provide and penetrateThe geometry of the flow holes 205 and the discharge chamber 302. As shown in FIG. 1(a), the insulator 202 is wrapped by a metal shell 201 and tightly fitted in a nested manner, and the material is a high-temperature-resistant ceramic insulator, preferably Al2O3A ceramic.
The metal shell 201 has an external shape structure, is a cylindrical structure as a whole, and has a hollow interior for placing the insulator 202 (the discharge electrode pair 203 and 301 is inside the insulator 202). For fixing with the outer wall of the combustion chamber, the middle section of the outer part of the metal casing 201 has a bolt structure, and the specific thread parameters are based on the installation joint of the outer wall of the combustion chamber, which is generally M18 thread. The threads near the end of the wire are used to connect to the aircraft cable, typically M18 threads.
The external lead wires 205 are three independent high-voltage-resistant electromagnetic shielding wires, and each external lead wire corresponds to a discharge electrode. Wherein, one electrode in the external discharge electrode pair 203 is connected with any electrode in the internal electrode pair 301 to be used as a discharge sub-electrode, and is directly connected with the voltage-dividing capacitor C after being connected with a lead01Are connected. The other internal discharge electrode is connected with the high-voltage end of the power supply through the second of the three lead wires, and the other external discharge electrode is connected with the low-voltage end of the power supply. The metallic conductive portions of the lead wires are in contact with the discharge electrodes embedded in the insulator 202, and the electrodes are isolated from each other by the insulator in a plug-in connection.
The spark image of a common spark igniter on the market, which is photographed by a high-speed camera, is shown in fig. 4, the operation schematic diagram of a strong penetration jet type spark igniter is shown in fig. 3(a), and the jet type spark obtained by the high-speed camera is shown in fig. 3 (b). As can be seen from the figure, the igniter can effectively improve the penetration depth and the size of the fire core, and can effectively improve the ignition capability.
The power supply circuit of the self-excitation type jet flow spark igniter is shown in fig. 5, the energy supply of the igniter is provided by a high-energy ignition power supply (or other high-energy spark ignition power supplies such as a fuel ignition power supply and a pulverized coal ignition power supply) of a common aviation engine at present, and a high-voltage output end and a low-voltage input end of the ignition power supply are respectively connected with a high-voltage end and a low-voltage end of a power supply system. The high-voltage end of the power supply system is connected with one discharge electrode in the internal discharge electrode group, the low-voltage end of the power supply system is connected with any external discharge electrode, the rest discharge electrodes are connected with the voltage dividing capacitor, and the other end of the voltage dividing capacitor is connected with the low-voltage end of the power supply system.
Compared with the conventional spark discharge ignition, the self-excitation type jet spark ignition has obvious technical advantages that: through increasing the discharge passage, effectively improved the energy utilization of power, through converting partial energy into efflux and acting on the spark, can effectively increase the penetration depth and the fire core size of spark, consequently can effectively improve the ignition ability under the low temperature low pressure condition.
DETAILED DESCRIPTION OF EMBODIMENT (S) OF INVENTION
The discharge electrode is a tungsten needle with the diameter of 1.5 mm. The distance between the external discharge electrodes 203 is 2mm, the external discharge electrodes are arranged on two sides of the jet hole, and the height of the part protruding out of the insulator 202 is 1 mm. The distance between the internal discharge electrodes is 2mm, and the internal discharge electrodes are arranged on two sides of the discharge cavity. The jet hole 205 is a circular hole with a diameter of 1mm and a height of 1 mm. The discharge chamber 302 is a circular chamber with a diameter of 1mm and a length of 2 mm. The insulator is made of Al2O3And firing the ceramic. The metal shell 201 is designed with reference to currently used aviation spark igniters, with an ignition tip diameter of 18 mm.

Claims (10)

1. A self-excited jet flow spark igniter, hereinafter referred to as an 'igniter', the shape of which is the same as that of a conventional igniter, and the self-excited jet flow spark igniter comprises a metal shell (201), an insulator (202), a discharge electrode, an outer discharge electrode pair (203), an inner electrode pair (301), a lead (204) and a jet hole (205); wherein
The igniter is in a flashlight shape, and a lead (204) is positioned at the tail part of the igniter; the metal shell (201) is positioned at the front half part of the igniter and is in a hollow cylindrical shape; the insulator (202) is cylindrical and is positioned inside the metal shell, the outer circumference of the insulator is tightly contacted with the inside of the metal shell (201), grooves and holes are machined inside the insulator, the insulator is used as a jet hole (205) and a discharge cavity (302), and is used for installing an external discharge electrode pair (203) and an internal electrode pair (301); the external discharge electrode pair (203) and the jet hole (205) are both positioned on the same diameter of the insulator (202), wherein the jet hole (205) is positioned at the center of the insulator (202), the external discharge electrode pair (203) is centered on the jet hole (205) and symmetrically arranged about a symmetry axis AA, the symmetry axis AA is a straight line which is vertical to a connecting line between two electrodes of the external discharge electrode pair (203), and the straight line is positioned in a plane where the outer surface of the insulator (202) is positioned; the jet hole (205) is arranged in the center of the insulator (202) and penetrates through the insulator (202) to lead to the discharge chamber (302); the external discharge electrode pair (203) penetrates through the insulator (202), one end of the external discharge electrode pair is positioned inside the insulator (202), and the external discharge electrode pair is connected with the lead (204); the other end is opened to the outside of the insulator (202); the discharge cavity (302) is positioned in the insulator (202) and is close to the position of the jet hole (205), and two internal discharge electrode pairs 301 are arranged at two ends; one electrode of the external discharge electrode pair (203) is connected with the low-voltage end of the ignition power supply, the other electrode of the external discharge electrode pair is connected with one electrode of the internal discharge electrode pair and then connected with the low-voltage end of the ignition power supply through a capacitor connected in series, and the other electrode of the internal discharge electrode pair is connected with the high-voltage end of the ignition power supply.
2. The self-exciting jet spark igniter of claim 1, wherein
The external discharge electrode pair (203) protrudes 0.2-2 mm from the end face of the insulator (202); the external discharge electrode pair (203) consists of two sub-electrodes, the shape of each sub-electrode is the same, each sub-electrode is of a cylindrical structure, the diameter of each sub-electrode is 0.5-2 mm, and the distance between the electrodes is matched with the diameter of the jet hole and is 1-3 mm; adopting tungsten or molybdenum as a metal material; the jet hole (205) is circular, the diameter is 0.5-2 mm, and the depth is 0.5-2 mm; the internal electrode pair (301) consists of two sub-electrodes, the shape of each sub-electrode is the same, each sub-electrode is of a long-strip cylindrical structure, the diameter of each sub-electrode is 0.5-2 mm, the electrode distance is matched with the length of the discharge cavity and is 1-3 mm, and the height of the electrode protruding out of the discharge cavity is 0.5-2 mm; the discharge cavity (302) is cylindrical, the diameter of the discharge cavity is 0.5-2 mm, and the length of the discharge cavity is 1.5-3 mm.
3. The self-excited jet spark igniter as claimed in claim 1, wherein the pair of outer discharge electrodes (203) protrudes 1mm from the end face of the insulator (202); the diameter of the external discharge electrode pair (203) is 1.5mm, and the electrode distance is 2 mm; adopting tungsten as a metal material; the diameter of the jet hole (205) is 1mm, and the depth is 1 mm; the diameter of the internal electrode pair (301) is 1.5mm, the electrode distance is 2mm, and the height of the electrode protruding out of the discharge cavity is 1 mm; the diameter of the discharge cavity (302) is 1mm, and the length is 2 mm.
4. The self-exciting jet spark igniter of claim 1, wherein the insulator (202) is encased by a metal shell (201) and is a nested close-fitting arrangement, and the material is selected from a high temperature resistant ceramic insulator.
5. The self-exciting jet spark igniter of claim 1, wherein the insulator (202) is an alumina ceramic.
6. The self-exciting jet spark igniter as claimed in claim 1, wherein the metal shell (201) has a bolt structure at the middle section of the outer portion thereof for fixing to the outer wall of the combustion chamber, and the specific thread parameters are based on the mounting joint of the outer wall of the combustion chamber; the thread close to the wire end is used for connecting with the aviation cable, and the specific thread parameters are based on the installation joint of the aviation cable.
7. The self-exciting jet spark igniter of claim 1, wherein the conductive wire (204) is three separate high voltage resistant electromagnetic shielding wires, each conductive wire (204) corresponding to a discharge electrode; wherein, one electrode in the external discharge electrode pair (203) is connected with any electrode in the internal electrode pair (301) to be used as a discharge sub-electrode, and is directly connected with the voltage-dividing capacitor C after being connected with the lead (204)01Connecting; the other internal discharge electrode is connected with the high-voltage end of the power supply through the second of the three conducting wires (204), and the other external discharge electrode is connected with the low-voltage end of the power supply; the metallic conductive portion of the lead wire (204) is in contact with a discharge electrode built in the insulator (202).
8. A method of operating a self-exciting jet spark igniter of any one of claims 1 through 7,
impedance adjustment voltage division capacitor C is added after electrode discharge gap01The separation of the high-voltage breakdown and the capacitor discharge process is realized; the self-excited jet igniter comprises 2-stage electrodesA gap; first-stage electrode gap and voltage-dividing capacitor C01After being connected in series, the low-voltage end is connected with the high-voltage end; second electrode gap and voltage-dividing capacitor C01Parallel connection; the first-stage electrode gap can be regarded as a capacitor before breakdown, and the capacitance value of the capacitor is about 1 pF; voltage dividing capacitor C01The capacitance range is 50-500 pF; according to the voltage division law of the series capacitor, firstly, most of high voltage from a high-voltage end is loaded to two ends of a first-stage electrode gap; when the first-stage electrode gap is broken down, air between the gaps is changed into a conductor from an insulator; at the moment, the whole circuit becomes a voltage-dividing capacitor C through a discharge channel01Charging; voltage dividing capacitor C01Connected in parallel with the second electrode gap, thus dividing the voltage of the capacitor C01The voltage of the two ends of the second-stage electrode gap is the same as that of the two ends of the second-stage electrode gap; the breakdown voltage of the electrode gap is far less than that of the voltage-dividing capacitor C01The voltage resistance value, the second electrode gap with low voltage resistance value is firstly broken down; at the moment, the power supply releases energy through a discharge loop formed by breakdown; in the whole discharging loop, except for a spark channel formed by discharging, only a connected wire is used, and no energy consumption elements such as extra resistors are introduced, so that the discharging efficiency is high.
9. The method of operating a self-exciting jet spark igniter of claim 8, wherein the voltage dividing capacitor C01The capacitance value is 100 pF.
10. The working method of the self-excited jet spark igniter as claimed in claim 8, wherein a discharge chamber (302) and a jet hole (205) are designed at an igniter head; when the ignition power supply works, air between the strip-shaped inner electrode pair (301) is broken down, and the discharge releases energy to heat gas in the discharge cavity; the gas in the discharge cavity is heated to the temperature and the pressure to be rapidly increased, and is sprayed out of the jet hole (205) under the action of the pressure difference to form jet flow; after the jet flow is sprayed out, the jet flow directly acts on sparks generated by the external discharge electrode pair (203), the discharge spark form can be changed, and jet flow sparks are formed, so that the penetration depth of the sparks is improved, and the size of a fire core is increased.
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