阅读说明：本技术 一种减少推进剂溶解气体对电弧推力器影响的结构 (Structure for reducing influence of propellant dissolved gas on electric arc thruster ) 是由 仝颖刚 魏福智 姚兆普 胡大为 沈岩 陈健 夏继霞 吴耀武 于 2020-04-28 设计创作，主要内容包括：一种减少推进剂溶解气体对电弧推力器影响的结构,包括阻尼器、电磁阀和燃气发生器。阻尼器、电磁阀和燃气发生器串联密封连接。当电弧推力器工作时,液体推进剂在通道内流动,按流动方向,先经过第一通道,后经过第二通道,最后经过第三通道进入反应室,在反应室内转换为燃气,燃气进入下游的电弧放电装置。通道至少有一个毛细节流段；沿液体推进剂流动方向,从第一个毛细节流段的入口到通道的出口之间的毛细通道全部为毛细通道；电弧推力器内部推进剂液体的压降全部分布在毛细通道内。本发明能够显著减少液体推进剂中溶解的气体对电弧推力器的影响。(A structure for reducing the influence of propellant dissolved gas on an electric arc thruster comprises a damper, a solenoid valve and a gas generator. The damper, the electromagnetic valve and the gas generator are connected in series and hermetically. When the electric arc thruster works, the liquid propellant flows in the channel, firstly passes through the first channel, then passes through the second channel, and finally enters the reaction chamber through the third channel according to the flowing direction, and is converted into fuel gas in the reaction chamber, and the fuel gas enters the downstream electric arc discharge device. The channel has at least one capillary throttling section; the capillary channels from the inlet of the first capillary throttling section to the outlet of the channel are all capillary channels along the flowing direction of the liquid propellant; the pressure drop of the propellant liquid inside the arc thruster is distributed in the capillary channel. The invention can obviously reduce the influence of the gas dissolved in the liquid propellant on the electric arc thruster.)

1. A structure for reducing an influence of a propellant dissolved gas on an arc thruster, comprising: the device comprises a damper (1), an electromagnetic valve (2) and a fuel gas generator (3);

a flow passage in the damper (1) is used as a first passage (4), a flow passage in the electromagnetic valve (2) is used as a second passage (5), and a reaction chamber (7) is arranged in the gas generator (3); the electromagnetic valve (2) is connected with a reaction chamber (7) of the gas generator (3) through a third channel (6); the inlet of the first channel (4) of the damper (1) is connected with an external liquid propellant pipeline;

the damper (1), the electromagnetic valve (2) and the fuel gas generator (3) are sequentially connected in series, and the connection parts between every two are sealed;

the first channel (4), the second channel (5) and the third channel (6) are communicated in sequence;

when the electric arc thruster works, the liquid propellant sequentially passes through the first channel (4), the second channel (5) and the third channel (6) and finally enters the reaction chamber (7), and the liquid propellant is converted into fuel gas in the reaction chamber (7) and then enters a downstream electric arc discharge device;

capillary throttling sections (9) are arranged in one or more of the first channel (4), the second channel (5) and the third channel (6); the number of the capillary throttling sections (9) is more than or equal to 1;

taking the inlet of the capillary throttling section (9) closest to the inlet of the first channel (4) as the starting point of a capillary channel, taking the outlet of the third channel (6) as the terminal point of the capillary channel, and taking a channel positioned between the starting point of the capillary channel and the terminal point of the capillary channel as a capillary channel (11);

the smallest cross-sectional area of the capillary channel (11) is located inside the capillary throttling section (9); the capillary channel (11) is used for reducing the pressure of the liquid propellant along the flow direction;

a cavity is formed between the armature (16) and the valve seat (15) of the electromagnetic valve (2), the cavity is not communicated with the second channel (5), or the cavity is communicated with the second channel (5), and the width of a slit at the communication position is not more than 0.1 mm; the armature (16) can move relative to the valve seat (15).

2. The structure for reducing the influence of a propellant-dissolved gas on an arc thruster according to claim 1, wherein: a filter screen (12) for filtering foreign particles in the liquid propellant is arranged in the flow passage positioned at the upstream of the first capillary throttling section (9); the filter screen (12) is a metal wire woven mesh, and the filter screen (12) can block impurity particles with the size of more than 10-50 microns.

3. The structure for reducing the influence of a propellant-dissolved gas on an arc thruster according to claim 1, wherein: the maximum cross-sectional area of the capillary channel (11) is less than 1.5mm²The flow of the liquid propellant in the capillary channel (11) satisfies a Reynolds number Re of less than 575, the Reynolds number Re being calculated as follows:

wherein rho is the density of the liquid propellant, mu is the dynamic viscosity of the liquid propellant, and u is the average flow velocity on the cross section; a is the cross-sectional area of the capillary channel (11), and L is the perimeter of the cross-sectional area of the capillary channel (11).

4. The structure for reducing the influence of a propellant dissolved gas on an arc thruster according to any one of claims 1 to 3, wherein: the inner wall of the capillary channel (11) is soaked in the liquid propellant, meanwhile, the inner wall material of the capillary channel (11) can be chemically compatible with the liquid propellant, and the roughness of the inner wall surface of the capillary channel (11) is smaller than Ra3.2.

5. The structure for reducing the influence of a propellant dissolved gas on an arc thruster according to claim 4, wherein: the reaction chamber (7) is filled with a granular catalyst (13), the catalyst (13) is porous alumina particles with iridium metal deposited on the inner and outer surfaces, and the catalyst (13) is used for decomposing hydrazine into a mixed gas of nitrogen, hydrogen and ammonia.

Technical Field

The invention relates to an arc discharge device, in particular to an arc thruster suitable for a satellite propulsion system.

Background

Most current arc propulsion systems for satellite in-orbit applications employ a surface tension reservoir to store a liquid propellant (e.g., anhydrous hydrazine). Part of the extrusion gas (generally helium) in the surface tension storage tank is dissolved in the liquid propellant, and when the liquid propellant undergoes throttling decompression in the electric arc thruster, the part of the extrusion gas dissolved in the propellant is separated out and accumulated into large bubbles in the long-term working process. When large bubbles pass through the electric arc thruster, the mass flow of the propellant in a discharge area inside the electric arc thruster is greatly reduced, so that the problems of unstable electric arc discharge, electrode ablation, sudden reduction of thrust, electric arc extinguishing and the like are caused, and the performance and the service life of the electric arc thruster are restricted.

Disclosure of Invention

The invention aims to overcome the defects in the prior art, provide a structure for reducing the influence of propellant dissolved gas on an electric arc thruster and solve the problems of electrode ablation and the like caused by bubbles.

The above purpose of the invention is mainly realized by the following technical scheme:

a structure for reducing an influence of a propellant dissolved gas on an arc thruster, comprising: a damper, a solenoid valve and a gas generator;

a flow passage in the damper is used as a first passage, a flow passage in the electromagnetic valve is used as a second passage, and a reaction chamber is arranged in the gas generator; the electromagnetic valve is connected with the reaction chamber of the gas generator through a third channel; the inlet of the first damper channel is connected with an external liquid propellant pipeline;

the damper, the electromagnetic valve and the fuel gas generator are sequentially connected in series, and the connection parts between every two dampers are sealed;

the first channel, the second channel and the third channel are communicated in sequence;

when the electric arc thruster works, the liquid propellant sequentially passes through the first channel, the second channel and the third channel and finally enters the reaction chamber, and the liquid propellant is converted into fuel gas in the reaction chamber and then enters the downstream electric arc discharge device;

capillary throttling sections are arranged in one or more flow passages in the first passage, the second passage and the third passage; the number of the capillary throttling sections is more than or equal to 1;

taking the inlet of the capillary throttling section closest to the inlet of the first channel as the starting point of the capillary channel, taking the outlet of the third channel as the terminal point of the capillary channel, and taking the channel between the starting point of the capillary channel and the terminal point of the capillary channel as the capillary channel;

the smallest cross-sectional area of the capillary passage is located inside the capillary throttling section; the capillary channel is used for reducing the pressure of the liquid propellant along the flow direction;

a cavity is formed between the armature and the valve seat of the electromagnetic valve and is not communicated with the second channel, or the cavity is communicated with the second channel and the width of a slit at the communicated position is not more than 0.1 mm; the armature is movable relative to the valve seat.

A filter screen for filtering impurity particles in the liquid propellant is arranged in the flow channel positioned at the upstream of the first capillary throttling section; the filter screen is a metal wire woven mesh, and the filter screen can block impurity particles with the size of more than 10-50 microns.

The maximum cross-sectional area of the capillary channel is less than 1.5mm²The flowing of the liquid propellant in the capillary channel meets the Reynolds number Re which is less than 575 and is calculated according to the following formula:

wherein rho is the density of the liquid propellant, mu is the dynamic viscosity of the liquid propellant, and u is the average flow velocity on the cross section; a is the cross-sectional area of the capillary channel and L is the perimeter of the cross-sectional area of the capillary channel.

The inner wall of the capillary channel is soaked in the liquid propellant, meanwhile, the inner wall material of the capillary channel can be chemically compatible with the liquid propellant, and the roughness of the inner wall surface of the capillary channel is smaller than Ra3.2.

The reaction chamber is internally filled with a granular catalyst which is porous alumina particles with iridium metal deposited on the inner and outer surfaces, and the catalyst is used for decomposing hydrazine into a mixed gas of nitrogen, hydrogen and ammonia.

Compared with the prior art, the invention has the beneficial effects that:

the invention has simple structure, is not limited by the bubble interception volume, can continuously and uniformly discharge bubbles, and has no limit to the single continuous working time of the electric arc thruster; the centralized bubble discharge is not needed, the discharge of the gas together with part of the liquid propellant is avoided during the gas discharge, and the utilization rate of the propellant is improved; no air bubble accumulation, and is beneficial to the engineering application of the satellite.

Drawings

FIG. 1 is a schematic structural diagram of the present invention.

Fig. 2 is a schematic view of the internal structure of the solenoid valve of the present invention.

Detailed Description

The following detailed description of embodiments of the invention is provided in conjunction with the appended drawings:

fig. 1 is a schematic structural diagram of the present invention, and as can be seen from fig. 1, a structure for reducing an influence of a propellant dissolved gas on an arc thruster includes: damper 1, solenoid valve 2 and gas generator 3. The liquid propellant is a single-component propellant grade anhydrous hydrazine.

A flow passage in the damper 1 is used as a first passage 4, a flow passage in the electromagnetic valve 2 is used as a second passage 5, and a reaction chamber 7 is arranged in the gas generator 3; the electromagnetic valve 2 is connected with the reaction chamber 7 of the gas generator 3 through a third channel 6; the inlet of the first channel 4 of the damper 1 is connected with an external liquid propellant pipeline;

the damper 1, the electromagnetic valve 2 and the gas generator 3 are sequentially connected in series, and the connection parts between every two dampers are sealed;

the first channel 4, the second channel 5 and the third channel 6 are communicated in sequence;

when the electric arc thruster works, the liquid propellant sequentially passes through the first channel 4, the second channel 5 and the third channel 6 and finally enters the reaction chamber 7, and the liquid propellant is converted into fuel gas in the reaction chamber 7 and then enters a downstream electric arc discharge device;

capillary throttling sections 9 are arranged in one or more of the first channel 4, the second channel 5 and the third channel 6; the number of the capillary throttling sections 9 is more than or equal to 1;

along the flowing direction of the liquid propellant, taking the inlet of the capillary throttling section 9 closest to the inlet of the first channel 4 as the starting point of a capillary flow channel, taking the outlet of the third channel 6 as the terminal point of the capillary flow channel, and taking a flow channel between the starting point of the capillary flow channel and the terminal point of the capillary flow channel as a capillary channel 11;

the smallest cross-sectional area of the capillary channel 11 is located inside the capillary throttling section 9; the capillary channel 11 is used for reducing the pressure of the liquid propellant in the flow direction, namely the pressure drop of the propellant liquid inside the arc thruster is completely distributed in the capillary channel 11;

a cavity is formed between the armature 16 and the valve seat 15 of the electromagnetic valve 2, the cavity is not communicated with the second channel 5, or the cavity is communicated with the second channel 5, and the width of a slit at the communication position is not more than 0.1 mm; that is, the width of the communication gap between all the cavities connected in parallel with the capillary channel 11 and the capillary channel 11 is less than 0.1 mm. The armature 16 is movable relative to the valve seat 15.

A filter screen 12 for filtering foreign particles in the liquid propellant is arranged in the flow channel at the upstream of the first capillary throttling section 9, the cross section of the flow channel is completely covered by the filter screen 12, and the liquid propellant passes through the filter screen 12 before flowing into the first capillary throttling section 9; the filter screen 12 is a metal wire woven screen, and the filter screen 12 can block impurity particles with the size of more than 10-50 microns. The filtering net 12 is a 1Cr18Ni9Ti stainless steel wire mesh grid, and the filtering precision is to avoid the particles in the upstream flow from blocking the capillary channel 11, and at the same time, the filtering precision is to have enough pollutant carrying capacity and small flow resistance, and is generally selected to be 10-50 microns.

The maximum cross-sectional area of the capillary channel 11 is less than 1.5mm²The cross section is preferably circular; the liquid propellant flows in the capillary channel 11 to meet the Reynolds number Re less than 575, and is in a laminar flow state. Reynolds number Re was calculated as follows:

wherein rho is the density of the liquid propellant, mu is the dynamic viscosity of the liquid propellant, and u is the average flow velocity on the cross section; a is the cross-sectional area of the flow passage, and L is the perimeter of the cross-sectional area of the flow passage. The capillary throttling section 9 is the main position for generating throttling, the throttling performance of the capillary throttling section is related to parameters such as the sectional shape and size, the wall surface roughness, the channel length and the like, and the capillary throttling section needs to be preliminarily calculated theoretically and then is measured through experiments.

The inner wall of the capillary channel 11 is soaked with the liquid propellant, meanwhile, the inner wall material of the capillary channel 11 can be chemically compatible with the liquid propellant, and the roughness of the inner wall surface of the capillary channel 11 is smaller than Ra3.2.

The reaction chamber 7 is filled with a granular catalyst 13, the catalyst 13 is porous alumina particles with iridium metal deposited on the inner and outer surfaces, and the catalyst 13 is used for decomposing hydrazine into a mixed gas of nitrogen, hydrogen and ammonia.

The solid wall surface of the capillary channel 11 is infiltrated by the liquid propellant and is chemically compatible with the liquid propellant, the roughness is less than Ra3.2, and the retention and the convergence of bubbles on the solid wall surface can be further reduced. The material of the damper 1 is preferably 1Cr18Ni9Ti stainless steel; the wall material of the third channel 6 in the electromagnetic valve 2 is preferably 1Cr18Ni9Ti stainless steel, 1J36 soft magnetic alloy and ethylene propylene rubber; the solid wall material of the third channel 6 and the reaction chamber 7 is preferably a high temperature alloy.

The reaction chamber 7 is filled with a granular catalyst 13, and the catalyst 13 is porous alumina particles with iridium metal deposited on the inner and outer surfaces and can decompose hydrazine into a mixed gas of nitrogen, hydrogen and ammonia.

Fig. 2 is an enlarged illustration of the internal structure of the solenoid valve 2 in fig. 1. As can be seen from fig. 2, the solenoid valve 2 includes a valve body 14 and a valve seat 15, and an armature 16 movable by an electromagnetic force, and a flapper 17 and a leaf spring 18 are fixed to the armature 16. The valve seat 15 has a valve orifice 19. The design of the solenoid and the magnet of the solenoid valve 2 is known to the person skilled in the art and is not shown in detail in fig. 2. The second channel 5 is distributed over the valve body 14, the valve seat 15 and the armature 16. An o-ring 19 is mounted between the armature 16 and the valve seat 15 to isolate the second passage 5 from a chamber 20 within the solenoid valve. When the solenoid valve is closed, the flapper 17 is in close contact and sealed with the valve port 19, and the second passage 5 is interrupted. When the solenoid valve is opened, the baffle 17 and the valve port 19 are separated by 0.2-0.5mm, the second channel 5 is communicated, liquid propellant can flow into the valve seat 15 from the valve body 14, and the clearance between the armature 16 and the valve body 14 at the position 21 is smaller than 0.1mm, and due to the surface tension effect, the liquid propellant can fill the clearance and block bubbles from entering the accommodating cavity 20. The valve body 14, valve seat 15 and armature 16 are preferably a segmented combination of 1Cr18Ni9Ti stainless steel and 1J36 soft magnetic alloy.

The invention limits the convergence between microbubbles mainly by three aspects: 1, the flow area of a capillary channel 11 is small, micro-bubbles mainly move along the axis direction of the channel, the flow speed is high, and the residence time of the micro-bubbles in the channel is short; 2 the flowing state of the liquid propellant in the capillary channel 11 is laminar flow, which is not beneficial to the mixing and gathering of micro bubbles; 3 the inner wall of the capillary channel 11 is soaked with the liquid propellant, the cavity in the channel is filled with liquid, the reflux area is small, and micro bubbles are difficult to stagnate and converge in the channel. Therefore, the invention can continuously and uniformly discharge the separated gas from the capillary channel 11 into the reaction chamber 7 in the form of micro-bubbles, does not influence the operation of the arc thruster, does not need to intercept bubbles, does not need to accumulate bubbles, can stably work for a long time, and is not limited by the bubble interception volume.

For a hydrazine electric arc thruster prototype with the power of 1.8kW, the hydrazine flow is 60mg/s, the pressure drop of the capillary channel 11 is 1MPa, the outlet pressure of the capillary channel 11 is 0.7MPa, the inner diameter of the capillary throttling section 9 is 0.1-0.2mm, and the section diameter of other positions of the capillary channel 11 is 0.5-1.35 mm; the extrusion gas is helium; the reynolds number Re of the flow of the liquid propellant in the capillary channel 11 is at most 201; the structure can obviously reduce the bubble size at the outlet position of the capillary channel 11, so that bubbles can continuously and uniformly enter the reaction chamber 7 without influencing the stable operation of the electric arc thruster.

The above description is only for the best mode of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention.