阅读说明：本技术 一种减少电弧推力器电极启动烧蚀的系统及方法 (System and method for reducing starting ablation of electrode of arc thruster ) 是由 仝颖刚 魏福智 姚兆普 胡大为 沈岩 吴耀武 李胜军 于 2020-04-28 设计创作，主要内容包括：一种减少电弧推力器电极启动烧蚀的系统及方法,包括燃气发生器、冷却器和电弧放电装置。冷却器安装在燃气发生器与电弧放电装置之间；液体推进剂无水肼在燃气发生器内经过催化分解反应,变成高温燃气,燃气先流经冷却器,与冷却器进行换热,再流入电弧放电装置,经过电弧放电后喷出。一种减少电弧推力器电极启动烧蚀的方法,包括在冷却器处于较低温度时启动燃气发生器,冷却器冷却高温燃气受,使推进剂流量增大,在推进剂流量从峰值向下逐渐回落过程中的预设范围内启动电弧。本发明能够显著减少电弧推力器电极在启动过程的烧蚀。(A system and method for reducing arc thruster electrode start erosion includes a gas generator, a cooler, and an arc discharge device. The cooler is arranged between the gas generator and the arc discharge device; the liquid propellant anhydrous hydrazine is subjected to catalytic decomposition reaction in the gas generator to be changed into high-temperature gas, the gas firstly flows through the cooler to exchange heat with the cooler, then flows into the arc discharge device, and is sprayed out after arc discharge. A method for reducing starting ablation of an electrode of an electric arc thruster comprises the steps of starting a fuel gas generator when a cooler is at a lower temperature, cooling a high-temperature fuel gas receiver by the cooler to increase the flow rate of a propellant, and starting an electric arc within a preset range in the process that the flow rate of the propellant gradually falls back downwards from a peak value. The invention can obviously reduce the ablation of the electrode of the electric arc thruster in the starting process.)

1. A system for reducing arc thruster electrode start-up erosion, comprising: a gas generator (1), a cooler (2) and an arc discharge device (3);

the cooler (2) is arranged between the gas generator (1) and the arc discharge device (3); the liquid propellant anhydrous hydrazine is subjected to catalytic decomposition reaction in the gas generator (1) to be changed into high-temperature gas, the gas firstly flows through the cooler (2) and then flows into the arc discharge device (3), and is sprayed out after participating in arc discharge in the arc discharge device (3);

the cooler (2) is used for cooling the fuel gas, heat exchange is carried out through the temperature difference between the material of the inner wall of the cooler (2) and the fuel gas, the total temperature of the fuel gas is reduced, and therefore the mass flow of the fuel gas passing through the arc discharge device (3) is increased.

2. The system for reducing starting erosion of an electrode of an arc thruster of claim 1, wherein: when the arc discharge device (3) starts the arc, the highest value T of the total temperature of the fuel gas at the outlet of the cooler (2)₁Comprises the following steps:

wherein, T₀Is the total temperature of the fuel gas at the inlet of the cooler (2),

3. The system for reducing starting erosion of an electrode of an arc thruster of claim 1, wherein: the cooler (2) comprises: an inlet joint (4), a cooling section (5) and an outlet joint (6);

the inlet joint (4), the cooling section (5) and the outlet joint (6) are connected in series and hermetically, a through channel (7) is formed inside the inlet joint, and fuel gas flows into the cooler (2) from the inlet joint (4) and flows out of the cooler (2) from the outlet joint (6); the gas flows in the channel (7).

4. The system for reducing starting erosion of an electrode of an arc thruster of claim 3, wherein: the cooling section (5) comprises: a plurality of groups of front plates (8) and rear plates (9);

the front plate (8) and the rear plate (9) are both of circular plate structures, the front end surface of the front plate (8) and the front end surface of the rear plate (9) are both provided with groove structures, and the radial cross sections of the groove structures along the cooling section (5) are petal-shaped; the groove structure positioned on the front end surface of the front plate (8) is used as a front plate groove (10), and the groove structure positioned on the front end surface of the rear plate (9) is used as a rear plate groove (12);

the front end surface of the front plate (8) and the front end surface of the rear plate (9) face the inlet joint (4);

the front plate (8) is provided with a front plate hole (11) along the axial direction, the rear plate (9) is provided with a rear plate hole (13) along the axial direction, the front plate hole (11) and the rear plate hole (13) are both used for enabling a groove structure of the front end surface to be communicated with the rear end surface, and the front plate groove (10) and the rear plate groove (12) are communicated to form a channel (7);

the inlet joint (4) and the outlet joint (6) are combined by a plurality of groups of front plates (8) and rear plates (9) which are arranged in sequence.

5. The system for reducing starting erosion of an electrode of an arc thruster of claim 4, wherein: the cooler (2) is made of a material which is compatible with fuel gas chemistry and comprises stainless steel, high-temperature alloy, titanium alloy, tungsten-molybdenum alloy and the like; and the inlet joint (4) and the cooling section (5), the cooling section (5) and the outlet joint (6), the gas generator (1) and the cooler (2) and the arc discharge device (3) are hermetically connected by adopting electron beam welding, argon arc welding, brazing or diffusion welding.

6. A method for reducing arc thruster electrode start erosion by using the system for reducing arc thruster electrode start erosion as set forth in claim 5, which is characterized by comprising the following steps:

1) the gas generator (1) and the arc discharge device (3) are both switched off;

2) the temperature of the catalytic bed in the gas generator (1) is brought to the normal start-up range by heating or cooling the gas generator (1), while the temperature of the cooler (2) is not higher than T₂(ii) a Wherein, when the total temperature of the fuel gas at the inlet of the cooler (2) is T₀The total temperature of the fuel gas at the outlet of the cooler (2) is T₁And the gas mass flow at the inlet of the arc discharge device (3) isWhen the temperature of the cooler (2) is T₂；

3) Starting the gas generator (1), enabling liquid propellant anhydrous hydrazine to enter the gas generator (1) and become high-temperature gas through catalytic decomposition reaction, cooling the high-temperature gas by the cooler (2) when the high-temperature gas flows through the cooler (2) with relatively low temperature, and then flowing into the arc discharge device (3);

in the initial starting stage of the gas generator (1), the temperature difference between gas and the cooler (2) is maximum, the total temperature of the cooled gas is lowest, and the mass flow is maximum; along with the time, the temperature of the cooler (2) is gradually increased, and the mass flow of the fuel gas is gradually reduced; when the gas mass flow is maximum, the arc discharge device (3) starts an arc;

4) maintaining the operation of the gas generator (1) and the arc discharge device (3) for a predetermined time;

5) the gas generator (1) and the arc discharge device (3) are closed.

Technical Field

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

Background

In the starting process of the electric arc thruster, electric arcs are firstly generated at a contraction section at the upstream of a throat of the anode nozzle, and at the moment, the electric arcs are attached to the wall surface of the contraction section in a gathering mode; the arc attachment point then moves downstream through the anode nozzle throat and eventually attaches to the nozzle diverging section wall in a diverging pattern. When the electric arc is gathered and attached to the anode contraction section and the throat wall surface, the heat flow density is high, the wall surface is easy to ablate, and the performance and the service life of the electric arc thruster are limited. To solve this problem, it is necessary to switch the arc from concentrated attachment to divergent attachment as quickly as possible. In the prior art, a parallel special starting device is mainly adopted, pressure pulses of a propellant are generated at the starting moment, and a series of active control is performed according to a time sequence, so that an electric arc is started in the pressure pulse period. The prior art increases the volume, weight and complexity of the system, and is not beneficial to the engineering application of the satellite.

Disclosure of Invention

The invention aims to overcome the defects in the prior art and provides a system and a method for reducing starting ablation of an electrode of an arc thruster, which have the characteristics of small volume, light weight, simplicity and convenience.

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

a system for reducing arc thruster electrode start-up erosion, comprising: a gas generator, a cooler and an arc discharge device;

the cooler is arranged between the gas generator and the arc discharge device; the liquid propellant anhydrous hydrazine is subjected to catalytic decomposition reaction in the gas generator to be changed into high-temperature gas, and the gas firstly flows through the cooler and then flows into the arc discharge device to participate in arc discharge in the arc discharge device and then is sprayed out.

The cooler is used for cooling the fuel gas, and heat exchange is carried out through the temperature difference between the material of the inner wall of the cooler and the fuel gas, so that the total temperature of the fuel gas is reduced, and the mass flow of the fuel gas passing through the arc discharge device is increased.

When the arc discharge device starts the arc, the highest value T of the total temperature of the fuel gas at the outlet of the cooler₁Comprises the following steps:

wherein, T₀Is the total temperature of the fuel gas at the inlet of the cooler,is the mass flow of the corresponding fuel gas when the temperature difference between the fuel gas and the cooler is zero,

the minimum mass flow design value for preventing the electrode from starting to ablate the fuel gas is disclosed, A is the minimum cross-sectional area of the anode throat of the electric arc thruster, k is the adiabatic index of the fuel gas, and R is the ideal gas constant; m is the molar mass of the fuel gas, and C is a correction coefficient related to the size of the anode throat of the arc thruster; p is the total pressure of the combustion gas at the inlet of the cooler 2.

The cooler includes: an inlet connection, a cooling section and an outlet connection;

the inlet joint, the cooling section and the outlet joint are connected in series and hermetically, a through channel is formed in the inlet joint, and fuel gas flows into the cooler from the inlet joint and flows out of the cooler from the outlet joint; gas flows in the channel.

The cooling section includes: a plurality of sets of front and rear panels;

the front plate and the rear plate are both of circular plate structures, the front end surface of the front plate and the front end surface of the rear plate are both provided with groove structures, and the cross sections of the groove structures along the radial direction of the cooling section are petal-shaped; the groove structure positioned on the front end surface of the front plate is used as a front plate groove, and the groove structure positioned on the front end surface of the rear plate is used as a rear plate groove;

the front end surface of the front plate and the front end surface of the rear plate face the inlet joint;

the front plate is provided with a front plate hole along the axial direction, the rear plate is provided with a rear plate hole along the axial line, and the front plate hole and the rear plate hole are both used for communicating the groove structure of the front end surface with the rear end surface, so that the front plate groove and the rear plate groove are communicated to form a channel;

the inlet joint and the outlet joint are combined by a plurality of groups of front plates and rear plates which are arranged in sequence.

The cooler is made of a material which is compatible with fuel gas chemistry, and comprises stainless steel, high-temperature alloy, titanium alloy, tungsten-molybdenum alloy and the like; and the inlet joint and the cooling section, the cooling section and the outlet joint, the gas generator and the cooler and the arc discharge device are hermetically connected by adopting electron beam welding, argon arc welding, brazing or diffusion welding.

A method for reducing starting erosion of an electrode of an arc thruster by using the system for reducing starting erosion of the electrode of the arc thruster comprises the following steps:

1) turning off both the gas generator and the arc discharge device;

2) the temperature of the catalytic bed in the gas generator is brought to the normal start-up range by heating or cooling the gas generator, while the cooler temperature is not higher than T₂(ii) a Wherein, when the total temperature of the fuel gas at the inlet of the cooler is T₀The total temperature of the gas at the outlet of the cooler is T₁And the gas mass flow at the inlet of the arc discharge device is

At a temperature of T of the cooler₂；

3) Starting the gas generator, enabling liquid propellant anhydrous hydrazine to enter the gas generator, converting the anhydrous hydrazine into high-temperature gas through catalytic decomposition reaction, cooling the high-temperature gas by a cooler when the high-temperature gas flows through the cooler with relatively low temperature, and then flowing into an arc discharge device;

in the initial starting stage of the gas generator, the temperature difference between the gas and the cooler is maximum, the total temperature of the cooled gas is lowest, and the mass flow is maximum; as time goes on, the temperature of the cooler gradually rises, and the mass flow of the fuel gas gradually decreases; when the gas mass flow is maximum, the arc discharge device starts an arc;

4) maintaining operation of the gas generator and the arc discharge apparatus for a predetermined time;

5) the gas generator and the arc discharge device are shut down.

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

the invention obviously reduces the volume, the weight and the complexity of the electric arc thruster, and is beneficial to the engineering application of satellites.

Drawings

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

Fig. 2 is a schematic axial cross-section of the cooler of the present invention.

FIG. 3 is a schematic view of a cooler front plate trough of the present invention.

FIG. 4 is a schematic view of a cooler back plate slot of the present invention.

Detailed Description

The invention is described in further detail below with reference to the figures and specific embodiments.

The invention discloses a system for reducing starting erosion of an electrode of an arc thruster, which is shown in figure 1 and comprises: a gas generator 1, a cooler 2 and an arc discharge device 3. The cooler 2 is installed between the gas generator 1 and the arc discharge device 3; the liquid propellant anhydrous hydrazine is subjected to catalytic decomposition reaction in the gas generator 1 to be changed into high-temperature gas, the gas firstly flows through the cooler 2 and then flows into the arc discharge device 3, and the gas is sprayed out after participating in arc discharge in the arc discharge device 3 to generate thrust.

The cooler 2 is used for cooling the fuel gas, and heat exchange is carried out through the temperature difference between the material of the inner wall of the cooler 2 and the fuel gas, so that the total temperature of the fuel gas is reduced, and the mass flow of the fuel gas passing through the arc discharge device 3 is increased.

When the arc discharge device 3 starts the arc, the highest value T of the total temperature of the fuel gas at the outlet of the cooler 2₁Comprises the following steps:

wherein, T₀Is the total gas temperature at the inlet of the cooler 2 i.e. the absolute temperature,is the mass flow of the corresponding gas when the temperature difference between the gas and the cooler 2 is zero,

the minimum mass flow design value for preventing the electrode from starting to ablate the fuel gas is disclosed, A is the minimum cross-sectional area of the anode throat of the electric arc thruster, k is the adiabatic index of the fuel gas, and R is the ideal gas constant; m is the molar mass of the fuel gas, and C is a correction coefficient related to the size of the anode throat of the arc thruster; p is the total pressure of the combustion gas at the inlet of the cooler 2.

As shown in fig. 2, the cooler 2 includes: an inlet connection 4, a cooling section 5 and an outlet connection 6. The inlet joint 4, the cooling section 5 and the outlet joint 6 are connected in series and hermetically, a through channel 7 is arranged in the inlet joint 4, and the fuel gas flows into the cooler 2 from the inlet joint 4 and flows out of the cooler 2 from the outlet joint 6; the fuel gas flows in the channel 7 and exchanges heat with the fixed wall of the channel 7, the direction of the channel 7 is repeatedly changed for many times, and the heat exchange coefficient is improved; the cooler 2 absorbs the heat of the gas by the heat capacity of its structure.

The cooling section 5 includes: sets of front plates 8 and rear plates 9. The front plate 8 and the rear plate 9 are both of circular plate structures and are alternately connected in series, superposed and sealed along the thickness direction. The front end surface of the front plate 8 and the front end surface of the rear plate 9 are both provided with groove structures, and the cross sections of the groove structures along the radial direction of the cooling section 5 are petal-shaped; petal structures which are uniformly distributed in the circumferential direction are formed; the thickness direction of the groove structure is the same as the axial direction of the cooling section 5. As shown in fig. 3, the groove structure located on the front end surface of the front plate 8 is used as a front plate groove 10, and as shown in fig. 4, the groove structure located on the front end surface of the rear plate 9 is used as a rear plate groove 12;

the front end surface of the front plate 8 and the front end surface of the rear plate 9 face the inlet joint 4;

front plate 8 is opened along the axial has front plate hole 11, and back plate hole 13 has been opened along the axis to back plate 9, front plate hole 11, back plate hole 13 all are used for making the groove structure and the rear end face intercommunication of preceding terminal surface, make front plate groove 10 and back plate groove 12 intercommunication form passageway 7. The channels 7 are the areas of gas flow and convective heat transfer, and the cross-sectional area is preferably such that the gas flow reaches a turbulent state, and is uniformly distributed in the structure, so as to facilitate the improvement of heat transfer efficiency and the full utilization of the structural heat capacity.

The inlet joint 4 and the outlet joint 6 are combined by a plurality of groups of front plates 8 and rear plates 9 which are arranged in sequence.

The material of the cooler 2 is a material compatible with fuel gas chemistry, and comprises stainless steel, high-temperature alloy, titanium alloy, tungsten-molybdenum alloy and the like; and the inlet joint 4 and the cooling section 5, the cooling section 5 and the outlet joint 6, the gas generator 1 and the cooler 2, and the cooler 2 and the arc discharge device 3 are hermetically connected by adopting electron beam welding, argon arc welding, brazing or diffusion welding.

A method for reducing starting erosion of an electrode of an arc thruster by using the system for reducing starting erosion of the electrode of the arc thruster comprises the following steps:

1) the gas generator 1 and the arc discharge device 3 are both switched off;

2) the temperature of the catalytic bed in the gasifier 1 is brought to the normal start-up range by heating or cooling the gasifier 1, while the temperature of the cooler 2 is brought to not higher than T₂(ii) a Wherein, when the total temperature of the fuel gas at the inlet of the cooler 2 is T₀The total temperature of the gas at the outlet of the cooler 2 is T₁And the gas mass flow at the inlet of the arc discharge device 3 isAt a temperature T of the cooler 2₂；

3) Starting the gas generator 1 according to a conventional program, starting liquid propellant anhydrous hydrazine to enter the gas generator 1, converting the anhydrous hydrazine into high-temperature gas through catalytic decomposition reaction, wherein the temperature of the high-temperature gas is generally 700-;

initial start-up of the gas generator 1, gas and coolingThe temperature difference of the device 2 is maximum, the total temperature of the cooled fuel gas is minimum, and the mass flow is maximum; as time goes on, the temperature of the cooler 2 gradually rises, and the mass flow of the fuel gas gradually decreases; when the gas mass flow rate is reduced toPreviously, the arc discharge device 3 started the arc when the gas mass flow was maximum.

4) Maintaining the gas generator 1 and the arc discharge device 3 in operation for a predetermined time;

5) the gas generator 1 and the arc discharge device 3 are shut down.

The invention discloses a system for reducing starting ablation of an electrode of an electric arc thruster, which has the following working principle: the gas temperature at the inlet of the cooler 2 is typically 700 ℃ and 900 ℃, and the initial temperature of the cooler 2 is significantly lower than the total gas temperature. After the gas passes through the cooler, the total temperature is obviously reduced, the change of the total pressure is small, and the mass flow of the gas flowing through the arc discharge device 3 is determined under the condition that the internal structure size of the arc discharge device 3 is determinedApproximately satisfies the following formula with the total gas temperature T (absolute temperature):

the mass flow of the gas can be increased by cooling the gas by the cooler 2. The change process of the gas mass flow along with the time, which is related to the performance and the weight of the structural material, the shape, the length, the section size and the like of the channel 7, needs to be preliminarily calculated by theory and then determined by experiments. Starting the arc at high flow rates reduces the time required for the arc to switch from concentrated to divergent attachment at the anode, thereby reducing electrode erosion.