阅读说明：本技术 一种基于平板电极的磁旋电弧烧蚀测试系统 (Magnetic rotating arc ablation test system based on flat plate electrode ) 是由 关慰勉 王宏涛 方攸同 刘嘉斌 于 2020-03-18 设计创作，主要内容包括：一种基于平板电极的磁旋电弧烧蚀测试系统,该测试系统包括阳极,用于装载阴极材料样品的样品安装件,对阴极材料样品进行冷却的冷却系统,和保护罩；电弧产生于阴极和阳极之间,电弧位于保护罩内；阳极和阴极分别具有与燃弧供电电源相连的端口；阴极样品与样品安装件可拆卸式装配；阴极样品固定,电弧绕阴极样品的中心旋转。本发明的优点在于：将阴极样品制备成片状样品,搭建能够产生电弧并在对阴极样品进行电弧烧蚀的同时对阴极样品进行冷却,模拟高温电弧风洞的烧蚀工况；通过设置电磁线圈,使电弧发生旋转,在阴极样品固定时,实现电弧对阴极样品的移动烧蚀。(A magnetic rotary arc ablation test system based on a flat plate electrode comprises an anode, a sample mounting part for loading a cathode material sample, a cooling system for cooling the cathode material sample, and a protective cover; an electric arc is generated between the cathode and the anode, and the electric arc is positioned in the protective cover; the anode and the cathode are respectively provided with a port connected with an arc power supply; the cathode sample and the sample mounting part are detachably assembled; the cathode sample was stationary and the arc rotated around the center of the cathode sample. The invention has the advantages that: preparing a cathode sample into a sheet sample, building a structure capable of generating electric arcs, cooling the cathode sample while carrying out electric arc ablation on the cathode sample, and simulating an ablation working condition of a high-temperature electric arc wind tunnel; the electromagnetic coil is arranged, so that the electric arc rotates, and when the cathode sample is fixed, the electric arc can remove and ablate the cathode sample.)

1. The utility model provides a magnetic rotation arc ablation test system based on flat electrode which characterized in that: the testing system comprises an anode, a sample mounting member for loading a cathode material sample, a cooling system for cooling the cathode material sample, and a protective cover; an electric arc is generated between the cathode and the anode, and the electric arc is positioned in the protective cover; the anode and the cathode are respectively provided with a port connected with an arc power supply; the cathode sample and the sample mounting part are detachably assembled; the cathode sample was stationary and the arc rotated around the center of the cathode sample.

2. The plate electrode-based magnetic rotary arc ablation test system of claim 1, wherein: an electromagnetic coil is arranged outside the protective cover, the direction of a magnetic field of the electromagnetic coil is parallel to the direction of the anode pointing to the cathode, and the electromagnetic coil is provided with a port connected with a coil power supply; an insulating ring is arranged outside the sample loading area and is aligned with the sample loading area.

3. The plate electrode-based magnetic rotary arc ablation test system of claim 1, wherein: the sample mounting part comprises a base, the base is provided with a cooling medium cavity, the cooling medium cavity is respectively communicated with a liquid inlet pipe and a liquid outlet pipe, and the liquid inlet pipe and the liquid outlet pipe are connected with a circulating cooling system; the cathode sample encloses the cooling medium chamber when the cathode sample is loaded in the sample mount.

4. The plate electrode-based magnetic rotary arc ablation test system of claim 3, wherein: the cooling medium cavity is a concave cavity body which is arranged at the top opening of the base, and when a sample is loaded on the sample mounting piece, the cathode sample seals the cooling medium cavity.

5. The plate electrode-based magnetic rotary arc ablation test system of claim 3, wherein: the liquid inlet pipe and the liquid outlet pipe are arranged on the side surface of the base.

6. The plate electrode-based magnetic rotary arc ablation test system of claim 5, wherein: the liquid inlet pipe is lower than the liquid outlet pipe.

7. The plate electrode-based magnetic rotary arc ablation test system of claim 3, wherein: the circulating cooling system comprises a liquid storage tank and a pump, wherein the liquid storage tank is respectively connected with the liquid inlet pipe and the liquid outlet pipe through pipelines, and the pump is arranged on the pipelines.

8. The plate electrode-based magnetic rotary arc ablation test system of claim 3, wherein: the cathode sample is circular and the cooling medium cavity is circular.

9. The plate electrode-based magnetic rotary arc ablation test system of claim 1, wherein: the cross section of the protective cover is circular, the protective cover is provided with an atmosphere inlet, the atmosphere inlet is used for feeding air along the tangential direction, and/or the atmosphere inlet is at least one group, and when the atmosphere inlets are multiple groups, the multiple groups of atmosphere inlets are uniformly arranged along the circumferential direction of the outline.

10. The plate electrode-based magnetic rotary arc ablation test system of claim 1, wherein: the sample mount has a sample loading area, the cathode sample is loaded as a sheet sample, and the anode is aligned with the sample loading area.

11. The plate electrode-based magnetic rotary arc ablation test system of claim 1, wherein: and a cooling medium cavity of the cooling system is positioned in the sample loading area, and a metal sealing ring is arranged between the cathode sample and the cooling medium cavity.

12. The plate electrode-based magnetic rotary arc ablation test system of claim 1, wherein: the test system is provided with a base, and the sample mounting piece is enclosed between the protective cover and the base by the protective cover.

Technical Field

The invention belongs to the field of material performance test, and particularly relates to a method and a system for testing ablation performance of a material.

Background

The aerospace technology is an important mark of national science and technology strength and powerful guarantee of international influence, and reflects the comprehensive national strength level of a country. The hypersonic aircraft is an aerospace aircraft flying at supersonic speed, and comprises a hypersonic missile, a hypersonic airplane, an interstellar aircraft and the like. Due to the fact that the hypersonic aerocraft flies in the atmosphere at a high speed for a long time, severe outline ablation is caused by the surface aerodynamic thermal effect. The ablation of the shape can cause the aircraft to turn around, turn over or even break down. Therefore, the heat-proof design of the hypersonic aircraft must be subjected to strict heat-proof tests and examinations to check the reliability, effectiveness and applicability of the heat-proof materials and structures of the aircraft. At present, the assessment mode aiming at the aircraft mainly comprises three modes, namely model test flight, numerical simulation and ground wind tunnel test. As the hypersonic numerical calculation relates to multi-physical field coupling, the calculation difficulty is high, the precision is low, and the hypersonic numerical calculation is difficult to be used as a heat-proof evaluation basis; the model has limited data obtained by test flight and high failure risk and cost, so the ground wind tunnel test is a core mode for evaluating the thermal protection of the hypersonic aircraft. At present, high-temperature wind tunnel equipment capable of developing the heat-proof test research of hypersonic aircrafts mainly comprises a combustion wind tunnel, an electric arc wind tunnel, a shock wave wind tunnel, a ballistic target and the like. For the heat-proof assessment test with the Mach number of more than 8, the total upper temperature limit of the flow field of the combustion wind tunnel cannot meet the test requirement. The shock tunnel and the arc tunnel can provide a high-speed and high-temperature air flow field, but the test time of the shock tunnel is only millisecond level, and the requirement of high-Mach number long-time flight test research of the hypersonic aircraft cannot be met. In contrast, the electric arc wind tunnel can provide long-time continuous examination and test conditions, so that the electric arc wind tunnel becomes a necessary means for ground heat-proof examination of key components such as the nose cone, the front edge of the wing, the engine and the like of the hypersonic aircraft.

High voltage punctures the air of copper electrode in the electric arc heater during high temperature electric arc wind tunnel test, forms strong plasma arc discharge, heats rotatory high-pressure pure air who jets into violently to obtain high-pressure high enthalpy air current, and then through the spray tube expansion acceleration, form high temperature efflux, carry out the ablation test to the test piece of installing in the spray tube export.

The electrode is used as the heart of the high-temperature arc wind tunnel, has severe use environment and needs to bear high temperature, high air pressure, large current and high electricityAnd (6) pressing. Extremely high heat input at arc root (20000 MW/m)²) Resulting in local oxidation and melting of the electrode surface. The electrode is gradually thinned under the scouring of high-pressure airflow, and even partially burnt through, so that air leakage and water permeation failure are caused. Therefore, the ablation resistance of the electrode substantially determines the experimental capacity of the arc heater.

Currently, to reduce electrode erosion, the main measures include: 1. in terms of arc control, electrode erosion is reduced from the standpoint of shortening the arc root ablation time and reducing the arc root current. 2. In the aspect of electrode materials, basic theory exploration is mainly carried out around the thermophysical process related to arc ablation at present, and the influence rule of factors such as material properties, material microstructures, electrode surface atmosphere and temperature on the ablation degree of the electrode materials is discussed. However, there is a great difference between the material theory research and the actual service conditions of the arc wind tunnel electrode, and whether the influence rule obtained by the related research can be directly applied to the arc wind tunnel remains to be verified.

Technical content

The invention aims to provide a test system which can reproduce the arc ablation working condition of an arc wind tunnel electrode and test the ablation resistance of an electrode material by using a small-size electrode material sample.

The magnetic rotating arc ablation test system based on the flat plate electrode comprises an anode, a sample mounting part for loading a cathode material sample, a cooling system for cooling the cathode material sample, and a protective cover; an electric arc is generated between the cathode and the anode, and the electric arc is positioned in the protective cover; the anode and the cathode are respectively provided with a port connected with an arc power supply; the cathode sample and the sample mounting part are detachably assembled; the cathode sample and the sample mounting part are detachably assembled; the cathode sample was stationary and the arc rotated around the center of the cathode sample.

The cathode sample made of cathode material is loaded on the sample mounting piece, the protective cover is covered, the anode and the cathode are electrified, the anode generates electric arc towards the cathode, the electric arc ablates the cathode, and in the ablation process, the electric arc rotates relative to the cathode. Meanwhile, the cooling system cools the cathode, the arc and the cooling system are controlled, the arc ablation working condition of the arc wind tunnel electrode can be simulated, and after the arc ablation test is finished, the cathode sample is taken down and subjected to material test after ablation so as to judge the ablation resistance of the cathode sample.

The preferable specific scheme is as follows: an electromagnetic coil is arranged outside the protective cover, the direction of a magnetic field of the electromagnetic coil is parallel to the direction of the anode pointing to the cathode, and the electromagnetic coil is provided with a port connected with a coil power supply; an insulating ring is arranged outside the sample loading area and is aligned with the sample loading area.

When the magnetic field direction of the electromagnetic coil is parallel to the direction of the anode pointing to the cathode, the moving direction of the charged particles in the arc column is the same as the direction of the magnetic field, and the generated electric field force is zero. However, the concentration of the charged particles within the arc column section gradually decreases from the center to the periphery, and this concentration difference of the charged particles causes the charged particles to diffuse from the center to the periphery. The cross section of the arc column is an XOY plane, and the diffusion motion of the charged particles caused by concentration difference simultaneously has a radial motion componentVxAndVyand, a motion componentVxAndVyperpendicular to the magnetic field. At this time, due to the diffusion of the charged particles in the x-direction and the y-direction, lorentz force is generated by the magnetic field, and the lorentz force acts on the diffusing electrons (or ions) to generate circular motion, and the motion speed is set to beVz. The charged particles moving circularly along the radius r generate centripetal force under the action of magnetic fieldFx. And the charged particles are simultaneouslyVxAndVythe motion components in both directions, so the actual path of motion of the charged particles is a helix with radius r. Under the action of an external magnetic field, the movement of charged particles in the arc from the anode to the cathode is changed into spiral movement. The larger the intensity of the applied magnetic field, the smaller the radius of the spiral. The charged particles are spirally moved under the action of Lorentz force, and continuously collide with neutral particles in the moving process, so that the electric arc is driven to rotate. As the magnetic field strength increases, the radius of rotation decreases and the arc contracts. The magnetic field intensity is reduced, the rotating radius is increased, and the electric arc is diffused. Therefore, the intensity of the electromagnetic field is changed by adding an electromagnetic coil, and the purpose of rotating the electric arc relative to the sheet sample is achieved.

The insulator is outside and the cathode sample inside, the insulator confines the arc inside.

Preferably, the sample mounting part comprises a base, the base is provided with a cooling medium cavity, the cooling medium cavity is respectively communicated with a liquid inlet pipe and a liquid outlet pipe, and the liquid inlet pipe and the liquid outlet pipe are connected with a circulating cooling system; the cathode sample encloses the cooling medium chamber when the cathode sample is loaded in the sample mount. The cathode sample closes the cooling medium cavity, which means that the cooling medium cavity has no other openings except for the liquid inlet pipe and the liquid outlet pipe.

The cooling medium is in contact with the cathode sample, so that the cooling and heat dissipation effects on the cathode sample are achieved, the cathode sample is prevented from being broken down when being in contact with electric arcs, and the working condition that the cathode material is ablated for a long time is simulated.

Preferably, the cooling medium cavity is a concave cavity arranged at the top of the base, and the cooling medium cavity is sealed by the cathode sample when the sample is loaded on the sample installation member.

Preferably, the liquid inlet pipe and the liquid outlet pipe are arranged on the side surface of the base.

Preferably, the liquid inlet pipe is lower than the liquid outlet pipe.

Preferably, the circulating cooling system comprises a liquid storage tank and a pump, the liquid storage tank is respectively connected with the liquid inlet pipe and the liquid outlet pipe through pipelines, and the pump is arranged on the pipelines.

Preferably, the cathode sample is circular and the cooling medium cavity is circular.

Preferably, the shroud is circular in cross-section and the atmosphere inlet feeds air tangentially. And when a plurality of groups of atmosphere inlets are arranged, the plurality of groups of atmosphere inlets are uniformly arranged along the circumferential direction of the outline. The atmosphere enters the arc generation area along the tangential direction, and is beneficial to providing the arc with rotary assistance.

Preferably, the sample mounting member has a sample loading region, the cathode sample to be loaded is a sheet sample, and the anode is aligned with the sample loading region. The flaky sample is easy to prepare, the preparation process is relatively simple, and the used materials are few. Compared with the cathode of the high-temperature arc wind tunnel, the method greatly reduces the requirements on the sample quantity and the size of the cathode.

Preferably, the cooling medium cavity of the cooling system is positioned in the sample loading area, and a metal sealing ring is arranged between the cathode sample and the cooling medium cavity. The metal sealing ring can resist high-temperature ablation without failure, and the good sealing performance of the cooling system is kept.

Preferably, the insulating ring presses the cathode sample against the sample mount.

Preferably, the test system is provided with a base, and the protective cover encloses the sample mount between the protective cover and the base.

Preferably, the protective cover is provided with an atmosphere inlet, and the atmosphere inlet is connected with a high-pressure gas supply system through a pipeline. The atmosphere entry enables the protective atmosphere to enter the space where arc erosion occurs. The atmosphere to be introduced is connected to the gas source. If the nitrogen is introduced, the nitrogen-containing gas is communicated with a nitrogen gas source. The air is introduced to be communicated with an air source.

Due to the extremely high temperature of the arc, if the discharge is continuously carried out at a certain part, the electrode is rapidly melted, ablated and failed. In order to avoid long-time ablation of the electric arc at any part, the high-temperature electric arc wind tunnel adopts a magnetic field rotation technology to move the electric arc. Therefore, when screening the arc ablation resistant material, the testing system of the invention also provides various technical schemes to enable the arc and the cathode sample to have relative rotary motion in order to more truly reproduce the arc ablation condition of the arc tunnel.

The invention has the advantages that: 1. the cathode sample is prepared into a sheet sample, the arc can be generated, the cathode sample is cooled while the arc ablation is carried out on the cathode sample, and the ablation working condition of the high-temperature arc wind tunnel is simulated. Compared with a high-temperature arc wind tunnel, the invention can simulate the working condition of the arc wind tunnel, has the advantages of less material quantity required by a cathode sample, simplified structure and low cost, and is convenient for material screening.

2. The electromagnetic coil is arranged, so that the electric arc rotates, and when the cathode sample is fixed, the electric arc can remove and ablate the cathode sample.

Drawings

FIG. 1 is a schematic view of example 1.

Fig. 2 is a schematic view of the protective cover.

FIG. 3 is a view showing a configuration of a magnetic rotating arc generating apparatus.

Figure 4 is a schematic view of arc root rotation.

Fig. 5 is a schematic diagram of an electric arc making spiral motion by an electromagnetic field, wherein a) is a schematic diagram of an electromagnetic coil arranged outside the electric arc, b) is a schematic diagram of a motion component of a charged particle moving on a magnetic field axis, c) is a schematic diagram of a charged particle subjected to a centripetal force Fr and having a Z-direction speed by a centrifugal force, and d) is a schematic diagram of the centripetal force when the charged particle having the Z-direction speed makes circular arc motion.

Fig. 6 is a schematic view of the tangential admission of atmosphere from the protective cover.

FIG. 7 is a schematic diagram of the cathode sample active rotating arc generator.

Figure 8 is an exploded view of the arc generating device body.

Fig. 9 is a plan view of the arc generating device.

Fig. 10 is a schematic view of the top cover on the cathode base.

FIG. 11 is a schematic view of electrode backside cooling water flow.

FIG. 12 is a diagram of the arc root pivoting trajectory of the sample surface.

Fig. 13 is a graph of failure after ablation for a pure copper sample.

Fig. 14 is a three-dimensional profile of pure copper after ablation (arcing 720 s).

FIG. 15 is a three-dimensional profile of a Cu-Cr alloy Cu50Cr50 electrode after ablation (arc 720 s).

Fig. 16 is a three-dimensional profile (arcing 120 s) of pure copper after ablation.

Detailed Description

The specific structural scheme of the test system of the invention is explained in detail with the accompanying drawings.