Needle plate composite glow electrode for large-size model rarefied flow field display

Abstract

The utility model discloses a needle plate composite glow electrode for displaying a rarefied flow field of a large-size model, which relates to the technical field of wind tunnel tests and is oppositely arranged at an outlet of a wind tunnel nozzle, and each needle plate composite glow electrode comprises an electrode fixing device and an insulating sleeve, the probe plate composite glow electrode module is arranged on the electrode fixing device and is electrically connected with an external power supply through a high-voltage cable; the needle plate composite glow electrode module comprises an electrode plate; the electrode insulating cover sleeves the outer side of the electrode plate; and the needle-shaped structure is vertically arranged on the electrode plate so as to shorten the distance between the two needle plate composite glow electrode modules. The utility model provides a needle plate composite glow electrode for displaying a rarefied flow field of a large-size model, which is more favorable for puncturing gas between the electrodes to form plasmas under the condition of the same voltage, and reduces the breakdown voltage and the maintaining voltage of glow discharge.

Description

Technical Field

[0001] The utility model relates to the technical field of wind tunnel testing, in particular to a needle-plate composite glow electrode used for displaying rarefied flow fields of large-scale models. Background Art

[0002] Wind tunnel testing is an important tool for studying aerodynamics. During wind tunnel testing, flow field visualization technology is required to visualize the structural characteristics of the flow field around the test model. Glow discharge is a flow field visualization technology well-suited for rarefied flow fields, due to its simple principle and ease of application.

[0003] Traditional glow discharge uses two opposing metal plates (usually disc-shaped) as discharge electrodes. A certain AC or DC voltage is applied to the electrodes, and the strong electric field excites the low-pressure gas between the electrodes to form a plasma and emit colored visible light (i.e., glow). In rarefied flow fields, glow discharge can display flow field structural features such as shock waves around the model. For example, patent application number 202010017795.2 discloses a large-caliber hypersonic, low-density wind tunnel flow field display system based on high-frequency glow. The system includes a power module, a glow module, and an acquisition module. The power module is electrically connected to the glow module to provide two-phase high-frequency, high-voltage AC power with a frequency range of 35 to 40 kHz and a voltage range of 25 to 30 kV. The glow module is located at the wind tunnel nozzle outlet and includes two opposing electrode units. Each electrode unit includes an electrode plate and an electrode insulation cover, and the electrode plate has a circular cross-section.

[0004] However, the above-mentioned glow module will have the following problems when used in large-caliber wind tunnel tests: due to the large electrode spacing, the single disc structure will have the problem of being unable to break through. To solve this problem, traditional glow discharge requires applying a very high voltage to excite the gas and maintain a stable glow, which can easily cause arcing, leakage, ablation and other problems, posing a huge challenge to the safety of wind tunnel tests and even making it impossible to achieve flow field display, especially when the total pressure of the wind tunnel is high. Utility Model Content

[0005] An object of the present invention is to solve the above-mentioned problems and / or disadvantages and to provide advantages as will be described below.

[0006] In order to achieve these objects and other advantages of the present invention, a pin-plate composite glow electrode for displaying rarefied flow fields in large-scale models is provided. The pin-plate composite glow electrodes are relatively arranged at the outlet of a wind tunnel nozzle, and each pin-plate composite glow electrode includes an electrode fixing device, an insulating kit, and a pin-plate composite glow electrode module arranged on the electrode fixing device and electrically connected to an external power supply via a high-voltage cable. The pin-plate composite glow electrode module is configured to include:

[0007] electrode plates;

[0008] An electrode insulation cover sleeved on the outside of the electrode plate;

[0009] A needle-shaped structure that is vertically mounted on the electrode plate and extends into the wind tunnel test section to shorten the distance between the two needle-plate composite glow electrode modules;

[0010] Wherein, a mounting groove matching the needle-shaped structure is provided at the center of the electrode plate.

[0011] Preferably, the electrode plate is configured to adopt an elliptical or oval flat plate structure.

[0012] Preferably, the long axis direction of the electrode plate is parallel to the nozzle axis direction of the wind tunnel.

[0013] Preferably, the electrode insulation cover includes a bottom plate matched with the electrode plate, and an annular surrounding edge extending vertically from the edge of the bottom plate into the wind tunnel test section.

[0014] Preferably, the electrode plate and the needle-shaped structure are configured to be made of one of aluminum alloy and tungsten.

[0015] The utility model has at least the following beneficial effects:

[0016] First, compared to the existing disc-type electrode structure, the present invention designs a needle-plate composite electrode. By adding a needle-shaped structure to the traditional flat-plate glow electrode, the discharge distance is physically shortened. The needle-shaped structure creates a needle-tip discharge effect, generating an ionization zone with high electric field strength and high electron density around the needle tip. Under the same voltage, compared with the existing disc electrode, it is more conducive to breaking down the gas between the electrodes to form plasma, effectively reducing the breakdown voltage and maintenance voltage of the glow discharge, and producing a more stable glow discharge.

[0017] Secondly, the utility model innovatively improves the disc-type electrode plate to adopt an elliptical or elliptical structure, and the long axis of the elliptical shape is parallel to the axis of the wind tunnel nozzle (that is, consistent with the length direction of the wind tunnel test model). Compared with traditional disc-type electrodes, it is more suitable for large-scale models with longer lengths in wind tunnel tests, and can form a more uniform glow discharge plasma along the axis of the model between the two electrode plates, which is beneficial to improving the flow field display effect.

[0018] Other advantages, objectives and features of the present invention will be reflected in part through the following description, and in part will be understood by those skilled in the art through research and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a schematic structural diagram of the cooperation between a pin-plate composite glow electrode and a wind tunnel nozzle outlet for displaying rarefied flow fields in large-scale models in one embodiment of the present invention;

[0020] Figure 2 This is a schematic structural diagram of a pin-plate composite glow electrode and a wind tunnel nozzle used for displaying rarefied flow fields in large-scale models in one embodiment of the present invention;

[0021] Figure 3 This is a schematic diagram of the structure of a needle-plate composite glow electrode module in one embodiment of the present utility model;

[0022] Figure 4 This is a structural diagram of the cooperation between the needle-plate composite glow electrode module and the electrode fixing device in one embodiment of the present utility model;

[0023] Figure 5 This is a cross-sectional schematic diagram of the cooperation between the pin-plate composite glow electrode module and the electrode fixing device in one embodiment of the present utility model;

[0024] In the figure, power supply 1, high-voltage cable 10, wind tunnel nozzle 2, nozzle axis 21, needle-plate composite glow electrode module 3, electrode insulation cover 31, electrode plate 32, needle-shaped structure 33, long axis 34, bottom plate 35, annular edge 36, fixing plate 37, electrode terminal 38, electrode fixing device 4, electrode bracket 41, electrode fixing seat 42, insulation kit 5, insulation plate 50, insulation sleeve 51, test model 6, wind tunnel test section 7. DETAILED DESCRIPTION

[0025] The present invention will be described in further detail below in conjunction with the accompanying drawings so that those skilled in the art can implement the invention with reference to the description.

[0026] It should be understood that terms such as “having”, “including” and “comprising” used herein do not preclude the existence or addition of one or more other elements or combinations thereof.

[0027] It should be noted that in the description of the present invention, the orientation or position relationship indicated by the terms is based on the orientation or position relationship shown in the accompanying drawings, which is only for the convenience of describing the present invention and simplifying the description. It does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0028] In the description of the present invention, unless otherwise clearly specified and limited, the terms "installed", "provided with", "sleeved / connected", "connected", etc. should be understood in a broad sense. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection. It can be a mechanical connection or an electrical connection. It can be a direct connection or an indirect connection through an intermediate medium. It can be a communication between the internal parts of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0029] In addition, in the present invention, unless otherwise expressly specified or limited, when a first feature is "above" or "below" a second feature, it can mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Furthermore, when a first feature is "above," "above," or "above" a second feature, it can mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is higher in level than the second feature. When a first feature is "below," "below," or "below" a second feature, it can mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is lower in level than the second feature.

[0030] Example 1

[0031] A pin-plate composite glow electrode for displaying rarefied flow fields in large-scale models, the structure of which is as follows: Figure 1-Figure 3 As shown, the pin-plate composite glow electrode is relatively arranged at the outlet of the wind tunnel nozzle 2. The pin-plate composite glow electrode and the test model 6 are both located in the wind tunnel test section 7. The test model 6 is generally long and narrow, and its length direction is substantially consistent with the direction of the axis 21 of the wind tunnel nozzle 2.

[0032] Each pin-plate composite glow electrode includes:

[0033] The electrode fixing device 4 includes: an electrode fixing seat 42 and an electrode bracket 41. The electrode fixing seat 42 and the electrode bracket 41 adopt a multi-threaded hole array design, which can adjust the distance between the two electrode devices 3 and the distance between the needle-plate composite glow electrode module 3 and the nozzle 2 outlet within a certain range. When in use, the electrode bracket 41 is moved relative to the electrode fixing seat 42 to the desired position (including radial movement and axial movement along the wind tunnel nozzle 2), and then the multiple threaded mounting holes on the electrode bracket 41 are aligned with the multiple threaded mounting holes on the electrode fixing seat 42. The electrode bracket 41 can be fixed to the electrode fixing seat 42 by screws or bolts. The electrode fixing seat 42 and the electrode bracket 41 are processed with insulating bakelite (bakelite is phenolic plastic) to ensure good insulation and high mechanical strength.

[0034] The insulating kit 5 mainly includes: an insulating sleeve 51 arranged on the aluminum alloy electrode terminal 38 (the insulating sleeve 51 is also called an electrode lock nut. When in use, the electrode terminal 38 and the electrode plate are first fixed together by bolts, and then the electrode terminal 38 is completely covered by the electrode lock nut. The electrode lock nut is also made of insulating material, so it can also be called an insulating sleeve) and an insulating plate 50 arranged on the end face of the nozzle connection flange; in actual application, the insulating plate 50, the electrode insulating cover 31, and the insulating sleeve 51 of the electrode terminal 38 are all made of polytetrafluoroethylene material, and the electrode terminal 38 is completely wrapped by the insulating sleeve 51. The electrode terminal 38 and the joint between it and the high-voltage cable 10 are locked with nuts and sealed with glue, thereby ensuring good insulation and preventing leakage and arc creep. Because the connection method between the electrode terminal 38 and the high-voltage cable 10 belongs to the prior art, its structure and connection method are not described in detail here;

[0035] The invention also includes: a pin-plate composite glow electrode module 3 provided on the electrode fixing device 4 and electrically connected to the external power supply 1 via a high-voltage cable 10, and an electrode terminal 38 on the electrode plate 32 is connected to the power supply 1 via the high-voltage cable 10;

[0036] The pin-plate composite glow electrode module 3 includes:

[0037] Electrode plate 32;

[0038] An electrode insulating cover 31 is sleeved on the outside of the electrode plate 32;

[0039] A needle-shaped structure 33 is vertically disposed on the electrode plate 32 and extends into the wind tunnel test section 7 to shorten the distance between the two needle-plate composite glow electrode modules 3. This solution adds a needle-shaped structure to the traditional flat-plate glow electrode to obtain a needle-plate composite glow electrode module. Compared with the existing simple disk electrode, the discharge distance can be shortened in physical space. In addition, the needle-shaped structure will form a needle-tip discharge effect when used, generating an ionization zone with high electric field strength and high electron density around the needle tip, which is conducive to breaking down the gas between the electrodes to form plasma, reducing the breakdown voltage and maintenance voltage of the glow discharge, and helping to produce a more stable glow discharge.

[0040] Furthermore, the front of the electrode plate 32 is provided with multiple circles of corrugated protrusions adapted to the shape of the electrode plate 32. The center point of the front of the electrode plate 32 is provided with a round hole threaded slot for convenient screwing of the needle tip structure. The back of the electrode plate 32 is provided with a threaded hole for connecting the electrode terminal 38. In actual applications, the needle-shaped structure 33 and the electrode terminal 38 are both connected to the electrode plate 32 by threads, and the electrode plate 32 and the needle-shaped structure 33 are configured to be made of one of the materials selected from aluminum alloy or tungsten.

[0041] Furthermore, in actual applications, the elliptical electrode plate 32 is made of 6061 aluminum alloy material, and the needle-shaped structure 33 is made of 7075 aluminum alloy material, taking into account good conductivity and ablation resistance. The needle-shaped structure 33 can also be made of tungsten and other materials with good conductivity and high melting point.

[0042] Example 2

[0043] This embodiment 2 is a preferred embodiment of the present invention, and its specific structure is as follows: Figure 1-Figure 2 As shown, the following improvements are disclosed based on Implementation 1:

[0044] The electrode plate 32 is configured to adopt an elliptical or elliptical flat plate structure. In addition to the advantages of the needle-shaped structure 33 introduced in Example 1, the electrode plate 32 is an elliptical or elliptical flat plate structure, and its long axis 34 is parallel to the axis direction 21 of the wind tunnel nozzle 2. This is very beneficial for the wind tunnel test model 6 with a longer length. A uniform glow can be formed between the two elliptical electrode plates 32 along the entire length of the model, thereby realizing a large-scale flow field structure display around the model 4, rather than just a local area; therefore, the electrode plate of the present invention adopts an elliptical or elliptical structure, which is more suitable for longer and large-scale models in wind tunnel tests than traditional disc electrodes. A more uniform glow discharge plasma can be formed between the two electrode plates along the axis direction of the model, which is beneficial to improving the flow field display effect.

[0045] Example 3

[0046] This embodiment 3 is a preferred embodiment of the present invention, and its specific structure is as follows: Figure 1 、 Figure 4-Figure 5 As shown, the following improvements are disclosed based on Implementation 1:

[0047] The electrode insulation cover 31 includes a base plate 35 that cooperates with the electrode plate 32, an annular edge 36 that extends vertically from the edge of the base plate into the wind tunnel test section, and four fixing plates 37 that are integrally formed with the base plate 35 and the annular edge 36. In actual application, the four fixing plates 37 are respectively arranged on both sides of the aluminum alloy electrode terminal 38. Their function is to fix the needle-plate composite glow electrode module 3 on the electrode bracket 41, that is, the four fixing plates and the electrode bracket 41 are fixed by bolts.

[0048] Working principle: The electrode insulation cover 31 adopts an annular hollow structure, which is tightly mounted on the outside of the electrode plate 32. The annular edge extends outward perpendicular to the electrode plate to increase the arc creepage distance between the electrode plate and other metal materials. The electrode insulation cover 31 is made of polytetrafluoroethylene insulation material. The insulation material can also be selected from conventional bakelite, nylon and other materials according to actual needs, and no further restrictions are given here.

[0049] The above solutions are only examples of preferred embodiments, but are not limited thereto. When implementing the present invention, appropriate replacements and / or modifications can be made according to user needs.

[0050] The number of devices and processing scales described herein are used to simplify the description of the present invention. Applications, modifications and variations of the present invention will be apparent to those skilled in the art.

[0051] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and exemplary embodiments. They can be applied to a variety of fields suitable for the present invention. Further modifications will be readily apparent to those skilled in the art. Therefore, the present invention is not limited to the specific details and illustrations shown and described herein without departing from the general concept defined by the claims and their equivalents.

Claims

1. A pin-plate composite glow electrode for displaying rarefied flow fields in large-scale models, wherein the pin-plate composite glow electrodes are arranged relative to each other at the outlet of a wind tunnel nozzle, and each pin-plate composite glow electrode includes an electrode fixing device and an insulating kit, characterized in that: Also includes: The pin-plate composite glow electrode module is provided on the electrode fixing device and electrically connected to the external power supply via a high-voltage cable, and is configured to include: electrode plates; An electrode insulation cover sleeved on the outside of the electrode plate; A needle-shaped structure that is vertically mounted on the electrode plate and extends into the wind tunnel test section to shorten the distance between the two needle-plate composite glow electrode modules; Wherein, a mounting groove matching the needle-shaped structure is provided at the center of the electrode plate.

2. The pin-plate composite glow electrode for displaying rarefied flow fields of large-scale models according to claim 1, characterized in that: The needle-shaped structure is connected to the electrode plate by using threads.

3. The pin-plate composite glow electrode for displaying rarefied flow fields of large-scale models according to claim 1, characterized in that: The electrode plate is configured to adopt an elliptical or oval flat plate structure.

4. The pin-plate composite glow electrode for displaying rarefied flow fields of large-scale models according to claim 3, characterized in that: The long axis direction of the electrode plate is parallel to the nozzle axis direction of the wind tunnel.

5. The pin-plate composite glow electrode for displaying rarefied flow fields of large-scale models according to claim 1, characterized in that: The electrode insulation cover comprises a bottom plate matched with the electrode plate, and an annular surrounding edge extending vertically from the edge of the bottom plate into the wind tunnel test section.

6. The pin-plate composite glow electrode for displaying rarefied flow fields of large-scale models according to claim 1, characterized in that: The electrode plate and the needle-shaped structure are configured to be made of one of aluminum alloy and tungsten.

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