High voltage resistant insulating diaphragm for coaxial cylindrical deflagration drive

Abstract

The present invention discloses a high-voltage-resistant insulating diaphragm for a coaxial cylindrical deflagration drive device. The diaphragm comprises a first diaphragm, with a second diaphragm disposed circumferentially thereon, the second diaphragm facing the deflagration drive segment and the first diaphragm facing the driven segment. The second diaphragm comprises at least three sub-diaphragms, and along the center of the first diaphragm, the at least three sub-diaphragms overlap around the center of the first diaphragm. The diameter of the first diaphragm is greater than that of the second diaphragm. The first diaphragm is made of metal, and the second diaphragm is made of polytetrafluoroethylene. The present invention not only maximizes insulation thickness and avoids insulation defects caused by direct splicing, but also prevents the second diaphragm from tearing randomly, reducing the probability of the second diaphragm falling off. It also avoids excessive interference with the flow field, thereby improving flow field quality.

Description

Technical Field

[0001] The present invention relates to the technical field of experimental research on high-temperature and high-speed gas dynamics, high-speed aircraft, etc., and more specifically, to a high-voltage resistant insulating diaphragm for a coaxial cylindrical deflagration drive device. Background Art

[0002] Shock tube / wind tunnel is a kind of experimental equipment widely used in the fields of high temperature and high speed gas dynamics, high speed aircraft, etc. The basic principle is: high pressure driving gas compresses low pressure test gas through shock wave to make it reach the required test state. Figure 1 As shown, a typical shock tube / wind tunnel includes a driving section 1', a driven section 2', a nozzle 3', and a test section 4'. Before the test, the driving section 1' and the driven section 2' are separated by a diaphragm 5'. The driving section 1' is filled with high-pressure driving gas, and the driven section 2' is filled with low-pressure test gas. During the test, the diaphragm 5' ruptures, and the high-pressure gas expands and enters the driven section 2', simultaneously generating a rapidly moving shock wave in the driven section 2'. If the test is conducted directly using the gas after the shock wave, the equipment operates in shock tube mode. If the test is conducted using the test gas accelerated by the nozzle 3', the equipment operates in shock tunnel mode.

[0003] The total temperature and total pressure range of the test gas are key indicators of equipment capability, both of which depend on the driving power of the high-pressure drive gas. Room-temperature, high-pressure gas is no longer sufficient to meet increasingly demanding testing requirements. To address this, three high-performance drive technologies have been developed domestically and internationally: piston drive, heated light gas drive, and detonation drive. Detonation drive, with its low cost, simple structure, and relative safety, is currently the mainstream technology in China.

[0004] The detonation-driven shock tube was first proposed by Bird in 1957. In 1981, Mr. Yu Hongru of the Institute of Mechanics, Chinese Academy of Sciences, built a 13.3-meter-long detonation-driven shock tube, which was put into operation in 1983. In 1994, the Institute of Mechanics, Chinese Academy of Sciences, developed the JF-10 detonation-driven high-enthalpy shock tunnel [see Yu Hongru, Zhao Wei, and Yuan Shengxue, Performance of Hydrogen-Oxygen Detonation-Driven Shock Tunnels - Aerodynamic Test and Measurement Control, 1993, 7(3): 38-42]. With the help of Mr. Yu Hongru, Gronig et al. built a high-enthalpy shock tunnel (TH2-D) using reverse detonation drive at the RWTH Aachen University in Germany in 1993. In 1994, NASA modified the original free-piston-driven design and built the forward detonation-driven high-enthalpy shock tunnel (HYPULSE) at GASL. The tunnel can operate in both reflected shock tunnel mode and expansion tube mode [see Chue RSM, Tsai CY, Bakos RJ, Erdos JI, Rogers RC (2002) NASA's HYPULSE Facility at GASL - A Dual Mode, Dual Driver Reflected-Shock / Expansion Tunnel. In: Lu F, Marren D (eds), Advanced Hypersonic Test Facilities, Progress in Astronautics and Aeronautics, Vol. 198, AIAA, Chapter 3, pp29-71].

[0005] Detonation drive requires the formation of an axially propagating detonation wave within the drive section. The uneven flow field behind the detonation wave causes the following problems with this drive technology: First, the range of gas mixture ratios that can detonate is much narrower than the range that can deflagrate, and the temperature and sound velocity ranges of the driving gas are also correspondingly narrower, thus limiting the total temperature range of the test gas that can be provided by the detonation drive; second, the effective driving pressure provided by the detonation drive does not exceed 40% of the equipment's pressure limit, limiting the total pressure range of the test gas.

[0006] Due to the above-mentioned problems of detonation drive, it is necessary to overcome them and introduce coaxial cylindrical deflagration drive technology. However, the coaxial cylindrical deflagration drive technology requires high-voltage electrodes to be plugged into both ends of the drive section, and an ignition wire is arranged between the two high-voltage electrodes along the center line of the drive section axis. Usually, a metal diaphragm is used to separate the deflagration drive section and the driven section. Since the ignition voltage of large-scale deflagration drive technology is as high as tens of thousands of volts, the high-voltage electrode and the metal diaphragm are close to each other, and breakdown may occur, resulting in equipment damage or endangerment to personnel safety.

[0007] Existing document 1 (CN205228769U) discloses a thin-edged metal diaphragm for a large-scale pulse wind tunnel; it includes a metal disc with multiple tensile holes, a crisscross groove that does not penetrate the metal disc is opened on one side surface of the metal disc, the crisscross groove has the center of the metal disc as the intersection point, and multiple tensile holes are opened around the crisscross groove at equal intervals on the same circumference, and the ratio of the distance from the center of the tensile hole to the center of the metal disc to the radius of the metal disc is about 0.9; the thin-edged metal diaphragm for a large-scale pulse wind tunnel, on the basis of maintaining the original size, is mechanically processed with tensile holes, by changing the external structure of the diaphragm, adding external constraints, and changing the force structure of the diaphragm. On the basis of not changing the clamping area of ​​the clamping mechanism, it is not easy for the diaphragm to break or fall off under the action of pulse tension. However, this device does not solve the above-mentioned technical problems.

[0008] Existing document 2 (CN102407947A) discloses a shock tunnel detonation dual-drive device, comprising: a shock tunnel, the shock tunnel having a detonation drive section, one end of the detonation drive section being provided with a detonation discharge section, and the other end being provided with a driven section; a first diaphragm being provided between the detonation discharge section and the detonation drive section, and a second diaphragm being provided between the driven section and the detonation drive section; a forward detonation drive ignition device being provided at a section of the detonation drive section close to the detonation discharge section, and a reverse detonation drive ignition device being provided at a section of the detonation drive section close to the driven section; a controllable time-delay triggering device being connected between the forward detonation drive ignition device and the reverse detonation drive ignition device, and the method thereof is as follows: Below: 1) A forward detonation ignition device is provided at one end of the detonation driving section of the shock tunnel close to the detonation unloading section, and a reverse detonation driving ignition device is provided at one end of the detonation driving section close to the driven section; 2) ignition is performed by the forward detonation ignition device to form a forward-driven detonation wave; 3) after the forward detonation wave propagates along the detonation driving section for a predetermined time, ignition is performed by the reverse detonation driving ignition device to form a reverse-driven detonation wave; 4) the reverse-driven detonation wave tears the diaphragm provided between the driven section and the detonation driving section, and the forward detonation wave and the reverse detonation wave intersect to form a moving shock wave, which enters the driven section to compress the test gas in the driven section.

[0009] In order to avoid dangerous breakdown between the high-voltage electrode and the diaphragm of the coaxial cylindrical deflagration drive technology, the present invention proposes a high-voltage resistant insulating diaphragm for a coaxial cylindrical deflagration drive device, which can not only maximize the insulation thickness and avoid insulation defects caused by direct splicing, but also avoid the randomness of the second diaphragm tearing, reduce the probability of the second diaphragm falling off, and avoid excessive interference with the flow field, which helps to improve the flow field quality. In addition, the high-voltage resistant insulating diaphragm for the coaxial cylindrical deflagration drive device is not easily thought of by technical personnel in this field. Summary of the Invention

[0010] In view of this, the present invention provides a high-voltage resistant insulating diaphragm of a coaxial cylindrical deflagration drive device, comprising a first diaphragm, wherein a second diaphragm is arranged along the circumferential direction of the first diaphragm, the second diaphragm faces the deflagration driving section, and the first diaphragm faces the driven section;

[0011] The second diaphragm includes at least three sub-diaphragms, and along the center direction of the first diaphragm, the at least three sub-diaphragms overlap around the center of the first diaphragm;

[0012] The diameter of the first diaphragm is greater than the diameter of the second diaphragm;

[0013] The first diaphragm is made of metal, and the second diaphragm is made of polytetrafluoroethylene.

[0014] Optionally, the second diaphragm includes a first sub-diaphragm, a second sub-diaphragm, a third sub-diaphragm and a fourth sub-diaphragm evenly arranged along the center of the first diaphragm, and the first sub-diaphragm, the second sub-diaphragm, the third sub-diaphragm and the fourth sub-diaphragm are overlapped with each other in a clockwise or counterclockwise direction to form a first overlapping area and a second overlapping area, the first overlapping area is close to the center of the first diaphragm, and the second overlapping area is away from the center of the first diaphragm, the thickness of the first overlapping area along the first direction is greater than the thickness of the second overlapping area along the first direction, and the first direction is the direction from the first diaphragm to the second diaphragm.

[0015] Optionally, the spacing between the first overlapping areas along the second direction is 10-30 mm, the spacing between some of the second overlapping areas along the second direction is 10-30 mm, and the second direction intersects with the first direction.

[0016] Optionally, central angles of the first sub-membrane, the second sub-membrane, the third sub-membrane, and the fourth sub-membrane are respectively 90°.

[0017] Optionally, the first sub-membrane, the second sub-membrane, the third sub-membrane and the fourth sub-membrane are each fan-shaped.

[0018] Optionally, the thickness of the first overlapping area along the first direction is 4-20 mm, and the thickness of the second overlapping area along the first direction is 2-10 mm.

[0019] Optionally, the first overlapping area is rectangular in shape.

[0020] Compared with the prior art, the high-voltage resistant insulating diaphragm for a coaxial cylindrical deflagration drive device provided by the present invention achieves at least the following beneficial effects:

[0021] The present invention arranges a second diaphragm on the first diaphragm, the second diaphragm faces the deflagration drive section, and at least three sub-diaphragms overlap around the center of the first diaphragm. The second diaphragm is made of polytetrafluoroethylene, which not only maximizes the insulation thickness and avoids insulation defects caused by direct splicing, but also avoids the randomness of the second diaphragm tearing, reduces the probability of the second diaphragm falling off, and also avoids excessive interference with the flow field, which helps to improve the flow field quality.

[0022] Of course, any product implementing the present invention does not necessarily need to achieve all of the technical effects described above at the same time.

[0023] Further features and advantages of the present invention will become apparent from the following detailed description of exemplary embodiments of the present invention with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

[0025] Figure 1 This is a schematic diagram of the structure of a shock tube / wind tunnel provided in the prior art;

[0026] Figure 2 This is a schematic diagram of the use state of the high-voltage resistant insulating diaphragm for the coaxial cylindrical deflagration driving device provided by an embodiment of the present invention;

[0027] Figure 3 Schematic diagram of the structure of a high-voltage resistant insulating diaphragm for a coaxial cylindrical deflagration drive device provided by an embodiment of the present invention;

[0028] Figure 4 1 is a schematic structural diagram of a first sub-diaphragm provided in an embodiment of the present invention;

[0029] Figure 5 Schematic diagram of the structure of a coaxial cylindrical deflagration drive device for a shock tube / wind tunnel provided by an embodiment of the present invention;

[0030] Figure 6 yes Figure 5 A magnified view of the structure at point B in the middle;

[0031] Figure 7 yes Figure 5 A magnified diagram of the structure of the discharge system;

[0032] Figure 8 This is a logic block diagram of a discharge system provided by an embodiment of the present invention;

[0033] Figure 9 Schematic diagram of the structure of a shock tube / wind tunnel provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0034] Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that unless otherwise specifically stated, the relative arrangement of components and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present invention.

[0035] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses.

[0036] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered part of the specification.

[0037] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0038] It should be noted that like reference numerals and letters refer to like items in the following figures, and therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0039] Figure 2 This is a schematic diagram of the use state of the high-voltage resistant insulating diaphragm for the coaxial cylindrical deflagration driving device provided by an embodiment of the present invention; Figure 3 Schematic diagram of the structure of a high-voltage resistant insulating diaphragm for a coaxial cylindrical deflagration drive device provided by an embodiment of the present invention; Figure 4 1 is a schematic structural diagram of a sub-diaphragm provided in an embodiment of the present invention; Figure 2-Figure 4 As shown, the present embodiment provides a high-voltage resistant insulating diaphragm 5 for a coaxial cylindrical deflagration drive device, comprising a first diaphragm 51, wherein the first diaphragm 51 is provided with a second diaphragm 52 along the circumferential direction, the second diaphragm 52 faces the deflagration drive section 1, and the first diaphragm 51 faces the driven section 2; the second diaphragm 52 comprises at least three sub-diaphragms, and along the center direction of the first diaphragm 51, at least three sub-diaphragms overlap around the center of the first diaphragm 51; the diameter of the first diaphragm 51 is greater than the diameter of the second diaphragm 52; the first diaphragm 51 is made of metal, and the second diaphragm 52 is made of polytetrafluoroethylene.

[0040] Specifically, the high-voltage insulating diaphragm 5 for the coaxial cylindrical deflagration drive device includes a first diaphragm 51, which is connected to a second diaphragm 52 along a circumferential direction. The second diaphragm 52 faces the deflagration driving section 1, and the first diaphragm 51 faces the driven section 2. The second diaphragm 52 includes at least three sub-diaphragms. Along the center direction of the first diaphragm 51, at least three sub-diaphragms overlap around the center of the first diaphragm 51. In other words, at least three sub-diaphragms overlap near the center of the first diaphragm 51. The sub-diaphragms in the second diaphragm 52 can be directly bonded to the first diaphragm 51, and glue can be used for easy operation.

[0041] The diameter of the first diaphragm 51 is greater than the diameter of the second diaphragm 52. The diameter of the first diaphragm 51 can be determined according to the actual diameter of the shock tube / shock wind tunnel. If the diameter of the first diaphragm 51 is lower than the inner diameter of the actual shock tube / shock wind tunnel, there will be problems with the sealing of the device. If the diameter of the first diaphragm 51 is higher than the outer diameter of the actual shock tube / shock wind tunnel, the first diaphragm 51 cannot be installed in the actual shock tube / shock wind tunnel. Therefore, the diameter of the first diaphragm 51 is designed to be the same as the diameter of the actual shock tube / shock wind tunnel, so that the first diaphragm 51 can be installed in the actual shock tube / shock wind tunnel to ensure the sealing of the device. The second diaphragm 52 covers the area of ​​the first diaphragm 51 exposed to the high-pressure gas. The diameter of the second diaphragm 52 is determined by the diameter of the first diaphragm 51.

[0042] The first diaphragm 51 can be made of metal, such as aluminum, copper, steel, alloy, etc., and the second diaphragm 52 can be made of non-metallic material, such as polytetrafluoroethylene; polytetrafluoroethylene is commonly known as Teflon, and has excellent chemical stability, corrosion resistance, sealing, high lubricity and non-stickiness, electrical insulation and good anti-aging resistance; the second diaphragm is made of polytetrafluoroethylene to ensure the insulation between the first diaphragm 51 and the first electrode 11.

[0043] During use, the second diaphragm 52 is directly connected to the first diaphragm 51, with each sub-diaphragm in the second diaphragm 52 facing the deflagration drive section. During the experiment, the second diaphragm is close to the high-voltage electrode. Since at least three sub-diaphragms overlap around the center of the first diaphragm 51 along the center direction of the first diaphragm 51, the insulation thickness is relatively large, ensuring the insulation between the high-voltage electrode and the first diaphragm 51. When the first diaphragm 51 is broken, the second diaphragm 52 is also separated, avoiding the random tearing of the second diaphragm 52, reducing the probability of the second diaphragm 52 falling off, and avoiding excessive interference with the flow field, thereby improving the flow field quality.

[0044] It can be seen from the above embodiments that the high-voltage resistant insulating diaphragm of the coaxial cylindrical deflagration drive device provided in this embodiment achieves at least the following beneficial effects:

[0045] In this embodiment, a second diaphragm is provided on the first diaphragm, and the second diaphragm faces the deflagration drive section. At least three sub-diaphragms overlap around the center of the first diaphragm. It is made of polytetrafluoroethylene, which not only maximizes the insulation thickness and avoids insulation defects caused by direct splicing, but also avoids the randomness of the second diaphragm tearing, reduces the probability of the second diaphragm falling off, and avoids excessive interference with the flow field, which helps to improve the flow field quality.

[0046] Optionally, continue with reference to Figure 3 As shown, the second diaphragm 52 includes a first sub-diaphragm 521, a second sub-diaphragm 522, a third sub-diaphragm 523 and a fourth sub-diaphragm 524 that are evenly arranged along the center of the first diaphragm 51. The first sub-diaphragm 521, the second sub-diaphragm 522, the third sub-diaphragm 523 and the fourth sub-diaphragm 524 are superimposed on each other in a clockwise or counterclockwise direction to form a first superimposed area 625 and a second superimposed area 626. The first superimposed area 625 is close to the center of the first diaphragm 51, and the second superimposed area 626 is far away from the center of the first diaphragm 51. The thickness of the first superimposed area 625 along the first direction E is greater than the thickness of the second superimposed area 626 along the first direction E. The first direction E is the direction from the first diaphragm 51 to the second diaphragm 52. The first superimposed area 625 is close to the center of the first diaphragm 51, and the second superimposed area 626 is far away from the center of the first diaphragm 51. The shape of area 625 can be rectangular; specifically, since the electric field strength is highest in the area closest to the high-voltage electrode in the deflagration driving technology, the first sub-diaphragm 521, the second sub-diaphragm 522, the third sub-diaphragm 523 and the fourth sub-diaphragm 524 are stacked together to maximize the insulation thickness, that is, the thickness of the first stacking area 625 is the largest, and the thickness of the second stacking area 626 is second; between the first sub-diaphragm 521 and the second sub-diaphragm 522, between the second sub-diaphragm 522 and the third sub-diaphragm 523, and between the third sub-diaphragm 523 and the fourth sub-diaphragm 524, and between the fourth sub-diaphragm 524 and the first sub-diaphragm 521, they are stacked together to avoid insulation defects caused by direct splicing, more effectively avoid the risk of breakdown, and ensure the safety of equipment and personnel.

[0047] It should be noted that the number of sub-diaphragms in the second diaphragm 52 can also be adjusted according to actual conditions, such as 3 sub-diaphragms, 6 sub-diaphragms, 8 sub-diaphragms, etc., as long as multiple sub-diaphragms are stacked on each other along the center direction of the first diaphragm to ensure the insulation between the high-voltage electrode and the first diaphragm 51.

[0048] Optionally, continue with reference to Figure 4As shown, the central angles of the first sub-diaphragm 521, the second sub-diaphragm 522, the third sub-diaphragm 523 and the fourth sub-diaphragm 524 are all 90°, and their shapes are all fan-shaped. That is, the shapes of the first sub-diaphragm 521, the second sub-diaphragm 522, the third sub-diaphragm 523 and the fourth sub-diaphragm 524 are exactly the same and are evenly distributed along the circumference in the form of petals; of course, other shapes, such as rectangles, can also be used according to actual conditions.

[0049] Optionally, continue with reference to Figure 3 As shown, the spacing d1 of the first overlapping areas 625 along the second direction F is 10-30 mm, and the spacing d2 of some second overlapping areas 626 along the second direction F is 10-30 mm. The second direction F intersects with the first direction E.

[0050] Specifically, if the spacing d1 of the first overlapping area 625 along the second direction F and the spacing d2 of part of the second overlapping area 626 along the second direction F are less than 10 mm, the second diaphragm 52 has poor anti-breakdown ability. If the spacing d1 of the first overlapping area 625 along the second direction F and the spacing d2 of part of the second overlapping area 626 along the second direction F are greater than 30 mm, it is easy to fall off during the membrane breaking process. Therefore, the spacing d1 of the first overlapping area 625 along the second direction F and the spacing d2 of part of the second overlapping area 626 along the second direction F are 10-30 mm, which can ensure the mutual overlapping effect between the first sub-diaphragm 521, the second sub-diaphragm 522, the third sub-diaphragm 523 and the fourth sub-diaphragm 524, thereby more effectively improving the anti-breakdown ability of the second diaphragm 52.

[0051] Optionally, the thickness of the first overlapping region 625 along the first direction E is 4-20 mm, and the thickness of the second overlapping region 626 along the first direction E is 2-10 mm.

[0052] Specifically, if the thickness of the first overlapping area 625 along the first direction E is less than 4 mm, the anti-breakdown capability is insufficient. If the thickness of the first overlapping area 625 along the first direction E is greater than 20 mm, the flexibility of the second diaphragm is reduced. Therefore, the thickness of the first overlapping area 625 along the first direction E is designed to be 4-20 mm, which can not only ensure the flexibility of the second diaphragm 52, but also improve the anti-breakdown capability.

[0053] If the thickness of the second stacking area 626 along the first direction E is less than 2 mm, the anti-breakdown capability is insufficient. If the thickness of the second stacking area 626 along the first direction E is greater than 10 mm, the flexibility of the second diaphragm is reduced. Therefore, the thickness of the second stacking area 626 along the first direction E is designed to be 2-10 mm, which can ensure both the flexibility of the second diaphragm 52 and the anti-breakdown capability.

[0054] It should be noted that: in order to ensure the anti-breakdown capability, the thickness of the first sub-diaphragm 521, the second sub-diaphragm 522, the third sub-diaphragm 523 and the fourth sub-diaphragm 524 along the first direction E can be designed to be 1-5 mm; if the thickness of the first sub-diaphragm 521, the second sub-diaphragm 522, the third sub-diaphragm 523 and the fourth sub-diaphragm 524 along the first direction E is greater than 5 mm, the flexibility will decrease, and if the thickness of the first sub-diaphragm 521, the second sub-diaphragm 522, the third sub-diaphragm 523 and the fourth sub-diaphragm 524 along the first direction E is less than 1 mm, the anti-breakdown capability will be insufficient; therefore, the thickness of the first sub-diaphragm 521, the second sub-diaphragm 522, the third sub-diaphragm 523 and the fourth sub-diaphragm 524 along the first direction E is 1-5 mm, which can ensure the flexibility and anti-breakdown capability of the second diaphragm 52.

[0055] It can be seen from the above embodiments that the high-voltage resistant insulating diaphragm for the coaxial cylindrical deflagration drive device provided by the present invention achieves at least the following beneficial effects:

[0056] The present invention arranges a second diaphragm on the first diaphragm, the second diaphragm faces the deflagration drive section, and at least three sub-diaphragms overlap around the center of the first diaphragm. The second diaphragm is made of polytetrafluoroethylene, which not only maximizes the insulation thickness and avoids insulation defects caused by direct splicing, but also avoids the randomness of the second diaphragm tearing, reduces the probability of the second diaphragm falling off, and also avoids excessive interference with the flow field, which helps to improve the flow field quality.

[0057] Figure 5 Schematic diagram of the structure of a coaxial cylindrical deflagration drive device for a shock tube / wind tunnel provided by an embodiment of the present invention; Figure 6 yes Figure 5 A magnified view of the structure at point B in the middle; Figure 7 yes Figure 5 A magnified diagram of the structure of the discharge system; Figure 8 This is a logic block diagram of a discharge system provided by an embodiment of the present invention.

[0058] like Figure 5-Figure 8 As shown, this embodiment provides a coaxial cylindrical deflagration drive device for a shock tube / wind tunnel, comprising a deflagration drive section 1, a driven section 2, a high-voltage insulating diaphragm 5 separating the deflagration drive section 1 and the driven section 2, a blind plate 14, and a discharge system 7. One end of the deflagration drive section 1 is connected to the driven section 2, and the other end is connected to the blind plate 14.

[0059] Deflagration driving section 1, driven section 2, high-voltage insulating diaphragm 5 separating the deflagration driving section 1 and the driven section 2, blind plate 14, and discharge system 7, wherein one end of the deflagration driving section 1 is connected to the driven section 2, and the other end is connected to the blind plate 14;

[0060] The deflagration driving section 1 is a straight tube of uniform cross-section. A first electrode 11 and a second electrode 12 extending along a radial direction Y are connected to the deflagration driving section 1. The first electrode 11 is located on the side of the deflagration driving section close to the blind plate 14, and the second electrode 12 is located on the side of the deflagration driving section 1 close to the driven section 2. An ignition wire 13 extending along an axial direction X is electrically connected between the first electrode 11 and the second electrode 12. The axial direction X is the direction of the axial centerline from the deflagration driving section 1 to the driven section 2, and the radial direction Y intersects the axial direction X.

[0061] Along the axial direction X, the length between the first electrode 11 and the blind plate 14 is L1, and the length between the second electrode 12 and the first high-voltage insulating film 51 is L2. The lengths of L1 and L2 are limited to 0.5 cm-20 cm.

[0062] The deflagration driving section 1 is provided with an opening 8 that matches the first electrode 11 and the second electrode 12. A sealing ring 81 is provided on the contact surface between the first electrode 11 and the second electrode 12 and the opening 8.

[0063] The deflagration driving section 1 is filled with combustible mixed gas;

[0064] The discharge system 7 includes a high-voltage capacitor 71, an ignition switch 720 and a unloading switch 730. The ignition circuit 72 is composed of the positive electrode of the high-voltage capacitor 71, the ignition switch 720, the first electrode 11, the ignition wire 13, the second electrode 12 and the negative electrode of the high-voltage capacitor 71; the unloading circuit 73 is composed of the positive electrode of the high-voltage capacitor 71, the unloading switch 730 and the negative electrode of the high-voltage capacitor 71; the ignition circuit 72 and the unloading circuit 73 are connected in parallel, and the high-voltage capacitor 71 is used to store high voltage electricity and discharge it to the ignition wire 13.

[0065] Specifically, the coaxial cylindrical deflagration drive device for a shock tube / wind tunnel includes a deflagration drive section 1 and a driven section 2. One end of the deflagration drive section 1 is connected to the driven section 2, and the other end is connected to a blind plate 14. The deflagration drive section 1 and the driven section 2 are separated by a high-voltage insulating diaphragm 5. The high-voltage insulating diaphragm 5 is the high-voltage insulating diaphragm of the coaxial cylindrical deflagration drive device provided above. The driven section 2 is connected to the test section 4 through a nozzle 3. The blind plate 14 is a flange cover. The blind plate 14 is used to block the end of the deflagration drive section 1, eliminating the need for a traditional explosion unloading section and the provision of a diaphragm between the explosion unloading section and the deflagration drive section. This not only helps to reduce the occupied space area, but also reduces costs.

[0066] A first electrode 11 and a second electrode 12 extending along a radial direction Y are plugged into the deflagration driving segment 1, the first electrode 11 being located on a side of the deflagration driving segment 1 close to the blind plate 14, and the second electrode 12 being located on a side of the deflagration driving segment 1 close to the driven segment 2, that is, the first electrode 11 and the second electrode 12 are plugged into both ends of the deflagration driving segment 1; an ignition wire 13 extending along an axial direction is electrically connected between the first electrode 11 and the second electrode 12, the axial direction X being the direction from the blind plate 14 to the axial centerline of the driven segment 2, the radial direction Y intersecting the axial direction X, optionally, the ignition wire 13 can be made of any metal material selected from copper, silver, nickel-chromium, tungsten and alloys, and the length of the ignition wire 13 can be adjusted according to the length of the deflagration driving segment 1;

[0067] The axial distance from the first electrode 11 to the blind plate 14 is L1, and the axial distance from the second electrode 12 to the first high-voltage resistant insulating diaphragm 51 is L2. If the lengths of L1 and L2 are less than 0.5 cm, breakdown may occur, resulting in damage to the equipment or endangerment to personnel safety; if the lengths of L1 and L2 are greater than 20 cm, it may cause unstable combustion of the combustible mixture in the deflagration driving section 1. Therefore, limiting the lengths of L1 and L2 to 0.5 cm-20 cm not only makes the ignition wire 13 as long as possible in the axial direction in the deflagration driving section, which can further make the combustible mixture in the deflagration driving section 1 burn more fully, but also avoids the distances between the first electrode 11 and the end of the deflagration driving section and between the second electrode 12 and the first high-voltage resistant insulating diaphragm 51 being too close, thereby avoiding breakdown and ensuring the safety of equipment and personnel.

[0068] Figure 6 yes Figure 5 A magnified view of the structure at point B in the middle; Figure 5 The enlarged view of point C is the same as that of point B. The deflagration driving section 1 is provided with an opening 8 that matches the first electrode 11 and the second electrode 12. Figure 6 In order to show the opening 8 in the figure, the aperture of the opening 8 is drawn larger than the actual size. The opening 8 cooperates with the first electrode 11, and the second electrode 12 cooperates with the opening 8. The opening 8 facilitates the insertion of the first electrode 11 and the second electrode 12 into the combustion driving segment 1. In order to ensure the sealing inside the deflagration driving segment 1, after the first electrode 11 is inserted into the deflagration driving segment 1, a sealing ring 81 is provided on the contact surface of the deflagration driving segment 1 where the first electrode 1 contacts the opening 8, and a sealing ring 81 is provided on the contact surface of the deflagration driving segment 1 where the second electrode 12 contacts the opening 8;

[0069] The deflagration driving section 1 is filled with a combustible mixed gas, which may include a fuel, an oxidant and an inert gas, wherein the fuel is hydrogen, carbon monoxide or alkanes, alkenes and alkynes, or other combustible gases; the oxidant is oxygen or nitrous oxide, or other oxidizing gases; the inert gas is nitrogen, a rare gas or carbon dioxide, or other gases that do not participate in the combustion reaction; the ratio of fuel: oxidant: inert gas may be 1:1:1, the ratio of fuel: oxidant: inert gas may be 2:1:1, and the ratio of fuel: oxidant: inert gas may be 2:1:7. Of course, the ratio of fuel, oxidant and inert gas is set according to the specific equipment and experimental requirements.

[0070] The ignition system further includes a discharge system 7, which includes a high-voltage capacitor 71, an ignition switch 720, and an unloading switch 730. The positive electrode of the high-voltage capacitor 71, the ignition switch 720, the first electrode 11, the ignition wire 13, the second electrode 12, and the negative electrode of the high-voltage capacitor 71 constitute an ignition circuit 72; the positive electrode of the high-voltage capacitor 71, the unloading switch 730, and the negative electrode of the high-voltage capacitor 71 constitute an unloading circuit 73. The ignition circuit 72 and the unloading circuit 73 are connected in parallel. The high-voltage capacitor 71 is used to store high voltage electricity.

[0071] After the high-voltage capacitor 71 is charged, the ignition switch 720 is closed first, and the high-voltage capacitor 71 is connected to the ignition wire 13 through the first electrode 11 and the second electrode 12 respectively, and ignition begins; after a predetermined time, the unloading switch 730 is closed to short-circuit the positive and negative poles of the high-voltage capacitor 71, and the charge in the high-voltage capacitor 71 is instantly returned to the high-voltage capacitor 71 through the unloading circuit 73, completing the unloading. The above-mentioned predetermined time can be 5-30 milliseconds.

[0072] The assembly sequence for the coaxial cylindrical deflagration drive device for shock tubes / wind tunnels is as follows:

[0073] Providing a deflagration drive section 1;

[0074] First, an opening 8 is formed on the deflagration driving section 1 for placing the first electrode 11 and the second electrode 12. Second, a sealing ring 81 is installed on the contact surface between the first electrode 11 and the second electrode 12 and the opening 8. The first electrode 11 and the second electrode 12 are inserted into the opening 8. The first electrode 11 is located on the side of the deflagration driving section close to the blind plate 14, and the second electrode 12 is located on the side of the deflagration driving section 1 close to the driven section 2. An ignition wire 13 extending along the axial direction X is connected between the first electrode 11 and the second electrode 12.

[0075] A high-voltage resistant insulating diaphragm 5 is installed between the deflagration driving section 1 and the driven section 2. One end of the deflagration driving section 1 close to the high-voltage resistant insulating diaphragm 5 is connected to the driven section 2, and the other end is connected to a blind plate 14.

[0076] The deflagration driving section 1 is filled with combustible mixed gas;

[0077] Connect the discharge system 7, and the positive electrode of the high-voltage capacitor 71, the ignition switch 720, the first electrode 11, the ignition wire 13, the second electrode 12, and the negative electrode of the high-voltage capacitor 71 form an ignition circuit 72; the positive electrode of the high-voltage capacitor 71, the unloading switch 730, and the negative electrode of the high-voltage capacitor 71 form an unloading circuit 73; the ignition circuit 72 and the unloading circuit 73 are connected in parallel.

[0078] Assembling the coaxial cylindrical deflagration drive device for shock tube / wind tunnel according to the above assembly sequence can not only better connect the first electrode and the second electrode, making the position of the ignition wire 13 more accurately arranged, but also avoid leakage of the combustible mixture, ensure personal safety, and facilitate operation.

[0079] Of course, without considering the discharge of the high-voltage capacitor to the ignition wire, the above assembly sequence can be adjusted appropriately. After installing the driven section 2 or the blind plate 14, the discharge system can be connected first, and then the combustible mixture can be filled into the deflagration driving section 1, as follows:

[0080] First, providing a deflagration drive section 1;

[0081] Second, first, an opening 8 for placing the first electrode 11 and the second electrode 12 is opened on the deflagration driving section 1; second, a sealing ring 81 is installed on the contact surface of the first electrode 11 and the second electrode 12 with the opening 8, and the first electrode 11 and the second electrode 12 are inserted into the opening 8, with the first electrode 11 located on the side of the deflagration driving section close to the blind plate 14, and the second electrode 12 located on the side of the deflagration driving section 1 close to the driven section 2; an ignition wire 13 extending along the axial direction X is connected between the first electrode 11 and the second electrode 12;

[0082] Third, a combined high-voltage resistant insulating diaphragm 5 is installed between the deflagration driving section 1 and the driven section 2. One end of the deflagration driving section 1 close to the combined high-voltage resistant insulating diaphragm 5 is connected to the driven section 2, and the other end is connected to a blind plate 14.

[0083] Fourth, connect the discharge system 7, and connect the positive electrode of the high-voltage capacitor 71, the ignition switch 720, the first electrode 11, the ignition wire 13, the second electrode 12, and the negative electrode of the high-voltage capacitor 71 to form an ignition circuit 72; connect the positive electrode of the high-voltage capacitor 71, the unloading switch 730, and the negative electrode of the high-voltage capacitor 71 to form an unloading circuit 73; and connect the ignition circuit 72 and the unloading circuit 73 in parallel;

[0084] Fifth, the deflagration driving section 1 is filled with combustible mixed gas.

[0085] It should be noted that: first, a deflagration driving section 1 is provided; second, first, an opening 8 for placing a first electrode 11 and a second electrode 12 is opened on the deflagration driving section 1; secondly, a sealing ring 81 is installed on the contact surface of the first electrode 11 and the second electrode 12 with the opening 8, and the first electrode 11 and the second electrode 12 are inserted into the opening 8, the first electrode 11 is located on the side of the deflagration driving section close to the blind plate 14, and the second electrode 12 is located on the side of the deflagration driving section 1 close to the driven section 2; an ignition wire 13 extending along the axial direction X is connected between the first electrode 11 and the second electrode 12; third, a combined high-voltage resistant insulating diaphragm 5 is installed between the deflagration driving section 1 and the driven section 2, and the driven section 2 is connected to one end of the deflagration driving section 1 close to the combined high-voltage resistant insulating diaphragm 5, and the other end is connected to the blind plate 14; the assembly sequence of the above three steps is irreversible, that is, the above assembly sequence cannot be reversed, and it cannot be implemented after reversal.

[0086] The working principle is as follows: There is an ignition wire 13 arranged along the axial direction X in the deflagration driving section 1. After the high-voltage capacitor 71 is charged, the ignition switch 720 is closed first. The high-voltage capacitor 71 is connected to the ignition wire 13 through the first electrode 11 and the second electrode 12 respectively. A high voltage of thousands to tens of thousands of volts is applied to both ends of the ignition wire 13. When the ignition switch 720 is energized, the ignition wire 13 heats up violently, igniting the combustible mixture near the ignition wire 13 within microseconds. After ignition, a columnar flame is formed and expands radially. The ignition wire 13 is strictly coaxial with the pipeline of the deflagration drive section 1 to ensure that they are burned out simultaneously at all locations along the axial direction; since the discharge process of the high-voltage capacitor 71 is longer than the combustion process, the remaining charge in the high-voltage capacitor 71 needs to be unloaded before the end of combustion. Therefore, after a predetermined time, the unloading switch 730 is closed to short-circuit the positive and negative poles of the high-voltage capacitor 71. The charge in the high-voltage capacitor 71 is instantly returned to the high-voltage capacitor 71 through the unloading circuit, completing the unloading, thereby preventing the combustion products from breaking down near the positive pole of the high-voltage capacitor 71 and causing a safety accident.

[0087] It should be noted that detonation drive requires the formation of a detonation wave that propagates axially in the drive section pipeline, while deflagration drive causes the gas in the pipeline of the deflagration drive section 1 to ignite simultaneously along the axial direction, completing combustion in a deflagration rather than detonation manner, and ending combustion simultaneously along the axial direction X.

[0088] Typically, the effective operating time of a shock tube / wind tunnel is on the order of a few milliseconds to 100 milliseconds. In order to provide precise test conditions, it is necessary to strictly ensure that the combustible mixture in the deflagration drive section is ignited and burned out at the same time.

[0089] It can be seen from the above embodiments that the coaxial cylindrical deflagration drive device for shock tubes / wind tunnels provided by the present invention achieves at least the following beneficial effects:

[0090] First, in the prior art, detonation drives a detonation wave that propagates axially within the driving section pipe. However, since the extremely high pressure peak of the detonation wave cannot be fully utilized for driving, the effective pressure provided by the detonation drive is significantly lower than the pressure limit of the equipment. In contrast, the present invention replaces detonation with deflagration, eliminating the pressure peak associated with detonation. 100% of the combustion pressure can be used to compress the test gas, thereby increasing the pressure of the test gas.

[0091] Second, the mixture ratio limit of deflagration is much wider than that of detonation, and the temperature and sound velocity range of the driving gas is larger. Therefore, the corresponding total temperature range of the test gas is also larger than that of detonation driving.

[0092] Third, the high-voltage insulating diaphragm not only maximizes insulation thickness, avoiding insulation defects caused by direct splicing, but also prevents the random tearing of the second diaphragm, reducing the probability of the second diaphragm falling off. It also avoids excessive interference with the flow field, helping to improve flow field quality.

[0093] Figure 9 is a schematic structural diagram of a shock tube / wind tunnel provided by an embodiment of the present invention; another embodiment of the present invention provides a shock tube / wind tunnel, including a coaxial cylindrical deflagration drive device for a shock tube / wind tunnel provided by an embodiment of the present invention;

[0094] Although some specific embodiments of the present invention have been described in detail by way of examples, it should be understood by those skilled in the art that the above examples are for illustration only and are not intended to limit the scope of the present invention. It should be understood by those skilled in the art that modifications may be made to the above embodiments without departing from the scope and spirit of the present invention. The scope of the present invention is defined by the appended claims.

Claims

1. A high voltage resistant insulating diaphragm for a coaxial cylindrical deflagration drive device, characterized in that: It includes a first diaphragm, wherein the first diaphragm is provided with a second diaphragm along the circumferential direction, the second diaphragm faces the deflagration driving section, and the first diaphragm faces the driven section; The second diaphragm includes at least three sub-diaphragms, and along the center direction of the first diaphragm, the at least three sub-diaphragms overlap around the center of the first diaphragm; The diameter of the first diaphragm is greater than the diameter of the second diaphragm; The first diaphragm is made of metal, and the second diaphragm is made of polytetrafluoroethylene.

2. The high-voltage resistant insulating diaphragm for a coaxial cylindrical deflagration drive device according to claim 1, characterized in that: The second diaphragm includes a first sub-diaphragm, a second sub-diaphragm, a third sub-diaphragm and a fourth sub-diaphragm uniformly arranged along the center of the first diaphragm. The first sub-diaphragm, the second sub-diaphragm, the third sub-diaphragm and the fourth sub-diaphragm are overlapped with each other in a clockwise or counterclockwise direction to form a first overlapping area and a second overlapping area. The first overlapping area is close to the center of the first diaphragm, and the second overlapping area is far away from the center of the first diaphragm. The thickness of the first overlapping area along the first direction is greater than the thickness of the second overlapping area along the first direction. The first direction is the direction from the first diaphragm to the second diaphragm.

3. The high voltage resistant insulating diaphragm for the coaxial cylindrical deflagration driving device according to claim 2, characterized in that: The spacing between the first overlapping areas along the second direction is 10-30 mm, and the spacing between some of the second overlapping areas along the second direction is 10-30 mm, and the second direction intersects with the first direction.

4. The high-voltage resistant insulating diaphragm for a coaxial cylindrical deflagration drive device according to claim 2, characterized in that: Central angles of the first sub-membrane, the second sub-membrane, the third sub-membrane, and the fourth sub-membrane are 90° respectively.

5. The high voltage resistant insulating diaphragm for the coaxial cylindrical deflagration driving device according to claim 2, characterized in that: The first sub-membrane, the second sub-membrane, the third sub-membrane and the fourth sub-membrane are each in a sector shape.

6. The high-voltage resistant insulating diaphragm for a coaxial cylindrical deflagration drive device according to claim 2, characterized in that: The thickness of the first overlapping area along the first direction is 4-20 mm, and the thickness of the second overlapping area along the first direction is 2-10 mm.

7. The high-voltage resistant insulating diaphragm for a coaxial cylindrical deflagration drive device according to any one of claims 2 to 6, characterized in that: The first overlapping area is in a rectangular shape.

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