Direct-current combustion wind tunnel

Abstract

The invention discloses a direct-current combustion wind tunnel. A wind tunnel main body sequentially comprises a power section, a round-to-square transition section, a stable section, a contraction section, a test section and a diffusion section, a linkage sewage discharge system is arranged in the bottom of the stable section, first leakage holes formed in a top cover in an array mode are matched with second leakage holes formed in a sealing plate, the first leakage holes and the second leakage holes are staggered at the initial position, and a fixed frame, a movable frame and a telescopic rod are matched, so that the stable section hidden type linkage sewage discharge system is formed; complete sealing in a non-working state and one-key triggering of a cleaning working condition are achieved, and the problem that in the prior art, after a combustion wind tunnel experiment is conducted, the quality of a flow field is affected by cleaning of a smoke dust discharge port in a stable section is effectively solved.

Description

Technical Field

[0001] The present invention relates to the technical field of combustion testing, in particular to a direct current combustion wind tunnel. Background Art

[0002] Large low-speed wind tunnels are core infrastructure for studying aerodynamics and combustion science. Although current mainstream international facilities (such as the 12.2-meter × 24.4-meter low-speed wind tunnel at NASA's Ames Research Center) have the potential to conduct combustion experiments, their designs have significant limitations.

[0003] The inherent contradiction between the stabilization section blowdown system and flow field quality is particularly prominent. Traditional wind tunnels typically have fixed blowdown outlets at the bottom of the stabilization section to clean soot and pollutants accumulated in rectifier components such as honeycombs and damping meshes. These outlets are not concealed and protrude from the top. Airflow can be discharged through these outlets, affecting the flow field, increasing pressure drop, disrupting airflow uniformity, and changing the guiding effect of the wind tunnel walls, leading to increased turbulence and resulting in deviations in experimental data.

[0004] Therefore, the existing needs are not met, and we propose a direct current combustion wind tunnel. Summary of the Invention

[0005] To this end, the present invention provides a direct current combustion wind tunnel to solve the problem in the prior art that the smoke discharge outlet during stable section cleaning affects the flow field quality.

[0006] In order to achieve the above object, the present invention provides the following technical solutions: According to a first aspect of the present invention, a direct current combustion wind tunnel comprises a wind tunnel body, wherein the wind tunnel body comprises, in sequence, a power section, a circular-to-square transition section, a stabilization section, a contraction section, a test section, and a diffusion section; The bottom of the stabilizing section is provided with a linkage sewage discharge system, which is composed of a bottom plate, a top cover and a rectangular side frame; the linkage sewage discharge system includes: The array has a first leakage hole formed on the top cover; A sealing plate is provided with a second leakage hole corresponding to the first leakage hole, and the sealing plate is slidably connected to the limited space at the bottom of the top cover; in the initial position, the first leakage hole and the second leakage hole are misaligned; a fixing frame fixedly connected to the lower side of the top cover; A movable frame, wherein both sides of the bottom end of the sealing plate are connected to the movable frame, and both sides of the movable frame are slidably connected to the fixed frame; A telescopic rod driving the mobile frame, wherein the telescopic rod is installed on one side of the fixed frame, and the output end of the telescopic rod is connected to the mobile frame; A sewage outlet is provided on the bottom plate.

[0007] Furthermore, the input end of the power section is provided with an outward-turned air inlet lip, the inner middle section of the power section is provided with a guide cover, and an axial flow fan is installed in the middle of the guide cover.

[0008] Furthermore, the top end of the bottom plate at the bottom of the stabilizing section is a conical surface, and the sewage outlet is opened at the lowest point of the conical surface.

[0009] Furthermore, L-shaped plates are fixedly connected to both sides of the bottom of the top cover, and the L-shaped plates and the top cover form a limiting space.

[0010] Furthermore, a funnel-shaped conical sewage discharge frame is provided below the sewage outlet, the output end of the conical sewage discharge frame is connected to a sewage discharge pipe, the inner wall of the sewage outlet is slidably connected to a sewage outlet cover, and a sealing ring is provided on the edge of the sewage outlet cover.

[0011] Furthermore, a first spring is installed between the middle part of the bottom end of the sewage outlet cover plate and the conical sewage outlet frame, and a guide frame is slidably connected at the four corners of the sewage outlet cover plate, and the bottom end of the guide frame is connected to the bottom end of the inner wall of the sewage outlet; a pulley group is fixedly installed on one side of the top end of the guide frame, and a pull rope is fixedly installed on the middle part of the top end of the sewage outlet cover plate, and the pull rope passes through the pulley group and the two driven wheels and is fixedly connected to the movable frame.

[0012] Furthermore, the linkage sewage discharge system also includes: an elastic sealing assembly, which includes: a series frame, an array-distributed sealing block is installed on the top of the series frame, and the sealing block is slidably connected to the inner wall of the second leakage hole; both sides of the series frame are fixedly connected with a fixed plate, the inner side of the fixed plate is slidably connected to the outer wall of the connecting rod at the top of the movable frame, and the outer wall of the connecting rod is sleeved with a second spring, and the second spring is located between the fixed plate and the top cover; both sides of the bottom of the series frame are fixedly connected with a first offset block, and the top of the bottom plate is fixedly installed with a second offset block, and in the initial state, the oblique side of the first offset block contacts and presses against the roller on the oblique side of the second offset block, so that the second spring remains compressed and the sealing block is tightly inserted into the second leakage hole to achieve sealing.

[0013] Furthermore, the outer side of the blocking block is an arc-shaped cover, and the bottom of the inner wall of the second leakage hole is provided with a matching arc-shaped groove, and the two cooperate to form a guiding sealing structure.

[0014] Furthermore, a honeycomb, a damping net and a static flow section are provided in the stabilizing section, the honeycomb is located upstream of the damping net, and the static flow section is located downstream of the damping net.

[0015] Furthermore, four layers of heat-insulating and fire-proof protective layers are respectively provided at the top and bottom of the test section, including from the outside to the inside: a supporting wall, a heat-insulating layer, a fire-proof layer, and a surface layer.

[0016] The present invention has the following advantages: The present invention discloses a direct current combustion wind tunnel, the wind tunnel main body of which comprises a power section, a circular to square transition section, a stable section, a contraction section, a test section and a diffusion section in sequence; a linkage sewage discharge system is arranged in the bottom of the stable section, and a first leakage hole arranged in an array on the top cover and a second leakage hole arranged on the sealing plate are matched with each other. In the initial position, the first leakage hole and the second leakage hole are misaligned, and a fixed frame, a movable frame and a telescopic rod are matched with each other to form a hidden linkage sewage discharge system for the stable section, which realizes complete sealing in a non-working state and one-button triggering of a cleaning condition, effectively solving the problem in the prior art that the smoke and dust discharge outlet of the stable section cleaning affects the flow field quality after the combustion wind tunnel experiment. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a front view of a DC combustion wind tunnel proposed by the present invention; Figure 2 for Figure 1 An internal cross-sectional view of Figure 3 This is a front view of the bottom of the stabilization section of a DC combustion wind tunnel proposed by the present invention; Figure 4 for Figure 3 An exploded schematic front view of the Figure 5 for Figure 3 Interior view of Figure 6 for Figure 4 Schematic diagram of the decomposition; Figure 7 for Figure 6 Bottom view of Figure 8 for Figure 4 A magnified cross-sectional view of the middle sewage outlet area; Figure 9 It is a cross-sectional view of the conical sewage frame; Figure 10 This is a cross-sectional view of the thermal insulation and fire protection layer in the test section; Figure 11 This is a schematic diagram of the decomposition of the air guide cover and axial flow fan structure.

[0018] In the figure: 1. Power section; 11. Air inlet lip; 12. Air guide cover; 13. Axial flow fan; 2. Round to square transition section; 3. Stable section; 31. Honeycomb; 32. Damping net; 33. Quiet flow section; 34. Bottom of stable section; 301. Drain port; 302. Drain port cover; 303. Conical drain frame; 304. Drain pipe; 305. Steel pipe; 306. First spring; 307. Guide frame; 308. Pull rope; 309. Pulley block; 4. Retraction section; 5. Test section; 51. Fire observation window; 52. Lifting cover; 501. Support Support wall; 502, thermal insulation layer; 503, fireproof layer; 504, surface layer; 505, self-tapping screws; 6, diffusion section; 701, top cover; 702, bottom plate; 703, side frame; 72, first leakage hole; 73, sealing plate; 74, second leakage hole; 75, L-shaped plate; 76, movable frame; 77, fixed frame; 78, telescopic rod; 81, blocking block; 811, arc-shaped cover; 812, arc-shaped groove; 82, serial frame; 83, fixed plate; 84, second spring; 85, first offset block; 86, second offset block; 87, roller; 9, conical surface. DETAILED DESCRIPTION

[0019] The following describes the implementation of the present invention using specific embodiments. Those skilled in the art will readily understand the other advantages and benefits of the present invention from the disclosure herein. Obviously, the embodiments described are only a portion of the present invention, not all of it. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are intended to fall within the scope of protection of the present invention. Example

[0020] Reference Figure 1-2 The embodiment of the present invention involves a DC combustion wind tunnel, which is a large low-speed DC combustion wind tunnel, including a wind tunnel main body; the wind tunnel main body is composed of a power section 1, a circular to square transition section 2, a stable section 3, a contraction section 4, a test section 5 and a diffusion section 6 from left to right.

[0021] refer to Figure 11 The input end of the power section 1 is set as an outward-turned air inlet lip 11, and a deflector 12 is provided at the middle end of the inner part of the power section 1. The two ends of the deflector 12 are fixedly connected to the inner wall of the power section 1 by connecting rods, and an axial flow fan 13 is installed in the middle of the deflector 12; the power section 1 generates a flowing airflow by one or more specially made axial flow fans 13, which blows into the wind tunnel main body; the wind speed in the wind tunnel main body is controlled by frequency conversion to simulate a multi-level wind speed environment.

[0022] The circular-to-square transition section 2 is a transition section downstream of the power section 1 and is designed using a diffusion method. Its input end is connected to the output end of the power section 1 , and its output end is connected to the input end of the stable section 3 .

[0023] A rectifying device consisting of a honeycomb 31 and a damping net 32 ​​is provided in the stabilizing section 3 ; its function is to provide the contracting section 4 with a uniform inlet airflow with fully attenuated turbulent pulsations.

[0024] The honeycomb 31 within the stabilization section 3 is typically composed of stacked, elongated square, circular, or hexagonal tubes. Its primary function is to straighten and divide large vortices in the airflow, thereby accelerating vortex decay. Furthermore, the friction created by the honeycomb 31 tubes on the airflow also helps improve the velocity distribution of the airflow and, to a certain extent, reduce the turbulence of the airflow.

[0025] The damping mesh 32 is usually installed downstream of the honeycomb 31. Its main function is to improve the uniformity of the flow velocity distribution and reduce the turbulence of the airflow. In order to fully play its role, first, the opening ratio β of the damping mesh 32 should be greater than 57%; second, when multiple layers of damping mesh 32 are used, the distance between the damping meshes 32 should be greater than 30 times the mesh width W, or greater than 500 times the mesh diameter d, so that the turbulence generated by the upstream layer of mesh can be fully attenuated before entering the downstream layer of mesh.

[0026] A static flow section 33 is provided downstream of the damping net 32 ​​in the stabilizing section 3. It is necessary to design the static flow section 33 after the damping net 32 ​​in order to make the airflow sufficiently uniform and stable and to further fully attenuate the turbulence of the airflow.

[0027] The input end of the contraction section 4 is connected to the output end of the stable section 3, and the output end of the contraction section 4 is connected to the input end of the test section 5; the opening cross-sectional area of ​​the contraction section 4 decreases successively from the input end to the output end; its function is to uniformly accelerate the airflow so that it reaches the flow rate required by the test section 5.

[0028] The input end of the test section 5 is connected to the output end of the contraction section 4, and the output end of the test section 5 is connected to the input end of the diffusion section 6. The boundary layer thickness of the wall gradually increases along the airflow direction of the closed test section 5. This causes the potential flow cross-section of the closed test section 5 along the airflow direction to gradually decrease, thereby generating a negative static pressure gradient in the axial direction of the closed test section 5, so that the test model is subjected to an additional resistance that does not exist during atmospheric flight. A fireproof observation window 51 is provided on the side wall of the test section 5; and a cover plate 52 that can be hung and sealed is provided on the top.

[0029] The input end of the diffuser section 6 is connected to the output end of the test section 5, and the opening area from the input end to the output end of the diffuser section 6 gradually increases; its main function is to gradually restore the kinetic energy of the airflow to pressure energy, thereby reducing the energy loss of the airflow in each section downstream of the diffuser section 6; the design point of the diffuser section 6 is to avoid flow separation and minimize the diffusion loss. Its design parameters mainly include the equivalent diffusion angle and area ratio; experiments show that the diffusion angle should be less than 7°, and when the diffusion angle is less than 7°, if the area ratio is too large or the inlet velocity profile is unevenly distributed, there is also a risk of separation.

[0030] During use: the combustion experiment is placed in the test section 5; the internal situation is observed through the fireproof observation window 51; the air flow enters from the external environment through the outward-folding trumpet-shaped air inlet lip 11, and by starting the axial flow fan 13, the air flow is pressed into the circular-to-square transition section 2. In this process, kinetic energy is gradually converted into pressure energy, reducing energy loss; the air flow then enters the core straightening cabin-stabilization section 3; the large-scale vortex is divided and the flow direction deviation angle is corrected in turn through the honeycomb 31 in the stabilization section 3; the double-layer stainless steel damping mesh 32 further homogenizes the velocity distribution and attenuates the turbulence to the experimental requirements; the static flow section 33 makes the air flow fully stable, and finally forms a low-disturbance, high-uniformity flow field.

[0031] The rectified airflow is accelerated through the contraction section 4: the inlet curvature is steep and contracts quickly, while the outlet curvature is gentle and contracts slowly, avoiding boundary layer separation while outputting parallel uniform flow, directly reaching the core test section 5; the 0.25° micro-expansion angle of the side wall of the test section 5 actively offsets the static pressure gradient caused by the thickening of the boundary layer, restoring the real wind field environment; the staff controls the combustion experiment through the fire observation window 51, capturing key data such as fire spread and plume characteristics under wind speed conditions; the airflow carrying combustion products finally enters the diffusion section 6, the diffusion angle of the diffusion section 6 is less than 7°, and the kinetic energy is again converted into pressure energy for slow release and discharge; the frequency conversion control system accurately adjusts the speed of the axial flow fan 13 throughout the process to achieve stepless simulation of wind speed. Example

[0032] Basically the same as the first embodiment, since the heat during the ignition experiment is mainly concentrated inside the test section 5 hole, a heat insulation and fire protection layer is added to the top and bottom of the test section 5 hole respectively; furthermore, referring to Figure 10The thermal insulation and fireproofing layer consists of four layers. From the outside in, the first layer is the support wall 501, constructed from steel plates from large steel mills that are superior to Q235B and contain Q235B. The plates are 8mm thick, with longitudinal ribs spaced 600-800mm apart, 150mm high, and 10mm thick, ensuring the strength of the wind tunnel. The second layer is the thermal insulation layer 502, constructed from 20mm high-aluminum aluminum silicate fiberboard, resistant to temperatures exceeding 1250°C. The third layer is the fireproofing layer 503, made from calcium silicate board. Calcium silicate board offers excellent high-temperature resistance, reaching temperatures exceeding 1050°C. It resists softening, deformation, or melting even in short-term exposure to temperatures exceeding 1500°C, thus providing stable protection for the wind tunnel's internal structures. The fourth layer is the surface layer 504, constructed from 3mm thick stainless steel to ensure a smooth finish. Self-tapping screws 505 are used to penetrate the upper three-layer structure and connect it to the supporting wall 501 of the first layer. The gaps are filled with refractory mud and polished smooth with sandpaper.

[0033] Working principle: Four-layer composite fire-resistant structure with heat insulation and fire protection layer; through the support wall 501 made of Q235B steel + heat insulation layer 502 made of high-aluminum aluminum silicate fiberboard + fire protection layer 503 made of calcium silicate board + surface layer 504 made of stainless steel plate, it can resist the erosion of flames greater than or equal to 1000℃. The high-gloss inner wall maintains the flow field quality, prevents the conduction of flames and high temperatures, and delays the spread of fire; forming a fire protection layer.

[0034] The advantages are as follows: ① Significant thermal insulation effect: The structure has a low thermal conductivity coefficient, which can reduce the conduction and loss of heat and has a good thermal insulation effect; this not only helps to maintain the high temperature environment inside the wind tunnel test section 5, but also helps the wind tunnel achieve energy saving and consumption reduction, and reduce costs; ② High strength and good toughness: The construction effect ensures that the test section 5 has high strength and toughness, which ensures that the test section 5 is not easy to deform in a high temperature environment, thereby ensuring the stability and usability of the wind tunnel test section 5; ③ Maintaining structural stability: This structure, with its high temperature resistance, helps to maintain the structural stability of the test section 5, reduce the risk of damage caused by high temperature, and extend the overall service life of the test section 5 structure; ④ Various structural materials have the following advantages: They are all green and environmentally friendly materials and do not contain toxic substances; the surface 504 stainless steel plate has a flat surface and high finish, which can reduce the flow resistance of the flow field and ensure the quality of the flow field airflow; the material performance is stable, anti-aging, shock-resistant, durable, mildew-proof and antibacterial; the structural material is a non-combustible A1 grade homogeneous material with a smoke toxicity index of zero.

[0035] The DC combustion wind tunnel disclosed in the embodiments of this invention utilizes an integrated design of a four-layer composite refractory structure (support wall + thermal insulation layer + fireproof layer + high-gloss surface layer) within the test section. This design allows for flame erosion resistance exceeding 1000°C while maintaining flow field quality, overcoming the experimental limitations of conventional wind tunnels due to their insufficient fire resistance. The smooth stainless steel inner surface effectively reduces flow resistance, and the 0.25° micro-expansion angle of the test section actively offsets the static pressure gradient caused by boundary layer thickening. This ensures that the wind tunnel combines the safety of high-temperature combustion experiments with the ability to reproduce realistic flow fields, significantly improving the accuracy of capturing key data such as fire spread and plume characteristics. Example

[0036] The same as the first embodiment, furthermore: refer to Figure 9 The stabilizing section 3 is composed of a stabilizing section top plate, a stabilizing section side plate and a stabilizing section bottom 34. A sewage outlet 301 is provided on the bottom surface of the stabilizing section bottom 34. A funnel-shaped conical sewage outlet frame 303 is provided below the sewage outlet 301. The output end of the conical sewage outlet frame 303 is connected to a sewage pipe 304. The inner wall of the sewage outlet 301 is slidably connected to a sewage outlet cover plate 302. The sewage outlet cover plate 302 is fixed to the inner wall of the sewage outlet 301 by flat head screws. A sealing ring is provided on the edge of the sewage outlet cover plate 302 to ensure sealing under normal working conditions.

[0037] In order to facilitate the removal of the sewage outlet cover 302, a steel pipe 305 is fixedly connected to the middle end of the bottom of the sewage outlet cover 302, and a first spring 306 is installed at the bottom end of the inner wall of the conical sewage discharge frame 303. The top end of the first spring 306 contacts the bottom end of the sewage outlet cover 302, and the first spring 306 is a thrust spring.

[0038] Working principle: When it is necessary to clean the inner wall of the wind tunnel body, the honeycomb 31 and the damping net 32, loosen the flat head bolts fixing the drain outlet cover 302, and the drain outlet cover 302 is lifted by the first spring 306, making it easy to remove the drain outlet cover 302 and leak out the drain outlet 301.

[0039] The hidden drain outlet 301 can avoid the drain outlet 301 affecting the flow field, increasing the pressure drop, destroying the airflow uniformity, changing the guiding effect of the wind tunnel inner wall, causing the turbulence to increase, and causing the experimental data deviation. Example

[0040] It is basically the same as the third embodiment, except that the flat head bolt, the first spring 306 and the drain outlet cover 302 are not installed. Figure 3-Figure 8 The stabilizing section 3 is composed of a stabilizing section top plate, a stabilizing section side plate and a stabilizing section bottom 34 . The stabilizing section bottom 34 is composed of a bottom plate 702 , a top cover 701 and a rectangular side frame 703 .

[0041] The top cover 701 is provided with first leakage holes 72 distributed in an array; the top of the bottom plate 702 is provided with an irregular conical surface 9 , and the bottom of the conical surface 9 is provided with a sewage outlet 301 .

[0042] Working principle: When it is necessary to clean the inner wall of the wind tunnel body, the honeycomb 31 and the damping net 32, the flushing sewage penetrates into the bottom 34 of the stable section through the first leakage hole 72, and is gathered to the sewage outlet 301 through the irregular conical surface 9 opened at the top of the bottom plate 702, and is discharged through the sewage outlet 301. Example

[0043] Basically the same as the fourth embodiment, the first leak hole 72 in the above solution is not blocked, resulting in air leakage, affecting the flow field. In order to solve this problem, further steps are: Figure 3-Figure 8 L-shaped plates 75 are fixedly connected to both sides of the bottom end of the top cover 701. The top cover 701 and the L-shaped plates 75 on both sides form a limited space. The inner wall of the space is slidably connected to a sealing plate 73, and a second leakage hole 74 is opened on the sealing plate 73. In the initial state, the first leakage hole 72 and the second leakage hole 74 are staggered with each other.

[0044] The bottom end of the sealing plate 73 is fixedly connected to a movable frame 76 on both sides, the bottom end of the top cover 701 is fixedly connected to a fixed frame 77, and the two sides of the movable frame 76 are slidingly connected to the fixed frame 77; a telescopic rod 78 is fixedly installed on one side of the fixed frame 77, and the output end of the telescopic rod 78 is fixedly connected to the movable frame 76.

[0045] Working principle: When it is necessary to clean the inner wall of the wind tunnel body, the honeycomb 31, and the damping net 32, the telescopic rod 78 is controlled to pull the movable frame 76 to move, and the sealing plate 73 is driven to move by the movable frame 76, so that the first leakage hole 72 corresponds to the second leakage hole 74; the flushing sewage penetrates into the bottom 34 of the stable section through the first leakage hole 72 and the second leakage hole 74, and is gathered to the sewage outlet 301 through the irregular conical surface 9 opened at the top of the bottom plate 702, and is discharged through the sewage outlet 301. Example

[0046] The same as the fifth embodiment, furthermore: refer to Figure 3-Figure 8 The inner wall of the sewage outlet 301 is slidably connected to the sewage outlet cover 302; a first spring 306 is installed between the middle of the bottom end of the sewage outlet cover 302 and the conical sewage frame 303. The first spring 306 is a tension spring. Sliding holes are opened at the four corners of the sewage outlet cover 302. The inner wall of the sliding hole is slidably connected to a guide frame 307. The bottom end of the guide frame 307 is fixedly connected to the bottom end of the inner wall of the sewage outlet 301; a pulley group 309 is fixedly installed on one side of the top of the guide frame 307, and a pull rope 308 is fixedly installed on the middle of the top of the sewage outlet cover 302. The pull rope 308 passes through the pulley group 309 as shown in FIG. Figure 8 After passing through two driven wheels, it is fixedly connected to the mobile frame 76 in the manner shown.

[0047] Working principle: when it is necessary to clean the inner wall of the wind tunnel body, the honeycomb 31, and the damping net 32; control the telescopic rod 78 to pull the movable frame 76 to move, and drive the sealing plate 73 to move through the movable frame 76, so that the first leakage hole 72 corresponds to the second leakage hole 74; at the same time, the movable frame 76 pulls the sewage outlet cover 302 along the guide frame 307 through the pull rope 308 to open the sewage outlet 301; the flushing sewage penetrates into the bottom 34 of the stable section through the first leakage hole 72 and the second leakage hole 74, and gathers to the sewage outlet 301 through the irregular conical surface 9 opened at the top of the bottom plate 702, and is discharged through the sewage outlet 301. Example

[0048] The same as the sixth embodiment, furthermore: refer to Figure 3-Figure 8 A DC combustion wind tunnel also includes a series frame 82, and an array of blocking blocks 81 are installed on the top of the series frame 82. The blocking blocks 81 are slidably connected to the inner wall of the second leakage hole 74; fixed plates 83 are fixedly connected on both sides of the series frame 82, and the inner side of the fixed plate 83 is slidably connected to the outer wall of the connecting rod at the top of the movable frame 76. The outer wall of the connecting rod is sleeved with a second spring 84, which is located between the fixed plate 83 and the top cover 701. The second spring 84 is a thrust spring, and its initial state is a compressed state; the outer side of the blocking block 81 is set as an arc-shaped cover 811, and the bottom of the inner wall of the second leakage hole 74 is opened as an arc-shaped groove 812, and the arc-shaped groove 812 corresponds to the arc-shaped cover 811, and the two cooperate to play a guiding and auxiliary sealing role.

[0049] The first offset block 85 is fixedly connected to both sides of the bottom of the series frame 82, and the second offset block 86 is fixedly installed on the top of the bottom plate 702. In the initial state, the oblique edge of the first offset block 85 contacts and presses against the roller 87 on the oblique edge of the second offset block 86, so that the second spring 84 remains compressed and the blocking block 81 is tightly inserted into the second leak hole 74 to achieve sealing. The oblique edge of the first offset block 85 corresponds to the oblique edge of the second offset block 86, and the oblique edge of the second offset block 86 is installed with an array of distributed and rotatably connected rollers 87; the outer wall of the roller 87 contacts the oblique edge of the first offset block 85; Working principle: In the initial state, the blocking block 81 is docked with the inner wall of the second leakage hole 74; the first leakage hole 72 is offset from the second leakage hole 74, the sealing plate 73 closes the first leakage hole 72, the bevel of the first offset block 85 presses against the roller of the second offset block 86, and the second spring 84 is compressed to make the blocking block 81 sealed and inserted into the second leakage hole 74; the sewage outlet cover 302 closes the sewage outlet 301 under the action of its own weight or spring force.

[0050] During use: when it is necessary to clean the inner wall of the wind tunnel body, the honeycomb 31 and the damping net 32, the telescopic rod 78 is controlled to pull the movable frame 76 to move.

[0051] The sealing plate 73 is moved by the movable frame 76 so that the first leakage hole 72 is aligned with the second leakage hole 74 .

[0052] The movement of the movable frame 76 drives the first offset block 85 to move synchronously, and the oblique edge of the first offset block 85 slides along the roller 87 on the oblique edge of the second offset block 86; at this time, under the thrust of the second spring 84, the serial frame 82, together with the fixed plate 83 and the blocking block 81, is pushed downward along the connecting rod of the movable frame 76, thereby driving the blocking block 81 to be pulled out of the second leakage hole 74.

[0053] At the same time, the movable frame 76 pulls the sewage outlet cover 302 upward along the guide frame 307 through the pull rope 308, and opens the sewage outlet 301; the flushing sewage penetrates into the bottom 34 of the stable section through the first leakage hole 72 and the second leakage hole 74, and gathers to the sewage outlet 301 through the irregular conical surface 9 opened at the top of the bottom plate 702, and is discharged through the sewage outlet 301.

[0054] In the above-mentioned embodiment of the present invention, the hidden linkage sewage discharge system in the stable section is disclosed, and the coordinated action of the elastic sealing component (sealing block / offset block / spring) and the linkage mechanism (pull rope / telescopic rod) realizes complete sealing in the non-working state and one-button triggering of the cleaning condition; in the initial state, the sealing block is tightly inserted into the second leakage hole, and the offset block presses the structure to ensure zero air leakage; after starting the cleaning, the telescopic rod is operated in a single operation to simultaneously complete the three actions of aligning the leakage hole, releasing the sealing block, and opening the sewage outlet, and the sewage is quickly collected and discharged through the conical surface; this design completely eliminates the interference of the traditional sewage outlet on the airflow, and ensures that the rectifier (honeycomb / damping net) maintains low turbulence and high uniformity inflow conditions for a long time.

[0055] The above-mentioned direct current combustion wind tunnel disclosed in the embodiment of the present invention forms a deep coupling of aerodynamics, structure and control from the stepless air adjustment of the variable frequency axial flow fan in the power section, the multi-stage rectification in the stable section (honeycomb vortex guide + damping net average speed + static flow section attenuation) to the low-loss pressure diffusion in the diffusion section; the outward-turned air inlet lip and the guide cover optimize the inflow efficiency, and the micro-expansion angle design of the dedicated combustion section avoids additional resistance; the linked sewage discharge system reduces maintenance downtime, and the four-layer insulation structure reduces heat conduction loss; ultimately, while achieving high-precision simulation of wind speed, it significantly reduces the overall operating energy consumption, providing a sustainable and efficient platform for large-scale combustion experiments.

Claims

1. A direct current combustion wind tunnel, comprising a wind tunnel body, characterized in that: The wind tunnel body includes a power section, a circular to square transition section, a stable section, a contraction section, a test section and a diffusion section in sequence; The bottom of the stabilizing section is provided with a linkage sewage discharge system, which is composed of a bottom plate, a top cover and a rectangular side frame; the linkage sewage discharge system includes: The array has a first leakage hole formed on the top cover; A sealing plate is provided with a second leakage hole corresponding to the first leakage hole, and the sealing plate is slidably connected to the limited space at the bottom of the top cover; in the initial position, the first leakage hole and the second leakage hole are misaligned; a fixing frame fixedly connected to the lower side of the top cover; A movable frame, wherein both sides of the bottom end of the sealing plate are connected to the movable frame, and both sides of the movable frame are slidably connected to the fixed frame; A telescopic rod driving the mobile frame, wherein the telescopic rod is installed on one side of the fixed frame, and the output end of the telescopic rod is connected to the mobile frame; A sewage outlet is provided on the bottom plate.

2. A direct current combustion wind tunnel according to claim 1, characterized in that: An outward-turned air inlet lip is provided at the input end of the power section, a flow guide cover is provided in the inner middle section of the power section, and an axial flow fan is installed in the middle of the flow guide cover.

3. The DC combustion wind tunnel according to claim 1, characterized in that: The top end of the bottom plate at the bottom of the stabilizing section is in the form of a conical surface, and the sewage outlet is arranged at the lowest point of the conical surface.

4. The direct current combustion wind tunnel according to claim 1, characterized in that: L-shaped plates are fixedly connected to both sides of the bottom of the top cover, and the L-shaped plates and the top cover form a limiting space.

5. A direct current combustion wind tunnel according to any one of claims 1 to 4, characterized in that: A funnel-shaped conical drainage frame is provided below the drainage port, the output end of the conical drainage frame is connected to a drainage pipe, the inner wall of the drainage port is slidably connected to a drainage port cover plate, and a sealing ring is provided on the edge of the drainage port cover plate.

6. The direct current combustion wind tunnel according to claim 5, characterized in that: A first spring is installed between the middle part of the bottom end of the sewage outlet cover plate and the conical sewage outlet frame. The sewage outlet cover plate is slidably connected with a guide frame at the four corners, and the bottom end of the guide frame is connected to the bottom end of the inner wall of the sewage outlet; a pulley group is fixedly installed on one side of the top end of the guide frame, and a pull rope is fixedly installed on the middle part of the top end of the sewage outlet cover plate. The pull rope passes through the pulley group and two driven wheels and is fixedly connected to the movable frame.

7. The direct current combustion wind tunnel according to claim 6, characterized in that: The linkage sewage discharge system also includes: an elastic sealing assembly, which includes: a series frame, an array-distributed sealing block is installed on the top of the series frame, and the sealing block is slidably connected to the inner wall of the second leakage hole; both sides of the series frame are fixedly connected with a fixed plate, the inner side of the fixed plate is slidably connected to the outer wall of the connecting rod at the top of the movable frame, and the outer wall of the connecting rod is sleeved with a second spring, and the second spring is located between the fixed plate and the top cover; both sides of the bottom of the series frame are fixedly connected with a first offset block, and the top of the bottom plate is fixedly installed with a second offset block. In the initial state, the oblique side of the first offset block contacts and presses against the roller on the oblique side of the second offset block, so that the second spring remains compressed and the sealing block is tightly inserted into the second leakage hole to achieve sealing.

8. The direct current combustion wind tunnel according to claim 7, characterized in that: The outer side of the blocking block is an arc-shaped cover, and the bottom of the inner wall of the second leakage hole is provided with a matching arc-shaped groove, and the two cooperate to form a guiding sealing structure.

9. The direct current combustion wind tunnel according to claim 1, characterized in that: A honeycomb, a damping net and a static flow section are arranged in the stabilizing section. The honeycomb is located upstream of the damping net, and the static flow section is located downstream of the damping net.

10. The direct current combustion wind tunnel according to claim 1, characterized in that: The top and bottom of the test section are respectively provided with four layers of heat-insulating and fire-proof protective layers, which include, from the outside to the inside: a supporting wall, a heat-insulating layer, a fire-proof layer, and a surface layer.

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