A forest fire combustion wind tunnel experimental platform

Abstract

The invention discloses a forest fire combustion wind tunnel experimental platform, comprising a plurality of shell sections connected in sequence from front to back, wherein the plurality of shell sections sequentially comprise: a power section, wherein a power rectifying mechanism is arranged in the power section; a transition section, wherein an inlet of the transition section is connected to an outlet of the power section, wherein the inlet cross section is circular, and the outlet cross section is square, and wherein the inlet cross section area is smaller than the outlet cross section area; a stable section, wherein the inlet of the stable section is connected to the outlet of the transition section; a contraction section, wherein the inlet of the contraction section is connected to the outlet of the stable section, wherein the inlet cross section area is larger than the outlet cross section area, and wherein an arc-shaped contraction section is arranged between the inlet and the outlet; an experimental section, wherein the inlet of the experimental section is connected to the outlet of the contraction section; and a diffusion section, wherein the inlet of the diffusion section is connected to the outlet of the experimental section, wherein the inlet cross section area is smaller than the outlet cross section area, and wherein the lower bottom edge of the diffusion section is arranged to be inclined downward from the inlet to the outlet.

Description

Technical Field

[0001] The invention relates to the field of combustion wind tunnels, in particular to a forest fire combustion wind tunnel experimental platform. Background Art

[0002] Forests are precious natural resources for human beings. They not only provide a large amount of wood and forest by-products, but also conserve water resources, maintain water and soil, regulate climate, prevent wind and sand, protect farmland, beautify the environment, purify the atmosphere, prevent pollution, and maintain ecological balance. However, fire is the enemy of forests. Among the various factors that destroy forests, forest fires are the most serious. Fighting forest fires requires a lot of manpower, material resources and financial resources, and may even cause casualties.

[0003] Wind tunnels with existing technology are usually used in aerospace, transportation, wind energy utilization and other fields, and there are few wind tunnels specifically used for forest fire research. Therefore, there is an urgent need for a forest fire combustion wind tunnel experimental platform to simulate forest fires, measure forest fire behavior characteristics and combustion parameters, build forest fire spread models, determine various technical parameters in fire fighting, and carry out research on fire monitoring, early warning and emergency decision-making technologies. Summary of the invention

[0004] Based on this, the object of the present invention is to provide a forest fire combustion wind tunnel experimental platform.

[0005] The forest fire combustion wind tunnel experimental platform of the present invention comprises a plurality of shells connected in sequence from front to back, wherein the plurality of shells in sequence comprise:

[0006] A power section, wherein a power rectifying mechanism is provided in the power section;

[0007] A transition section, wherein the inlet of the transition section is connected to the outlet of the power section, the inlet cross section of the transition section is circular, the outlet cross section of the transition section is square, and the inlet cross section area is smaller than the outlet cross section area;

[0008] a stabilizing section, wherein an inlet of the stabilizing section is connected to an outlet of the transition section;

[0009] A contraction section, wherein the inlet of the contraction section is connected to the outlet of the stabilization section, the inlet cross-sectional area of ​​the contraction section is larger than the outlet cross-sectional area, and an arc-shaped contraction section is provided between the inlet and the outlet;

[0010] an experimental section, wherein an inlet of the experimental section is connected to an outlet of the contraction section;

[0011] The diffuser section has an inlet connected to the outlet of the experimental section, an inlet cross-sectional area smaller than an outlet cross-sectional area, and a lower bottom edge of the diffuser section is inclined downward from the inlet to the outlet.

[0012] In one implementation of the above technical solution, the power fairing mechanism includes a fairing head cover, a fan, a fairing tail cover and a power motor;

[0013] The fairing head cover is arranged on the front side of the fan, the fan is pivotally connected to the central axis of the power section, the fairing tail cover is arranged on the rear side of the fan, the power motor is fixed in the fairing tail cover, and the output end of the power motor is drivingly connected to the fan.

[0014] In one implementation of the above technical solution, the power rectification mechanism further includes a support plate and a rotation-stop plate;

[0015] The support sheet is fixed to the front part of the power section, and the support sheet supports and fixes the fairing;

[0016] The anti-rotation plate is arranged along the periphery of the fairing.

[0017] In one implementation of the above technical solution, the ratio of the inlet cross-sectional area to the outlet cross-sectional area of ​​the transition section is 1:2, and the equivalent diffusion angle is 22.3°;

[0018] The ratio of the inlet cross-sectional area to the outlet cross-sectional area of ​​the contraction section is 2.78:1.

[0019] In one implementation of the above technical solution, an anti-separation net for preventing airflow from separating is installed in the transition section;

[0020] A damping net is installed in the stabilizing section for eliminating vortices in the incoming flow, reducing turbulence and improving airflow quality.

[0021] In one implementation of the above technical solution, an observation window is provided on the side wall of the experimental section;

[0022] A combustion bed is arranged in the experimental section.

[0023] In one embodiment of the above technical solution, the multiple-section shell also includes an outlet diffuser section, the inlet of the outlet diffuser section is connected to the outlet of the diffuser section, the inlet and outlet cross-sections of the outlet diffuser section are both square, the inlet cross-sectional area is smaller than the outlet cross-sectional area, and the lower bottom edge of the outlet diffuser section is inclined downward from its inlet to its outlet.

[0024] In one implementation of the above technical solution, the ratio of the inlet cross-sectional area to the outlet cross-sectional area of ​​the diffusion section is 1.57:1, and the equivalent diffusion angle is 6°;

[0025] The ratio of the inlet cross-sectional area to the outlet cross-sectional area of ​​the outlet diffusion section is 1.7:1, and the equivalent diffusion angle is 15°.

[0026] In one embodiment of the above technical solution, the multi-section shell further includes a collector, which is arranged at the front side of the power section, and is a bell mouth with a busbar of a quarter arc, and the bell mouth faces away from the power section.

[0027] In one implementation of the above technical solution, a protective net is provided at the inlet of the collector.

[0028] Compared with the prior art, the forest fire combustion wind tunnel experimental platform of the present invention improves the flow field quality and wind tunnel energy in the wind tunnel by setting a power section, a transition section, a stable section, a contraction section, a test section and a diffusion section, and utilizes multiple shell cross-section settings and connection relationships to form a wind tunnel that can simulate different forest fire conditions, which is convenient for measuring forest fire behavior characteristics and combustion parameters. It aims to study forest fire behavior characteristics and forest fire spread mechanisms, further understand fire dynamics, reveal forest fire spread laws and mechanisms, construct forest fire spread models, determine various technical parameters in fire fighting, carry out research on fire monitoring, early warning and emergency decision-making technologies, and provide technical support for forest fire prevention and control.

[0029] For better understanding and implementation, the present invention is described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a structural schematic diagram of the preferred structure of the forest fire combustion wind tunnel experimental platform of the present invention.

[0031] Figure 2 It is a structural diagram of the preferred structure of the power rectification mechanism.

[0032] Figure 3 It is a structural schematic diagram of the preferred structure of the transition section.

[0033] Figure 4 It is a side view of the preferred structure of the transition section.

[0034] Figure 5 It is a schematic diagram of the installation structure of the anti-separation net.

[0035] Figure 6 It is a structural schematic diagram of the preferred structure of the stable section and the contraction section.

[0036] Figure 7 It is a side view from the entrance of the stable section to the contraction section.

[0037] Figure 8 It is a schematic diagram of the installation structure of the damping net.

[0038] Fig. 9 It is a structural schematic diagram of the preferred structure of the experimental section.

[0039] Fig.10 It is a side view of the preferred structure of the combustion bed.

[0040] Fig.11 It is a top view of the preferred structure of the combustion bed.

[0041] Fig.12 It is a structural schematic diagram of the preferred structure of the diffusion section and the outlet diffusion section.

[0042] Fig.13 It is a side view from the outlet of the outlet diffuser toward the diffuser. DETAILED DESCRIPTION

[0043] The directional terms such as up, down, left, right, front, back, front, back, top, bottom, etc. mentioned or may be mentioned in this specification are defined relative to their structure and are relative concepts. Therefore, they may change accordingly according to their different locations and different usage conditions. Therefore, these or other directional terms should not be interpreted as restrictive terms.

[0044] The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present disclosure. Instead, they are merely examples of methods consistent with some aspects of the present disclosure as detailed in the appended claims.

[0045] The terms used in this disclosure are for the purpose of describing specific embodiments only and are not intended to limit the disclosure. The singular forms of "a", "said" and "the" used in this disclosure and the appended claims are also intended to include plural forms unless the context clearly indicates otherwise. It should also be understood that the term "and / or" used herein refers to and includes any or all possible combinations of one or more associated listed items.

[0046] See also Figure 1 , Figure 1 It is a structural schematic diagram of the preferred structure of the forest fire combustion wind tunnel experimental platform of the present invention.

[0047] The forest fire combustion wind tunnel experimental platform of this embodiment includes multiple sections of shells connected in sequence from front to back, and the multiple sections of the shells include a collector 1, a power section 2, a transition section 3, a stable section 4, a contraction section 5, an experimental section 6, a diffusion section 7 and an outlet diffusion section 8 in sequence.

[0048] Specifically, the collector 1 is arranged at the front side of the power section 2, and the collector 1 is a bell mouth with a generatrix of a quarter arc, and the bell mouth faces away from the power section 2. The collector 1 can ensure the quality of the inflow of the auxiliary contraction section 5, so that the airflow enters the contraction section 5 smoothly without separation.

[0049] Preferably, the radius of the arc forming the bell mouth is 0.5 m.

[0050] In order to prevent foreign matter from being sucked into the power section 2 , a protective net is preferably provided at the entrance of the collector 1 .

[0051] The power section 2 is cylindrical, and a power rectification mechanism 20 is disposed inside the power section 2 .

[0052] Specifically, the power section 2 of this embodiment has a diameter of 2.4 m and a length of 3 m.

[0053] Please read further Figure 2 , Figure 2 It is a structural diagram of the preferred structure of the power rectification mechanism.

[0054] The power rectification mechanism 20 includes a rectification head cover 21 , a fan 22 , a rectification tail cover 23 and a power motor 24 .

[0055] The fairing head cover 21 is arranged on the front side of the fan 22, the fan 22 is pivotally connected to the central axis of the power section 2, the fairing tail cover 23 is arranged on the rear side of the fan 22, the power motor 24 is fixed in the fairing tail cover 23, and the output end of the power motor 24 is transmission-connected to the fan 22.

[0056] The hub ratio of the fan 22 of this embodiment is 0.45, and the diameter of the fan 22 is 1.08 m.

[0057] The power motor 24 uses a high-performance AC variable frequency motor and is equipped with a current vector control universal frequency converter, a speed control card and a rotary encoder to form a closed-loop control circuit. Vector control AC frequency conversion makes the system have good low-speed characteristics, and can run stably even at extremely low speeds without speed pulsation; it has good dynamic performance, fast response speed, and strong load disturbance resistance. The use of variable frequency speed regulation technology enables the power rectifier mechanism 20 to have a high stable wind speed performance within the entire wind speed range, ensuring that the system operates with high efficiency and high precision.

[0058] In addition, the power motor 24 can be monitored in real time, and the safe operation of the motor can be effectively guaranteed by measuring the physical quantities of the motor such as the rotation speed, frequency, current, etc. and designing corresponding programs.

[0059] Preferably, the power rectification mechanism 20 further includes a support plate 25 and a rotation-stopping plate 26 .

[0060] The support piece 25 is fixed to the front part of the power section 2 , and the support piece 25 supports and fixes the fairing hood 21 .

[0061] The anti-rotation plate 26 is disposed along the periphery of the fairing tail cover 23 .

[0062] Please read further Figure 3 and Figure 4 . Figure 3 It is a structural schematic diagram of the preferred structure of the transition section. Figure 4 It is a side view of the preferred structure of the transition section.

[0063] The inlet 31 of the transition section 3 is connected to the outlet 32 ​​of the power section 2. The cross section of the inlet 31 is circular, the cross section of the outlet 32 ​​is square, and the cross section area of ​​the inlet 31 is smaller than the cross section area of ​​the outlet 32. The transition section 3 plays the role of changing the circular cross section into a square cross section, and is also a component for area diffusion.

[0064] In this embodiment, the circular diameter of the inlet 31 of the transition section 3 is 2.4m, the side length of the square of the outlet 32 ​​is 3m, and the length is 2.5m. In addition, the ratio of the cross-sectional area of ​​the inlet 31 of the transition section 3 to the cross-sectional area of ​​the outlet 32 ​​is 1:2, and the equivalent diffusion angle is 22.3°.

[0065] See also Figure 5 , Figure 5 It is a schematic diagram of the installation structure of the anti-separation net.

[0066] Preferably, in order to prevent the airflow from separating, a layer of anti-separation net 33 is installed at one-third of the transition section 3. Specifically, a fixed back plate 34 is arranged on the outside of the transition section 3, the anti-separation net 33 is pressed on the inner wall of the transition section 3 through a pressing plate 35, and the pressing plate 35 is tightened and fixed to the fixed back plate 34 through a slotted screw 36.

[0067] Please read further Figure 6 and Figure 7 . Figure 6 It is a structural schematic diagram of the preferred structure of the stable section and the contraction section. Figure 7 It is a side view from the entrance of the stable section to the contraction section.

[0068] The inlet of the stabilizing section 4 is connected to the outlet of the transition section 3 , and the cross section of the stabilizing section 4 is square.

[0069] The specifications of the stabilizing section 4 in this embodiment are 3m wide×3m high×2m long.

[0070] Preferably, a damping net 41 for eliminating vortices in the incoming flow, reducing turbulence, and improving the quality of the airflow is installed in the stabilizing section 4. The distance between the damping net 41 and the entrance of the stabilizing section 4 is 0.5 m. In addition, the damping net 41 can be selected to have a specification of 20 meshes / inch.

[0071] See also Figure 8 , Figure 8 It is a schematic diagram of the installation structure of the damping net.

[0072] Specifically, a fixed back plate 42 is arranged outside the stabilizing section 4 , the damping net 41 is pressed onto the inner wall of the stabilizing section 4 through a pressing plate 43 , and the pressing plate 43 is tightened and fixed onto the fixed back plate 42 through a slotted screw 44 .

[0073] The inlet of the contraction section 5 is connected to the outlet of the stabilization section 4 . The inlet and outlet cross sections of the contraction section 5 are both square, the inlet cross section area is larger than the outlet cross section area, and an arc-shaped contraction section 5 is provided between the inlet and the outlet.

[0074] The contraction section 5 is the main component that determines the flow field quality of the experimental section 6, and has a great influence on the turbulence and uniformity of the airflow in the experimental section 6. Generally speaking, an appropriate contraction ratio is beneficial to improving the flow field quality and wind tunnel energy ratio.

[0075] In this embodiment, the inlet width of the contraction section 5 is 3m, the height is 3m, the outlet width is 1.8m, the height is 1.8m, and the length is 2m. The ratio of the inlet cross-sectional area to the outlet cross-sectional area of ​​the contraction section 5 is 2.78:1, that is, the contraction ratio is 2.78, which can improve the flow field quality and wind tunnel energy.

[0076] See also Fig. 9 , Fig. 9 It is a structural schematic diagram of the preferred structure of the experimental section.

[0077] The inlet of the experimental section 6 is connected to the outlet of the contraction section 5 , and the cross section of the experimental section 6 is square.

[0078] An observation window 61 is provided on the side wall of the experimental section 6 , and a combustion bed 62 , an ignition device, a detection instrument, etc. are provided in the experimental section 6 .

[0079] The entrance of the experimental section 6 of this embodiment is 1.8m wide, 1.8m high and 12m long, and the maximum wind speed is designed to be 17.5m / s. In order to adjust the axial static pressure gradient of the experimental section 6, the experimental section 6 adopts a side wall preset diffusion angle, so that the outlet of the experimental section 6 is 1.9m wide and 1.8m high.

[0080] The observation windows 61 are arranged symmetrically up and down and left and right along the center line of the experimental section 6, and an observation platform is arranged below the windows, with guardrails on both sides of the platform.

[0081] Please read further Fig.10 and Fig.11 . Fig.10 It is a side view of the preferred structure of the combustion bed. Fig.11 It is a top view of the preferred structure of the combustion bed.

[0082] The combustion bed 62 includes a plurality of columns 621 , a side net 622 and a top net 623 .

[0083] The plurality of upright posts 621 are vertically fixed in the experimental section 6 , the side nets 622 are vertically arranged along the plurality of upright posts 621 , and the top net 623 is arranged on the upper portions of the plurality of upright posts 621 .

[0084] The ignition device is mainly composed of low-voltage electrical appliances, temperature control meters, temperature sensors, power adjustment units and high-temperature electric heating wires. The host computer issues instructions to control the start or stop of electric heating. The processing after temperature collection is completed by PLC, which communicates with the host computer and transmits the collected temperature data to the host computer. When the ignition temperature is reached, PLC controls the electric heating to stop.

[0085] In order to facilitate entry and exit of the experimental section 6 , a manhole door is provided on the cave wall in front of the experimental section 6 , and large test pieces enter and exit from the diffusion section 7 downstream of the experimental section 6 .

[0086] Please read further Fig.12 and Fig.13 . Fig.12 It is a structural schematic diagram of the preferred structure of the diffusion section and the outlet diffusion section. Fig.13 It is a side view from the outlet of the outlet diffuser toward the diffuser.

[0087] The inlet of the diffusion section 7 is connected to the outlet of the experimental section 6. The inlet and outlet cross-sections of the diffusion section 7 are both square, the inlet cross-sectional area is smaller than the outlet cross-sectional area, and the lower bottom edge of the diffusion section 7 is inclined downward from the inlet to the outlet.

[0088] The diffuser section 7 decelerates the airflow, converts dynamic pressure energy into static pressure energy, and reduces energy loss. Generally speaking, the energy loss caused by the diffuser section 7 is relatively large.

[0089] The inlet width of the diffuser section 7 of this embodiment is 1.9m, the height is 1.8m, the outlet width is 2.3m, the height is 2.3m, and the length is 5m. The ratio of the inlet cross-sectional area to the outlet cross-sectional area of ​​the diffuser section 7 is 1.57:1, and the equivalent diffusion angle is 6°.

[0090] The inlet of the outlet diffuser section 8 is connected to the outlet of the diffuser section 7. The inlet and outlet cross-sections of the outlet diffuser section 8 are both square, the inlet cross-sectional area is smaller than the outlet cross-sectional area, and the lower bottom edge of the outlet diffuser section 8 is inclined downward from the inlet to the outlet.

[0091] The outlet diffuser 8 further decelerates the airflow and directs the airflow to the atmosphere. The outlet loss of a DC wind tunnel is also a relatively important part of the loss. Properly increasing the outlet area is beneficial to reducing the outlet loss.

[0092] The inlet of the diffusion section 7 of this embodiment is 2.3 m wide and 2.3 m high, the outlet is 3 m wide and 3 m high, and the length is 3 m.

[0093] In order to reduce the footprint of the wind tunnel, the ratio of the inlet cross-sectional area to the outlet cross-sectional area of ​​the outlet diffuser section 8 is 1.7:1, so that the outlet diffuser section 8 is a large-angle diffuser section 7 with an area ratio of 1.7, and its equivalent diffusion angle is 15°.

[0094] (1) Estimation of wind tunnel energy ratio.

[0095] According to the maximum wind speed of 17.5 m / s in the 6-air wind tunnel of the experimental section, the wind tunnel energy ratio and power were estimated.

[0096] Table 1 Energy loss coefficients of various wind tunnel components

[0097]

[0098] Taking into account the possible difference between the roughness of the hole processing and the surface roughness used for calculation, as well as the influence of the ventilation conditions of the factory, the loss coefficient is magnified by 12%, the equivalent loss coefficient is about 1.25, and the energy ratio is 0.8.

[0099] The efficiency ηf of the fan 22 is 85%, and the shaft head power of the power motor 24 is calculated according to the following formula:

[0100] P=0.5ρAV 3 / ER t / η f

[0101] Then, the required shaft head power of the power motor 24 is 16 kW.

[0102] (2) Design of fan 22.

[0103] The fan 22 is designed according to the equal annular velocity distribution by using the improved Collar method.

[0104] Design parameters: speed 450Rpm, hub ratio 0.45, number of blades 10, wind tunnel energy ratio 0.8, fan 22 efficiency 0.85, cross-sectional area of ​​the experimental section 6 3.24m 2 , wind speed is 17.5m / s, blade airfoil is RAF-D airfoil, and lift coefficients at blade root and blade tip are 0.8 and 0.7 respectively.

[0105] (3) Design of the anti-rotation plate 26.

[0106] The design method is the same as fan 22.

[0107] Design parameters: The number of blades is 7, the blade thickness is 78mm, the blade airfoil changes from the tip to the root as NACA0010 to NACA0015 airfoil, and the pitch-chord ratio is 1.5. At the hub, the leading edge of the anti-rotation plate 26 is 290mm away from the trailing edge of the blade. The chord length of the anti-rotation plate 26 varies along the span direction, and the structural design is based on the leading edge of each station being straight and swept back 15ο.

[0108] (4) Selection of power motor 24.

[0109] Requirements for the power motor 24: when the speed is 450RPM, the shaft power should be greater than 16kW, and it can withstand an axial force of 950N and a torque of 350N·M; pay attention to the rotation direction of the power motor 24, the coordination of the pre-rotating vanes and the fan 22 blades.

[0110] In practice, a 30kW motor is chosen considering various losses and uncertainties.

[0111] The multiple shell sections of the forest fire combustion wind tunnel experimental platform of the present invention are preferably connected by flanges, and the entire structure is made of steel, with high manufacturing precision and short processing cycle.

[0112] The all-steel structure is conducive to the manufacture and installation of the equipment, and can well ensure the operating accuracy requirements of the fan 22 of the power section 2; the structural surface of the contraction section 5 is a quadratic surface, and the steel structure is easier to ensure the surface accuracy.

[0113] The steel structure can preferably be made of Q235 steel plate. Each section of the shell is made of 6mm thick steel plate; the upper part of each section of the shell can be provided with longitudinal and transverse ribs, which are 10mm thick steel plates and 150mm high; the connecting flange is made of 16mm thick steel plate and 150mm high.

[0114] Since the experimental section 6 is a combustion test site with high temperature, Q235 steel plates cannot be used to directly contact the burning material. Therefore, Q235 steel plates are used as the outer shell and the inner lining is high temperature resistant ceramic aluminum silicate fiberboard, which can withstand high temperatures of 1000°C.

[0115] The forest fire combustion wind tunnel experimental platform of the present invention can be preferably set up on a 33m×6m outdoor foundation platform, with a total length of 31m, a width of 3.4m, and a height of 3.8m. The highest point of the wind tunnel is 4m from the ground, and the surface area of ​​the wind tunnel is about 270m 2 The dimensions of each of the shells shall be determined according to the specific conditions on site.

[0116] During the specific experiment, the control system uses field bus communication and is equipped with a frequency conversion room and an experimental operation room. The host computer is the center of the wind tunnel experimental system and is used to issue speed control instructions; the speed control system uses PLC as the central controller, which is responsible for collecting wind speed signals, controlling the output frequency converter signal to adjust the wind speed, and completing different wind speed measurement tests through Ethernet communication with the host computer.

[0117] The temperature measurement of the experimental section 6 uses a K-type thermocouple temperature transmitter, which outputs a 4-20 mA signal, has a range of 0-1200° C., and an accuracy of ±1.5° C. The sensor insertion length is 500 mm, the diameter is 4 mm, and the thermal response time is 7-10 seconds (theoretical value).

[0118] The temperature and humidity measurement before the experimental section 6 uses the Kunlun Coast JWSK-6 series explosion-proof split temperature and humidity transmitter, with a transmission standard of 4-20mA, a humidity range of 0%RH-100%RH, an accuracy of ±2%RH, a temperature range of -20℃-60℃, and an accuracy of ±0.5℃.

[0119] The outdoor air temperature and humidity measurement uses the Kunlun Coast JWSK-6 series explosion-proof wall-mounted temperature and humidity transmitter, with a transmission standard of 4-20mA, a humidity range of 0%RH-100%RH, an accuracy of ±2%RH, a temperature range of -20℃-60℃, and an accuracy of ±0.5℃.

[0120] The wind speed can be measured by using a pitot tube to measure the dynamic pressure. The pitot tube uses a full-pressure air inlet hole to be placed in the flow direction of the experimental section 6 of the wind tunnel. The sensor can be a US SEAT micro-differential pressure transmitter with an accuracy of ±0.07% FS. According to the wind speed of 25m / s, the dynamic pressure is calculated to be 382Pa, and the range is selected to be 400Pa. The wind speed adjustment methods include manual adjustment and PID adjustment. Manual adjustment is open-loop control; the application of PID adjustment ensures the stability of the system wind speed.

[0121] Compared with the prior art, the forest fire combustion wind tunnel experimental platform of the present invention improves the flow field quality and wind tunnel energy in the wind tunnel by setting a power section, a transition section, a stable section, a contraction section, a test section and a diffusion section, and utilizes multiple shell cross-section settings and connection relationships to form a wind tunnel that can simulate different forest fire conditions, which is convenient for measuring forest fire behavior characteristics and combustion parameters. It aims to study forest fire behavior characteristics and forest fire spread mechanisms, further understand fire dynamics, reveal forest fire spread laws and mechanisms, construct forest fire spread models, determine various technical parameters in fire fighting, carry out research on fire monitoring, early warning and emergency decision-making technologies, and provide technical support for forest fire prevention and control.

[0122] The above-mentioned embodiments only express several implementation methods of the present invention, and the description is relatively specific and detailed, but it cannot be understood as limiting the scope of the invention patent. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A forest fire combustion wind tunnel experimental platform, characterized in that: The invention comprises a plurality of shell sections connected in sequence from front to back, wherein the plurality of shell sections in sequence comprise: A power section, wherein a power rectifying mechanism is provided in the power section; A transition section, wherein the inlet of the transition section is connected to the outlet of the power section, the inlet cross section of the transition section is circular, the outlet cross section of the transition section is square, and the inlet cross section area is smaller than the outlet cross section area; The ratio of the inlet cross-sectional area to the outlet cross-sectional area of ​​the transition section is 1:2, and the equivalent diffusion angle is 22.3°; a stabilizing section, wherein an inlet of the stabilizing section is connected to an outlet of the transition section; A contraction section, wherein the inlet of the contraction section is connected to the outlet of the stabilization section, the inlet cross-sectional area of ​​the contraction section is larger than the outlet cross-sectional area, and an arc-shaped contraction section is provided between the inlet and the outlet; The ratio of the inlet cross-sectional area to the outlet cross-sectional area of ​​the contraction section is 2.78:1; an experimental section, wherein an inlet of the experimental section is connected to an outlet of the contraction section; A combustion bed is provided in the experimental section, and the combustion bed includes a plurality of columns, a side net and a top net, wherein the plurality of columns are vertically fixed in the experimental section, the side nets are vertically arranged along the plurality of columns, and the top net is arranged on the upper part of the plurality of columns; A diffusion section, wherein the inlet of the diffusion section is connected to the outlet of the experimental section, the inlet cross-sectional area of ​​the diffusion section is smaller than the outlet cross-sectional area, and the lower bottom edge of the diffusion section is inclined downward from the inlet to the outlet; The ratio of the inlet cross-sectional area to the outlet cross-sectional area of ​​the diffusion section is 1.57:1, and the equivalent diffusion angle is 6°; An outlet diffuser section, wherein the inlet of the outlet diffuser section is connected to the outlet of the diffuser section, the inlet and outlet cross sections of the outlet diffuser section are both square, the inlet cross section area is smaller than the outlet cross section area, and the lower bottom edge of the outlet diffuser section is inclined downward from the inlet to the outlet; The ratio of the inlet cross-sectional area to the outlet cross-sectional area of ​​the outlet diffusion section is 1.7:1, and the equivalent diffusion angle is 15°.

2. The forest fire combustion wind tunnel experimental platform according to claim 1, characterized in that: The power rectification mechanism comprises a rectification head cover, a fan, a rectification tail cover and a power motor; The fairing head cover is arranged on the front side of the fan, the fan is pivotally connected to the central axis of the power section, the fairing tail cover is arranged on the rear side of the fan, the power motor is fixed in the fairing tail cover, and the output end of the power motor is drivingly connected to the fan.

3. The forest fire combustion wind tunnel experimental platform according to claim 2 is characterized by: The power rectification mechanism also includes a support plate and a rotation-stop plate; The support sheet is fixed to the front part of the power section, and the support sheet supports and fixes the fairing; The anti-rotation plate is arranged along the periphery of the fairing.

4. The forest fire combustion wind tunnel experimental platform according to claim 1, characterized in that: An anti-separation net is installed in the transition section to prevent the airflow from separating; A damping net is installed in the stabilizing section for eliminating vortices in the incoming flow, reducing turbulence and improving airflow quality.

5. The forest fire combustion wind tunnel experimental platform according to claim 1, characterized in that: An observation window is arranged on the side wall of the experimental section.

6. The forest fire combustion wind tunnel experimental platform according to any one of claims 1 to 5, characterized in that: The multi-section shell also includes a collector, which is arranged on the front side of the power section. The collector is a bell mouth with a busbar of a quarter arc, and the bell mouth faces away from the power section.

7. The forest fire combustion wind tunnel experimental platform according to claim 6, characterized in that: The inlet of the collector is provided with a protective net.

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