A test device and method for testing the resistance to reignition of forest surface combustible fires under the action of extinguishing agents.

Abstract

This invention belongs to the field of forest fire prevention technology, specifically a testing device and method for testing the resistance to reignition of forest surface combustible fires under the action of extinguishing agents. The device includes a combustion system, a fire extinguishing system, an air supply system, a slope adjustment system, and a data acquisition system. The combustion system includes a combustion bed, an aluminum silicate fireproof board, pulleys, and hooks to support the combustible material to be tested. The fire extinguishing system includes a water tank, a variable frequency water pump, water pipes, nozzles, solenoid valves, a spraying bracket, a flow meter, and a pressure gauge to set the spraying pressure, time, and flow rate, simulating different spraying conditions. The air supply system includes an axial flow fan and a frequency converter to adjust the wind speed. The slope adjustment system includes an electric hoist and a gantry frame to adjust the inclination angle of the combustion platform. The data acquisition system includes thermocouples, an infrared thermal imager, a camera, a heat flow meter, and a data acquisition instrument to collect information on temperature, radiant heat flux, and smoldering morphology during the period from fire extinguishing to reignition. This invention can provide data for studying the reignition patterns of forest combustibles, optimizing fire extinguishing agent spraying schemes, and formulating reignition prevention strategies.

Description

Technical Field

[0001] This invention belongs to the field of forest fire prevention technology, specifically relating to an experimental device for testing the reignition resistance of forest surface combustibles under the action of extinguishing agents. The invention also relates to a method for testing the reignition resistance of combustibles based on this device, applicable to the testing and research of the reignition characteristics of forest surface combustibles after the action of extinguishing agents. Background Technology

[0002] Reignition of forest combustibles after the application of extinguishing agents is a significant contributing factor to secondary fires, directly impacting the effectiveness of fire suppression and on-site safety management. Therefore, accurately testing the reignition characteristics of combustibles under extinguishing agent action and identifying the critical conditions for reignition resistance is of great practical significance for optimizing extinguishing agent spraying plans and developing reignition prevention and control strategies. Different types of combustibles exhibit significantly different reignition patterns after being extinguished with extinguishing agents of varying spray pressures and flow rates under different environmental conditions such as slope and wind speed. This necessitates testing equipment capable of simulating multi-dimensional experimental conditions while simultaneously achieving comprehensive and accurate data collection of key parameters during the reignition process, ultimately yielding the critical conditions for reignition resistance.

[0003] Currently, existing combustible re-ignition testing experimental devices have many technical defects. Similar devices have limited operating condition simulation capabilities, and most can only achieve fire extinguishing agent spraying tests in conventional flat, windless environments. They cannot simultaneously simulate natural environmental conditions such as slope and wind speed, as well as different fire extinguishing agent spraying conditions, resulting in low consistency with actual fire scenarios. In addition, similar experiments only focus on the instantaneous effect after fire extinguishing agent spraying and do not conduct long-term observation of re-ignition.

[0004] To address the shortcomings of existing technologies, this invention provides an experimental device for testing the resistance to reignition of forest surface combustible fires under the action of extinguishing agents. This device can simulate environmental conditions with different slopes and wind speeds, as well as different extinguishing agent spraying conditions. Simultaneously, it can comprehensively collect key parameters such as temperature, radiant heat flux, and smoldering area changes during the reignition process. The experimental results are accurate and repeatable, providing reliable experimental data support for the study of combustible fire reignition patterns. The purpose of this invention is to overcome the deficiencies of existing technologies and provide an experimental device for testing the resistance to reignition of forest surface combustible fires under the action of extinguishing agents. This device has a compact structure and is easy to operate. It can accurately simulate multiple operating conditions such as slope, wind speed, and extinguishing agent spraying pressure / flow rate. Simultaneously, it can comprehensively and continuously collect key parameters from the time of fire extinguishing to the reignition process, effectively determining the occurrence and characteristic parameters of reignition.

[0005] To achieve the above-mentioned objectives, the experimental apparatus provided by this invention adopts the following technical solution, including a combustion platform, a fire extinguishing system, an air supply system, a data acquisition system, and a slope adjustment system; the combustion platform is used to support the combustible material to be tested, the slope adjustment system is used to adjust the inclination angle of the combustion platform to simulate different slope conditions, the air supply system is used to change the wind speed of the experimental site to simulate different wind speed conditions, the fire extinguishing system is used to spray extinguishing agent onto the combustible sample and simulate different spraying conditions, and the data acquisition system is used to collect and record the temperature, radiant heat flux, and smoldering area information of the combustible sample after fire extinguishing and during the reignition process.

[0006] Furthermore, the combustion system includes a combustion bed support, an aluminum silicate fireproof board, pulleys, and hooks. The combustion bed support is a load-bearing support constructed by welding stainless steel pipes and steel plates. The aluminum silicate fireproof board is laid on the steel plate to insulate against heat and reduce the thermal impact of combustion heat on the load-bearing support, preventing deformation of the support due to high temperatures. The pulleys are installed at the four corners of the bottom of the combustion bed support, and the hooks are welded to the edge of the combustion bed frame. The pulleys are universal locking industrial pulleys with a load-bearing capacity of not less than 300 kg. The locking structure is a ratchet-type locking mechanism used to fix the position of the combustion platform during the experiment and prevent the platform from shifting during the experiment.

[0007] Furthermore, the combustion system has thermocouple mounting holes extending from the surface of the aluminum silicate fireproof board and penetrating the steel plate, with a hole spacing of 30cm. These thermocouple mounting holes are used to install thermocouples, enabling accurate acquisition of the surface temperature of the combustible material and the combustion platform.

[0008] Furthermore, the fire extinguishing system includes a liquid supply component, a spraying component, a support component, and a monitoring component. The liquid supply component includes a water tank, a variable frequency water pump, and water pipes. The spraying component includes nozzles and solenoid valves. The support component includes a spray bracket. The monitoring component includes a flow meter and a pressure gauge. The variable frequency water pump is used to adjust the spraying pressure, with stepless adjustment of the output water pressure within the range of 0.1~0.6MPa. The solenoid valve is installed on one side of the nozzle and is used to control the start and stop time of the extinguishing agent spraying. The flow meter is used to monitor the spraying flow rate and cumulative spray volume in real time. The pressure gauge is used to monitor the spraying pressure in real time. The fire extinguishing system can flexibly set the spraying pressure, control the spraying time and spraying flow rate, and simulate different extinguishing agent spraying conditions.

[0009] Furthermore, the water tank is made of stainless steel with a volume of 50L. The side wall of the water tank is equipped with a high-transparency liquid level observation window and a high-precision capacity scale with a scale accuracy of 0.1L, which facilitates intuitive reading of the remaining and consumed amount of extinguishing agent. A drain outlet is provided at the bottom of the water tank for easy cleaning and drainage after the experiment. The spray bracket is a stainless steel sleeve nested telescopic structure, with the telescopic section fixed by locking bolts. The height adjustment range is 0.5~3m, and the spraying height of the nozzle can be adjusted according to the experimental requirements.

[0010] Furthermore, the air supply system includes an axial flow fan and a frequency converter electrically connected to it. The frequency converter is used to adjust the rotational speed of the axial flow fan, thereby realizing stepless adjustment of the wind speed in the experimental site and simulating natural environmental conditions with different wind speeds.

[0011] Furthermore, the slope adjustment system includes a gantry and an electric hoist. The electric hoist is connected to the hook of the combustion platform via a chain. The lifting and lowering of the electric hoist causes one side of the combustion platform to rise, thereby changing the tilt angle of the combustion platform and simulating different slope environmental conditions.

[0012] Furthermore, the data acquisition system includes thermocouples, an infrared thermal imager, a camera, and a heat flow meter. The thermocouples are type K armored thermocouples with a temperature range of 0~1200℃, used to collect temperature data of combustibles and the combustion platform. The heat flow meter is a water-cooled heat flow meter with a measurement range of 0~50kW / m². 2 The heat flow meter is positioned at different heights above the combustion platform to acquire the radiant heat flux at different heights during the reignition process; the camera is positioned facing the combustion platform and the fire extinguishing system to record the entire process of fire extinguishing agent spraying, combustible combustion, and reignition; the infrared thermal imager is positioned facing the combustible sample on the combustion platform to observe the temperature distribution on the surface of the combustible sample and the change in the smoldering area of ​​the combustible sample after fire extinguishing in real time; and the data acquisition instrument is used to collect temperature and thermal radiation data.

[0013] The present invention also provides a method for testing the reignition of forest surface combustibles under the action of extinguishing agents based on the above-mentioned experimental device, comprising the following steps: S1. Arrange the combustible sample to be tested evenly on the aluminum silicate fireproof board of the combustion platform, install the thermocouple in the thermocouple mounting hole and make full contact with the combustible sample, start the data acquisition system, establish the initial record of temperature and radiant heat flux, and at the same time adjust the tilt angle of the combustion platform to the experimental requirement value through the slope adjustment system, and adjust the wind speed of the experimental site to the experimental requirement value through the air supply system. S2. Spray fuel at the ignition end of the combustion platform and ignite the fuel to advance the flame evenly, so that the combustible sample enters a stable combustion state. S3. Start the fire extinguishing system, set the spraying pressure through the variable frequency water pump, record the spraying time through the stopwatch, spray the extinguishing agent on the combustible sample according to the preset parameters until the preset spraying time is reached, and then stop spraying by controlling the solenoid valve to close the extinguishing agent spraying. S4. After the extinguishing agent spraying is completed, use the data acquisition system to continuously collect and record the temperature of the combustible sample, the radiant heat flux at different heights, and the morphological information of the smoldering area. Based on the collected information, determine whether the combustible sample has reignited and the characteristics of reignition.

[0014] Furthermore, in step S4, the presence of open flame, temperature changes, and changes in the area of ​​the high-temperature region are used to comprehensively determine whether the combustible material has reignited. Specifically: if an open flame reappears during continuous monitoring after the extinguishing agent has been sprayed, it is determined that reignition has occurred. If the following three conditions are met simultaneously, it is determined that reignition has not occurred and the experiment can be stopped: 1) No reappearance of open flame is detected throughout the entire process; 2) The thermocouple temperature drops below 100°C and remains stable; 3) Infrared thermal imaging shows that the area of ​​the high-temperature region, i.e., the area with a temperature ≥100°C, has decreased to 0.

[0015] Furthermore, for the working conditions where reignition occurs, while keeping the slope, wind speed, and spraying pressure constant, the amount of extinguishing agent sprayed and / or the spraying time are gradually increased and repeated experiments are conducted until the minimum amount of sprayed agent or the shortest spraying time to prevent reignition is obtained, and this condition is determined as the critical condition for preventing reignition under the corresponding working conditions.

[0016] The experimental apparatus and method for testing the reignition of combustibles under the action of fire extinguishing agents of the present invention have the following beneficial effects: This invention enables free adjustment of the combustion platform tilt angle within the range of 0~90° through a slope adjustment system, stepless adjustment of the wind speed in the experimental site through an air supply system, and flexible setting of spray pressure from 0.1 to 0.6 MPa and different spray flow rates through a fire extinguishing system. It can simultaneously simulate natural environmental conditions such as slope and wind speed, as well as different fire extinguishing agent spraying conditions, and has a high degree of consistency with actual fire scenarios. The data acquisition system of this invention integrates thermocouples, water-cooled heat flux meters, infrared thermal imagers, and cameras. It can simultaneously collect multi-dimensional parameters such as temperature, radiant heat flux at different heights, smoldering morphology and area changes, and open flame occurrence during the reignition process of combustibles. The collected data is comprehensive, continuous, and accurate, and can provide complete experimental data for analyzing the reignition patterns of combustibles. The device and method of the present invention can be applied to the reignition test of various combustibles in forests, and can also be adapted to different water-based fire extinguishing agents such as water-based and foam, which can meet the research needs of combustible reignition characteristics in different scenarios in the field of fire protection engineering. Attached Figure Description

[0017] Figure 1This is a schematic diagram of the overall structure of a test device for preventing reignition of forest surface combustible fires under the action of fire extinguishing agents, according to the present invention. Figure 2 This is a side view of the test device for testing the resistance to reignition of forest surface combustible fires under the action of fire extinguishing agents according to the present invention. Figure 3 This is a schematic diagram of the fire extinguishing system of the present invention; The markings in the diagram are as follows: 1. Fuel bed, 2. Pulley, 3. Hook and ring, 4. Thermocouple, 5. Heat flow meter, 6. Camera, 7. Thermal infrared camera, 8. Flow meter, 9. Pressure gauge, 10. Solenoid valve, 11. Sprinkler head, 12. Stainless steel water pipe, 13. Variable frequency water pump, 14. Water tank, 15. Sprinkler bracket, 16. Gantry frame, 17. Electric hoist, 18. Axial flow fan. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the assembly and actual testing application of the experimental apparatus for testing the reignition of combustibles under the action of extinguishing agents will be described in detail below with reference to the markings in the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0019] This embodiment uses pine needles, a combustible material in forests, as the test object. The reignition test experimental device of the present invention is used to conduct a reignition characteristic test of water-based fire extinguishing agents. The components of the device are labeled in the attached drawings.

[0020] This invention discloses an experimental device for testing the resistance to reignition of forest surface combustible fires under the action of fire extinguishing agents. The device is an integrated assembly of a combustion system, a fire extinguishing system, a ventilation system, a data acquisition system, and a slope adjustment system. The assembly process of each system and the connection relationships of the components are explained below with reference to the accompanying drawings: Combustion system assembly: The combustion platform 1 is a load-bearing structure welded from stainless steel pipes and steel plates. Four pulleys 2 are fixedly installed at the four corners of the bottom. These pulleys are universal locking industrial pulleys with a load capacity of 300kg and a ratchet locking structure, used to fix the position of the combustion platform 1 during the experiment. Hooks 3, made of stainless steel, are welded to the edge of the frame of the combustion platform 1 for connection with the electric hoist of the slope adjustment system. Aluminum silicate fireproof board is laid on the steel plate of the combustion platform 1. Thermocouple mounting holes are made through the surface of the fireproof board and penetrate the steel plate. The hole spacing is 30cm. Thermocouples 4 (K-type armored, temperature measurement range 0~1200℃) are inserted into the mounting holes. The temperature measuring end of the thermocouple is in contact with the surface of the combustible material to collect temperature data during the combustion and reignition process of the combustible material.

[0021] Fire extinguishing system assembly: The fire extinguishing system consists of four components: liquid supply, spraying, support, and monitoring. The 14 water tanks are made of 50L stainless steel, and the side walls are equipped with high-transparency liquid level observation windows and a scale accuracy of 0.1L. The system has a capacity scale and a drain outlet at the bottom. The water tank outlet is connected to the inlet of the variable frequency water pump 13 via a stainless steel water pipe 12. The output water pressure of the variable frequency water pump can be steplessly adjusted from 0.1 to 0.6 MPa. The outlet of the variable frequency water pump is connected to a stainless steel water pipe, with a flow meter 8, a pressure gauge 9, a solenoid valve 10, and a nozzle 11 connected in series on the pipe. The flow meter is used to monitor the spray flow rate and cumulative spray volume, the pressure gauge displays the spray pressure in real time, and the solenoid valve 10 is installed on the inlet side of the nozzle 11 to control the start and stop of the extinguishing agent spray. The stainless steel water pipe 12 is fixed to the upper part of the spray bracket 15. The spray bracket is a stainless steel sleeve nested telescopic structure, and the telescopic section is fixed by locking bolts. The height adjustment range is 0.5 to 3 m, and the spray height of the nozzle can be adjusted according to experimental needs. After assembly, the fire extinguishing system sprays the extinguishing agent onto the combustible sample on the combustion platform 1 through the nozzle.

[0022] Air supply system assembly: The axial flow fan 18 is placed on the side directly opposite the combustible material laying area of ​​the combustion platform 1. The axial flow fan is electrically connected to an external frequency converter. The speed of the axial flow fan is adjusted by the frequency converter to achieve stepless adjustment of the wind speed in the experimental site, simulating natural environmental conditions with different wind speeds. The air outlet of the axial flow fan faces the combustion platform 1 to ensure that the air field acts on the surface of the combustible material sample.

[0023] Slope adjustment system assembly: The gantry frame 16 is a steel portal frame that spans the experimental foundation ground outside the combustion platform 1. The electric hoist 17 is suspended on the crossbeam of the gantry frame 16. The lower end of the chain of the electric hoist is detachably connected to the hook ring 3 in the combustion platform. The lifting and lowering of the electric hoist drives one side of the combustion platform to be raised, thereby realizing the tilt angle adjustment of the combustion platform and simulating forest fire environments with different slopes.

[0024] Data acquisition system assembly: Heat flow meter 5 is a water-cooled heat flow meter with a measurement range of 0~50kW / m³. 2 Two cameras are installed, fixed at heights of 0.5m and 1.0m directly above the combustion platform 1, respectively, to collect radiative heat flux at different heights during the reignition process. The thermal infrared camera 7 is positioned facing the combustible material bearing area of ​​the combustion platform 1 to observe the temperature distribution on the surface of the combustible sample and the change in smoldering area after extinguishing the fire in real time. The camera 6 faces the combustion platform 1 and the fire extinguishing system to record the entire process of extinguishing agent spraying, combustible material combustion, and reignition. The signal output terminals of the thermocouple 4 and the heat flux meter 5 are connected to the data acquisition instrument to realize the real-time acquisition and storage of temperature and radiative heat flux data. The image data of the thermal infrared camera 7 and the camera 6 can be viewed in real time and stored synchronously.

[0025] After the assembly of each system is completed, check the reliability of the connection of each component: the stainless steel water pipe 12 of the fire extinguishing system has no leakage, the solenoid valve 10 opens and closes flexibly, and the flow meter 8 and pressure gauge 9 display normally; the electric hoist 17 of the slope adjustment system is firmly connected to the hook 3, and the wind speed of the axial flow fan 18 is smoothly adjusted; all detection components of the data acquisition system can collect data normally, ensuring that the experimental device can work together.

[0026] Using the experimental apparatus assembled above, a reignition test of water-based fire extinguishing agents on forest combustibles was conducted. The test procedures were strictly performed according to the reignition test method of this invention, and the specific operations are as follows: Spread pine needles evenly on the aluminum silicate fireproof board of the combustion platform 1; start the data acquisition instrument and adjust the thermocouple 4, heat flux meter 5, thermal infrared camera 7, and camera 6 to the working state to establish initial data records of temperature and radiant heat flux, and ensure the stability of baseline data.

[0027] The tilt angle of the combustion platform 1 is adjusted to 20° by the lifting and lowering of the electric hoist 17, and the ratchet locking structure of the locking pulley 2 is used to fix the position of the combustion platform 1, simulating the 20° slope of a forest slope. The frequency converter of the axial flow fan 18 is adjusted to adjust the wind speed of the axial flow fan to 1m / s, simulating the natural wind conditions at the forest fire site. After the wind speed stabilizes, the axial flow fan is kept running continuously.

[0028] Adjust the height of the sprinkler bracket 15 to 2m, tighten the fixing bolts of the telescopic section to ensure the spraying height of the nozzle 11 is stable, adjust and start the spraying pressure of the variable frequency water pump 13 to 0.4Mpa, and observe whether the reading of the pressure gauge 9 is stable at 0.3MPa.

[0029] Spray a small amount of ignition fuel at the ignition end of combustion platform 1, and use an igniter to ignite the fuel, so that the flame line is evenly pushed to the other side of the combustible sample until the combustible sample as a whole enters a stable combustion state.

[0030] When the fire line reaches the preset position, the solenoid valve 10 is opened, and the water-based extinguishing agent is delivered to the nozzle 11 through the stainless steel water pipe 12 to spray onto the burning combustible sample. The spray flow rate is monitored in real time by the flow meter 8, and the timer is set according to the preset spray time of 40 seconds. After the preset time is reached, the solenoid valve 10 is immediately closed to stop the extinguishing agent spraying. The cumulative spray volume is read by the flow meter 8, and the extinguishing agent consumption is checked by the capacity scale of the water tank 14. The two data are consistent.

[0031] After the extinguishing agent spraying is completed, the data acquisition system is kept running continuously. Thermocouple 4 and heat flow meter 5 collect combustible sample data every 1 second. Thermal infrared camera 7 captures the changes in the area of ​​high-temperature region on the sample surface in real time. Camera 6 records the smoldering and open flame occurrence of the sample throughout the process. Axial flow fan 18 maintains a wind speed of 1 m / s and runs continuously to simulate the continuous effect of natural wind field.

[0032] When no re-emergence of open flame is observed during the monitoring process after fire extinguishing, when the sample temperature measured by thermocouple 4 drops below 100℃ and remains stable, and when the area of ​​the high-temperature region shown by thermal infrared camera 7 decreases to 0, it is determined that the sample has not reignited under this experimental condition, the experiment is terminated, and the corresponding spraying parameters are recorded as the effective suppression conditions under this condition.

[0033] If open flame reappears during monitoring, reignition is considered to have occurred. In this case, maintaining the slope at 20°, wind speed at 1 m / s, and spraying pressure at 0.4 MPa, the spraying time is increased from 40 s to 50 s, and the experiment is repeated. If reignition still occurs, the time is increased to 60 s, until the experimental results meet the non-reignition criterion. The shortest spraying time and the minimum cumulative spraying volume recorded by the flow meter at this point can be determined as the critical spraying time and critical spraying volume for the pine needle sample under this condition to prevent reignition.

[0034] The experimental apparatus of this invention can flexibly adjust the experimental conditions according to the testing requirements. If it is necessary to simulate the reignition characteristics of combustibles in steep slopes and strong wind environments, the tilt angle of the combustion platform 1 can be adjusted to a preset value by the electric hoist 17, and the wind speed of the axial flow fan 18 can be adjusted to a preset value by the frequency converter. If it is necessary to test the effect of different spraying pressures on reignition characteristics, the output water pressure can be adjusted in the range of 0.1~0.6MPa by the frequency converter water pump 13, and the spraying parameters can be accurately controlled by the flow meter 8 and the pressure gauge 9.

[0035] Meanwhile, the extinguishing agent can also be replaced with other water-based extinguishing agents according to the test requirements. Only the spray mode of the nozzle 11 needs to be changed and the spray pressure of the variable frequency water pump 13 needs to be adjusted to adapt it, which has good versatility.

[0036] The above description is only a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any adjustments to the specifications of the components and test conditions, as well as technical solutions obtained by equivalent substitution or improvement, within the spirit and principles of the present invention, should be included within the scope of protection of the present invention.

Claims

1. A testing device and method for testing the resistance to reignition of forest surface combustible fires under the action of extinguishing agents, characterized in that, This includes a combustion system, a fire extinguishing system, a ventilation system, a slope adjustment system, and a data acquisition system. The combustion system includes a combustion bed, an aluminum silicate fireproof board, pulleys, and hooks, used to hold the combustible material to be tested; The fire extinguishing system includes a liquid supply component, a spraying component, a support component, and a monitoring component, which are used to set the spraying pressure, control the spraying time and spraying flow rate, and spray extinguishing agent onto the combustible sample to simulate different spraying conditions. The air supply system is used to change the wind speed in the experimental site to simulate different wind speed conditions. The slope adjustment system includes an electric hoist and a gantry frame, used to adjust the tilt angle of the combustion platform to simulate different slope conditions; The data acquisition system is used to collect and record the temperature, radiant heat flux, and smoldering morphology information of the combustible sample during the process from extinguishing the fire to reignition.

2. The test device for testing the resistance to reignition of forest surface combustible fires under the action of extinguishing agents according to claim 1, characterized in that, The combustion system includes a combustion bed composed of stainless steel pipes and steel plates. An aluminum silicate fireproof board is laid on the steel plate. The aluminum silicate fireproof board is used for heat insulation and to reduce the thermal impact of combustion heat on the combustion bed. The pulleys are installed at the four corners of the bottom of the combustion bed, and the hooks are welded to the edge of the platform frame.

3. The experimental apparatus according to claim 1, characterized in that, The liquid supply assembly includes a water tank, a variable frequency water pump, and water pipes; the spraying assembly includes a nozzle and a solenoid valve; the support assembly includes a spraying bracket; and the monitoring assembly includes a flow meter and a pressure gauge. The variable frequency water pump is used to adjust the spraying pressure; the solenoid valve is used to control the spraying start and stop time; the flow meter is used to monitor the spraying flow rate and cumulative spraying volume; and the pressure gauge is used to monitor the spraying pressure.

4. The experimental apparatus according to claim 1, characterized in that, The air supply system includes an axial flow fan and a frequency converter electrically connected to it. The frequency converter is used to adjust the speed of the axial flow fan to achieve wind speed regulation.

5. The experimental apparatus according to claim 1, characterized in that, The data acquisition system includes thermocouples, infrared thermal imagers, cameras, heat flow meters, and data acquisition instruments. The heat flow meters are set at different heights above the combustion platform to acquire the radiant heat flux at different heights during the reignition process.

6. The experimental apparatus according to claim 1, characterized in that, The slope adjustment system includes a gantry and an electric hoist. The electric hoist is connected to the combustion platform via a chain to change the inclination angle of the combustion platform.

7. The experimental apparatus according to claim 2, characterized in that... The combustion system has thermocouple mounting holes drilled from the surface of the fireproof board and through the steel plate, with a hole spacing of 30cm. The pulley is a universal locking industrial pulley with a load-bearing capacity of not less than 300kg. The locking structure is a ratchet-type locking mechanism used to fix the position of the combustion platform during the experiment.

8. The experimental apparatus according to claim 3, characterized in that, The variable frequency water pump can steplessly adjust the output water pressure; the solenoid valve is installed on one side of the nozzle to control the spraying of the extinguishing agent; the water tank is made of stainless steel, and the side wall of the water tank is equipped with a high-transparency liquid level observation window and a high-precision capacity scale with a scale accuracy of 0.1L; a drain port is provided at the bottom of the water tank; the spray bracket is a stainless steel sleeve nested telescopic structure, and the telescopic section is fixed by locking bolts, allowing for free height adjustment.

9. The experimental apparatus according to claim 5, characterized in that, The thermocouple is a type K armored thermocouple; the heat flow meter is a water-cooled heat flow meter; the camera is facing the combustion platform and the fire extinguishing system to record the entire fire extinguishing process; the infrared thermal imager is aimed at the fuel sample on the fuel fixing bracket to observe the temperature distribution on the surface of the fuel sample and the change in smoldering area after fire extinguishing in real time; the data acquisition instrument is used to collect temperature and thermal radiation data.

10. A method for testing the reignition of combustibles under the action of an extinguishing agent using the experimental apparatus according to any one of claims 1 to 9, characterized in that, Includes the following steps: S1. Arrange the combustible sample to be tested on the combustion platform, establish initial records of temperature and radiant heat flux through the data acquisition system, and adjust the wind speed and slope to the experimental requirements. S2. Spray fuel at the ignition end of the platform and ignite the fuel to make the ignition line advance evenly; S3. Start the fire extinguishing system and spray the extinguishing agent onto the combustible sample according to the set spraying pressure and spraying time until the preset spraying time is reached, and then stop spraying by controlling the solenoid valve. S4. After the extinguishing agent spraying is completed, use the data acquisition system to continuously collect information on temperature, radiant heat flux and smoldering area morphology, and determine whether reignition has occurred and the characteristic parameters of reignition.

11. The test method according to claim 10, characterized in that, In step S4, the presence of open flame, temperature changes, and changes in the area of ​​the high-temperature zone are used to comprehensively determine whether the combustible material has reignited. Specifically: if an open flame reappears during continuous monitoring after the extinguishing agent has been sprayed, it is considered reignition. If the following three conditions are met simultaneously, it is considered that reignition has not occurred, and the experiment can be stopped: 1) No recurrence of open flame was detected throughout the entire process; 2) The thermocouple temperature drops below 100℃ and remains stable; 3) Infrared thermal imaging shows that the area of ​​high-temperature regions, i.e., areas with a temperature ≥100℃, is reduced to 0; For situations where reignition occurs, while keeping the slope, wind speed, and spraying pressure constant, gradually increase the amount of extinguishing agent sprayed and / or extend the spraying time for repeated experiments until the minimum spraying amount or the shortest spraying time to prevent reignition is obtained, and this condition is determined as the critical condition for preventing reignition under the corresponding working conditions.

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