Tunnel moving liquid fire spreading motion simulation experiment device

Abstract

A tunnel moving liquid fire spreading motion simulation experiment device comprises a moving body of a hollow double-layer nested structure, and a liquid fire spreading simulation unit, a moving mass loss monitoring system and a moving temperature monitoring system are integrated in the moving body. The liquid fire spreading simulation unit is located at the top of the moving body and comprises a long and narrow oil groove and a fireproof plate, and the long and narrow oil groove is formed in the fireproof plate; the moving mass loss monitoring system is located below the liquid fire spread simulation unit and comprises a USB flash disk type balance and a height-adjustable metal frame, and the height-adjustable metal frame is fixed to the bottom of the moving body and arranged below the USB flash disk type balance; the mobile temperature monitoring system comprises a thermocouple and a wireless temperature sensor; a probe of the thermocouple is fixed at a preset position above the long and narrow oil tank; the wireless temperature sensor is connected with the thermocouple and is fixed in the moving body. The wireless temperature sensor uploads temperature data to a computer terminal in real time. According to the invention, mobile monitoring of flame temperature and fuel mass loss can be realized.

Description

Technical Field

[0001] This invention relates to a tunnel fire spread simulation experimental device, specifically a tunnel moving liquid fire spread motion simulation experimental device, which is particularly suitable for studying the combustion characteristics of liquid leaks forming moving ignition sources in hazardous chemical transportation accidents, and belongs to the field of tunnel fire safety technology. Background Technology

[0002] With the rapid evolution of the global economic landscape and the rapid development of engineering and technological systems, transportation infrastructure in various countries is constantly improving, leading to a significant increase in the demand for the transportation of hazardous chemicals. However, if a hazardous materials transport vehicle is involved in a traffic accident during tunnel transport, resulting in a fuel leak or a collision that ignites the vehicle, and if the vehicle continues to move out of control, it can become a mobile source of fire.

[0003] Compared to stationary fire sources, mobile fire sources pose a greater risk. Due to the dynamic nature of mobile fire sources, their movement causes the burning area to expand dynamically, exacerbating the damage to the surrounding environment. Simultaneously, the movement of the fire source alters surrounding airflow, affecting the spread of fire and the transport of smoke. When mobile fire sources appear in narrow, confined spaces such as tunnels and underground passages, fire detection and alarm systems are less effective at detecting them, making personnel evacuation and firefighting rescue operations more difficult.

[0004] Currently, there are few experimental methods for mobile ignition sources. Existing methods use gas burners or rectangular oil tanks to simulate the mobile ignition source during the full combustion stage, resulting in a relatively high and stable heat release rate. However, research on the initial stage of mobile ignition source formation, i.e., the flame spread stage, is relatively lacking. Furthermore, existing experimental methods lack experimental research on the dynamic coupling effect of ignition source movement and liquid fire spread, and also cannot achieve dynamic monitoring of flame temperature and mass loss. Summary of the Invention

[0005] The purpose of this invention is to provide a simulation experimental device for the spread of liquid fire in a tunnel. By dynamically simulating the spread of liquid fire in a moving state, it is possible to monitor the flame temperature and fuel mass loss during movement, which is of great significance for the prevention and early detection of mobile fires.

[0006] To achieve the above objectives, the present invention provides a tunnel moving liquid fire spread motion simulation experimental device, including a moving body with a precision wheel set at the bottom. The moving body is a hollow double-layer nested structure composed of an inner shell and an outer shell. Inside the moving body, a liquid fire spread simulation unit, a moving mass loss monitoring system, and a moving temperature monitoring system are integrated.

[0007] The liquid fire spread simulation unit is located on top of the moving body and includes a narrow oil tank for holding flammable liquid and a fireproof plate. The narrow oil tank is set on the upper part of the fireproof plate. One side wall of the narrow oil tank is made of fireproof glass to form a visual observation window. The high temperature resistance of the fireproof glass can ensure safety in long-term combustion experiments.

[0008] The mobile mass loss monitoring system is located below the liquid fire spread simulation unit and is used to measure the mass change during the liquid combustion process in real time. It includes a USB-type balance and an adjustable height metal frame. The adjustable height metal frame is fixed to the bottom of the moving body and placed below the USB-type balance. During the experiment, the long and narrow oil tank and the fireproof plate are placed on the USB-type balance.

[0009] The mobile temperature monitoring system is used to measure the flame temperature distribution in real time. It includes a thermocouple, a wireless temperature sensor, and a thermocouple bracket. The thermocouple probe is fixed at a preset position above the narrow oil tank by the thermocouple bracket. The wireless temperature sensor is connected to the thermocouple probe by a thermocouple wire and fixed inside the moving body. The wireless temperature sensor can wirelessly upload temperature data to a computer terminal equipped with a receiver in real time, realizing mobile monitoring of flame temperature.

[0010] The outer surface of the inner shell of the moving body is provided with multiple mounting holes at different heights. These mounting holes and the fixing bolts set on the outer shell of the moving body form an adjustable mating structure. By selecting mounting holes of different heights and fixing bolts for assembly, the position of the inner shell of the moving body in the vertical direction can be adjusted, thereby changing its cross-sectional area to accurately simulate vehicles of different sizes.

[0011] The invention also includes a fireproof and heat-insulating layer, which is set in the upper middle part of the USB-type balance. It adopts a composite structure of rock wool and gypsum board. Under the premise of ensuring the measurement accuracy of the balance, the fireproof and heat-insulating layer can effectively block the high temperature of the flame from causing thermal damage to the balance and the electronic equipment below. The thickness and position of the fireproof and heat-insulating layer have been optimized to ensure that it can provide sufficient heat insulation protection without interfering with the weighing function of the balance.

[0012] The present invention has a protruding structure at the bottom of the narrow oil tank, and the narrow oil tank is connected to the fireproof plate through the protruding structure. Specifically, the protruding structure at the bottom of the narrow oil tank is bonded to the fireproof plate with a high-temperature resistant adhesive, and the protruding structure is fixed to the fireproof plate with fixing screws.

[0013] The wireless temperature sensor of this invention has a temperature monitoring range of 0-800℃, a measurement resolution of 0.1℃, a sampling interval of 1s, and is powered by a 3.6V lithium-ion battery.

[0014] The USB-type balance of this invention has a measuring range of 5000g, an accuracy of 0.01g, and a minimum sampling interval of 0.125s.

[0015] Theoretical analysis of the liquid fire spread simulation unit in this invention:

[0016] Taking the spread of fire from a moving liquid in a tunnel as an example, during the movement of the moving body, due to the piston effect, a backflow wind speed w will be generated in the annular space formed by the moving body and the tunnel wall. This backflow wind speed w is relative to the speed of the moving body, i.e., the relative wind speed v. s It can be represented as:

[0017]

[0018] Where: v0 is the velocity of the moving body, m / s;

[0019] v1 is the piston wind speed inside the tunnel, in m / s;

[0020] w represents the recirculating air velocity within the annular space, in m / s;

[0021] α0 is the blocking ratio of the moving body to the tunnel.

[0022] This invention addresses the issue that the mass loss rate of a mobile mass loss monitoring system is a necessary parameter for processing flame data, and its calculation formula is as follows:

[0023]

[0024] In the formula: It is the rate of mass loss per unit area of ​​a single flame at the head, in m / s;

[0025] It is the rate of mass loss per unit area of ​​the flame spread region, in m / s;

[0026] l is the length of the flame spread area, in meters;

[0027] l * It is the length of a single flame at the head, in meters (m).

[0028] L is the total length of the long, narrow oil tank, in meters;

[0029] It is the rate of total mass loss per unit area of ​​a narrow, elongated oil tank fire, in m / s;

[0030] The flame tilt angle is defined as the angle between the axis of the first flame at the head of the fire spread and the vertical direction, and its calculation formula is as follows:

[0031] cos(θ)=a(v * ) b

[0032]

[0033] In the formula: θ is the flame tilt angle, °;

[0034] v * The longitudinal ventilation velocity is a dimensionless velocity.

[0035] a and b are constants;

[0036] v represents the longitudinal ventilation velocity, in m / s;

[0037] g is the acceleration due to gravity, m / s² 2 ;

[0038] D is the equivalent oil tank diameter, in meters;

[0039] ρ0 is the air density, g / m³ 3 ;

[0040] Flame height is defined as the vertical distance from the tip of the first flame at the fire spread head to the fuel surface, and its calculation formula is as follows:

[0041]

[0042] In the formula: H is the flame height, in meters;

[0043] d is the width of the narrow oil groove, in meters (m).

[0044] This refers to dimensionless mass loss per unit area.

[0045] α and β are constants;

[0046] In this invention, the dynamic characteristics of a moving fire source induce complex changes in the flow field within the tunnel, further leading to a significant impact of the airflow within the tunnel on the spread of the flame. Under these circumstances, the longitudinal ventilation velocity v can be determined by the relative wind speed v s Characterized by this, the formula for calculating the flame tilt angle can be expressed as:

[0047]

[0048] The formula for calculating flame height can be expressed as:

[0049]

[0050] To obtain the piston wind data required in the above formula, the present invention installs an anemometer at a key location on the mobile fire source experimental platform and measures the above data using the anemometer. At the same time, the mass loss rate data during the fire spread process is collected by the mobile mass loss monitoring system. The predicted values ​​of the flame tilt angle θ and flame height H can be obtained by calculating using the above formula.

[0051] Compared with existing technologies, this invention proposes an experimental device for studying the characteristics of liquid fire spread under the influence of a moving fire source in a tunnel. By setting a liquid fire spread simulation unit on the moving body, dynamic simulation of liquid fire spread in a moving state is achieved. The adjustable-height moving body design allows for flexible changes in its cross-sectional area. The use of a moving monitoring system enables dynamic monitoring of the flame temperature field and the heat release rate of the fire source. Combined with a narrow oil tank with an observation window, the liquid fire spread behavior can be observed in detail. By mounting the experimental device of this invention onto an experimental platform equipped with a power traction system and guide rails, experimental research on the spread of moving liquid fire under various scenarios and the coupled influence of multiple factors can be conducted. Attached Figure Description

[0052] Figure 1 This is a schematic diagram of the structure of the present invention;

[0053] Figure 2 This is a front view of the internal structure of the moving body of the present invention;

[0054] Figure 3 This is a side view of the internal structure of the moving body of the present invention.

[0055] In the diagram: 1. Precision wheel assembly; 2. Moving body; 3. Outer shell of the moving body; 4. Inner shell of the moving body; 5. Fireproof board; 6. Narrow oil tank; 7. Fireproof glass; 8. Thermocouple bracket; 9. Thermocouple probe; 10. Fixing screw; 11. Fixing bolt; 12. Wireless temperature sensor; 13. USB flash drive balance; 14. Adjustable height metal frame; 15. Thermocouple wire; 16. Fireproof and heat-insulating layer. Detailed Implementation

[0056] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0057] like Figures 1 to 3As shown, this example provides a tunnel mobile liquid fire spread motion simulation experimental device. This experimental device can be used as a motion experimental model on a tunnel mobile fire source experimental platform (such as patent application ZL202410924707.5). The experimental device includes a moving body 2 with a precision wheel set 1 at the bottom, which can ensure the stability of the moving body during operation. The moving body 2 is a hollow double-layer nested structure composed of a moving body inner shell 4 and a moving body outer shell 3. Specifically, the hollow double-layer nested structure has multiple mounting holes at different heights on the outer surface of the moving body inner shell 4. The mounting holes and the fixing bolts 11 set on the moving body outer shell 3 form an adjustable mating structure. By selecting mounting holes of different heights and assembling with fixing bolts 11, the position of the moving body inner shell 4 in the vertical direction can be adjusted, thereby changing the cross-sectional area of ​​the moving body 2 to accurately simulate vehicles of different sizes.

[0058] The moving body 2 integrates a liquid fire spread simulation unit, a moving mass loss monitoring system, and a moving temperature monitoring system. These systems work together to simulate and collect data on the moving liquid fire spread.

[0059] The liquid fire spread simulation unit is located on top of the moving body 2, and includes a narrow oil tank 6 for holding flammable liquids (such as n-butanol, diesel, etc.) and a fireproof plate 5. The narrow oil tank 6 is located on the upper part of the fireproof plate 5. One side wall of the narrow oil tank 6 is made of fireproof glass to form a visual observation window. This visual observation window is used to monitor the dynamic behavior of liquid fire spread in real time (such as flame height, flame tilt angle, and flame front). The high temperature resistance of the fireproof glass 7 of the present invention can ensure safety in long-term combustion experiments.

[0060] The mobile mass loss monitoring system is located below the liquid fire spread simulation unit and is used to measure the mass change during the liquid combustion process in real time. It includes a USB-type balance 13 and an adjustable height metal frame 14. The USB-type balance 13 has a range of 5000g, an accuracy of 0.01g, and a minimum sampling interval of 0.125s, which can accurately record the mass loss data of the liquid fuel. The adjustable height metal frame 14 is fixed to the bottom of the moving body 2 and placed below the USB-type balance 13. The adjustable height metal frame 14 is used to adjust the height of the USB-type balance 13 to adapt to the measurement requirements under different experimental conditions. During the experiment, the narrow oil tank 6 and the fireproof plate 5 are placed on the USB-type balance 13 as a whole to ensure accurate acquisition of mass data.

[0061] The mobile temperature monitoring system is used to measure the flame temperature distribution in real time. It includes a thermocouple probe 9, a wireless temperature sensor 12, and a thermocouple bracket 8. The thermocouple probe 9 is fixed at a preset position above the narrow oil tank 6 via the thermocouple bracket 8 to collect flame temperature data at different locations. The wireless temperature sensor 12 is connected to the thermocouple 9 via thermocouple wire 15 and fixed inside the moving body 2. The wireless temperature sensor 12 can wirelessly upload temperature data in real time to a computer terminal equipped with a receiver. Combined with the accompanying data acquisition software (which is a mature existing technology and will not be described in detail here), it can realize real-time monitoring, storage, and analysis of flame temperature, ultimately achieving mobile monitoring of flame temperature. The wireless temperature sensor 12 of this invention has a temperature monitoring range of 0-800℃, a measurement resolution of 0.1℃, a sampling interval of 1s, and is powered by a 3.6V lithium-ion battery.

[0062] The present invention also includes a fireproof and heat-insulating layer 16, which is disposed in the upper middle part of the USB-type balance 13. It adopts a composite structure of rock wool and gypsum board. Under the premise of ensuring the measurement accuracy of the balance, the fireproof and heat-insulating layer 16 can effectively block the high temperature of the flame from causing thermal damage to the balance and the electronic equipment below. The thickness and position of the fireproof and heat-insulating layer 16 have been optimized to ensure that it can provide sufficient heat insulation protection without interfering with the weighing function of the balance.

[0063] The bottom of the elongated oil tank 6 of the present invention has a protruding structure, which is connected to the fireproof plate 5 by a dual fixing method of bonding with high temperature resistant adhesive and fastening with fixing screws 10, thereby further improving the stability of the device.

[0064] Theoretical analysis of the liquid fire spread simulation unit:

[0065] Taking the spread of a moving liquid fire in a tunnel as an example, during the movement of the moving body, due to the piston effect, a backflow wind speed w will be generated in the annular space formed by the moving body 2 and the tunnel wall. This backflow wind speed w is relative to the speed of the moving body 2, i.e., the relative wind speed v. s It can be represented as:

[0066]

[0067] Where: v0 is the velocity of the moving body, m / s;

[0068] v1 is the piston wind speed inside the tunnel, in m / s;

[0069] w represents the recirculating air velocity within the annular space, in m / s;

[0070] α0 is the blocking ratio of the moving body to the tunnel.

[0071] The mass loss rate is a necessary parameter for processing flame data in mobile mass loss monitoring systems, and its calculation formula is as follows:

[0072]

[0073] In the formula: It is the rate of mass loss per unit area of ​​a single flame at the head, in m / s;

[0074] It is the rate of mass loss per unit area of ​​the flame spread region, in m / s;

[0075] l is the length of the flame spread area, in meters;

[0076] l * It is the length of a single flame at the head, in meters (m).

[0077] L is the total length of the long, narrow oil tank, in meters;

[0078] It is the rate of total mass loss per unit area of ​​a narrow, elongated oil tank fire, in m / s;

[0079] The flame tilt angle is defined as the angle between the axis of the first flame at the head of the fire spread and the vertical direction, and its calculation formula is as follows:

[0080] cos(θ)=a(v * ) b

[0081]

[0082] In the formula: θ is the flame tilt angle, °;

[0083] v * The longitudinal ventilation velocity is a dimensionless velocity.

[0084] a and b are constants;

[0085] v represents the longitudinal ventilation velocity, in m / s;

[0086] g is the acceleration due to gravity, m / s² 2 ;

[0087] D is the equivalent oil tank diameter, in meters;

[0088] ρ0 is the air density, g / m³ 3 ;

[0089] Flame height is defined as the vertical distance from the tip of the first flame at the fire spread head to the fuel surface, and its calculation formula is as follows:

[0090]

[0091] In the formula: H is the flame height, in meters;

[0092] d is the width of the narrow oil groove, in meters (m).

[0093] This refers to dimensionless mass loss per unit area.

[0094] α and β are constants;

[0095] In this invention, the dynamic characteristics of a moving fire source induce complex changes in the flow field within the tunnel, further leading to a significant impact of the airflow within the tunnel on the spread of the flame. Under these circumstances, the longitudinal ventilation velocity v can be determined by the relative wind speed v s Characterized by this, the formula for calculating the flame tilt angle can be expressed as:

[0096]

[0097] The formula for calculating flame height can be expressed as:

[0098]

[0099] The piston wind data required in the above formula of this invention is obtained by measuring the anemometer installed at key locations on the mobile fire source experimental platform. At the same time, the mass loss rate data during the fire spread process is collected by the mobile mass loss monitoring system. The predicted values ​​of flame tilt angle and flame height can be obtained by calculating through the above formula.

[0100] Specific usage of this invention:

[0101] I. Installation and Debugging of Experimental Apparatus

[0102] 1.1 The experimental apparatus of the present invention is installed on a tunnel mobile fire source experimental platform equipped with a power traction system and guide rails;

[0103] 1.2 High-precision anemometers were placed at key locations on the experimental platform to collect piston wind data;

[0104] 1.3 Multiple high-speed cameras were set up on one side of the experimental platform to capture the liquid fire spread behavior and surface flow characteristics;

[0105] II. Experimental Preparation

[0106] 2.1 By adjusting the relative position of the inner shell 4 and the outer shell 3 of the moving body, the blocking ratio parameter is changed;

[0107] 2.2 Adjust the height of the adjustable metal frame 14 according to the actual height of the moving body 2 so that the narrow oil tank 6 is in the preset experimental position;

[0108] 2.3 Position the moving body 2 to its starting position (generally the beginning or end of the tunnel);

[0109] 2.4 Set the motion parameters of moving body 2, including parameters such as motion speed and acceleration;

[0110] 2.5 Activate the mobile temperature monitoring system, mobile mass loss monitoring system, high-speed camera, and anemometer;

[0111] 2.6 Adjust all monitoring instruments to normal working condition;

[0112] III. Experiment Implementation

[0113] 3.1 Inject a predetermined amount of liquid fuel into the narrow oil tank 6;

[0114] 3.2 Perform the following operations simultaneously: Ignite one end of the narrow oil tank 6; Start the moving body 2 to move according to preset parameters;

[0115] 3.3 When the moving body 2 reaches the tunnel end, shut down the data acquisition system;

[0116] 3.4 Extinguish the experimental flame promptly;

[0117] IV. Experimental Cycle

[0118] 4.1 After the temperature field and flow field inside the tunnel have returned to a stable state, adjust the experimental parameters;

[0119] 4.2 Repeat steps two and three to conduct the next set of experiments;

[0120] V. Data Processing and Analysis

[0121] 5.1 Image processing techniques are used to process fire spread images to obtain flame morphology features and flame front location data;

[0122] 5.2 The data collected by multiple high-speed cameras were processed by arithmetic averaging to obtain the experimental measured values ​​of liquid fire spread rate, flame tilt angle and flame height;

[0123] 5.3 Based on the piston wind data collected by the anemometer and the mass loss data collected by the moving mass loss monitoring system, the theoretical predicted values ​​are obtained by substituting them into the calculation formulas for flame tilt angle and flame height.

[0124] 5.4 Comparative analysis of the differences between experimental measurements and theoretical predictions.

[0125] Using the above methods, we studied the propagation law of liquid fuel in the co-current and counter-current flow under the coupled effects of multiple factors such as different motion states (uniform speed, acceleration, deceleration) and different blockage ratios, and revealed the interaction mechanism between the complex flow field changes caused by motion and the two dynamic processes of liquid fire propagation.

Claims

1. A tunnel-moving liquid fire spread simulation experimental device, characterized in that, The moving body (2) includes a precision wheel set (1) at the bottom. The moving body (2) is a hollow double-layer nested structure consisting of an inner shell (4) and an outer shell (3). Inside the moving body (2) are integrated a liquid fire spread simulation unit, a moving mass loss monitoring system and a moving temperature monitoring system. The liquid fire spread simulation unit is located on the top of the moving body (2), including a narrow oil tank (6) for holding flammable liquid and a fireproof plate (5). The narrow oil tank (6) is set on the upper part of the fireproof plate (5). One side wall of the narrow oil tank (6) is made of fireproof glass to form a visual observation window. The mobile mass loss monitoring system is located below the liquid fire spread simulation unit and is used to measure the mass change during the liquid combustion process in real time. It includes a USB-type balance (13) and an adjustable height metal frame (14). The adjustable height metal frame (14) is fixed to the bottom of the moving body (2) and placed below the USB-type balance (13). During the experiment, the long and narrow oil tank (6) and the fireproof plate (5) are placed on the USB-type balance (13). The mobile temperature monitoring system is used to measure the flame temperature distribution in real time. It includes a thermocouple probe (9), a wireless temperature sensor (12), and a thermocouple bracket (8). The thermocouple probe (9) is fixed above the narrow oil tank (6) at a preset position by the thermocouple bracket (8). The wireless temperature sensor (12) is connected to the thermocouple probe (9) by a thermocouple wire (15) and fixed inside the moving body (2). The wireless temperature sensor (12) uploads the temperature data to a computer terminal equipped with a receiver in real time via wireless means.

2. The tunnel moving liquid fire spread simulation experimental device according to claim 1 or 2, characterized in that, The outer surface of the inner shell (4) of the moving body is provided with multiple mounting holes at different heights. The mounting holes and the fixing bolts (11) set on the outer shell (3) of the moving body form an adjustable mating structure. By selecting mounting holes of different heights and fixing bolts (11) for assembly, the position of the inner shell (4) of the moving body can be adjusted in the vertical direction.

3. The tunnel moving liquid fire spread simulation experimental device according to claim 1 or 2, characterized in that, It also includes a fireproof and heat-insulating layer (16), which is located in the upper middle part of the U-shaped balance (13) and adopts a composite structure of rock wool and gypsum board.

4. The tunnel moving liquid fire spread simulation experimental device according to claim 1 or 2, characterized in that, The bottom of the narrow oil tank (6) is provided with a protruding structure, which is connected to the fireproof plate (5) by a dual fixing method of bonding with high temperature resistant adhesive and fixing screws (10).

5. The tunnel moving liquid fire spread simulation experimental device according to claim 4, characterized in that, The wireless temperature sensor (12) has a temperature monitoring range of 0-800℃, a measurement resolution of 0.1℃, a sampling interval of 1s, and is powered by a 3.6V lithium-ion battery.

6. The tunnel moving liquid fire spread simulation experimental device according to claim 2, characterized in that, Theoretical analysis of the liquid fire spread simulation unit: Taking the spread of a moving liquid fire in a tunnel as an example, during the movement of the moving body, due to the piston effect, a backflow wind speed w will be generated in the annular space formed by the moving body (2) and the tunnel wall. This backflow wind speed w is relative to the speed of the moving body (2), i.e., the relative wind speed v. s Represented as: Where: v0 is the velocity of the moving body, m / s; v1 is the piston wind speed inside the tunnel, in m / s; w represents the recirculating air velocity within the annular space, in m / s; α0 is the blocking ratio of the moving body to the tunnel.

7. The tunnel moving liquid fire spread simulation experimental device according to claim 6, characterized in that, The mass loss rate is a necessary parameter for processing flame data in mobile mass loss monitoring systems, and its calculation formula is as follows: In the formula: It is the rate of mass loss per unit area of ​​a single flame at the head, in m / s; It is the rate of mass loss per unit area of ​​the flame spread region, in m / s; l is the length of the flame spread area, in meters; l * It is the length of a single flame at the head, in meters (m). L is the total length of the long, narrow oil tank, in meters; It is the rate of total mass loss per unit area of ​​a narrow, elongated oil tank fire, in m / s; The flame tilt angle is defined as the angle between the axis of the first flame at the head of the fire spread and the vertical direction, and its calculation formula is as follows: cos(θ)=a(v * ) b In the formula: θ is the flame tilt angle, °; v * The longitudinal ventilation velocity is a dimensionless velocity. a and b are constants; v represents the longitudinal ventilation velocity, in m / s; g is the acceleration due to gravity, m / s² 2 ; D is the equivalent oil tank diameter, in meters; ρ0 is the air density, g / m³ 3 ; Flame height is defined as the vertical distance from the tip of the first flame at the fire spread head to the fuel surface, and its calculation formula is as follows: In the formula: H is the flame height, in meters; d is the width of the narrow oil groove, in meters (m). This refers to dimensionless mass loss per unit area. α and β are constants; The dynamic characteristics of a moving fire source induce complex changes in the flow field within the tunnel, further leading to a significant impact of airflow on flame spread. Under these circumstances, the longitudinal ventilation velocity v changes due to the relative wind speed v0. s To characterize this, the formula for calculating the flame tilt angle is expressed as: The formula for calculating flame height is expressed as:

8. The tunnel moving liquid fire spread simulation experimental device according to claim 6, characterized in that, It also includes an anemometer, which is installed on the corresponding mobile fire source experimental platform.

9. The tunnel moving liquid fire spread simulation experimental device according to claim 6, characterized in that, The range of the USB-type balance (13) is 5000g, the accuracy is 0.01g, and the minimum sampling interval is 0.125s.

Images