Method and device for correcting the fire propagation speed of a liquid fire based on the ambient temperature

Abstract

The present application relates to the technical field of liquid fire experiment, more particularly, to a correction method and device for liquid fire spread speed based on ambient temperature, wherein the fuel density, surface tension coefficient and maximum temperature of surface flow are obtained, and the three unknown quantities are substituted into the expression of surface flow speed; then, the parameters of the expression are inversely solved according to the data of reference experiment, and the relationship between the liquid fire spread speed and ambient temperature is obtained, so as to realize the correction of the error caused by the difference between the ambient temperature of subsequent experiment and that of reference experiment. The whole process is fast and convenient, and the correction relationship of the present application has good correction effect after verification, which can effectively eliminate the error caused by ambient temperature and solve the problem that the liquid fire spread speed is not corrected in the prior art.

Description

Technical Field

[0001] This invention relates to the field of experimental technology for liquid fires, and more specifically, to a method and apparatus for correcting the spread rate of liquid fires based on ambient temperature. Background Technology

[0002] In their experimental research on liquid fires, the inventors found that temperature has a significant impact on the rate of fire spread. Maintaining a constant ambient temperature is particularly important when studying the effects of other parameters on fire spread characteristics under constant environmental temperature conditions.

[0003] Liquid fire experiments are a lengthy process. In reality, daily temperatures can vary slightly, sometimes even experiencing significant fluctuations in a single day, or fire spread experiments may need to be conducted in different seasons. Therefore, the influence of ambient temperature, an uncontrollable factor, on fire spread characteristics, especially the speed of fire spread, needs to be corrected for through other methods. Summary of the Invention

[0004] Therefore, it is necessary to provide a method and apparatus for correcting the spread rate of liquid fires based on ambient temperature, addressing the existing lack of methods for correcting the spread rate of liquid fires.

[0005] This invention is achieved using the following technical solution:

[0006] In a first aspect, the present invention discloses a method for correcting the fire spread rate of liquid fire based on ambient temperature, which is used to correct the error caused by the difference between the ambient temperature of subsequent experiments and the ambient temperature of reference experiments, while keeping other experimental parameters unchanged; wherein, the other experimental parameters are experimental parameters other than ambient temperature.

[0007] The correction method includes the following steps:

[0008] S1, the expression for constructing the surface flow velocity is: In the formula, u s Let ν be the surface flow velocity, i.e., the fire spread velocity in a liquid fire; let ν be the viscosity coefficient of the fuel; let μ be the dynamic viscosity of the fuel; let λ be the thermal conductivity of the fuel; and let σ be the viscosity coefficient of the fuel. T Let be the surface tension coefficient, (ΔT) s The maximum temperature T at the surface flow point max The difference between the ambient temperature T0 and the ambient temperature, i.e., (ΔT) s =T max -T0, α is the thermal diffusivity of the fuel, c p The specific heat capacity of the fuel. R The characteristic length of the surface flow region;

[0009] The second expression for the surface tension coefficient is: In the formula, σ T ρ is the surface tension coefficient, k is the Etvs constant, ρ is the fuel density, M is the molar mass of the fuel, and T is the surface tension coefficient. c The maximum critical temperature exists when surface tension is present, and T is the temperature at the surface flow point.

[0010] The third expression for fuel density is: ρ=(a+bT+cT) 2 ) -3 / 2 In the formula, a, b, and c are undetermined coefficients; or ρ can be a known value.

[0011] The fourth expression for the maximum temperature at the surface flow point is: δ k For surface flow thickness, Q cv The heat received by the surface flow region. Δh represents the amount of fuel consumed per unit area per unit time, and Δh represents the latent heat of vaporization of the fuel.

[0012] S2, obtain the experimental parameters of the reference experiment, calculate the fuel density, surface tension coefficient, and maximum temperature at the surface flow under the reference experiment, and substitute them into expression one to construct u. s Equation 1 regarding the relationship between T0 and k;

[0013] S3, taking the ambient temperature of the reference experiment as T0, and the experimental result of the surface flow velocity of the reference experiment as u. s Substitute into relation one and calculate k in reverse;

[0014] S4, substitute the calculated k into relation one to construct u s Equation 2 is used to determine the relationship between T0 and the fire spread rate of liquid fire in subsequent experiments based on the ambient temperature of the subsequent experiments.

[0015] This method for correcting the spread rate of liquid fire based on ambient temperature implements the method or process according to embodiments of this disclosure.

[0016] Secondly, the present invention discloses a device for correcting the spread rate of a liquid fire based on ambient temperature, which uses the method for correcting the spread rate of a liquid fire based on ambient temperature disclosed in the first aspect.

[0017] A device for correcting the spread rate of liquid fire based on ambient temperature includes: an expression construction module, a relation construction module one, a coefficient inverse calculation module, and a relation construction module two.

[0018] The expression construction module is used to construct Expression 1 for the surface flow velocity. The relation construction module 1 is used to obtain the experimental parameters of the reference experiment, obtaining the calculated results of fuel density, surface tension coefficient, and maximum temperature at the surface flow under the reference experiment, and substituting them into Expression 1 to construct u. s Equation 1 shows the relationship between T0 and k. The coefficient inverse calculation module is used to take the ambient temperature of the reference experiment as T0 and the experimental result of the surface flow velocity of the reference experiment as u. s Substitute the values ​​into relation one and calculate k in reverse. Relation construction module two is used to substitute the calculated k into relation one to construct u. s Equation 2 is used to determine the relationship between T0 and the fire spread rate of liquid fire in subsequent experiments based on the ambient temperature of the subsequent experiments.

[0019] This device for correcting the spread rate of liquid fire based on ambient temperature implements the method or process according to embodiments of this disclosure.

[0020] Thirdly, the present invention discloses a readable storage medium. The readable storage medium stores computer program instructions, which, when read and executed by a processor, perform the steps of the method for correcting the spread rate of a liquid fire based on ambient temperature disclosed in the first aspect.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] This invention obtains fuel density, surface tension coefficient, and maximum surface flow temperature, and substitutes these three quantities into the expression for surface flow velocity. Then, based on data from a reference experiment, the parameters are inversely calculated from the expression to derive the relationship between the fire spread rate of a liquid fire and ambient temperature. This corrects for errors caused by differences in ambient temperature between subsequent experiments and the reference experiment. The entire process is quick and convenient, and the corrective relationship of this invention has been verified to have good correction effects, effectively eliminating errors caused by ambient temperature. Attached Figure Description

[0023] Figure 1 This is a flowchart of the method for correcting the fire spread rate of a liquid fire based on ambient temperature in Embodiment 1 of the present invention;

[0024] Figure 2 This is a graph showing the correction result of ambient temperature on the spread rate of ethanol fire in Embodiment 2 of the present invention;

[0025] Figure 3 This is a graph showing the correction result of ambient temperature on the fire spread rate of isoamyl alcohol in Example 2 of the present invention. Detailed Implementation

[0026] 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.

[0027] It should be noted that when a component is said to be "installed on" another component, it can be directly on the other component or it may be in a component that is centered on it. When a component is said to be "set on" another component, it can be directly set on the other component or it may also be in a component that is centered on it. When a component is said to be "fixed to" another component, it can be directly fixed to the other component or it may also be in a component that is centered on it.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "or / and" as used herein includes any and all combinations of one or more of the associated listed items.

[0029] Example 1

[0030] Please see Figure 1 , Figure 1 This is a flowchart of the method for correcting the fire spread rate of liquid fires based on ambient temperature in this invention. The purpose of this correction method is to correct the error caused by the difference between the ambient temperature of subsequent experiments and the ambient temperature of the reference experiment, while keeping other experimental parameters unchanged. It should be noted that the other experimental parameters are experimental parameters other than ambient temperature, such as fuel type, etc.

[0031] This modified method is applicable to experiments on the spread of liquid fire in narrow spaces with thick oil layers. The experimental subject is the spread of fire in narrow spaces with thick oil layers. Here, "thick oil layer" refers to a fuel depth of ≥25mm.

[0032] The correction method includes the following steps:

[0033] S1, the expression for constructing the surface flow velocity is: In the formula, u s Let ν be the surface flow velocity, i.e., the fire spread velocity in a liquid fire; let ν be the viscosity coefficient of the fuel; let μ be the dynamic viscosity of the fuel; let λ be the thermal conductivity of the fuel; and let σ be the viscosity coefficient of the fuel. T Let be the surface tension coefficient, (ΔT) s The maximum temperature T at the surface flow point max The difference between the ambient temperature T0 and the ambient temperature, i.e., (ΔT)s =T max -T0, α is the thermal diffusivity of the fuel, c p R is the specific heat capacity of the fuel, and R is the characteristic length of the surface flow region.

[0034] Specifically, a mechanical analysis is performed on the surface flow region, an equivalent Reynolds number Re′ is constructed, and combined with the Reynolds number Re, to obtain the fourth expression for the surface flow velocity:

[0035] For surface flow regions, three typical velocities exist: thermocapillary velocity, thermal diffusivity, and molecular diffusivity. Based on these three typical velocities, the equivalent Reynolds number is obtained.

[0036] Where Ma is the Marangoni number, a dimensionless number. Ma is the ratio of thermocapillary effect to viscous force, i.e.:

[0037] Since μ / ν=ρ, Ma is changed to:

[0038] In the formula, For thermocapillary velocity, For molecular diffusion rate, This represents the thermal diffusion rate.

[0039] Pr is the Prandtl number.

[0040] The equivalent Reynolds number Re′ is the ratio of inertial force to viscous force, i.e., thermocapillary velocity. Except for molecular diffusion rate Right now

[0041] The Reynolds number Re = ρu s R / μ, let Re′=Re, that is After substituting and transforming, we get

[0042] Furthermore, for fuels: the ratio of their dynamic viscosity to their viscosity coefficient is their density, i.e., μ / ν = ρ; their thermal conductivity can be written as the product of their diffusion coefficient, specific heat capacity, and density, i.e., λ = α·c p ·ρ.

[0043] Based on μ / ν=ρ, λ=α·c p ·ρ can also be simplified to obtain the expression for the surface flow velocity:

[0044] The simplified expression four has fewer parameters—only four unknown parameters on the right side.

[0045] So, the next step is to obtain the parameter expression on the right:

[0046] The following section introduces the surface tension coefficient, fuel density, and maximum surface flow temperature. These three parameters are not required to be in any particular order and can be evaluated simultaneously.

[0047] This embodiment 1 follows Figure 1 The order will be explained as follows:

[0048] S1.1, the fuel density is expressed by expression three as follows:

[0049] ρ=(a+bT+cT 2 ) -3 / 2 ;

[0050] In the formula, ρ is the fuel density, a, b, and c are undetermined coefficients, and T is the surface flow temperature.

[0051] In this embodiment 1, a, b, and c are determined experimentally. Currently, the coefficients for approximately 150 types of fuels have been determined experimentally, and can be selected accordingly based on the type of fuel chosen in the experiment. T is obtained by photographing the flame with an imager and measuring the temperature using thermocouples arranged along the direction of fire spread. Specifically, the flame spreads forward, so the position in front of the flame is constantly changing. The flame is located by photographing it with a camera or other imager, and the real-time position in front of the flame is measured. The real-time data from the thermocouples at that position is then obtained, which is T.

[0052] Of course, ρ can also be directly taken from existing known values. That is, after measuring T, the corresponding fuel density value can be found from existing experimental values ​​or publicly available empirical values.

[0053] S1.2, the surface tension coefficient is expressed by expression two as follows:

[0054]

[0055] In the formula, σ T ρ is the surface tension coefficient, k is the Etvs constant, ρ is the fuel density, M is the molar mass of the fuel, and T is the surface tension coefficient. c The maximum critical temperature is denoted by , where surface tension exists, and T is the temperature at the surface flow point.

[0056] Specifically, by taking the first derivative of the Etvs formula with respect to temperature, we obtain the second expression for the surface tension coefficient.

[0057] Right now, In the formula, σ represents the Etvs formula.

[0058] It is important to note that the premise for constructing Expression 2 is that it applies to small-scale liquid fires that are in the liquid-phase dominant stage. Here, "liquid-phase dominant stage" refers to a fire spread rate of less than 10 cm / s; "small-scale" means the width of the oil tank is ≤15 cm.

[0059] S1.3, the maximum temperature at the surface flow point is expressed by expression four;

[0060]

[0061] In the formula, T max δ represents the maximum temperature at the surface flow point. k For surface flow thickness, Q cv The heat received by the surface flow region. Δh is the amount of fuel consumed per unit time per unit area, λ is the latent heat of vaporization of the fuel, T0 is the thermal conductivity of the fuel, and T0 is the ambient temperature.

[0062] Where Δh and λ are both physical properties of the fuel, and can be empirical values. δ k Temperature is measured using thermocouples arranged along the fuel depth direction, and images are taken of these thermocouples using an image sensor. Specifically, since the area with a temperature higher than the cold oil temperature along the depth direction falls within the surface flow thickness range, the temperature data obtained from the thermocouples arranged along the fuel depth direction can determine the thermocouples corresponding to the surface flow thickness range. Further analysis of the images taken by the image sensor yields the δ value. k . The measurement was taken using a balance placed at the bottom of the oil tank.

[0063] It is important to note that the premise for constructing expression four is the assumption that δ... k , It is not affected by ambient temperature.

[0064] Specifically, based on the thermal boundary conditions at the gas-liquid interface and considering the heat loss from vaporization, the fourth expression for the maximum temperature at the surface flow is derived:

[0065] The thermal boundary layer conditions at the gas-liquid interface are derived from the thermal equilibrium and continuity of temperature:

[0066]

[0067] The subscript 'l' indicates a liquid, and the subscript 'g' indicates a gas. This represents the temperature variation of the liquid phase (fuel) with depth. Here, q′ represents the temperature variation of the gas with depth, k is the thermal conductivity, and parameters marked with * are dimensionless. R q represents the radiant heat received by the object being analyzed. g，* ρ′ represents the heat of vaporization of the gas.g V' represents the density of the evaporated gas. g h′ represents the gas evaporation rate. fg It is the latent heat of vaporization.

[0068] For the initial temperature gradient below the gas-liquid interface, neglecting the initial thermal conductivity and gas vaporization, therefore v′ g =0. And get:

[0069] It can be approximated as Therefore, it can be written as: Where δ k It is the surface flow thickness, therefore:

[0070] In S1.3, the heat received by the surface flow region is represented by Q. cv The thermal conductivity is represented by λ. Furthermore, Q... cv Part of it is used for liquid vaporization, and the heat of vaporization formula is... Therefore, we get:

[0071]

[0072] After conversion, it becomes

[0073] Additionally, regarding Q cv Its main heat transfer is liquid phase heat transfer, so it can be written as equation (1):

[0074]

[0075] In equation (1), y represents depth; u s (y) The velocity of the surface flow region at different depths, c p Let be the specific heat capacity of the fuel. The final unit of equation (1) is kW / m³.

[0076] Multiplying equation (1) by the width of the oil tank and then dividing by the surface flow area, we can convert it to a quantity with dimensions of kW / m². 2 In the form of formula (2):

[0077]

[0078] In equation (2), L s This is the actual length of the surface flow region.

[0079] L sBy measuring the temperature using thermocouples arranged along the fire spread direction and combining this with images of the flame position captured by an imager, the following can be obtained: Specifically, since the length of the region in front of the flame where the fuel temperature is higher than the cold oil temperature falls within the surface flow length range, the temperature data obtained from the thermocouples arranged along the fire spread direction can determine the thermocouples corresponding to the surface flow length range. Further analysis of the flame images captured by the imager yields L. s .

[0080] After the surface flow stabilizes, there are no parameters in equation (2) that change with ambient temperature, and the ratio of the surface flow velocity to its average velocity is 3 / 2. Equation (2) then becomes equation (3):

[0081]

[0082] S2, obtain the experimental parameters of the reference experiment, calculate the fuel density, surface tension coefficient, and maximum temperature at the surface flow under the reference experiment, and substitute them into expression one to construct u. s Equation 1 shows the relationship between T0 and k.

[0083] In other words, first put u s T0 and k are taken as unknowns. Then, according to the parameter acquisition process of S1, the experimental parameters are obtained from the reference experiment as knowns for calculation. The calculation results are then substituted into expression one to obtain u. s The first equation relating to T0 and k is u. s The relationship between the changes in T0 and k.

[0084] S3, taking the ambient temperature of the reference experiment as T0, and the experimental result of the surface flow velocity of the reference experiment as u. s Substitute the equation into relation 1 and calculate k in reverse.

[0085] In other words, T0 is taken as the ambient temperature of the reference experiment, as a known quantity; u s Take the surface flow velocity experimental results from the reference experiment as a known quantity. Then, substitute them into equation one to calculate k.

[0086] The surface flow velocity obtained in the reference experiment is equal to the fire spread velocity measured in the reference experiment. This is because the experimental subject is the spread of a thick oil layer fire in a narrow space, and the surface flow velocity that propagates steadily can be considered the fire spread velocity. Therefore, the surface flow velocity can be obtained by measuring the fire spread velocity. Generally, a camera can be placed in the flame propagation space to capture the fire spread, and the distance the flame spreads at a certain moment can be obtained by processing the data. The derivative of this data is then used to obtain the fire spread velocity.

[0087] S4, substitute the calculated k into relation one to construct u sEquation 2 is used to determine the relationship between T0 and the fire spread rate of liquid fire in subsequent experiments based on the ambient temperature of the subsequent experiments.

[0088] In other words, the calculated k is taken as a known quantity, u s With T0 as the unknown, substituting the calculated k into relation one, we obtain u. s Equation 2 with respect to T0, that is, u s The relationship between the change and T0.

[0089] Since the type of fuel does not change within the same experimental group, the k obtained from the reference experiment can be used in the next experiment.

[0090] This embodiment 1 also discloses a device for correcting the spread rate of liquid fires based on ambient temperature, which uses the above-mentioned method for correcting the spread rate of liquid fires based on ambient temperature.

[0091] The device for correcting the spread rate of liquid fires based on ambient temperature includes: an expression construction module, a relation construction module one, a coefficient inverse calculation module, and a relation construction module two.

[0092] The expression construction module is used to construct Expression 1 for the surface flow velocity. The relation construction module 1 is used to obtain the experimental parameters of the reference experiment, obtaining the calculated results of fuel density, surface tension coefficient, and maximum temperature at the surface flow under the reference experiment, and substituting them into Expression 1 to construct u. s Equation 1 shows the relationship between T0 and k. The coefficient inverse calculation module is used to take the ambient temperature of the reference experiment as T0 and the experimental result of the surface flow velocity of the reference experiment as u. s Substitute the values ​​into relation one and calculate k in reverse. Relation construction module two is used to substitute the calculated k into relation one to construct u. s Equation 2 is used to determine the relationship between T0 and the fire spread rate of liquid fire in subsequent experiments based on the ambient temperature of the subsequent experiments.

[0093] Example 2

[0094] This embodiment 2 verifies the modified method disclosed in embodiment 1.

[0095] Verification Example 1:

[0096] An experimental setup with an oil tank measuring 100cm x 4cm x 10cm (length x width x height) was selected, and ethanol was used as the fuel. Since ethanol has a low flash point, the ambient temperature for verification example 1 should be close to 0℃. The molar mass M of ethanol is 46 g / mol, the latent heat of vaporization Δh is 880 kJ / kg, the thermal conductivity λ is 0.32 W / m·K, and the specific heat capacity c... pIt is 2.4 kJ / (kg / ℃), and the maximum critical temperature T c The temperature is 10℃.

[0097] The initial experimental temperature of 0℃ was set as the ambient temperature value for the entire experimental system. Subsequent experiments with ambient temperatures other than 0℃ will require adjustments to the fire spread rate. In other words, the initial experiment at 0℃ will be used as a reference experiment.

[0098] Verification steps:

[0099] A1: Based on data measured by thermocouples arranged along the fuel depth direction, combined with camera positioning, the temperature of the liquid fuel at the surface flow is approximately 10℃. According to available data, the three undetermined coefficients a, b, and c in the empirical formula for density change with temperature are 1.154, 7.955 × 10⁻⁶, and 7.955 × 10⁻⁶, respectively. -4 10.149×10 -7 .

[0100] A2: Take the first derivative of the Etvs formula with respect to temperature, then substitute the density-temperature formula from A1 into the equation to obtain the surface tension coefficient σ. T Relationship with Etvs constant k.

[0101] A3: Process two sets of thermocouple data along the fire spread direction and the fuel depth direction. Define the region along the length of the heating zone in front of the flame as the surface flow region, and measure the surface flow thickness δ. k and actual length L s , The maximum surface flow temperature T was obtained by placing a balance at the bottom of the oil tank. max With surface flow velocity u s From this relationship, we can further derive (ΔT). s =T max -T0 and surface flow velocity u s relation.

[0102] A4: Let μ / ν=ρ and λ=α·c p ·ρ, then we get

[0103] A5: Regarding Surface tension coefficient σ T Substituting the results from A2, the difference (ΔT) between the maximum surface flow temperature and the ambient temperature is calculated. s Substitute the results from A3 into the equation, and the density ρ into the equation from A1; R is the characteristic length of the surface flow, which is the width of the oil tank in the experiment of Verification Example 1, and is 4 cm.

[0104] will u s T0 and k are considered as unknowns. That is, convert to u sThe relationship between T0 and k.

[0105] A6: Substitute the experimental results of the initial ambient temperature T0 = 0℃ and the surface flow velocity into u in A5. s From the relationship between T0 and k, k can be calculated.

[0106] Since the fuel type remains unchanged in a set of experiments, the k calculated from the results of the first experiment can be used in the next experiment, thus enabling the use of u in A5. s The relationship between the changes in T0 and k is converted into u. s The relationship between T0 and the change of T0.

[0107] A7: The ambient temperatures for subsequent experiments became: 1℃, 1.5℃, 2℃, 2.5℃, 3℃, 3.5℃, 4℃, utilizing the u from A6. s The relationship between the change in T0 and the fire spread rate was successively corrected. The correction results are as follows: Figure 2 As shown, the fire spread rate in subsequent experiments was corrected to be close to the experimental results of the first experiment (u0=2cm / s), and the correction effect was good.

[0108] Verification Example 2:

[0109] An experimental setup with an oil tank measuring 100cm × 3.3cm × 2.5cm (length × width × height) was selected, and isoamyl alcohol was used as the fuel. Because isoamyl alcohol has a high flash point, the ambient temperature for verification example 2 can be higher, for example, close to 20℃. The molar mass M of isoamyl alcohol is 88 g / mol, its latent heat of vaporization Δh is 486 kJ / kg, its thermal conductivity λ is 15 W / mK, and its specific heat capacity c... p It is 2.87 kJ / (kg / ℃), and the maximum critical temperature T c The temperature is 46℃.

[0110] The initial experimental temperature of 20℃ was set as the ambient temperature value for the entire experimental system. The fire spread rate needs to be modified for subsequent experiments where the ambient temperature is not 20℃. In other words, the initial experiment at an ambient temperature of 20℃ will be used as a reference experiment.

[0111] The correction method is the same as that in verification example 1, and will not be repeated here.

[0112] This verifies the corrections made to Example 2's five sets of experiments at 25℃, 30℃, 35℃, 40℃, and 45℃. The correction results are as follows: Figure 3 As shown, the fire spread rate in subsequent experiments was corrected to be close to the experimental results of the first experiment (u0=1cm / s), and the correction effect was good.

[0113] Example 3

[0114] This embodiment 3 discloses a readable storage medium storing computer program instructions. When the computer program instructions are read and executed by a processor, the steps of the method for correcting the spread rate of liquid fire based on ambient temperature in embodiment 1 are performed.

[0115] When applying the method of Example 1, it can be applied in the form of software, such as by designing it as a program that can run independently on a computer-readable storage medium. The computer-readable storage medium can be a USB flash drive, designed as a USB security token, and the program can be designed to start the entire method through an external trigger.

[0116] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0117] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A method for correcting the fire spread rate of liquid fires based on ambient temperature, used to correct errors caused by differences between the ambient temperature of subsequent experiments and the ambient temperature of a reference experiment, while keeping other experimental parameters constant; wherein, The remaining experimental parameters are those other than the ambient temperature; its characteristic is that... The correction method includes the following steps: S1, the expression for constructing the surface flow velocity is: In the formula, u s Let ν be the surface flow velocity, i.e., the fire spread velocity in a liquid fire; let ν be the viscosity coefficient of the fuel; let μ be the dynamic viscosity of the fuel; let λ be the thermal conductivity of the fuel; and let σ be the viscosity coefficient of the fuel. T Let be the surface tension coefficient, (ΔT) s The maximum temperature T at the surface flow point max The difference between the ambient temperature T0 and the ambient temperature, i.e., (ΔT) s =T max -T0, α is the thermal diffusivity of the fuel, c p The specific heat capacity of the fuel. R The characteristic length of the surface flow region; The second expression for the surface tension coefficient is: In the formula, σ T ρ is the surface tension coefficient, k is the Etvs constant, ρ is the fuel density, M is the molar mass of the fuel, and T is the surface tension coefficient. c The maximum critical temperature exists when surface tension is present, and T is the temperature at the surface flow point. The third expression for fuel density is: ρ=(a+bT+cT) 2 ) -3 / 2 In the formula, a, b, and c are undetermined coefficients; or ρ can be a known value. The fourth expression for the maximum temperature at the surface flow point is: δ k For surface flow thickness, Q cv The heat received by the surface flow region. Δh represents the amount of fuel consumed per unit area per unit time, and Δh represents the latent heat of vaporization of the fuel. S2, obtain the experimental parameters of the reference experiment, calculate the fuel density, surface tension coefficient, and maximum temperature at the surface flow under the reference experiment, and substitute them into expression one to construct u. s Equation 1 regarding the relationship between T0 and k; S3, taking the ambient temperature of the reference experiment as T0, and the experimental result of the surface flow velocity of the reference experiment as u. s Substitute into relation one and calculate k in reverse; S4, substitute the calculated k into relation one to construct u s Equation 2 is used to modify the fire spread rate of liquid fires in subsequent experiments based on the ambient temperature of the subsequent experiments.

2. The method for correcting the fire spread rate of a liquid fire based on ambient temperature according to claim 1, characterized in that, In S1, a mechanical analysis is performed on the surface flow region, an equivalent Reynolds number Re′ is constructed, and combined with the Reynolds number Re, to obtain the expression for the surface flow velocity.

3. The method for correcting the fire spread rate of a liquid fire based on ambient temperature according to claim 1 or 2, characterized in that, In S1, it is also based on μ / ν=ρ, λ=α·c p ·ρ, simplifying expression one, yields:

4. The method for correcting the fire spread rate of a liquid fire based on ambient temperature according to claim 1, characterized in that, In S1, the first derivative of the Etvs formula with respect to temperature is used to obtain the second expression for the surface tension coefficient.

5. The method for correcting the fire spread rate of a liquid fire based on ambient temperature according to claim 1, characterized in that, In S1, based on the thermal boundary conditions at the gas-liquid interface and considering the heat loss of vaporization, the expression for the maximum temperature at the surface flow is derived.

6. The method for correcting the fire spread rate of a liquid fire based on ambient temperature according to claim 1, characterized in that, In S1, a, b, and c are determined experimentally; T is obtained by photographing the flame with an imager and measuring the temperature using thermocouples arranged along the direction of fire spread.

7. The method for correcting the fire spread rate of a liquid fire based on ambient temperature according to claim 1, characterized in that, In S1, δ k Temperature was measured using thermocouples arranged along the fuel depth direction, and the images were taken of these thermocouples using an image sensor. Measured by a balance placed at the bottom of the oil tank; Q cv The expression is: L s L is the actual length of the surface flow region. s The temperature is measured by thermocouples arranged along the direction of fire spread, and the location of the flame is captured by an imager.

8. The method for correcting the fire spread rate of a liquid fire based on ambient temperature according to claim 6, characterized in that, In S4, the experimental result of the surface flow velocity of the reference experiment is equal to the fire spread velocity measured by the reference experiment.

9. A device for correcting the fire spread rate of a liquid fire based on ambient temperature, characterized in that, It uses the method for correcting the spread rate of liquid fires based on ambient temperature as described in any one of claims 1-8; The device for correcting the fire spread rate of liquid fires based on ambient temperature includes: The expression building module is used to construct the expression for the surface flow velocity. The first module for constructing the relation is used to obtain the experimental parameters of the reference experiment, calculate the fuel density, surface tension coefficient, and maximum temperature at the surface flow under the reference experiment, and substitute them into expression one to construct u. s Equation 1 regarding the relationship between T0 and k; The coefficient inverse calculation module is used to take the ambient temperature of the reference experiment as T0 and the experimental result of the surface flow velocity of the reference experiment as u. s Substitute into relation one and calculate k in reverse; as well as Relational construction module two is used to substitute the inversely calculated k into relation one to construct u. s Equation 2 is used to modify the fire spread rate of liquid fires in subsequent experiments based on the ambient temperature of the subsequent experiments.

10. A readable storage medium, characterized in that, The readable storage medium stores computer program instructions, which are read and executed by a processor to perform the steps of the method for correcting the spread rate of a liquid fire based on ambient temperature as described in any one of claims 1-8.

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