A method for measuring the power of lightning arc-forest fuel heat transport and a key parameter calibration device and method thereof

Abstract

The present application provides a kind of simulated lightning arc-forest combustible heat transport power measurement method, comprising the following steps: S1) carry out simulated lightning arc ignites forest combustible experiment, obtains arc real-time current and voltage data;S2) by formula, the arc input power is calculated, wherein, for simulated lightning arc discharge duration;S3) according to the relationship formula, the simulated lightning arc-forest combustible heat transport power is calculated, wherein, for simulated lightning arc basic power.Meanwhile, the present application proposes a kind of device and method for calibrating the arc basic power in the above measurement method.The calibration device includes: solid-state heat exchange container, liquid heat exchange working medium and temperature sensor.

Description

Technical Field

[0001] This invention relates to the field of fire experiment measurement technology, and in particular to a method for measuring the heat transport power of simulated lightning arc-forest combustibles, and a calibration device and method for its key parameters. Background Technology

[0002] The proportion of forest and grassland fires caused by lightning strikes is increasing year by year. According to data from the Ministry of Emergency Management, the proportion of forest and grassland fires caused by lightning strikes in my country increased from 5.1% in 2019 to 38.7% in 2024. Research on the mechanism of lightning-induced fires and its prediction models is urgently needed. Studies have found that at the moment a lightning arc interacts with forest combustibles, the combustibles within the arc channel instantly vaporize and disappear, while the resulting arc continuously heats the combustibles surrounding the channel. Quantifying the heat power transported by the lightning arc to the combustibles through simulation experiments of lightning arcs igniting forest combustibles is one of the keys to studying the mechanism of lightning ignition and prediction models. Research indicates that lightning arcs with long continuous currents (duration greater than 40 ms, current on the order of hundreds of amperes) are the main type of lightning that causes lightning-induced fires. Researchers have developed a lightning-induced fire simulation experimental device that can generate such lightning arcs between two electrodes to simulate the process of lightning igniting forest combustibles in the laboratory. Because the duration of such simulated lightning arcs is extremely short (tens to hundreds of ms) and the heat flux density is extremely high (~10... 4 kW / m 2 Conventional measurement sensors (such as heat flow meters and thermocouples) have insufficient response speed and cannot be directly used under the high voltage and high temperature conditions of lightning strike fire simulation experiments, thus failing to obtain the heat transport power of the simulated lightning arc to combustibles. Therefore, there is an urgent need to develop a simple and effective laboratory method for measuring the heat transport power of simulated lightning arcs to forest combustibles. Summary of the Invention

[0003] To address the aforementioned experimental measurement challenges, this invention proposes a method for measuring the heat transport power of simulated lightning arc-forest combustibles, along with a calibration device and method for its key parameters. This method can calculate the heat transport power based on the electrical parameters of simulated lightning arc igniting forest combustibles, thus helping to quantify the danger of simulated lightning arc igniting forest combustibles.

[0004] To solve the aforementioned experimental measurement challenges, this invention provides the following technical solution: A method for measuring the heat transport power of simulated lightning arc-forest combustibles includes the following steps: S101) When conducting experiments simulating the ignition of forest combustibles by lightning arcs, the real-time current of the arc was obtained. and voltage data; S102) Through formula Calculate the input power of the electric arc ; S103) According to the relation Calculate and simulate the heat transport power of lightning arc-forest combustibles. ,in, The base power for simulating a lightning arc represents the electrical power required to sustain the simulated lightning arc.

[0005] As a further technical solution of the present invention: the simulated lightning arc mentioned in step S101 is an arc generated by a lightning strike fire simulation experimental device, and the arc duration is... For 40~400 ms, current intensity The range is 100~250 A; the lightning strike fire simulation experimental device simulates lightning arcs through capacitor discharge; As a further technical solution of the present invention: the steps described in S101 and To simulate real-time data of lightning arc current and voltage, measurements were taken using an oscilloscope.

[0006] A simulated lightning arc base power A calibration device for calibrating the base power of the simulated lightning arc as described in claim 1. This includes solid heat exchange containers, liquid heat exchange working fluids, and temperature sensors.

[0007] As a further technical solution of the present invention: the solid heat exchange container is a container made of a solid material with known density and specific heat capacity; the solid heat exchange container is composed of an annular trough-shaped container and an annular cap; the liquid heat exchange working fluid is a liquid with known density and specific heat capacity; the liquid heat exchange working fluid is installed inside the solid heat exchange container; the temperature sensor probe is immersed in the liquid heat exchange working fluid; the number of temperature sensors is not less than two and the measuring points are at different locations.

[0008] A simulated lightning arc base power The calibration method includes the following steps: S201) Fill the solid measurement container with liquid heat exchange medium and immerse the temperature sensor in the liquid heat exchange medium; S202) The calibration device is coaxially arranged with the discharge electrodes of the lightning strike fire simulation experimental device to measure the real-time temperature of the liquid heat exchange medium before the generation of the simulated lightning arc. ; S203) Conducting simulated lightning arc foundation power During the calibration experiment, the real-time current of the simulated lightning arc was measured. and voltage Data, measuring the real-time temperature of the liquid heat exchange working fluid. ; S204) Through formula Calculate the input power of the simulated lightning arc ; S205) Extraction calibration device initial temperature and steady-state temperature ; S206) Based on the initial temperature of the calibration device and steady-state temperature Calculate the heat transport power of the simulated lightning arc calibration device. ; S207) According to the relation: Calculate the base power of the simulated lightning arc .

[0009] As a further technical solution of the present invention: step S202 involves measuring the real-time temperature of the liquid heat exchange medium before the generation of the simulated lightning arc. The measurement duration shall be no less than 1 minute; step S203 describes measuring the real-time temperature of the liquid heat exchange medium after the simulated lightning arc is generated. The measurement duration shall be no less than 1 minute; the real-time temperature of the liquid heat exchange medium before and after the generation of the simulated lightning arc, as described in steps S202 and S203, shall be measured. and During this process, it is necessary to ensure that the temperature of the liquid heat exchange medium reaches a steady state, and that the measurement error of the temperature sensor at different locations does not exceed 0.5 within 3 seconds. o C is considered to be the temperature of the liquid heat exchange medium reaching a steady state, and the measured temperature value at this point is considered a valid measurement value; the temperature data mentioned in steps S202 and S203 and All require smoothing processing; the initial temperature of the calibration device described in step S205 Temperature of the liquid heat exchange working fluid The mean value when reaching steady state; the steady-state temperature of the calibration device described in step S205. These are correction values ​​for the temperature evolution data of the liquid heat exchange working fluid after discharge, for use... The temperature at time t=0 s is obtained by fitting the function to the steady-state temperature data of the heat exchange working fluid; the temperature obtained in step S6. The heat capacity of the calibration device is expressed as... ,in These are the mass and specific heat of the solid heat exchange container and the liquid heat exchange working fluid, respectively.

[0010] Beneficial effects: The method for measuring the heat transport power of simulated lightning arc-forest combustibles and the calibration device and method for its key parameters of the present invention can calculate the heat transport power of simulated lightning arc-combustibles based on the real-time electrical parameters of the arc in simulated lightning strike fire experiments. This avoids the problems of slow response speed and extreme heat flow damage when the sensor directly measures the arc heat flow. It can provide measurement technology support for studying the characteristics of lightning arcs and their ability to ignite combustibles. Attached Figure Description

[0011] Figure 1 This is a flowchart of the method for measuring the simulated lightning arc-forest combustible heat transport power according to the present invention; Figure 2 This is a schematic diagram of the simulated lightning arc foundation power calibration device of the present invention; Among them, 1. solid heat exchange container; 2. liquid heat exchange working fluid; 3. temperature sensor.

[0012] Figure 3 This is a flowchart of the simulated lightning arc foundation power calibration method of the present invention. Figure 4 The embodiments of the present invention provide temperature change curves and steady-state temperatures of the liquid heat exchange medium after the generation of a simulated lightning arc. Detailed Implementation

[0013] The technical solutions in the embodiments of the present invention will be clearly and completely described below. 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.

[0014] In the description of this invention, it should be noted that the specific physical quantities such as "inner diameter 6 mm", "wall thickness 1.5 mm", "length 10 mm", "duration time 40 ms", and "current intensity 160 A" are preferred parameters based on this embodiment and are only for the purpose of clearly describing this invention, and are not intended to indicate or imply that the physical quantities involved can only be these values, and therefore should not be construed as limiting this invention.

[0015] In the description of this invention, it should be noted that the terms "upper", "middle", "side", "inner", "outer", "coaxial", "vertical", etc., which indicate directions or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings of this example, and are only for the purpose of clearly describing this invention, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be installed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0016] In the description of this invention, unless otherwise specified, it should be noted that the terms "insertion," "fixation," "filling," "immersion," and "arrangement," etc., should be interpreted broadly. For example, in some contexts, they can be understood as multiple elements being directly connected or connected through an intermediate medium, and can be either fixedly connected or non-fixedly placed. Those skilled in the art can understand the specific meaning of the above terms according to the specific circumstances, and they should not be construed as limiting the invention.

[0017] A method for measuring the heat transport power of simulated lightning arc-forest combustibles, characterized by comprising the following steps: S101) When conducting experiments simulating the ignition of forest combustibles by lightning arcs, the arc current was obtained. and voltage data; S102) Through formula Calculate the input power of the electric arc ; S103) According to the relation Calculate and simulate the heat transport power of lightning arc-forest combustibles. ,in, The base power for simulating a lightning arc represents the electrical power required to sustain the simulated lightning arc.

[0018] The simulated lightning arc mentioned in step S101 is an arc generated by a lightning strike fire simulation experimental device, and the duration of the arc is... For 40~400 ms, current intensity The range is 100~250 A; the lightning strike fire simulation experimental device uses capacitor discharge to simulate lightning arcs; The steps described in step S101 and To simulate lightning arc current and voltage data, measurements were taken using an oscilloscope.

[0019] This invention also provides a simulated lightning arc base power. The calibration device is used to calibrate the base power of the simulated lightning arc in the above measurement method. ,like Figure 2 As shown, the device includes a solid heat exchange container 1, a liquid heat exchange medium 2, and a temperature sensor 3. The solid heat exchange container 1 is a container made of a solid material with known density and specific heat capacity. The solid heat exchange container 1 consists of an annular trough-shaped container and an annular cap. The liquid heat exchange medium 2 is a liquid with known density and specific heat capacity. The liquid heat exchange medium 2 is installed inside the solid heat exchange container. The temperature sensor 3 probe is immersed in the liquid heat exchange medium. There are at least two temperature sensors 3 with different measuring points.

[0020] This invention also provides a simulated lightning arc base power. The calibration method, using the above-mentioned calibration device, includes the following steps: S201) Fill a solid heat exchange container with liquid heat exchange medium and immerse a temperature sensor in the liquid heat exchange medium; S202) The calibration device is coaxially arranged with the discharge electrode to measure the real-time temperature of the liquid heat exchange medium before the generation of the simulated lightning arc. ; S203) Conducting simulated lightning arc foundation power During the calibration experiment, the real-time current of the simulated lightning arc was measured. and voltage Data, measuring the real-time temperature of the liquid heat exchange working fluid. ; S204) Through formula Calculate the input power of the simulated lightning arc ; S205) Extraction calibration device initial temperature and steady-state temperature ; S206) Based on the initial temperature of the calibration device and steady-state temperature Calculate the heat transport power of the simulated lightning arc calibration device. ; S207) According to the relation: Calculate the base power of the simulated lightning arc .

[0021] Step S202 involves measuring the real-time temperature of the liquid heat exchange medium before the simulated lightning arc is generated. The measurement duration shall be no less than 1 minute; step S203 describes measuring the real-time temperature of the liquid heat exchange medium after the simulated lightning arc is generated. The measurement duration shall be no less than 1 minute; the real-time temperature of the liquid heat exchange medium before and after the generation of the simulated lightning arc, as described in steps S202 and S203, shall be measured. and During this process, it is necessary to ensure that the temperature of the liquid heat exchange medium reaches a steady state, and that the measurement error of the temperature sensor at different locations does not exceed 0.5 within 3 seconds. o C is considered to be the temperature of the liquid heat exchange medium reaching a steady state, and the measured temperature value at this point is considered a valid measurement value; the temperature data mentioned in steps S202 and S203 and All require smoothing processing; the initial temperature of the calibration device described in step S205 Temperature of the liquid heat exchange working fluid The mean value when reaching steady state; the steady-state temperature of the calibration device described in step S205. These are correction values ​​for the temperature evolution data of the liquid heat exchange working fluid after discharge, for use... The temperature at time t=0 s is obtained by fitting the function to the steady-state temperature data of the heat exchange working fluid; the temperature described in step S206 The heat capacity of the calibration device is expressed as... ,in These are the mass and specific heat of the solid heat exchange container and the liquid heat exchange working fluid, respectively.

[0022] Example: like Figure 1 In this embodiment, preferably, the simulated lightning arc is an arc generated by a lightning strike fire simulation experimental device, with a length of 10 mm, a duration of 40 ms, and a current intensity of 160 A; the forest combustible material is blocky peat combustible material, and the peat block is a ring-shaped sample with an inner diameter of 4.5 mm, an outer diameter of 50 mm, and a thickness of 10 mm, as shown below. Figure 2 The oscilloscope used is model SIGLENT SDS5104DS, with a bandwidth of 1GHz and a real-time sampling rate of 5G Sa / s.

[0023] In this embodiment, peat, a typical forest humus, is used as the forest combustible sample. The specific steps for simulating the heat transport power measurement of lightning arc-forest combustible are as follows: S301) The peat combustible sample is coaxially arranged with the discharge electrode; S302) Conduct experiments to simulate lightning arc igniting forest combustibles, using a lightning strike fire simulation experimental device to generate a simulated lightning arc with a duration of 40 ms and a current intensity of 160 A. S303) Using an oscilloscope to measure the real-time current of an electric arc. and voltage data; S304) Calibrate the base power of the simulated lightning arc ; S305) The arc input power is calculated using the following formula. And combined with the calibrated simulated lightning arc base power Calculate and simulate the heat transport power of lightning arc-forest combustibles. : like Figure 2In this embodiment, preferably, the solid-state heat exchange container 1 has an inner diameter of 6 mm, an outer diameter of 12 mm, and a wall thickness of 1.5 mm, with a small hole of 0.2 mm in diameter located 3.5 mm from the upper surface on the outer wall; the solid-state heat exchange container 1 is made of aluminum nitride material with a density of 3.26 g·cm³. -3 Specific heat capacity is 0.72 J·g -1 K -1 The liquid heat exchange working fluid, composed of distilled water, is contained in a solid heat exchange container and has a density of 1.00 g·cm³. -3 Specific heat capacity is 4.18 J·g -1 K -1 The temperature sensor 3 uses a K-type thermocouple with a thermocouple node diameter of 0.15 mm, and is paired with a data acquisition unit (NI 9213) to achieve real-time temperature acquisition and storage, with a temperature measurement accuracy of 0.04%~0.07%. The thermocouple is fixed in a small hole on the side wall of the solid heat exchange container 1, inserted into the liquid heat exchange medium 2, and perpendicular to the liquid surface of the liquid heat exchange medium 2. Two thermocouples are selected, one of which is arranged 1 mm away from the wall of the solid heat exchange container 1, and the other is arranged 2 mm away from the wall. The vertical distance between the thermocouple node and the upper surface of the solid heat exchange container is 3.5 mm. During the measurement process, the average value of the two thermocouples is used as the temperature measurement value.

[0024] like Figure 3 In this embodiment, the simulated lightning arc base power The calibration steps are as follows: S401) Fill a solid heat exchange container made of aluminum nitride with distilled water as a liquid heat exchange medium and let it stand for about 5 minutes. (S402) Insert two K-type thermocouples into small holes in the outer wall of the solid heat exchange container, immersing the two thermocouples in distilled water. One thermocouple is positioned 1 mm from the wall of the solid heat exchange container, and the other is positioned 2 mm from the wall. S403) The calibration device and the discharge electrode are arranged coaxially; (S404) Turn on the temperature acquisition device, record the distilled water temperature, and compare the difference in thermocouple readings at different locations within 3 seconds. If the difference is greater than 0.5... o C. Continue to allow the calibration device to stand still and repeat this step. If it is less than 0.5... o C then records this temperature segment as the real-time temperature of the distilled water before the simulated lightning arc occurred. ; S405) Conduct a simulated lightning arc basic power calibration experiment, using a lightning strike fire simulation experimental device to generate a simulated lightning arc with a duration of 40 ms and a current intensity of 160 A. S406) Using an oscilloscope to measure the real-time current of a simulated lightning arc. and voltage Data was collected by simultaneously measuring the real-time temperature of distilled water using two thermocouples, and the results were recorded as the real-time temperature of the distilled water after the simulated lightning arc occurred. and ; S407) Calculate the real-time temperature of the liquid heat exchange medium before the generation of the simulated lightning arc. The time average value is used as the initial temperature of the calibration device. ,use The functional form of the real-time temperature of distilled water after the generation of a simulated lightning arc. and The steady-state data were fitted, and the steady-state temperature of the obtained calibration device was averaged to obtain... ; S408) The simulated lightning arc input power is calculated using the following formula. and the heat transport power of the simulated lightning arc calibration device Then, the base power of the simulated lightning arc is calculated. : In the formula, These are the mass and specific heat of the solid heat exchange container and the liquid heat exchange working fluid, respectively.

[0025] Figure 4 The real-time temperature curves of the internal thermocouples of the calibration device after simulating lightning arc heating in this embodiment, and the steady-state temperature of the calibration device obtained according to step S407 above, are 38.1°C. o C and 37.1 o C, the average of both is 37.60 o C.

[0026] In this embodiment, the specific values ​​of the measured and calculated parameters are as follows: the heat transport power of the simulated lightning arc-peat fuel calculated according to S305 is 18.27 kW.

[0027] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of the equivalents of the claims are intended to be included within the present invention. Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This method of description is merely for clarity, and those skilled in the art should consider the specification as a whole. The technical solutions in the various embodiments have been appropriately combined to form other embodiments readily understood by those skilled in the art.

Claims

1. A method for measuring the heat transport power of simulated lightning arc-forest combustible materials, characterized in that... Includes the following steps: S101) Conduct experiments simulating lightning arc ignition of forest combustibles to obtain real-time arc current. and voltage data; S102) Through formula Calculate the input power of the electric arc ; S103) According to the relation Calculate and simulate the heat transport power of lightning arc-forest combustibles. ,in, To simulate the base power of a lightning arc.

2. The method for measuring the heat transport power of simulated lightning arc-forest combustible materials according to claim 1, characterized in that: The simulated lightning arc mentioned in step S101 is the arc generated by the lightning strike fire simulation experimental device, and the duration of the arc is... For 40~400 ms, current intensity The range is 100~250 A; the lightning strike fire simulation experimental device uses capacitor discharge to simulate lightning arc.

3. The method for measuring the heat transport power of simulated lightning arc-forest combustibles according to claim 1, characterized in that: The steps described in step S101 and To simulate real-time data of lightning arc current and voltage, measurements were taken using an oscilloscope.

4. A method for simulating the base power of a lightning arc A calibration device for calibrating the base power of the simulated lightning arc as described in claim 1. Its features are: This includes solid heat exchange containers, liquid heat exchange working fluids, and temperature sensors.

5. The simulated lightning arc foundation power according to claim 4 The calibration device is characterized by: The solid heat exchange container is a container made of a solid material with known density and specific heat capacity; the solid heat exchange container consists of an annular trough-shaped container and an annular cap; the liquid heat exchange working fluid is a liquid with known density and specific heat capacity; the liquid heat exchange working fluid is installed inside the solid heat exchange container; the temperature sensor probe is immersed in the liquid heat exchange working fluid; the number of temperature sensors is not less than two and the measuring points are at different locations.

6. A method for simulating the base power of a lightning arc The calibration method is characterized by Includes the following steps: S201) Fill the solid measurement container with liquid heat exchange medium and immerse the temperature sensor in the liquid heat exchange medium; S202) The calibration device is coaxially arranged with the discharge electrodes of the lightning strike fire simulation experimental device to measure the real-time temperature of the liquid heat exchange medium before the generation of the simulated lightning arc. ; S203) Conducting simulated lightning arc foundation power During the calibration experiment, the real-time current of the simulated lightning arc was measured. and voltage Data, measuring the real-time temperature of the liquid heat exchange working fluid. ; S204) Through formula Calculate the input power of the simulated lightning arc ; S205) Extraction calibration device initial temperature and steady-state temperature ; S206) Based on the initial temperature of the calibration device and steady-state temperature Calculate the heat transport power of the simulated lightning arc calibration device. ; S207) According to the relation: Calculate the base power of the simulated lightning arc .

7. A simulated lightning arc foundation power according to claim 6 The calibration method is characterized by: Step S202 involves measuring the real-time temperature of the liquid heat exchange medium before the simulated lightning arc is generated. The measurement duration shall be no less than 1 minute; step S203 describes measuring the real-time temperature of the liquid heat exchange medium after the simulated lightning arc is generated. The measurement duration shall be no less than 1 minute; the real-time temperature of the liquid heat exchange medium before and after the generation of the simulated lightning arc, as described in steps S202 and S203, shall be measured. and During this process, it is necessary to ensure that the temperature of the liquid heat exchange medium reaches a steady state, and that the measurement error of the temperature sensor at different locations does not exceed 0.5 within 3 seconds. o C is considered to be the temperature of the liquid heat exchange medium reaching a steady state, and the measured temperature value at this point is considered a valid measurement value; the temperature data mentioned in steps S202 and S203 and All require smoothing processing; the initial temperature of the calibration device described in step S205 Temperature of the liquid heat exchange working fluid The mean value when reaching steady state; the steady-state temperature of the calibration device described in step S205. These are correction values ​​for the temperature evolution data of the liquid heat exchange working fluid after discharge, for use... The temperature at time t=0 s is obtained by fitting the function to the steady-state temperature data of the heat exchange working fluid; the temperature described in step S206 The heat capacity of the calibration device is expressed as... ,in These are the mass and specific heat of the solid heat exchange container and the liquid heat exchange working fluid, respectively.

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