Fire standard experiment method for simulating coniferous forest branch or canopy fuel

Abstract

The invention belongs to the technical field of crown fire experiments, and particularly relates to a standard fire experiment method for simulating coniferous forest branches or canopy fuels, which comprises the following steps of: manufacturing the simulated coniferous forest branches, and performing a combustion experiment by taking the simulated coniferous forest branches as a standard fuel body; or, simulated coniferous forest branches are manufactured, the simulated coniferous forest branches are built into a simulated coniferous forest canopy, and the simulated coniferous forest canopy serves as a standard fuel body to conduct the combustion experiment. According to the method, the fuel body preparation process is high in repeatability, fuel characteristic parameters can be changed at will, standard experiment requirements are met, and the method can be used for quantitative analysis of crown fire and has important scientific value.

Description

Technical Field

[0001] The invention belongs to the technical field of tree crown fire experiments, and in particular relates to a standard experimental method for simulating fire of coniferous forest branches or canopy fuels. Background Art

[0002] Crown fire is an extreme fire behavior that is initiated by surface fire and spreads in the canopy. Compared with surface fire, the intensity and spread rate of crown fire can increase by 10 2 The study of crown fire includes transformation, spread and combustion characteristics. Understanding the physical control mechanism of crown fire is a prerequisite for preventing and controlling forest fires.

[0003] Canopy fuel is distributed in three dimensions. In particular, the density of fuel varies in all directions. In coniferous forests, the surface area to volume ratio of fuel is large, the heat transfer efficiency is fast, and crown fires occur most frequently. The effective combustibles in the canopy include pine needles and twigs (usually less than 6 mm in diameter). There are many studies on crown fires, but they are basically empirical analyses using actual crown fires or field experimental data. The main reason is that it is difficult to simulate actual canopy fuels in a laboratory environment, there are no standard experimental subjects, the repeatability of experimental conditions is poor, and the conditions for scientific research are not available. Therefore, there is an urgent need for a standard fuel body similar to a woodpile that can simulate the characteristics of canopy fuels to assist in quantitative analysis. Summary of the invention

[0004] In view of this, the object of the present invention is to provide a standard experimental method for simulating fire of coniferous forest branches or canopy fuels, which can be used for quantitative analysis of crown fires.

[0005] The present invention provides a standard experimental method for simulating fire of coniferous forest branches or canopy fuels, comprising the following steps:

[0006] Making simulated coniferous forest branches, and using the simulated coniferous forest branches as standard fuel bodies to conduct a combustion experiment;

[0007] or,

[0008] Simulated coniferous forest branches are made, and the simulated coniferous forest branches are constructed into a simulated coniferous forest canopy. The simulated coniferous forest canopy is used as a standard fuel body for a combustion experiment.

[0009] Preferably, the basic fuel used to make the simulated coniferous forest branches is pine needles or wood strips.

[0010] Preferably, the specific process of making simulated coniferous forest branches using the pine needles as the basic fuel includes: using a twisted wire brush production method to make pine needles into simulated coniferous forest branches.

[0011] Preferably, the specific process of making simulated coniferous forest branches using the wood strips as basic fuel includes: preparing a pipe with multiple holes distributed on the side, inserting the wood strips into the holes of the pipe, and obtaining simulated coniferous forest branches.

[0012] Preferably, the pipe is a stainless steel pipe.

[0013] Preferably, in the process of making the simulated coniferous forest branches, the moisture content and bulk density of the pine needles or wood strips used are controlled.

[0014] Preferably, the specific process of constructing the simulated coniferous forest canopy includes: directly splicing and stacking the simulated coniferous forest branches together to obtain the simulated coniferous forest canopy.

[0015] Preferably, the specific process of constructing the simulated coniferous forest canopy includes: installing the simulated coniferous forest branches on an artificially constructed simulated tree trunk skeleton to obtain a simulated coniferous forest canopy.

[0016] Compared with the prior art, the present invention provides a standard experimental method for simulating fire of coniferous forest branches or canopy fuel, comprising the following steps: making simulated coniferous forest branches, and using the simulated coniferous forest branches as standard fuel bodies for combustion experiments; or making simulated coniferous forest branches, and using the simulated coniferous forest branches to build a simulated coniferous forest canopy, and using the simulated coniferous forest canopy as a standard fuel body for combustion experiments. The fuel body manufacturing process of the method of the present invention is standardized, and the characteristic parameters of the fuel body can be changed arbitrarily and have high repeatability, which meets the standard experimental requirements, can be used for quantitative analysis of canopy fires, and has important scientific value. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0018] Figure 1 is a schematic diagram of a simulated coniferous forest branch made of pine needles provided by an embodiment of the present invention;

[0019] Figure 2 is a schematic diagram of a simulated coniferous forest branch made of wooden strips provided by an embodiment of the present invention;

[0020] Figure 3 is a schematic diagram of a simulated coniferous forest canopy provided by an embodiment of the present invention;

[0021] Figure 4 is a schematic diagram of a simulated tree trunk skeleton provided by an embodiment of the present invention;

[0022] Figure 5 Schematic diagram of a fire experiment scene provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0023] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] The present invention provides a standard experimental method for simulating fire of coniferous forest branches or canopy fuels, comprising the following steps:

[0025] Making simulated coniferous forest branches, and using the simulated coniferous forest branches as standard fuel bodies to conduct a combustion experiment;

[0026] or,

[0027] Simulated coniferous forest branches are made, and the simulated coniferous forest branches are constructed into a simulated coniferous forest canopy. The simulated coniferous forest canopy is used as a standard fuel body for a combustion experiment.

[0028] In the experimental method provided by the present invention, the basic fuel used to make the simulated coniferous forest branches is preferably pine needles or wood strips.

[0029] In the experimental method provided by the present invention, the specific process of using the pine needles as the basic fuel to make simulated coniferous forest branches preferably includes: using the twisted wire brush method to make pine needles into simulated coniferous forest branches (such as Figure 1 The fuel distribution in the figure is consistent with the fuel distribution in the actual conifer branches.

[0030] In the experimental method provided by the present invention, the specific process of using the wood strips as the basic fuel to make simulated coniferous forest branches preferably includes: preparing a pipe with a plurality of holes distributed on the side, inserting the wood strips into the holes of the pipe, and obtaining simulated coniferous forest branches (such as Figure 2 As shown). The density of the holes determines the volume density of the fuel space, and the fuel distribution is close to the fuel distribution in the actual conifer branches; the pipe is preferably a stainless steel pipe; and the wood strips are preferably of the same size.

[0031] In the experimental method provided by the present invention, in the process of making the simulated coniferous forest branches, it is preferred to control the moisture content and bulk density of the pine needles or wood strips used to ensure the consistency of the experimental objects and the repeatability of the initial experimental conditions. In the present invention, the instruments and equipment for controlling the moisture content and bulk density include but are not limited to a constant temperature drying oven, a moisture content meter, and an electronic balance.

[0032] In the experimental method provided by the present invention, the specific process of constructing the simulated coniferous forest canopy preferably includes: directly splicing and stacking the simulated coniferous forest branches together to obtain a simulated coniferous forest canopy with approximately uniform spatial volume density (such as Figure 3 shown).

[0033] In the experimental method provided by the present invention, another specific process of constructing the simulated coniferous forest canopy preferably includes: installing the simulated coniferous forest branches on an artificially constructed simulated tree trunk skeleton (such as Figure 4 As shown in the figure, a simulated coniferous forest canopy with a distribution that is approximately consistent with the actual canopy fuel space volume density is obtained.

[0034] The advantages and positive effects of the experimental method of the present invention include:

[0035] (1) Use pine needles or wood strips, which are effective combustibles in actual crown fires, to construct a single simulated branch, which is accurate and realistic;

[0036] (2) Parameters such as the size, moisture content, and volume density of a single simulated branch can be changed arbitrarily according to experimental needs, with a high degree of freedom;

[0037] (3) The approximately uniform fuel body or tree-like fuel body constructed using a single simulated tree branch is consistent, making the initial experimental conditions repeatable and the experimental results comparable.

[0038] The experimental method proposed in the present invention can be directly used for the study of mesoscale crown fire in the laboratory. Parameters such as fuel distribution, moisture content and effective combustible volume density can be artificially controlled, which is repeatable and convenient for quantitative scientific research.

[0039] For the purpose of greater clarity, the present invention is described in detail through the following embodiments in conjunction with the accompanying drawings.

[0040] Example 1

[0041] (1) Using pine needles to make simulated coniferous forest branches, the specific process includes:

[0042] First, use a cutting tool to process a batch of pine needles of uniform length. Then, according to the twisting wire brush processing method, place the pine needles evenly on the folded wire and rotate them to form. Figure 1 Simulated coniferous forest branches shown.

[0043] (2) Using wooden strips to make simulated coniferous forest branches, the specific process includes:

[0044] First, prepare a stainless steel tube with evenly distributed small holes on the side. Then insert small wooden sticks of the same diameter and length into the small holes on the side of the stainless steel tube. Figure 2 Simulated coniferous forest branches shown.

[0045] In this embodiment, the moisture content and weight of pine needles and wood strips can be controlled by a constant temperature drying oven, a moisture content meter, an electronic balance and other equipment, and the length can be changed according to experimental requirements to achieve arbitrary control of fuel load, spatial volume density and moisture content.

[0046] Example 2

[0047] (1) A simplified canopy fuel body is constructed using a single simulated branch. The specific process includes:

[0048] The simulated coniferous forest branches obtained in step (1) of Example 1 are directly spliced ​​and stacked together to obtain Figure 3 Single or multiple rows of simulated canopy fuel bodies are shown.

[0049] (2) Using a single simulated branch to build a complex canopy fuel body, the specific process includes:

[0050] First, make a simulated tree trunk skeleton (such as Figure 4 As shown), the trunk skeleton is constructed using the L-system algorithm, which can simulate most of the crown structure and facilitate modeling; then the simulated coniferous forest branches prepared in Example 1 are installed on the simulated trunk skeleton to obtain a simulated canopy fuel body.

[0051] In this embodiment, step (1) can achieve a fuel body with approximately uniform spatial volume density through simple combination and splicing of single simulated branches, which is suitable for simplified scientific quantitative research; the fuel distribution in the simulated canopy fuel body obtained in step (2) is basically consistent with the actual canopy, and the research results have the possibility of being extended to actual work.

[0052] Example 3

[0053] The simulated coniferous forest branches prepared in Example 1 or the simulated coniferous forest canopy prepared in Example 2 are used as the fuel body, and the fuel body is placed in Figure 5 In the experimental device shown, the wind speed and slope are changed to study the critical spreading characteristics and spreading speed of a single branch or canopy fuel during combustion. In addition, DV, infrared camera, thermocouple and heat flow meter can be used in the experiment to measure important physical parameters such as flame morphology, preheating zone temperature and heat flow, and conduct quantitative theoretical analysis.

[0054] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A standard test method for simulating fires in coniferous forest branches or canopy fuels, characterized in that: The following steps are involved: Making simulated coniferous forest branches, and using the simulated coniferous forest branches as standard fuel bodies to conduct a combustion experiment; or, Simulated coniferous forest branches are made, and the simulated coniferous forest branches are constructed into a simulated coniferous forest canopy. The simulated coniferous forest canopy is used as a standard fuel body for a combustion experiment.

2. The fire standard test method according to claim 1, characterized in that: The basic fuel used for making the simulated coniferous forest branches is pine needles or wood strips.

3. The fire standard test method according to claim 2, characterized in that: The specific process of making simulated coniferous forest branches by using the pine needles as basic fuel includes: using the twisted wire brush making method to make the pine needles into simulated coniferous forest branches.

4. The fire standard test method according to claim 2, characterized in that: The specific process of making simulated coniferous forest branches using the wood strips as basic fuel includes: preparing a pipe with multiple holes distributed on the side, inserting the wood strips into the holes of the pipe, and obtaining simulated coniferous forest branches.

5. The fire standard test method according to claim 4, characterized in that: The pipe is a stainless steel pipe.

6. The fire standard test method according to claim 2, characterized in that: In the process of making the simulated coniferous forest branches, the moisture content and volume density of the pine needles or wood strips used are controlled.

7. The fire standard test method according to claim 1, characterized in that: The specific process of building the simulated coniferous forest canopy includes: directly splicing and stacking the simulated coniferous forest branches together to obtain the simulated coniferous forest canopy.

8. The fire standard test method according to claim 1, characterized in that: The specific process of constructing the simulated coniferous forest canopy includes: installing the simulated coniferous forest branches on an artificially constructed simulated tree trunk skeleton to obtain the simulated coniferous forest canopy.

Images