A simulation device and simulation method for solid combustion flame

Abstract

The present invention discloses a simulation device for solid fuel flame, which mainly includes a gas source, a combustion wind tunnel, data acquisition and analysis equipment, etc. The present invention determines the combustion gas flow rate according to the real-time measurement and analysis of the combustion product gas analysis and the flame intensity according to the energy conversion and reaction balance, reflects the physical nature of solid combustion, and simulates the flame behavior of solid combustion, and can realize long-term, instantaneous, and fixed observation of the flame behavior. At the same time, the device integrates data acquisition and analysis functions such as flow field analysis, optical analysis, chemical analysis, and energy analysis, and can measure the gas and solid combustion behavior under different environmental conditions in real time and efficiently, which has important application value for combustion science and fire protection research.

Description

Technical Field

[0001] The invention relates to the field of combustion and fire safety control, and in particular to a simulation device and a simulation method for solid combustion flame. Technical Background

[0002] Solid combustion is one of the basic forms of combustion. It is one of the key areas of fire safety attention because of its wide variety of common combustibles, fast flame propagation speed and high heat generation. The solid combustion process includes the pyrolysis, ignition, fire spread and flame extinction of combustibles. It is a complex reaction that has both physical and chemical processes and multi-phase energy and material transfer.

[0003] At present, most experimental studies on fire safety observe flame behavior by directly igniting solid fuels. However, due to reasons such as combustion speed and environmental pollution, the size of the experimental objects is generally small and the burning time is short, making it difficult to observe long-term, large-scale flames close to a stable state, and the complete development behavior of the flame cannot be reflected. On the other hand, the flame propagates quickly during solid combustion, and can reach more than meters per second. If a fixed camera is used for measurement, it is easily affected by the brightness of the light source, optical distortion, etc., which may cause deformation of the measurement results and measurement errors, affecting the precision and accuracy of the analysis.

[0004] On the other hand, some fire safety experimental studies and fire protection standards at home and abroad use fixed gas burners to simulate solid combustion flames to study the impact of solid combustion flames on specific building materials or house structures during fires. However, because the research focus is on verifying that the materials or structures meet the fire protection performance under specific fire protection standards, fixed gas flow rates are generally used to control variables to ensure the reliability of experimental results. Therefore, it cannot truly reflect the correlation between solid combustion rate and heat production, and cannot reflect the physical nature of multiphase coupled reactions of solid combustion. Summary of the invention

[0005] Based on the current development status of experimental research devices for solid combustion flames, the present invention proposes a simulation device for solid combustion flames. According to the real-time monitoring results of the sensor flame intensity, the fuel gas flow rate is adaptively controlled by utilizing the energy conversion and reaction theory of combustion science. Therefore, the transient and long-term accurate simulation of the solid combustion flame can be achieved from the physical essence. In addition, multi-dimensional sensors such as flow field, chemical composition, optics, and heat transfer are integrated to realize efficient and accurate strategies for fixed flames, which has important application value for studying the behavior of solid combustion flames and fire safety protection.

[0006] A simulation device for solid combustion flame comprises a gas source, a combustion wind tunnel, a sensor and a computer terminal, wherein the gas source comprises an air source and a fuel gas, the air source flows into the wind tunnel from an inlet at one end of the wind tunnel after mixing, an air inlet for the fuel gas to flow in is provided below the wind tunnel, the fuel gas flows into the wind tunnel from the air inlet, diffuses and mixes with the gas in the wind tunnel to form a flame, the sensor measures the transient intensity of the flame in real time, and the flow rate of the fuel gas is adaptively controlled according to the transient intensity of the flame, and the computer terminal records and analyzes the simulated solid combustion flame development process.

[0007] Preferably, the air source includes oxygen and nitrogen, which are mixed and flow into the wind tunnel; the oxygen and nitrogen control their respective flow rates based on flow meters to change the flow rate and oxygen concentration in the combustion wind tunnel.

[0008] Preferably, the combustion wind tunnel comprises three sections in sequence: a steady flow section, a reaction section, and an outlet section. The steady flow section is used to control the full mixing of oxygen and nitrogen and their smooth output. The reaction section is used to simulate the flame behavior of solid combustion and observe flame characteristics. The outlet section is used for reaction product analysis and exhaust gas treatment.

[0009] Preferably, the sensors include a temperature sensor, a heat flow sensor and a gas analysis sensor. The temperature sensor and heat flow sensor are arranged downstream of the fuel outlet of the reaction section of the combustion wind tunnel, and are used for real-time monitoring, measurement and analysis of the heat flow and temperature of the flame. The flow rate of the fuel gas is adaptively controlled according to the real-time data of the heat flow sensor; the gas analysis sensor is arranged at the product outlet of the outlet section of the combustion wind tunnel, and is used for gas analysis.

[0010] Preferably, the steady flow section of the combustion wind tunnel includes a damping net, a honeycomb and a flow meter. The damping net and the honeycomb are placed at the entrance of the steady flow section to improve the straightness of the airflow and reduce the turbulence of the airflow; the flow meter is placed in the middle of the wind tunnel to measure the velocity of the fluid in the pipeline.

[0011] Preferably, the reaction section of the combustion wind tunnel also includes a stage, a camera and an igniter, wherein the igniter is used to ignite the fuel gas; the stage is placed at the bottom of the wind tunnel of the reaction section and is made of insulating material; the heat flow sensor is arranged on the stage and is used to measure the transient intensity of the flame in real time; the camera is connected to the computer terminal and is used to capture dynamic process images of the flame ignition and combustion process.

[0012] Preferably, the outlet section of the combustion wind tunnel further comprises a gas collecting device, a data collector and a flow meter. The gas collecting device collects gas products after combustion in real time and inputs them into the gas analysis sensor for gas analysis. The data collector connects the sensor with a computer terminal.

[0013] Preferably, the gas analysis sensor includes an oxygen sensor, a carbon dioxide sensor, and a carbon monoxide sensor, which are used to detect the dynamic changes in the concentration of each gas component.

[0014] Preferably, the fuel gas flow rate Determined according to energy balance and reaction balance, the formula is:

[0015]

[0016]

[0017] in, and ΔS represent the heat flow rate monitored by the heat flow sensor and the sensor area, L, c p and ΔT ig are the reaction heat, specific heat and ignition point of simulated solid fuels, is the equivalent reaction rate of the simulated solid fuel; α is the combustion ratio of the simulated solid fuel, which is determined according to the production ratio of carbon dioxide and carbon monoxide in the wind tunnel, Q cs , Q g They are the combustion heat of simulated solid fuel and experimental fuel gas, respectively, which are obtained from literature or general thermal analysis experiments.

[0018] The present invention also discloses a method for simulating solid combustion flames, based on the above-mentioned solid combustion flame simulation device, further comprising the following steps:

[0019] Step 1: Connect all gas cylinders, turn on the switches, and set the nitrogen and oxygen flow rates according to the experimental requirements to achieve appropriate flow rates and oxygen content in the wind tunnel;

[0020] Step 2, after turning on the fuel gas switch, start the igniter to ignite the fuel gas, monitor the combustion process in real time based on the sensor, and transmit the data to the data collector and the computer terminal;

[0021] Step 3, during the process from flame generation to flame burnout, the camera is used to continuously take flame pictures or obtain flame dynamic change videos, and all data of the flame transient development process, including product component content, flame image, and flame thermometer heat, are collected and displayed in real time on the computer for analysis.

[0022] Beneficial Effects

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] 1. The present invention adaptively controls the volume flow rate of fuel gas according to energy conversion and reaction balance, grasps the physical essence of multiphase coupled reaction of solid combustion, can effectively simulate the flame behavior of solid combustion, and can realize long-term, large-scale behavior observation and research of solid combustion flame.

[0025] 2. The present invention can fix the solid combustion flame, and the measured data is not affected by flame propagation, thereby reducing measurement errors. At the same time, the present invention adopts multidisciplinary integrated data acquisition and analysis such as optics, flow field, heat transfer, and components, which can measure solid combustion flame temperature, component concentration and other data in real time, improve measurement efficiency and data accuracy, and is conducive to in-depth research on solid combustion behavior. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is an overall model diagram of a solid combustion flame simulation device of the present invention;

[0027] Figure 2 A schematic diagram of a stage of a solid combustion flame simulation device of the present invention;

[0028] Figure 3 A flame dynamics grid model schematic diagram of a solid combustion flame simulation device of the present invention;

[0029] Figure 4 The heat flux density distribution of the bottom stage of a solid combustion flame simulation device of the present invention;

[0030] Figure 5 The flame shape of the middle symmetric surface of a simulation device for solid combustion flame of the present invention is compared with experiments in the literature. Specific implementation plan

[0031] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0032] Reference Figure 1 As shown, the present invention provides a simulation device for solid combustion flame, which realizes adaptive control of fuel gas flow based on sensors, so as to simulate solid combustion with gas combustion, and the device includes: air and fuel gas sources, a combustion wind tunnel, sensors and computer terminals. The gas sources include air sources and fuel gas sources, which are used to store and transmit fuel gas; the combustion wind tunnel includes three sections: a steady flow section, a reaction section and an outlet section, which are used for combustion reaction and observation of fuel gas; the sensors include temperature sensors, heat flow sensors, gas analysis sensors, camera optical observation, etc., which are used to detect the combustion process in real time; the computer terminal includes computers, etc., which are used to calculate and analyze data to obtain the final result.

[0033] The air and fuel gas sources are equipped with high-pressure gas cylinders to store fuel gas. The three types of gas cylinders are nitrogen cylinders, oxygen cylinders and fuel cylinders. The right ends of the nitrogen cylinders and oxygen cylinders are connected to safety switches, and the right end of the fuel cylinder is connected to an automatic control switch for controlling the transmission of fuel gas. If an accident occurs, the transmission channel can be closed by the safety switch. A flow meter is connected after the switch. The flow meter is a gas flow controller. The gas flow controller is electrically connected to a computer terminal. It can accurately control the flow rates of oxygen and nitrogen according to the data of the thermal flow sensor and observe in real time, thereby changing the flow rate and oxygen concentration in the combustion wind tunnel; the fuel gas flow rate is determined according to the real-time thermal flow sensor data of the reaction section of the combustion wind tunnel and is determined by the flame intensity. The flow meter is followed by the inlet for air and fuel.

[0034] The combustion wind tunnel consists of three sections: the steady flow section, the reaction section, and the outlet section. The fuel gas flows into the steady flow section after flowing out of the inlet. The air steady flow section is set on the left side of the reaction section, and the fuel inlet is set below the reaction section. The steady flow section is used to ensure that the gas is fully mixed and output smoothly. The cross-sectional dimensions of the steady flow section at the air and fuel gas inlets can be determined according to the needs of experiments and research. The steady flow section includes a damping net, a honeycomb, and a flow meter. The damping net and honeycomb are set at the inlet of the steady flow section to improve the straightness of the airflow and reduce the turbulence of the airflow. A flow meter is set in the middle of the wind tunnel. After it is turned on, the velocity of the pipeline fluid during the experiment can be detected in real time.

[0035] The reaction section is used to simulate the flame behavior of solid fuel and observe the flame characteristics. The reaction section includes a stage, igniter, sensor, camera, etc. Figure 2 As shown, it is made of insulating material, and the front opening of the stage is the fuel gas inlet, which simulates the intermediate gaseous products during solid combustion; the igniter is arranged at the bottom opening, and after use, an electric spark is generated to ignite the fuel gas to produce a stable flame; the sensor is arranged behind the opening, which is a heat flow sensor and a temperature sensor. In this embodiment, the heat flow sensor and the temperature sensor are arranged downstream of the fuel outlet of the reaction section of the combustion wind tunnel, and are used to detect the heat flow and temperature of the flame; the camera is connected to the computer, and the continuous shooting mode can be selected to obtain the flame ignition and combustion process images for subsequent optical analysis.

[0036] The outlet section is arranged on the right side of the reaction section for gas outflow, and the gas after combustion flows out through it, and then the exhaust gas is treated to avoid environmental pollution; a flow meter is arranged in the middle of the outlet section for real-time detection of the exhaust gas velocity in the pipeline; a gas collecting pipe is connected to the bottom of the outlet section, and the gas collecting device collects the gas products after combustion in real time, and then is connected to the gas analysis sensor. In this embodiment, the gas analysis sensor is arranged at the outlet of the product of the outlet section of the combustion wind tunnel, including an oxygen sensor, a carbon dioxide sensor, a carbon monoxide sensor, etc., which are used to detect the dynamic changes of the concentration of each gas.

[0037] The sensors mentioned in this embodiment are mainly temperature sensors, heat flow sensors, and gas analysis sensors, which are respectively arranged at different positions of the combustion wind tunnel, and can monitor the flame combustion conditions in real time and obtain flame combustion related data. The data acquisition device connects the sensor and the computer terminal to collect the data output by the sensor in real time, and then transmit or store it.

[0038] Computer terminal The computer is used to process and analyze the data from the data collector and the camera in real time to obtain the final result.

[0039] In order to simulate the flame behavior of solid combustion, the combustible gas flow rate is adaptively controlled according to the coupling mechanism of solid combustion, which is determined by the real-time intensity of the flame. Generally, when solid materials burn, the surface of the material is heated by the gas phase flame, and its energy conversion satisfies:

[0040]

[0041] in, represents the heat flux of the flame heating the simulated solid, It represents the simulated solid surface receiving convection and radiation heat transfer, s represents the sensor area, if the heat flux sensor with area ΔS is used for measurement, then

[0042]

[0043] Where ΔS represents the heat flux sensor area used for measurement.

[0044] According to the principle of solid combustion reaction, the solid phase reactant is heated to reach the reaction state, and decomposes to produce gas phase combustibles after pyrolysis reaction. Its energy conversion can be expressed as

[0045]

[0046] Among them, L, c p and ΔT ig are the reaction heat, specific heat and ignition point of simulated solid fuels, is the equivalent reaction rate of the simulated solid fuel.

[0047] In this experiment, methane, propane, ethylene, etc. can be selected as gaseous combustion products, and their combustion process can be expressed as

[0048] C x H y +((1+n)x / 2+y / 4)O 2 =(1-n)xCO+nxCO 2 +y / 2H 2 O~Q g

[0049] Among them, C x Hy Indicates fuel gases such as methane, propane, and ethylene. 2 ,CO,CO 2 , H 2 O stands for oxygen, carbon monoxide, carbon dioxide and water.

[0050] Q g is the combustion heat of the experimental fuel gas, which can be obtained from literature or general thermal analysis experimental methods, or by real-time measurement of oxygen content changes in this experiment. According to combustion theory,

[0051]

[0052] According to the equivalent relationship of combustion reaction heat, the flow control equation of combustible gas can be obtained:

[0053]

[0054] Among them, α is the combustion ratio of the simulated solid fuel, which is determined according to the production ratio of carbon dioxide and carbon monoxide in the wind tunnel, and Q cs To simulate the combustion heat of solid fuel, it can be obtained from literature or general thermal analysis experiments.

[0055] The present invention also discloses a simulation method for a solid combustion flame. During the test, firstly, each gas cylinder is connected and the switch is turned on, and the nitrogen and oxygen flow rates are set according to the experimental requirements so that the wind tunnel reaches an appropriate flow rate and oxygen content; after the fuel gas switch is turned on, a pneumatic igniter is used to ignite the fuel gas, and a flow meter and a sensor are used to monitor the combustion process in real time, and the data is transmitted to a data collector and a computer terminal; finally, during the process of the fuel gas being ignited and the flame developing to being burned out, a camera is used to continuously take flame pictures or obtain a video of the dynamic change of the flame, and all data of the transient development process of the flame, including the content of the product components, the flame image, the heat of the flame thermometer, etc., are collected in a computer for real-time display and analysis.

[0056] In order to verify the reliability of the simulation device of solid combustion flame in the present invention, computational fluid dynamics and computational combustion methods are used to simulate the solid combustion experiment in the literature [Li. et al, Experimental study of concurrent-flow flamespread over thin solids in confined space in microgravity, 2021, Combustion and Flame], and a finite element simulation numerical model is established. Figure 3Different boundaries are distinguished by colors. The model structure and size reference experiment is 29.5cm×7.6cm×5cm. The left side is the air inlet with a flow rate of 0.07m / s. The right side is the free outflow of exhaust gas. The lower opening is the fuel gas inlet. In this case, propane C is selected. 3 H 8 The simulation inlet size is 0.5 cm × 2.2 cm, which is 5 cm away from the gas inlet. The Standard ke model is used to calculate the turbulence, the ambient wall is a 300K no-slip boundary, and the initial ignition temperature is set to 1000K.

[0057] The heat flow cloud diagram at the bottom of the reaction section calculated by this patent is as follows Figure 4 As shown, it is consistent with the solid combustion theory, indicating that the patented method can achieve solid energy input consistent with the solid combustion process, thereby ensuring that the input amount of fuel gas is reasonable and accurate. The temperature cloud diagram of the middle section of the calculation result is as follows Figure 5 As shown in the figure, it can be seen that the flame temperature is highest at the rear of the propane inlet, and the temperature gradually decreases along the flow direction. The overall flame is parabolic, the flame root is thickest, and the thickness decreases along the flow direction, which is consistent with the actual flame shape observed in the experiment. The flame length is 2.86cm and 2.67cm respectively compared with the experiment, and the error is less than 7.1%, which meets the engineering calculation error requirement. It shows that the simulation device of a solid combustion flame of the present invention can accurately simulate the characteristics of a solid combustion flame, verifying the reliability of the present invention.

[0058] The above descriptions have explained and verified the principles and implementation schemes of the present invention. The descriptions of the above embodiments are only used to help understand the method and core ideas of the present invention. At the same time, for those skilled in the art, according to the ideas of the present invention, there will be changes in the specific implementation schemes and application scopes. In summary, the contents of this specification should not be understood as limiting the present invention.

Claims

1. A solid combustion flame simulation device, characterized in that: It includes a gas source, a combustion wind tunnel, a sensor and a computer terminal. The gas source includes an air source and a fuel gas. The air source flows into the wind tunnel from an inlet at one end of the wind tunnel after mixing. An air inlet for the fuel gas to flow in is opened below the wind tunnel. The fuel gas flows into the wind tunnel from the air inlet and diffuses and mixes with the gas in the wind tunnel to form a flame. The inlet and the air inlet form a double inlet structure for simulating the diffusion and mixing of gas fuel in the air and the combustion reaction process. Based on the real-time measurement of the flame transient intensity by the sensor, the flow rate of the fuel gas is adaptively controlled according to the flame transient intensity. Determined according to energy balance and reaction balance, the formula is: in, and ΔS represent the heat flow rate monitored by the thermal flow sensor and the sensor area, L, c p and ΔT ig are the reaction heat, specific heat and ignition point of the simulated solid fuel, is the equivalent reaction rate of the simulated solid fuel; α is the combustion ratio of the simulated solid fuel, which is determined according to the production ratio of carbon dioxide and carbon monoxide in the wind tunnel, Q cs , Q g are the combustion heats of simulated solid fuel and experimental fuel gas, respectively, obtained from literature or general thermal analysis experiments; The computer terminal records and analyzes the simulated solid combustion flame development process.

2. A solid combustion flame simulation device according to claim 1, characterized in that: The air source includes oxygen and nitrogen, which are mixed and flow into the wind tunnel; the oxygen and nitrogen control their respective flow rates based on a flow meter to change the flow rate and oxygen concentration in the combustion wind tunnel.

3. The solid combustion flame simulation device according to claim 1, characterized in that: The combustion wind tunnel includes three sections in sequence: a steady flow section, a reaction section, and an outlet section. The steady flow section is used to control the full mixing of oxygen and nitrogen and their smooth output. The reaction section is used to simulate the flame behavior of solid combustion and observe flame characteristics. The outlet section is used for reaction product analysis and tail gas treatment.

4. A solid combustion flame simulation device according to claim 3, characterized in that: The sensors include a temperature sensor, a heat flow sensor and a gas analysis sensor. The temperature sensor and the heat flow sensor are arranged downstream of the fuel outlet of the reaction section of the combustion wind tunnel, and are used to monitor, measure and analyze the heat flow and temperature of the flame in real time. The flow of the fuel gas is adaptively controlled according to the real-time data of the heat flow sensor; the gas analysis sensor is arranged at the product outlet of the outlet section of the combustion wind tunnel, and is used to perform gas analysis.

5. The solid combustion flame simulation device according to claim 3, characterized in that: The steady flow section of the combustion wind tunnel includes a damping net, a honeycomb and a flow meter. The damping net and the honeycomb are placed at the entrance of the steady flow section to improve the straightness of the airflow and reduce the turbulence of the airflow; the flow meter is placed in the middle of the wind tunnel to measure the velocity of the fluid in the pipeline.

6. The solid combustion flame simulation device according to claim 4, characterized in that: The reaction section of the combustion wind tunnel also includes a stage, a camera and an igniter, wherein the igniter is used to ignite the fuel gas; the stage is placed at the bottom of the wind tunnel of the reaction section and is made of insulating material; the heat flow sensor is arranged on the stage and is used to measure the transient intensity of the flame in real time; the camera is connected to the computer terminal and is used to capture the dynamic process images of the flame ignition and the combustion process.

7. The solid combustion flame simulation device according to claim 4, characterized in that: The outlet section of the combustion wind tunnel also includes a gas collecting device, a data collector and a flow meter. The gas collecting device collects the gas products after combustion in real time and inputs them into the gas analysis sensor for gas analysis. The data collector connects the sensor with a computer terminal.

8. The solid combustion flame simulation device according to claim 7, characterized in that: The gas analysis sensor includes an oxygen sensor, a carbon dioxide sensor, and a carbon monoxide sensor, which are used to detect the dynamic changes in the concentration of each gas component.

9. A method for simulating solid combustion flame, characterized in that: The solid combustion flame simulation device according to any one of claims 1 to 8 comprises the following steps: Step 1: Connect all gas cylinders, turn on the switches, and set the nitrogen and oxygen flow rates according to the experimental requirements to achieve appropriate flow rates and oxygen content in the wind tunnel; Step 2, after turning on the fuel gas switch, start the igniter to ignite the fuel gas, monitor the combustion process in real time based on the sensor, and transmit the data to the data collector and the computer terminal; Step 3, during the process from flame generation to flame burnout, the camera is used to continuously take flame pictures or obtain flame dynamic change videos, and all data of the flame transient development process, including product component content, flame image, and flame thermometer heat, are collected and displayed in real time on the computer for analysis.

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