CN101476973A - Flue gas plume movement simulated experiment apparatus in thermal stratification surroundings - Google Patents

Abstract

The invention relates to an experiment device for simulating the motion of smoke plume under environment of thermal stratification. The device solves the problems that the development of the experimental research on a rising transmission rule of the smoke plume of early fire under environment of thermal stratification lacks an experiment device. The experiment device comprises a closed cavity, a smoke formation mechanism, a data acquisition and processing mechanism and a smoke exhaust mechanism; the closed cavity is a cube; the lower part of a ceiling of the inside of the closed cavity is provided with a square cover of which inner wall is a mirror face; the inside of the square cover is distributed with a plurality of quartz heating tubes; the middle part of the bottom of the square cover is vertically provided with a smoke gas outlet mechanism; the smoke gas outlet mechanism comprises an inlet section, an expansion section, a heating section, a steady flow section, a contraction section and an outlet section; the expansion section is trumpet-shaped; the inside of the heating section is axially provided with a heating resistance wire; the inside of the steady flow section is axially distributed with steady flow tubes; and the contraction section is of an inverse trumpet shape. The experiment device has good controllability, and experiment expandability, can directly place small-power experimental fire in the closed cavity, can also control smoke generation outside the closed cavity by a smoke box and has experiment repeatability.

Description

An experimental device for simulating flue gas plume movement in a thermally stratified environment

technical field

The invention relates to a device applied to study the transport law of early fire smoke in high-large space HVAC and sunlight radiation environments, and provides technical support for the scientific and reasonable installation and arrangement method of smoke-sensitive fire detectors in high-large spaces.

Background technique

Due to reasons such as HVAC or solar radiation, tall and large space buildings are prone to form a thermal stratification environment where the internal air temperature is high and low. The smoke temperature of the early fire is the same as the surrounding air at a certain height, and the buoyancy of the smoke is zero and gradually turns to zero. Negative value and eventually stop at a certain altitude. Study the smoke transport law in a thermally stratified environment, determine the maximum height and width of the early fire smoke plume and other parameters in a thermally stratified environment, so as to provide theory and experiment for the scientific and reasonable installation and arrangement of fire detectors in high and large spaces support. At present, most of the domestic and foreign research on large-scale fire smoke is focused on the analysis of the filling law of high-power fire smoke, that is, the study of large-scale large-scale fire smoke transport laws. Most of the research methods use regional simulation and experimental analysis. The experimental research on the law of smoke transport in power fires, especially the law of upward propagation in thermal stratified environments has not been carried out.

Contents of the invention

In order to carry out experimental research on the ascending and propagating law of the early fire smoke plume in a thermally stratified environment, the present invention provides an experimental device for simulating the motion of the smoke plume in a thermally stratified environment.

The technical solution for realizing the above-mentioned purpose is as follows:

A flue gas plume motion simulation experiment device in a thermally stratified environment includes a closed chamber, a smoke generating mechanism, a data collection and processing mechanism, and a smoke exhausting mechanism; a thermally stratified heating mechanism is arranged below the top of the closed chamber, The height direction of the side wall is provided with a scale, and more than two temperature sensors are connected in series through the data line. The closed chamber is connected to the external data acquisition and processing mechanism through the wire; the top of the closed chamber is connected to the smoke exhaust mechanism, and the bottom of the closed chamber is It is connected to the flue gas outlet mechanism, and its side wall is provided with an observation window;

The closed chamber is a cube, its horizontal cross-section is square or rectangular, and its length, width, and height are 1-1.2 meters, 1-1.2 meters, and 1.8-2 meters respectively; the heat layered heating mechanism includes a side cover , the length, width, and height of the square cover are 0.8-1.1 meters, 0.8-1.1 meters, and 0.2 meters respectively. The distance between the square cover and the top of the closed chamber is 0.2-0.3 meters. The inner wall of the square cover is a mirror surface. 15 quartz electric heating tubes; a smoke outlet mechanism is installed vertically in the middle of the bottom of the closed chamber.

The flue gas outlet mechanism includes a vertically arranged flue gas pipe body. The flue gas pipe body is cylindrical and tubular, and it includes an inlet section, an expansion section, a heating section, a steady flow section, a contraction section and an outlet section from bottom to top; The diameter of the section is 1.8-2 cm; the extension section is trumpet-shaped; the diameter of the heating section and the steady flow section are 5-6 cm, the height of the heating section is 15-18 cm, and the height of the steady flow section is 10-12 cm; A heating resistance wire is arranged in the axial direction in the heating section, and a steady flow tube is evenly arranged in the axial direction in the steady flow section; the contraction section is in the shape of an inverted trumpet.

The inlet section of the flue gas pipe body is connected to the smoke generating mechanism through the smoke pipeline. The smoke mechanism includes a smoke box and a smoke pipeline. The smoke pipeline is provided with a regulating valve and a DC voltage exhaust fan. outside the chamber.

The material of the flue gas pipe body is aluminum alloy.

The outer wall of the heating section, the steady flow section and the contraction section of the flue gas pipe body is provided with an insulating layer.

50-60 hollow flow-stabilizing pipes are arranged vertically and parallelly in the flow-stabilizing section of the flue gas pipe body, and the diameter of the flow-stabilizing pipes is 1.8-2 mm.

The outlet section of the flue gas pipe body has a diameter of 1-3 cm.

The smoke outlet mechanism is located at the bottom of the closed chamber.

This device simulates and reproduces the actual plume movement of the early fire smoke in the environment of high thermal stratification in a large space, and its beneficial technical effects are reflected in the following aspects:

1. The controllability of the experiment: In the experiment, the ambient air temperature of the thermal stratification, the flow rate of the flue gas outlet and the outlet temperature can all be controlled. For example, the ambient air of the thermal stratification is regulated and heated by the AC transformer, and the heating power can be fine-tuned. The top and bottom of the enclosed space The air temperature difference can be controlled at about 20°C, and the accuracy of the air temperature is controlled at about 0.5°C; the flue gas outlet velocity is controlled at about 0.01 m/s due to the use of a DC exhaust fan pair to realize the flue gas transportation in the pipeline , the internal heating of the heating resistance wire is adopted, and the temperature accuracy of the flue gas outlet is controlled at about 0.5°C;

2. The expansibility of the experiment: the general fire experiment can place the low-power fire smoke box directly in the closed chamber, so that the movement of the actual fire smoke plume in the thermal stratification environment can be studied; on the other hand, it can be The smoke production and transportation are realized by the smoke generating mechanism outside the closed chamber. Since the smoke outlet mechanism adopts controllable flow velocity, flow rate, outlet diameter, etc., it is possible to study the heat of the smoke plume of different materials under the condition of the same thermal buoyancy flux. The movement situation in the layered environment, so as to investigate the actual influence of factors such as the smoke density of different materials on the smoke transport law and the maximum rising height;

3. The repeatability of the experiment: due to the controllable parameters of the experimental conditions, the repeatability of the experiment is high.

Description of drawings

Fig. 1 is a schematic diagram of the structure of the present invention,

Figure 2 is a schematic diagram of the flue gas outlet mechanism,

Figure 3 is an effect diagram of the movement of cotton rope smoldering smoke in a closed chamber,

Figure 4 is an effect diagram of the movement of smoke from a diesel oil pool fire in a closed chamber.

Detailed ways

Below in conjunction with accompanying drawing 1, Fig. 2, Fig. 3, Fig. 4, through embodiment 1, 2, 3, 4 the present invention will be further described.

Example 1:

When the smoke outlet mechanism 20 is arranged in the middle of the bottom of the closed chamber 1, it is suitable for studying the axisymmetric central plume or jet fire smoke of different materials. Under the same smoke outlet diameter, outlet velocity and hot air ambient temperature, the fire The movement status of smoke in thermal stratification environment, and investigate the influence of fire smoke density on the movement and maximum height of smoke in thermal stratification environment. Wherein, when changing the outlets of the flue gas outlet mechanism 20 with different diameters, it is suitable for studying the movement of the axisymmetric central flue gas with different outlet diameters under the same outlet speed in a thermally stratified environment.

As shown in Figure 1, a flue gas plume motion simulation experiment device in a thermally stratified environment includes a closed chamber 1, whose horizontal cross-section is square or rectangular, and whose length, width, and height are 1.2 meters, 1.2 meters, and 1.2 meters, respectively. 2 meters, including smoke generating mechanism, data collection and processing mechanism and smoke exhaust mechanism. A square cover 2 is installed under the top of the closed chamber 1. The length, width, and height of the square cover 2 are about 1.1 meters, 1.1 meters, and 0.2 meters respectively. The square cover 2 is 0.3 meters away from the top of the closed chamber 1. The inner wall of the square cover is a mirror surface. , 15 quartz heating tubes 3 are installed in the mirror surface, and the mirror surface plays a role in reducing heat absorption when the quartz heating tubes 3 are heated. The sensor 11 and the closed chamber 1 are connected to the external data acquisition and processing mechanism through wires; the top of the closed chamber 1 is connected to the smoke exhaust mechanism, and the middle of the bottom of the closed chamber is vertically connected to the smoke outlet mechanism 20, and an observation window is installed on the side wall 5;

The smoke exhaust mechanism includes a smoke exhaust pipe 9, a smoke exhaust switch 8 is installed at the entrance of the smoke exhaust pipe 9, and a smoke exhaust machine 10 is installed at its outlet;

The data acquisition and processing mechanism includes three rows of temperature sensors 11, sensor data lines 12, electronic balance 18 and computer 6;

The smoke generating mechanism includes a smoke box 17, and the smoke box 17 is connected to the inlet section 21 of the smoke outlet mechanism 20 through the smoke pipeline 14; the regulating valve 15 and the DC exhaust fan 16 are installed on the smoke pipeline 14; the DC exhaust fan 16 is driven by a DC Transformer 13 realizes speed regulation;

As shown in Figure 2, the flue gas outlet mechanism 20 includes a vertically arranged flue gas pipe body. The flue gas pipe body is cylindrical and tubular, and it includes an inlet section 21, an expansion section 22, a heating section 23, and a steady flow section 24 from bottom to top. , contraction section 25 and outlet section 26; Its inlet section diameter is 2 centimetres; Its expansion section is trumpet shape; Its heating section and steady flow section diameter are 5 centimetres, and the heating resistance wire 30 is axially installed in the described heating section, 50-60 hollow steady-flow tubes 29 are vertically and parallelly arranged in the steady-flow section, the diameter of the steady-flow tube is 1.8-2 mm, the height of the heating section is 15 cm, and the height of the steady-flow section is 10 cm; the shrinkage section is an inverted trumpet shape; the outlet Segments are 1-3 cm in diameter. The material of the flue gas pipe body is aluminum alloy, and the outer walls of the heating section 23 , the steady flow section 24 and the contraction section 25 of the flue gas pipe body are provided with an insulating layer 28 .

Before the experiment, prepare the smoke-generating material and various measuring devices, close the smoke exhauster 10 in the closed chamber, close the smoke exhaust switch 8, and close the regulating valve 15 and the DC exhaust fan 16 of the smoke pipeline.

During the experiment, the quartz heating tube 3 on the top was energized and the ambient air inside the closed chamber 1 was preheated by the AC transformer 19. The initial preheating power and preheating time were adjusted according to the requirements of the thermal stratification intensity and the real-time display value of the temperature sensor. Control, the initial preheating power is generally larger, and the preheating time is longer. According to the temperature monitoring of the thermal stratification environment, after heating the top of the closed chamber for a certain period of time, the vertical distribution of the temperature sensor is approximately linear from top to bottom. , turn down the preheating power, at this time the temperature distribution of the three rows of temperature sensors 11 in the closed chamber space is basically consistent and can be maintained for a certain period of time, indicating that the linear thermal stratification environment tends to be stable;

While preheating the air inside the closed chamber 1, the heating resistance wire 30 of the smoke outlet mechanism 20 is powered and heated by the AC transformer 19, and the heating power is adjusted according to the set value; Different fire materials (such as smoldering cotton rope, n-heptane open flame), etc., the fire materials are placed on the electronic balance 18 of the smoke box 17 to measure their combustion mass loss. The DC exhaust fan 16 is transported to the flue gas outlet mechanism 20 by the smoke delivery pipe 14, where the flue gas is heated by the internal heating resistance wire 30 of the flue gas outlet mechanism 20 to a certain temperature. The closed chambers 1 with different thermal stratification intensities are entered from cylindrical outlets 27 with different diameters. Due to the controllable flow rate, flow rate and temperature of the flue gas, flue gas plumes with different thermal buoyancy fluxes can be obtained, and the repeatability is extremely high;

At the flue gas outlet of the flue gas outlet mechanism 20, the temperature of the flue gas outlet and the temperature of the flue gas plume are measured, and at the same time, the exit image is obtained by taking a camera, and the speed of the flue gas exit is obtained by image analysis; the flue gas plume is closed Generally, in the space thermal stratification environment, it cannot rise to the ceiling, thus forming a mushroom cloud shape. Through the observation window of the closed chamber, the camera analysis method of the image acquisition system 7 is used to obtain the maximum value according to the analysis of the relative position of the smoke in the closed space on the scale. Height; smoke exhaust is performed after each group of experiments. When exhausting smoke, first turn on the smoke exhaust switch 8, and then start the smoke exhaust machine 10. The smoke exhaust time generally depends on the volume of the smoke in the model space. After the smoke exhaust, etc. Wait for a certain period of time to wait for the airflow in the enclosed space to be stable and static before proceeding to the next set of experiments.

The movement effects of cotton rope and diesel fire smoke in the thermally stratified environment of closed chamber 1 are shown in Fig. 3 and Fig. 4 respectively.

Example 2:

When the smoke outlet mechanism 20 is arranged on the side wall of the closed chamber 1, it is suitable for studying the fire smoke of different material wall plumes or wall jets. In order to investigate the effect of fire smoke density on the movement of wall fire smoke and the maximum height of rise in thermal stratification environment. Wherein, changing the outlet of the smoke outlet mechanism 20 with different diameters is suitable for studying the movement of fire smoke on walls with different outlet diameters under the same outlet speed in a thermally stratified environment.

The experimental method is as in Example 1.

Example 3:

When the smoke box 17 is directly arranged in the bottom center of the closed chamber 1, it is suitable for studying the transport law of the axisymmetric center plume of real fire smoke in a thermally stratified environment.

The air temperature control and measurement method of the closed chamber 1, the data collection and processing method of the temperature sensor 11, the smoke image acquisition method, and the smoke exhaust method are as in Example 1.

Example 4:

When the smoke box 17 is arranged on the side wall of the closed chamber 1, it is suitable for studying the transport law of the real fire smoke wall plume in a thermally stratified environment.

The experimental method is as in Example 3.

Claims (6)

1. A flue gas plume motion simulation experiment device in a thermally stratified environment, including a closed chamber, a smoke generating mechanism, a data collection and processing mechanism, and a smoke exhausting mechanism; a thermal layered heating device is arranged below the top of the closed chamber Mechanism, the height direction of the side wall is provided with a scale, and more than two temperature sensors are connected in series through the data line, and the closed chamber is connected to the external data collection and processing mechanism through the wire; the top of the closed chamber is connected to the smoke exhaust mechanism , the bottom of which is connected to the flue gas outlet mechanism, and the side wall is provided with an observation window, which is characterized in that: The closed chamber is a cube, its horizontal cross-section is square or rectangular, and its length, width, and height are 1-1.2 meters, 1-1.2 meters, and 1.8-2 meters respectively; the heat layered heating mechanism includes a side cover , the length, width, and height of the square cover are 0.8-1.1 meters, 0.8-1.1 meters, and 0.2 meters respectively. The distance between the square cover and the top of the closed chamber is 0.2-0.3 meters. The inner wall of the square cover is a mirror surface. 15 quartz electric heating tubes; a smoke outlet mechanism is vertically installed in the middle of the bottom of the closed chamber; The flue gas outlet mechanism includes a vertically arranged flue gas pipe body. The flue gas pipe body is cylindrical and tubular, and it includes an inlet section, an expansion section, a heating section, a steady flow section, a contraction section and an outlet section from bottom to top; The diameter of the section is 1.8-2 cm; the extension section is trumpet-shaped; the diameter of the heating section and the steady flow section are 5-6 cm, the height of the heating section is 15-18 cm, and the height of the steady flow section is 10-12 cm; A heating resistance wire is arranged in the axial direction in the heating section, and a steady flow tube is evenly arranged in the axial direction in the steady flow section; the contraction section is in the shape of an inverted trumpet; The inlet section of the flue gas pipe body is connected to the smoke generating mechanism through the smoke pipeline. The smoke mechanism includes a smoke box and a smoke pipeline. The smoke pipeline is provided with a regulating valve and a DC voltage exhaust fan. outside the chamber. 2. The flue gas plume motion simulation experiment device in a thermally stratified environment according to claim 1, characterized in that: the material of the flue gas pipe body is aluminum alloy. 3. A flue gas plume motion simulation experiment device in a thermally stratified environment according to claim 1, characterized in that: the outer walls of the heating section, steady flow section, and contraction section of the flue gas pipe body are provided with insulating layers . 4. The flue gas plume motion simulation experiment device in a thermally stratified environment according to claim 1, characterized in that: 50-60 hollow steady flow pipes are arranged vertically and parallelly in the steady flow section of the flue gas pipe body Tube, steady flow tube diameter is 1.8-2 mm. 5. The flue gas plume motion simulation experiment device in a thermally stratified environment according to claim 1, characterized in that: the diameter of the outlet section of the flue gas pipe body is 1-3 cm. 6. The flue gas plume motion simulation experiment device in a thermally stratified environment according to claim 1, wherein the flue gas outlet mechanism is located at the bottom of the closed chamber.

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