CN116050107A - FDS numerical simulation method under different fire scenes - Google Patents

Abstract

The application discloses an FDS numerical simulation method under different fire scenes, which is characterized by comprising the following steps: creating a structural model of the L-shaped subway transfer station; the structural model of the L-shaped subway transfer station is imported into an FDS for numerical simulation; setting different fire scenes to obtain a method for restricting fire in different fire scenes. According to the method, a 'model-simulation' research mode is adopted, a structural model of an 'L' -shaped subway transfer station is established and is led into an FDS (fully drawn vehicle) for numerical simulation, different fire scenes are designed, the distribution rules of environmental parameters such as a temperature field, a visibility field and the like in the station when different fan switches are adopted to be matched under each fire scene are discussed, and an optimal fan matching mode under different fire scenes is provided so as to achieve the purpose of limiting the development of a fire by using ventilation means.

Description

A FDS numerical simulation method under different fire scenarios

technical field

The invention relates to the field of fire prevention and control, in particular to an FDS numerical simulation method under different fire scenarios.

Background technique

In a fire, smoke is usually the main cause of death. Installing a suitable forced ventilation smoke control system in a subway station and using reasonable control measures to make the fans cooperate with each other can effectively prolong the escape time of personnel and bring great benefits to firefighters in disaster relief work. Come conveniently. In fact, a large number of studies have shown that the important fire-fighting measures in subway fires are to control the spread of smoke through effective ventilation and smoke exhaust, thereby increasing the safety time of evacuation, strengthening fire rescue, and reducing casualties. Therefore, it is necessary to carry out research on subway fire accidents. At present, research on subway fires at home and abroad has formed a research model, that is, building a station structure model with the support of on-site investigations and engineering drawings, and then building a laboratory scale model to carry out laboratory scale-down mechanical smoke exhaust experiments or in the laboratory. The fire experiment was carried out on site. On the other hand, the fire simulation software (FDS) was used to simulate the change of the environmental parameters in the station during the fire and compared with the experimental results. The overall research on subway fires is insufficient. The above-mentioned studies mostly focus on the "cross-shaped" transfer of two-line transfers or the transfer form of multi-line transfers, and there is a gap in the research on "L" transfers of two-line transfers.

In fact, the "L" type transfer form of the two-line transfer is a commonly used transfer form and has its own unique fire hazards: the main building of the subway station itself is underground, and the station is highly dependent on ventilation and lighting facilities; Compared with ordinary stations, the number of electrical equipment and the flow of people in the bus station are relatively large, which increases the fire hazard of the transfer station: the "L" type subway transfer station has a long evacuation distance due to its unique long and narrow structure. The problem of long time; and the fact that the direction of fire smoke spread is consistent with the direction of personnel evacuation also increases the possibility of personnel being injured by smoke.

Contents of the invention

The purpose of this application is to adopt the "model-simulation" research mode to establish the structural model of the "L" type subway transfer station and import it into FDS for numerical simulation, to design different fire scenarios and to discuss how to adopt different fire scenarios in each fire scenario. The distribution rules of environmental parameters such as temperature field and visibility field in the station when different fan switches are coordinated, and the best fan coordination methods under different fire scenarios are proposed, in order to achieve the purpose of limiting the development of fire by means of ventilation. In order to achieve the above object, the application provides the following solutions:

A FDS numerical simulation method under different fire scenarios, comprising the following steps:

S1. Create a structural model of an "L"-shaped subway transfer station;

S2. Import the structural model of the "L"-shaped subway transfer station into FDS for numerical simulation;

S3. Different fire scenes are set, and methods for limiting fires in different fire scenes are obtained.

Preferably, the structural model of the "L" type subway transfer station specifically includes:

Station structure model and station ventilation model;

Among them, the station structure model includes the main body of the "L" type station; the exit, the station hall floor and the platform floor; the ventilation model includes the piston air pavilion and the ordinary ventilation air pavilion.

Preferably, the function of the piston air pavilion specifically includes:

The piston wind pavilion is used to connect the tunnels in the section to reduce the piston wind generated when the vehicle enters the station.

Preferably, the common ventilation pavilion is provided in the "L"-shaped station to be responsible for all mechanical ventilation.

Preferably, it is imported into FDS for numerical simulation:

A plurality of grid overlaps are adopted for the structural model of the "L" type subway transfer station to obtain a model grid overlap diagram;

Using the heat release rate model, the combustion in FDS is set as unsteady combustion, and the relationship between the heat release rate and time is obtained:

Q=αt ²

Among them, Q is the heat release rate; α is the growth coefficient; t is the time;

Numerical simulation is performed according to the model mesh lap diagram and the relationship between the heat release rate and time.

Preferably, in the growth stage of the fire, α determines the heat release rate of the fire, which can be divided into four models. This application adopts the ultra-fast type, that is, α=0.1878.

Preferably, the different fire scenarios specifically include:

Fire scene 1: The cigarette butt ignites the burning material and causes a fire;

Fire Scenario 2: A circuit fault causes a fire;

Fire Scenario 3: Gate circuit failure leads to fire.

Preferably, the method for restricting fires in different fire scenarios specifically includes:

Make longitudinal comparisons of different fan coordination schemes; introduce the parameter "distance from the fire source" as the abscissa parameter for the longitudinal comparison of temperature and carbon monoxide concentration, and introduce the parameter "proportion of the area with visibility below 10m" as the ordinate parameter for the longitudinal comparison of visibility.

The beneficial effect of this application is:

This application adopts the research mode of "model-simulation", establishes the structural model of "L" type subway transfer station and imports it into FDS for numerical simulation, designs different fire scenarios and discusses the adoption of different fan switches in each fire scenario Cooperate with the distribution law of environmental parameters such as temperature field and visibility field in the station, and propose the best fan cooperation mode under different fire scenarios, in order to achieve the purpose of limiting the development of fire by means of ventilation.

Description of drawings

In order to illustrate the technical solution of the present application more clearly, the accompanying drawings used in the embodiments are briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present application. Technical personnel can also obtain other drawings based on these drawings without paying creative labor.

FIG. 1 is a flow chart of a method for restricting fires in different fire scenarios according to an embodiment of the present application;

Fig. 2 is an "L" type subway transfer station design structure model diagram of a method for restricting fires in different fire scenarios according to an embodiment of the present application;

Fig. 3 is a diagram of mechanical ventilation pipelines of A, B, and C air kiosks in an "L"-shaped subway station and its relative position relationship diagram of a method for restricting fires in different fire scenarios according to an embodiment of the present application;

Fig. 4 is an "L" type subway transfer station model network overlap diagram of a method for restricting fires in different fire scenarios according to an embodiment of the present application;

Fig. 5 is a state diagram of smoke spreading on the platform of an "L" type subway transfer station based on fire scene 1 in a method of restricting fire in different fire scenes according to an embodiment of the present application;

Fig. 6 is a temperature distribution diagram of an "L" type subway transfer station based on a fire scene 1 of a method for restricting fires in different fire scenes according to an embodiment of the present application;

Fig. 7 is a visibility distribution diagram of an "L" type subway transfer station based on a fire scene 1 of a method for restricting fires in different fire scenes according to an embodiment of the present application;

Fig. 8 is a CO concentration distribution map of an "L" type subway transfer station based on fire scene 1 in a method of restricting fire in different fire scenes according to an embodiment of the present application;

Fig. 9 is a longitudinal comparison diagram of environmental parameters in the "L" type subway transfer station based on different fan coordination modes in the fire scene 1 of a method for limiting fires in different fire scenes according to an embodiment of the present application;

Fig. 10 is a state diagram of smoke spread on the platform of an "L" type subway transfer station based on fire scene 2 in a method of restricting fire in different fire scenes according to an embodiment of the present application;

Fig. 11 is a temperature distribution diagram of an "L" type subway transfer station based on fire scene 2 in a method of restricting fire in different fire scenes according to an embodiment of the present application;

Fig. 12 is a visibility distribution diagram of an "L"-shaped subway transfer station based on fire scene 2 in a method of restricting fire in different fire scenes according to an embodiment of the present application;

Fig. 13 is a CO concentration distribution map of an "L" type subway transfer station based on fire scene 2 in a method of restricting fire in different fire scenes according to an embodiment of the present application;

Fig. 14 is a longitudinal comparison diagram of environmental parameters in the "L" type subway transfer station based on different fan coordination modes in fire scene 2, according to a method of restricting fire in different fire scenes according to an embodiment of the present application;

Fig. 15 is a state diagram of smoke spreading on the platform of an "L" type subway transfer station based on a fire scene three in a method of restricting fires in different fire scenes according to an embodiment of the present application;

Fig. 16 is a temperature distribution diagram of an "L" type subway transfer station based on a fire scene three in a method of restricting fires in different fire scenes according to an embodiment of the present application;

Fig. 17 is a visibility distribution diagram of an "L"-shaped subway transfer station based on a fire scene three in a method for restricting fires in different fire scenes according to an embodiment of the present application;

Fig. 18 is a distribution map of CO concentration on the platform of an "L"-shaped subway transfer station based on a fire scene three based on a method for restricting fires in different fire scenes according to an embodiment of the present application;

Fig. 19 is a longitudinal comparison diagram of environmental parameters in an "L"-shaped subway transfer station based on different fan coordination methods in fire scene 3, according to a method of restricting fires in different fire scenarios according to an embodiment of the present application.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the application with reference to the drawings in the embodiments of the application. Apparently, the described embodiments are only some of the embodiments of the application, not all of them. Based on the embodiments in this application, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the scope of protection of this application.

In order to make the above objects, features and advantages of the present application more obvious and comprehensible, the present application will be further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

In this embodiment, as shown in Figure 1-19, a method for restricting fires in different fire scenarios includes the following steps:

Create a structural model of an "L"-shaped subway transfer station;

CAD3D is used to establish the structural model of the subway station. Through the preliminary field investigation and reference to some drawings, the design structure model diagram of a large "L"-shaped subway transfer station is shown in Figure 2.

This station is in the form of "L" transfer, the main body of the station is in the shape of "L", and there are 6 exits in total. The main body of the station is "L" shaped, and is divided into three floors in the vertical direction. From top to bottom, it is the station hall floor, the platform floor of Line 2 and the platform floor of Line 1. The underground floor is the station hall of the subway station. The effective length of the station hall of Line 1 is 160m in the east-west direction and 56m in the north-south direction. The effective length of the station hall of Line 2 is 23m in the east-west direction and 180m in the north-south direction. There are 6 entrances and exits connected to the ground in the station hall layer. There are 3 escalators and a straight barrier-free elevator on the station hall floor of Line 1 to connect with the platform floor of Line 1 on the third underground floor. The station hall floor of Line 2 is equipped with There are 3 escalators and a straight barrier-free elevator connected to the platform floor of Line 2 on the second basement floor. The second underground floor is an island platform of Line 2, with an effective east-west width of 14m and a north-south effective length of 160m. The effective length of the tunnel of Line 2 is 120m, and the effective width is 3m. There are 3 cable and equipment rooms in the space under the three escalators, and closed screen doors with a size of 6000mm×3000mm are installed on both sides, with 20 doors on each side. Line 2 and Line 1 passengers can transfer through this space. The third underground floor is the island platform of Line 1. The effective length of the platform floor is 141m in the east-west direction, and the effective width in the north-south direction is 18m. There are 3 cable and equipment rooms in the space under the three escalators, and there are 6000mm× There are 3000mm screen doors, 20 on each side, and there is a transfer space on the east side of the platform level of Line 1 to connect with the platform level of Line 2.

A total of 4 piston air booths are set up in this station, which are used to connect the tunnels in the section to reduce the piston wind generated when vehicles enter the station. There is no mechanical ventilation in the piston air booths. As shown in Figure 3. In addition, there are 3 general ventilation pavilions in this station, which are responsible for all the mechanical ventilation in the station, and they are named A, B, and C ventilation pavilions respectively. A, B, C air pavilion mechanical ventilation pipeline diagram and their relative position relationship are shown in Figure 4.

A wind pavilion is located near Exit 13 on the west side of the station, connecting two sets of east-west ventilation pipelines, responsible for the mechanical ventilation of the Line 1 platform and the Line 1 area on the station hall floor. Among them, the ventilation pipeline of the platform of Line A Fengting Line 1 is located on the ceiling of the platform floor of Line 1. There is a ventilation pipeline on the north and south sides of the platform, and each ventilation pipeline has 4 ventilation openings, a total of 8 ventilation openings, responsible for Ventilation at the platform level of the line. A ventilation pipeline on the station hall floor of Fengting is located in the area of Line 1 on the ceiling of the station hall floor. There is a ventilation pipeline on the north and south sides of the ventilation pipeline. Ventilation of Line 1 area on hall floor. Ventilation Pavilion B is located near Exit 5 on the south side of the station, connecting two sets of north-south ventilation pipelines, responsible for the mechanical ventilation of the Line 2 platform and the south side of the Line 2 area on the station hall floor. Among them, the ventilation pipeline of the platform of B Fengting Line 2 is located on the ceiling of the platform floor of Line 2. There is a ventilation pipeline on the east and west sides of the platform, and each pipeline has 5 ventilation openings, a total of 10 ventilation openings, responsible for Line platform level ventilation. B Fengting station hall floor ventilation pipeline is located on the south side ceiling of Line 2 on the station hall floor. The pipeline runs north-south. There is a ventilation pipeline on the east and west sides of the platform. One vent is responsible for the ventilation on the south side of the Line 2 area on the station hall floor. The C wind pavilion is located near Exit 9 on the north side of the station, connected to a set of north-south ventilation pipelines, responsible for the mechanical ventilation on the north side of the Line 2 area on the station hall floor. The C air pavilion pipeline is located on the north side ceiling of Line 2 on the station hall floor. There is a ventilation pipeline on the east and west sides of the station hall. Each pipeline is equipped with 3 vents, a total of 6 vents. Part of Line 2 is ventilated on the north side.

Import the structural model of the "L" type subway transfer station into FDS for numerical simulation;

This simulation will adopt the heat release rate model. In order to more scientifically reflect the change of environmental parameters in the station during the fire process, this paper sets the combustion in FDS as unsteady combustion, and the relationship between the heat release rate and time is as follows:

Q=αt ² ;

in:

Q—heat release rate, kw;

α—growth coefficient, kw s-2;

t—time, s;

In the growth stage of the fire, the heat release rate of the fire is determined by α, which can be divided into four models: slow type (α=0.002931), medium speed type (α=0.01127), fast type (α=0.04689) , the ultra-fast type (α=0.1878), this study adopts the ultra-fast type. According to SFPE "Fire Protection Engineering Handbook", set the energy output of the fire within the range of 100KW to 50MW, select a medium-sized fire, and set the fire power to 5MW. Therefore, a cube with a size of 1m×1m×1m is set in this paper, and fire source surfaces with a maximum heat release power of 1000kw/㎡ are set on the other five surfaces of the cube except the surface in contact with the ground, so that the entire fire source cube The source power reaches 5MW. Considering the need to observe the flow of flue gas, the reactant selects polyurethane with a large amount of smoke. By searching the SFPE "Fire Protection Engineering Handbook", it is determined that the value of "COyield" in the combustion product of polyurethane is 0.2.

Among them, the ultra-fast type used in this application can not only save simulation time, but also adopt the highest heat release rate. The corresponding fire scene is more severe during simulation, and the final ventilation scheme is more reliable. On the other hand, from The angle set by the Fire Scenario parameter increases the safety threshold of the ventilation scheme.

Since the structure of the "L" type subway transfer station is an irregular shape, this paper adopts the form of overlapping multiple grids in the grid drawing of pyrosim. The grid size is 1m×1m×1m, with a total of 4,000,896 grids. The grid overlap of the model is shown in Figure 4.

When building the model, the influence of the load-bearing columns in the building, the equipment room under the stairs, and the smoke-blocking walls and glass fences at the escalator entrance on the smoke flow is considered. The influence of real-time personnel flow and evacuation on the smoke flow in the subway station is ignored. Among them, the load-bearing columns and equipment rooms use the default concrete material and do not participate in combustion.

In order to observe the changes of environmental parameters more macroscopically, the sensor adopts 2D slice setting, which is divided into temperature sensor (thermocouple), CO volume flow sensor and smoke visibility sensor. CO volume flow sensor, thermocouple and visibility sensor are placed on the z-axis slice at the vertical height of 1.7m from the ground on the station hall floor and the platform floor of Line 1 and Line 2.

Establishment of mechanical smoke exhaust: In this research, the "exhaust" surface is used to establish mechanical smoke exhaust, and the "vent" surface is drawn from the vent hole reserved in the ventilation pipeline in the model to create a new "surface", and the "surface" surface The property is set to "exhaust" surface, and according to the number of vents in each layer in the model, the constant flow rate of the vent "ex haust" is selected as 8m ³ /s.

According to the case analysis of major fires in subways and subways abroad, the results show that among the causes of subway fires, electrical fires, smoking and mechanical failures account for 26%, 13% and 11% of the total fires respectively. The subway fires caused by these three reasons account for 50% of the total number of subway fires. Therefore, in order to facilitate the observation of the smoke spread and environmental parameters when different subway station structures are on fire, this paper will set up one of the above-mentioned subway fire causes in each of the three-story structures of the subway station, and the fire sources are gates. , between circuit equipment and unextinguished cigarette butts.

Fire scene: The ambient temperature in the subway station is 20°C, and the external ambient pressure is selected as a standard atmospheric pressure of 101.325Kpa. After the train enters the station, the screen door is opened, and three fire source locations are set: the equipment room under the central stairs of Line 1, The equipment room under the stairs of Line 2 and the gate at the entrance of the station hall level.

Fire scene 1: Cigarette butts ignite the large trash can next to the equipment room under the central stairs of Line 1. (that is, the fire on the west side of the platform of Line 1)

Fire scene 2: A circuit fault in the equipment room under the stairs of Line 2 caused a fire. (i.e. the fire on the Taipei side of Line 2 Station)

Fire Scenario 3: Turnstile circuit failure and fire. (That is, the fire at the entrance of Line 1 on the station hall floor)

According to the fire scene and the location characteristics of the fire source, the cooperation mode of turning on and off the fan in the corresponding fire scene is determined. The fire scene design in the station and the cooperation mode of the corresponding fan are shown in Table 1.

Table 1

Under the conditions of fire scene 1, we simulated the smoke spread characteristics, temperature, CO concentration and visibility of the platform of Line 1 within 360s under different fan coordination conditions. The smoke spread state of the platform at 360s is shown in Figure 5, the temperature distribution of the platform at 360s is shown in Figure 6, the visibility of the platform at 360s is shown in Figure 7, and the CO concentration distribution of the platform at 360s is shown in Figure 8.

In order to better compare the impact of the various fan coordination schemes responsible for mechanical ventilation in the station on the environmental parameters in the station, we will conduct a longitudinal comparison of different fan coordination schemes. The "distance from the fire source" parameter is introduced as the abscissa parameter for the longitudinal comparison of temperature and CO concentration, and the "area proportion of the visibility area below 10m" parameter is introduced as the ordinate parameter for the longitudinal comparison of visibility. The longitudinal comparison of the environmental parameters in the station under different fan coordination modes in the fire scene is shown in Figure 9.

For fire scenario 1 (fire on the west side of the platform of Line 1), the maximum temperature in the station can reach 95°C without turning on the mechanical smoke exhaust, and after turning on the ventilation of the platform of Line 1, the temperature drops to about 85°C. The superimposed opening of other fans on the station will not further reduce the upper temperature limit in the station. Regardless of whether the mechanical smoke exhaust is turned on or not, the high-temperature areas in the platform will first appear near the two ends of the platform and near the smoke-blocking wall under the stairwell. When the ventilation of the A wind pavilion on Lines 1 and 2 and the station hall floor is turned on, the superimposed ventilation of the B wind pavilion will accelerate the diffusion of high-temperature smoke in the platform to form a relatively local high temperature area at the same time, and the superposition of the C wind pavilion will not affect the temperature. The distribution has a noticeable effect. For the fire in the middle area of Line 1, if the mechanical smoke exhaust is not turned on, the smoke will spread to all spaces except the northern part of Line 2 on the station hall floor. 120s achieves the effect of controlling the smoke at the platform level of Line 1, but once the time exceeds 120s, this scheme is no longer advantageous. When the ventilation of Lines 1 and 2 and the ventilation pavilion on the station hall floor A are turned on, the smoke can be controlled within the minimum smoke diffusion range within 6 minutes. When the ventilation pavilions on the station hall floor B and C are opened sequentially, the smoke will be expanded instead. range of influence. For the fire in the central area of Line 1, the visibility first dropped significantly near the end of the platform. After the ventilation of Lines 1 and 2 and the ventilation booth A on the station hall floor, the superimposed ventilation of B and C ventilation pavilions will not affect the visibility level. obvious impact. On the basis of turning on the ventilation of Lines 1 and 2, turning on the fan ventilation on the station hall floor will not have a significant impact on the distribution of CO concentration, but after turning on the ventilation pavilion on the station hall floor, it can effectively reduce the upper limit of the concentration of CO in the platform. Less than 250ppm safety critical value.

In terms of temperature control, it has a relatively good effect with four temperature control. In terms of visibility control, the proportion of areas with visibility below 10m in Coordination 4 and Coordination 5 is at the relatively lowest level, and the intersecting other coordination methods have been greatly improved. In terms of CO concentration control, coordination 3, 4, and 5 have similar effect trends and relatively best control effects within 60m from the fire source point, and the control effect of coordination 3 is better than that of coordination 4 and 60m in the area beyond 60m. Match five.

fire scene two

Under the conditions of fire scene 1, the smoke spread state of the platform at 360s is shown in Figure 10, the temperature distribution of the platform at 360s is shown in Figure 11, the visibility of the platform at 360s is shown in Figure 12, and the CO concentration distribution of the platform at 360s is shown in Figure 11. 13. Figure 14 shows the longitudinal comparison of environmental parameters in the station with different fan coordination modes in fire scene 2. For fire scene 2 (fire on the Taipei side of Line 2 station), the maximum temperature inside the platform can reach 95°C without turning on the mechanical smoke exhaust. The temperature distribution is obviously transformed from a relatively uniform distribution to a cross distribution of different temperature regions. The high temperature area first appears near the end of the platform. When only the smoke exhaust on the platform level of Line 2 is turned on, the smoke can be controlled on the platform of Line 2 for 6 minutes, but the smoke concentration in the platform is extremely high. Ventilating the air pavilions on hall floor B and C or turning on all the ventilation on the platform can respectively control the smoke diffusion range of Line 2 part of the station hall floor or your platform floor of Line 2. Turning on the platform ventilation of Line 2 and ventilation booth C in the station hall can still maintain a visibility level of more than 28.5m on the north side of the station 360s after the fire broke out. After that, the superimposed ventilation of B and A ventilation booths has no effect on visibility. The opening of the mechanical smoke exhaust can significantly reduce the upper limit concentration of CO on the platform. After the ventilation of the platform of Line 2 and the ventilation of the B and C ventilation pavilions are turned on, the superimposed ventilation of the A ventilation pavilion will not have a significant impact on the CO concentration of the platform. In terms of temperature control, the effects of the four coordination methods are not much different, and the temperature control performance of the three coordination methods is relatively good in the area 100m away from the fire source. In terms of visibility parameters, the proportion of the visibility area below 10m in coordination 3 is the least, but the visibility control effects of coordination 3 and 4 are also relatively good and are almost lower than 50% with the coordination of three phases. In terms of CO concentration control, within the range of 40m from the fire source point, the CO concentration control effects of the four coordination methods are not much different. Significantly better. Therefore, when choosing the fan cooperation method, the influence of the influence range of flue gas should be considered emphatically. Cooperating with No. 3 Middle School, the smoke spreads in a larger area during the ventilation of the platform of Line 2, while the area affected by the smoke in the station hall floor is relatively small. However, Cooperating with No. 4 Middle School is just the opposite. Cooperating with No. Most areas are not affected by the spread of smoke, but the range of smoke spread in the station hall floor is obviously larger.

Fire scene three:

Under the conditions of fire scene 1, the smoke spread state of the platform at 360s is shown in Figure 15, the temperature distribution of the platform at 360s is shown in Figure 16, the visibility of the platform at 360s is shown in Figure 17, and the CO concentration distribution of the platform at 360s is shown in Figure 16 18. Figure 19 shows the longitudinal comparison of environmental parameters in the station with three different fan coordination modes in the fire scene.

For fire scenario 3 (fire at the entrance of part of Line 1 on the station hall floor), when ventilation booth A is turned on, the spread of smoke can be controlled from the part of Line 1 on the station hall floor to the connecting corner, and the smoke will be exhausted within 6 minutes. The air hardly diffuses to the Line 2 part of the station hall, and the superimposed ventilation of the B and C air pavilions will expand the diffusion area of the smoke. When the A ventilation booth is turned on and the B and C ventilation booths are superimposed, the local high-temperature area in the station expands significantly, which is manifested in the temperature of the southern part of Line 2 connecting the corner and the station hall floor at the same time. Visibility and CO concentration show the same law as temperature. It can be seen that the superposition of wind pavilion ventilation can not improve the environment of the station hall for fire scene 3, but will worsen the environmental parameters.

Through the longitudinal comparison, it can be found that only the ventilation method of the A wind pavilion has a significant effect on improving the visibility, and the area ratio of the visibility area below 10m is far smaller than that of other fan cooperation methods. In terms of CO concentration comparison, only the A wind pavilion ventilation and A The two schemes of simultaneous ventilation and B can control the CO concentration at a relatively low level. In terms of temperature longitudinal comparison, only the ventilation scheme of A wind pavilion is at the relatively lowest temperature on the whole, especially the area 40m away from the fire source can be relatively good. control temperature.

According to the above simulation results, this conventional fan coordination scheme cannot maximize the control of flue gas and improve the environment in the station. Therefore, considering the results of longitudinal comparison of environmental parameters in the station and the spread of smoke, we will give suggestions for fire scenarios 1, 2, and 3 that are different from conventional fire fan coordination schemes.

(1) For fire scene 1 (fire on the west side of the platform of Line 1), it is recommended to open the ventilation (coordination 4) of ventilation booths on Lines 1 and 2 and station hall floors A and B for ventilation. For the second fire scenario (fire on the Taipei side of Line 2 station), it is necessary to strengthen the consideration of the smoke spread range, so the proposed method will be divided into two situations, that is, when the focus is on evacuating people from the platform of Line 2, it is recommended to use Line 2 Ventilation method for all wind pavilions on the platform floor and the station hall floor (coordination 4). And when the focus of evacuation is on the station hall floor, it is recommended to adopt ventilation booths on Line 2 and station hall floors B and C (Coordination 3), which can effectively reduce the spread of smoke to the station hall floor. For fire scene 3 (fire at the entrance of Line 1 on the station hall floor), the ventilation coordination method for ventilation booth A on the station hall floor.

(2) For the "L" type subway transfer station, all the fans cannot be turned on for ventilation when a fire occurs. On the one hand, the superimposed ventilation of the fans can control the diffusion of smoke, lower the upper limit of temperature, lower the regional temperature, and improve the local visibility level and reduce local CO concentrations. But on the other hand, superimposed ventilation by fans will cause wind flow confusion in the station, which may accelerate the diffusion of high-temperature smoke to form local high-temperature areas, accelerate the diffusion of local smoke to reduce visibility in local areas, and increase local CO concentrations. Therefore, corresponding fan coordination methods should be adopted for different fire scenarios.

The above-mentioned embodiments are only descriptions of the preferred modes of the present invention, and do not limit the scope of the present invention. Variations and improvements should fall within the scope of protection defined by the claims of the present invention.

Claims (8)

1. The FDS numerical simulation method under different fire scenes is characterized by comprising the following steps of:

s1, creating a structural model of an L-shaped subway transfer station;

s2, importing a structural model of the L-shaped subway transfer station into an FDS (finite description space) for numerical simulation;

s3, setting different fire scenes to obtain a method for limiting fire in the different fire scenes.

2. The method for simulating FDS numerical values in different fire scenes according to claim 1, wherein the structural model of the L-shaped subway transfer station specifically comprises:

a station body structure model and an in-station ventilation model;

the station body structure model comprises an L-shaped station main body; an exit, a hall floor and a platform floor; the ventilation model comprises a piston air pavilion and a common ventilation air pavilion.

3. The method for simulating FDS values in different fire scenes according to claim 2, wherein the piston wind booth has the following functions:

the piston wind pavilion is used for connecting tunnels in the section and reducing piston wind generated when vehicles enter the station.

4. A method of numerical simulation of FDS in different fire scenarios according to claim 3, characterized in that said common ventilation air booth is provided in said "L" station for taking care of all mechanical ventilation.

5. The method for numerical simulation of FDS in different fire scenarios according to claim 1, wherein the numerical simulation is performed by introducing the FDS:

a plurality of grid lap joints are adopted for the structural model of the L-shaped subway transfer station, and a model grid lap joint diagram is obtained;

setting combustion in the FDS as unsteady combustion by using a heat release rate model to obtain a relationship between a heat release rate and time:

Q＝αt ²

wherein Q is the rate of heat release; alpha is a growth coefficient; t is time;

and carrying out numerical simulation according to the model grid overlap graph and the relation between the heat release rate and time.

6. The method according to claim 5, wherein α determines the heat release rate of the fire during the growth phase of the fire, and is divided into four models, wherein the present application adopts an ultrafast type, i.e., α= 0.1878.

7. The method for FDS numerical simulation under different fire scenarios according to claim 1, wherein the different fire scenarios specifically include:

fire scene 1: the cigarette end ignites the burner to cause a fire;

fire scene 2: a circuit failure causes a fire;

fire scene 3: the gate circuit failure causes a fire.

8. The method for simulating FDS numerical values under different fire scenes according to claim 7, wherein the method for limiting fire under different fire scenes specifically comprises:

longitudinally comparing different fan matching schemes; the parameter of 'distance from the trend of the fire source' is introduced as an abscissa parameter for longitudinal comparison of the temperature and the concentration of carbon monoxide, and the parameter of 'area occupation ratio of a visibility region below 10 m' is introduced as an ordinate parameter for longitudinal comparison of the visibility.

Images