CN115859582A - Method and equipment for predicting height of gas horizontal leakage injection fire - Google Patents
Method and equipment for predicting height of gas horizontal leakage injection fire Download PDFInfo
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Abstract
The invention relates to a method and equipment for predicting the height of a gas horizontal leakage injection fire, belonging to the technical field of fire safety. Compared with the prior art, the prediction method and the model provided by the invention make up the defects of neglecting the restriction effect of the barrier and the shape and size of the leakage hole, can obtain the extension height value of the gas horizontal leakage jet fire under the restriction condition according with the actual condition, and improve the prediction accuracy of the extension height of the horizontal jet fire under the restriction condition of the vertical barrier.
Description
Technical Field
The invention relates to the technical field of fire safety, in particular to a method and equipment for predicting the height of a fuel gas horizontal leakage jet fire.
Background
The jet fire is the fire accident with the highest probability in the fire accidents of gas leakage. In the service process of the gas transportation pipeline and the gas storage equipment, the outer wall is easy to crack due to equipment corrosion and aging, third party damage or construction factors and the like, so that gas leakage occurs; after the fuel gas leaks, when the fuel gas meets an ignition source or is subjected to high-temperature friction to fire, the fuel gas is easy to jet fire, and a fire accident occurs.
Due to different positions of the leakage holes, gas jet fires with different jet directions can be caused, wherein horizontal leakage is the main leakage direction of the gas pipeline and the storage tank and is easy to cause the horizontal jet fire, different types of buildings and equipment facilities are usually arranged around the horizontal leakage jet fire, the free development of the jet fire is limited, and meanwhile, the jet fire damages the surrounding buildings or equipment facilities. The vertical barrier is one of the main forms of jet fire limitation in industrial production, and can directly block the flame development and change the flame diffusion direction. The horizontal jet fire limited by vertical barrier is mainly harmful and characterized by flame, which can directly ignite surrounding combustible substances to enlarge the fire scale, and damage surrounding equipment facilities due to direct impact strong heat convection, and the flame surface can emit high-intensity heat radiation to cause the surrounding equipment facilities and personnel to be affected by strong heat radiation and high temperature, thus causing casualties and property loss around. Therefore, how to determine the height of the horizontal jet fire under the limit of the vertical barrier is an important ring for the safety evaluation of the gas fire.
In the related art, the heat transfer characteristic parameters of the steel plate surface impacted by the jet fire are usually obtained through experimental tests and model calculation; or, an experimental method for the thermal radiation test of the fire jet is provided, the thermal radiation source of the fire jet is considered as a point source, and the safety distance is calculated based on different thermal radiation critical values. Obviously, most of the current fire injection prediction models are thermal radiation prediction values on the basis of point source models, the influence of a cutoff effect on fire injection development caused by a limiting barrier is not considered, and the height of a horizontal fire injection under the limitation of a vertical barrier cannot be calculated, so that safety assessment is deviated.
Disclosure of Invention
In view of the above, the present invention provides a method and an apparatus for predicting a horizontal leakage jet fire height of a gas, so as to overcome the problem that the horizontal jet fire height under the limitation of a vertical obstacle cannot be calculated at present, so that a deviation exists in a safety evaluation.
In order to achieve the purpose, the invention adopts the following technical scheme:
in one aspect, a method for predicting the height of a fuel gas horizontal leakage injection fire is applied to each scene under the limitation of a vertical obstacle, and the method comprises the following steps:
determining initial parameters of a gas leakage hole and environmental parameters of the gas leakage hole in a target scene to be predicted; wherein, the initial parameter of gas leakage hole includes: leak rate, leak hole shape, leak hole size, and hole-to-plate spacing; the gas leakage hole environmental parameters are as follows: ambient temperature and ambient density;
calculating the heat release rate of a fire source of gas leakage and the horizontal fire ejection length under the non-limited condition according to the initial parameters of the gas leakage hole and the environmental parameters of the gas leakage hole;
calculating the volume fraction of the fuel gas horizontal leakage injection fire along the vertical wall surface under the limitation of the vertical barrier according to the size of the leakage hole, the shape of the leakage hole and the length of the horizontal injection fire under the unlimited condition;
calculating the gas leakage dimensionless heat release rate of flame extending along the vertical wall surface according to the volume fraction of the gas horizontal leakage jet fire along the vertical wall surface under the restriction of the straight barrier, the heat release rate of the fire source, the environment density and the environment temperature;
inputting the gas leakage dimensionless heat release rate of the flame extending along the vertical wall surface into a prediction model with a pre-constructed value to obtain a predicted value of the extension height of the gas horizontal leakage flaming fire along the vertical wall surface under the limitation of a vertical barrier; the preset model is a corresponding relation model of dimensionless extension height of gas horizontal leakage injection fire and dimensionless heat release rate under the limitation of a vertical barrier.
Optionally, the method of calculating the heat release rate of the fire source and the horizontal fire ejection length under the unlimited condition according to the initial parameter of the gas leakage hole and the environmental parameter of the gas leakage hole includes:
the leakage hole is rectangular in shape, and the size of the leakage hole comprises a long side L and a short side W;
calculating to obtain the equivalent diameter D =2 LW/(L + W) of the leakage hole according to the size of the leakage hole;
according to the leakage rate u j And calculating the equivalent diameter D of the leakage hole to obtain a determined Froude number, fr = u j 2 /(gD)；
Calculating the horizontal fire length under the unrestricted condition, l, according to the Froude number and the hole-plate spacing lf /D＝23Fr 1/5 ；
According to the gas leakage rate u j Determining the heat release rate Q =18.61+29.1u of the fire source j 。
Optionally, the volume fraction of the gas horizontal leakage fire jet along the vertical wall surface under the limitation of the vertical obstacle is calculated according to the size of the leakage hole, the shape of the leakage hole, and the length of the horizontal fire jet under the unlimited condition, and the method includes:
according to the size of the leakage hole, the flame volume under the unrestricted condition is determined:
according to the flame volume under the unrestricted condition, determining the volume fraction of the gas horizontal leakage injection fire along the vertical wall surface under the restriction of the vertical barrier:
optionally, the calculating, according to the volume fraction of the gas horizontal leakage jet fire along the vertical wall surface under the restriction of the straight obstacle, the fire source heat release rate, the ambient density, and the ambient temperature, the gas leakage dimensionless heat release rate of the flame extending along the vertical wall surface includes:
according to the heat release rate Q of the fire source and the ambient temperature T ∞ And ambient density ρ ∞ Determining the heat release rate of the dimensionless fire source:
calculating the gas leakage dimensionless heat release rate of the flame extending along the vertical wall surface according to the volume fraction of the gas horizontal leakage injection flame along the vertical wall surface under the limitation of the vertical barrier and the dimensionless fire source heat release rate:
optionally, the method for constructing the preset model includes:
constructing a gas horizontal leakage injection fire scene under the limit of a vertical obstacle based on a prediction and evaluation target, wherein the scene comprises a gas leakage hole, an ignition source and the vertical obstacle; the combustible gas is sprayed out of the leakage hole and then is ignited;
acquiring flame profiles under different initial parameters of the gas leakage holes and environmental parameters of the gas leakage holes to obtain a flame shape video; wherein, the initial parameter of gas leakage hole includes: leak rate, leak hole shape, leak hole size, and hole-plate spacing; the environmental parameters of the gas leakage hole are as follows: ambient temperature and ambient density;
calculating to obtain the corresponding gas leakage dimensionless heat release rate of flame extending along the vertical wall surface according to different initial parameters of the gas leakage hole and environmental parameters of the gas leakage hole;
for any gas horizontal leakage fire spraying scene under the limitation of a vertical barrier of gas leakage dimensionless heat release rate of flame extending along the vertical wall surface, processing a flame shape video corresponding to the gas horizontal leakage fire spraying scene under the limitation of the vertical barrier by adopting an Otsu method to obtain an extending height value of the flame along the vertical wall surface, and traversing all horizontal fire spraying scenes;
and carrying out nonlinear fitting according to the corresponding relation between the gas leakage dimensionless heat release rate of the flame extending along the vertical wall surface and the dimensionless value of the gas horizontal leakage jet fire height to obtain a preset model which is a corresponding relation model between the gas horizontal leakage jet fire dimensionless extension height and the dimensionless heat release rate under the limitation of a vertical barrier.
Optionally, the processing, by using an Otsu method, a flame shape video corresponding to the gas horizontal leakage injection fire scene under the limitation of the vertical obstacle to obtain an extension height value of the flame along the vertical wall surface includes:
simulating horizontal gas leakage fire injection under the limitation of vertical obstacles of each prediction scene by adopting fire dynamic simulation software to obtain a flame shape video of each scene;
and processing the flame shape video of each scene by adopting an Otsu method to obtain a flame pulsation probability picture, measuring the flame size in the picture by taking 50% of pulsation boundary as the flame boundary, and obtaining the extension height value of the flame along the vertical wall surface.
In another aspect, a gas level leakage injection fire height prediction device comprises a processor and a memory, wherein the processor is connected with the memory:
the processor is used for calling and executing the program stored in the memory;
the memory is used for storing the program, and the program is at least used for executing the method for predicting the height of the fuel gas horizontal leakage injection fire.
The technical scheme provided by the invention at least has the following beneficial effects:
according to the method and the device for predicting the height of the gas horizontal leakage injection fire, provided by the embodiment of the invention, the quantitative prediction of the extension height of the injection fire along the vertical wall surface formed by the gas horizontal leakage under the limitation of the vertical barrier is realized by pre-constructing the corresponding relation model of the dimensionless extension height of the gas horizontal leakage injection fire and the dimensionless heat release rate under the limitation of the vertical barrier. Compared with the prior art, the prediction method and the model provided by the invention make up the defects of neglecting the restriction effect of the barrier and the shape and size of the leakage hole, can obtain the extension height value of the gas horizontal leakage jet fire under the restriction condition according with the actual condition, and improve the prediction accuracy of the extension height of the horizontal jet fire under the restriction condition of the vertical barrier.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
FIG. 1 is a schematic flow chart of a method for predicting the height of a fuel gas horizontal leakage injection fire according to an embodiment of the present invention;
fig. 2 is a schematic view of a physical model adopted in a model building process of a correspondence relationship between a dimensionless extension height of a gas horizontal leakage injection fire and a dimensionless heat release rate under the limitation of a vertical obstacle according to an embodiment of the present invention;
FIG. 3 is a schematic diagram illustrating a relationship between a gas horizontal leakage injection fire along a vertical wall and a leakage rate under a vertical obstacle limitation according to an embodiment of the present invention;
fig. 4 is a schematic diagram of a relationship curve between dimensionless extension height of a gas horizontal leakage injection fire and dimensionless heat release rate under the limitation of a vertical obstacle in different scenarios according to an embodiment of the present invention;
fig. 5 is a schematic structural diagram of a device for predicting the height of a horizontal leakage gas injection fire according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be described in detail below. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the examples given herein without any inventive step, are within the scope of the present invention.
The gas leakage rate, the size of the leakage hole and the distance between the barrier and the leakage hole can directly influence the vertical development height of the horizontal jet fire under the limitation of the vertical barrier, and accident harm consequences of different degrees can be caused. The quantitative prediction of the height of the horizontal jet fire under the limitation of the vertical barrier is carried out, and the method has important significance for the safety evaluation of the gas fire. However, current gas fire hazard assessment is based on a point source model to solve the hazard radius of the thermal radiation, and a prediction model regarding the shape of the horizontal jet fire under consideration of the vertical obstacle limit is not seen. In the related technology, the heat transfer characteristic parameters of the steel plate surface impacted by the jet fire are obtained through experimental tests and model calculation; or, an experimental method for testing the fire-jet thermal radiation is provided, the fire-jet thermal radiation source is considered as a point source, and the safety distance is calculated based on different thermal radiation critical values. Obviously, most of the current fire injection prediction models are heat radiation prediction values based on a point source model, the influence of the fire injection shape is not considered, the influence of a truncation effect on the fire injection development by a limiting barrier is not considered, and the height of a horizontal fire injection under the limitation of a vertical barrier cannot be calculated.
Based on the method, the embodiment of the invention provides a method and equipment for predicting the height of a fuel gas horizontal leakage injection fire.
Fig. 1 is a schematic flow diagram of a method for predicting a height of a fuel gas horizontal leakage injection fire according to an embodiment of the present invention, where the prediction method provided by the present application is applied to each scene under the limitation of a vertical obstacle, an execution main body of the method may be a controller, and the controller may be a single chip microcomputer, a programmable PLC, and the like, referring to fig. 1, the present embodiment may include the following steps:
s1, determining initial parameters of a gas leakage hole and environmental parameters of the gas leakage hole in a target scene to be predicted; wherein, the initial parameter of gas leakage hole includes: rate of leakage u j Leakage hole shape, leakage hole size and hole-plate spacing l l (ii) a Environmental parameters of the gas leakage hole: ambient temperature and ambient density.
In a specific implementation process, any scene needing to be predicted can be used as a target scene to be predicted, and initial parameters of the gas leakage hole and environmental parameters of the gas leakage hole in the target scene to be predicted are determined.
The shape of the leakage hole can be circular or rectangular; the corresponding leak hole size may be diameter, long side, short side.
And S2, calculating the heat release rate of a fire source of gas leakage and the length of horizontal jet fire under an unlimited condition according to the initial parameters of the gas leakage hole and the environmental parameters of the gas leakage hole.
In some embodiments, optionally, calculating the heat release rate of the fire source of the gas leakage and the horizontal fire injection length under the unrestricted condition according to the initial parameter of the gas leakage hole and the environmental parameter of the gas leakage hole, including:
the leakage hole is rectangular, and the size of the leakage hole comprises a long side L and a short side W;
calculating to obtain the equivalent diameter D =2 LW/(L + W) of the leakage hole according to the size of the leakage hole;
according to the leakage rate u j And the equivalent diameter D of the leakage hole, and calculating to obtain the determined Froude number Fr, fr = u j 2 /(gD)；
According to Froude number and hole-plate spacing l l Calculating the horizontal jet fire length l under the unrestricted condition lf /D＝23Fr 1/5 ；
According to the gas leakage rate u j Determining the heat release rate Q =18.61+29.1u of the fire source j 。
And S3, calculating the volume fraction of the gas horizontal leakage injection fire along the vertical wall surface under the limitation of the vertical barrier according to the size of the leakage hole, the shape of the leakage hole and the length of the horizontal injection fire under the unlimited condition.
In some embodiments, optionally, the volume fraction of the gas horizontal leakage fire along the vertical wall surface under the limitation of the vertical obstacle is calculated according to the size of the leakage hole, the shape of the leakage hole and the length of the horizontal fire under the unrestricted condition, and the method includes:
according to the size of the leakage hole, the flame volume under the unrestricted condition is determined:
according to the flame volume under the non-limited condition, determining the volume fraction of the gas horizontal leakage injection fire along the vertical wall surface under the limitation of the vertical barrier:
and S4, calculating to obtain the gas leakage dimensionless heat release rate of the flame extending along the vertical wall surface according to the volume fraction of the gas horizontal leakage jet fire along the vertical wall surface under the restriction of the straight barrier, the fire source heat release rate, the environment density and the environment temperature.
In some embodiments, calculating a gas leakage dimensionless heat release rate of a flame extending along a vertical wall based on a volume fraction of a gas horizontal leakage jet fire along the vertical wall under the restriction of a straight obstacle, a fire source heat release rate, an ambient density, and an ambient temperature comprises:
according to the heat release rate Q of the fire source and the ambient temperature T ∞ And ambient density ρ ∞ Determining the heat release rate of the dimensionless fire source:
Calculating the gas leakage dimensionless heat release rate of flame extending along the vertical wall surface according to the volume fraction of the gas horizontal leakage jet fire along the vertical wall surface and the dimensionless fire source heat release rate under the limitation of the vertical barrier:
s5, inputting the gas leakage dimensionless heat release rate of the flame extending along the vertical wall surface into a prediction model which is constructed in advance, and obtaining a prediction value of the extension height of the gas horizontal leakage flame along the vertical wall surface under the limitation of a vertical obstacle; the preset model is a corresponding relation model of the dimensionless extension height of the gas horizontal leakage injection fire and the dimensionless heat release rate under the limitation of the vertical barrier.
Wherein the preset model can be
After the gas leakage dimensionless heat release rate of the flame extending along the vertical wall surface is obtained through calculation, the gas leakage dimensionless heat release rate of the flame extending along the vertical wall surface is input into a pre-constructed prediction model, and a predicted value h of the extension height of the gas horizontal leakage injection fire along the vertical wall surface under the limitation of a vertical obstacle is obtained f 。
According to the method for predicting the height of the gas horizontal leakage injection fire, provided by the embodiment of the invention, the quantitative prediction of the extension height of the injection fire along the vertical wall surface formed by the gas horizontal leakage under the limitation of the vertical barrier is realized by pre-constructing the corresponding relation model of the dimensionless extension height of the gas horizontal leakage injection fire and the dimensionless heat release rate under the limitation of the vertical barrier. Compared with the prior art, the prediction method and the model provided by the invention make up the defects of neglecting the restriction effect of the barrier and the shape and size of the leakage hole, can obtain the extension height value of the gas horizontal leakage jet fire under the restriction condition according with the actual condition, and improve the prediction accuracy of the extension height of the horizontal jet fire under the restriction condition of the vertical barrier.
In some embodiments, a process of constructing a model of correspondence between dimensionless extension height of gas horizontal leak injection fire and dimensionless heat release rate under the limitation of a vertical obstacle constructed in advance is described.
Fig. 2 is a schematic physical model diagram adopted in a model building process of correspondence between a gas horizontal leakage injection fire dimensionless extension height and a dimensionless heat release rate under the limitation of a vertical obstacle according to an embodiment of the present invention.
Referring to fig. 2, in modeling, data collection may be performed by using the physical model shown in fig. 2 as a model. In the physical model, a leak hole, an ignition source, a vertical barrier, and a temperature measurement point are provided. Wherein, perpendicular barrier and leakage hole are relative, and the temperature measurement point can set up interval 0.5m, measures the temperature of temperature measurement point through measuring instrument. The physical model may have a length of 8m, a width of 7m, and a height of 7m.
In the application, the fire dynamic simulation software FDS can be used for simulating the gas horizontal leakage fire jet in the preset scene, and the flame image and the temperature value of each measuring point of the gas horizontal leakage fire jet are obtained through the fire dynamic simulation software FDS. It is understood that the fire dynamic simulation software FDS is suitable for gas leakage injection fire simulation, and the reliability of the software for solving the gas fire dynamic parameters is verified in many documents, so that the embodiment adopts the FDS to simulate the gas horizontal leakage injection fire.
Optionally, the building process may include: the construction method of the preset model comprises the following steps:
based on a prediction and evaluation target, constructing a gas horizontal leakage jet fire scene under the limitation of a vertical barrier, wherein the scene comprises a gas leakage hole, an ignition source and the vertical barrier; the combustible gas is sprayed out of the leakage hole and then is ignited; in the constructed gas horizontal leakage injection fire scene, referring to fig. 2, the distance between a vertical barrier and a leakage hole is adjustable, the flow rate of gas ejected from the leakage hole is adjustable, the gas is ejected from the leakage hole and is ignited, and an ignition source is removed after the ignition is successful.
Acquiring flame profiles under different initial parameters of the gas leakage holes and environmental parameters of the gas leakage holes to obtain a flame shape video; wherein, gas leakage hole initial parameter includes: leak rate, leak hole shape, leak hole size, and hole-plate spacing; environmental parameters of the gas leakage hole: ambient temperature and ambient density;
calculating to obtain the corresponding gas leakage dimensionless heat release rate of flame extending along the vertical wall surface according to the initial parameters of different gas leakage holes and the environmental parameters of the gas leakage holes;
for any gas horizontal leakage fire spraying scene under the limitation of a vertical barrier of the gas leakage dimensionless heat release rate of the flame extending along the vertical wall surface, processing a flame shape video corresponding to the gas horizontal leakage fire spraying scene under the limitation of the vertical barrier by adopting an Otsu method to obtain the extension height value of the flame along the vertical wall surface, and traversing all horizontal fire spraying scenes;
and carrying out nonlinear fitting according to the corresponding relation between the gas leakage dimensionless heat release rate of the flame extending along the vertical wall surface and the dimensionless value of the gas horizontal leakage jet fire height to obtain a preset model which is a corresponding relation model between the gas horizontal leakage jet fire dimensionless extension height and the dimensionless heat release rate under the limitation of a vertical barrier.
In this embodiment, different initial parameters of the gas leakage hole and environmental parameters of the gas leakage hole can be set. For example, table 1 is a schematic table of initial parameters of the gas leakage hole and environmental parameters of the gas leakage hole provided in the embodiment of the present invention.
TABLE 1 gas leakage hole initial parameter and gas leakage hole environmental parameter schematic table
Referring to table 1, this example shows seven gas leakage rates, three rectangular leakage hole sizes for gas horizontal leakage fire scenarios, and two hole-to-plate spacings.
In the present application, the leaked fuel gas is tested by taking methane as an example.
And after different initial parameters of the gas leakage hole and environmental parameters of the gas leakage hole are obtained, carrying out flame spraying tests according to different parameters, recording and obtaining horizontal leakage flame spraying of the gas under the limitation of vertical obstacles of each prediction scene, and obtaining a flame shape video of each scene. And processing the flame shape video of each scene by adopting an Otsu method to obtain a flame pulsation probability picture, measuring the flame size in the picture by taking 50% of pulsation boundary as the flame boundary, and obtaining the extension height value of the flame along the vertical wall surface.
For example, the flame extension height size can be obtained by recording a flame projection image, processing a video by using Premiere as a picture, processing a flame picture by using Photoshop as a gray-scale image, processing a flame gray-scale image by using Matlab as a flame probability distribution map, and taking the flame pulsation intermittent probability of 50% as a flame boundary.
According to the initial parameters of the gas leakage hole and the environmental parameters of the gas leakage hole, calculating the equivalent diameter of the leakage hole (the equivalent diameter of a circular leakage hole is r), the length of a horizontal jet fire under an unrestricted condition, the volume fraction of a vertically extended flame (namely the volume fraction of the horizontal leakage jet fire of the gas along the vertical wall surface under the restriction of a vertical obstacle), the dimensionless heat release rate, and traversing all jet fire scenes.
Determining the height (h) of the gas horizontal leakage flame extending along the vertical wall surface under the limit of the vertical barrier f ) Regarding leakage hole size, hole-plate spacing (l) l ) And leakage rate (u) j ) According to the relationship between the extension height result of the jet fire and the effective heat release rate of the fire source of the horizontal leakage jet fire along the extension part of the vertical wall surface under the condition of vertical obstacle limitation, nonlinear fitting is carried out to obtain a functional relation between the two, and the functional relation is specifically as follows:
after the vertical barrier blocks the flame extends along the vertical wallThe dimensionless heat release rate of the extension is related to the flame volume (V) of the vertically extending portion fu ) Flame volume (V) under non-limiting conditions f ) And dimensionless rate of heat release (Q) * ) A function of, in particular
According to the length (L), width (W) and leakage rate (u) of the leakage hole j ) Determining a dimensionless heat release rate of a horizontal fire spray under non-limiting conditions to be
The heat release rate of the fire source under the non-limited condition is Q =18.61+29.1u j 。
The flame volume fraction of the extension of the vertical wall of the gas horizontal leakage jet flame under the vertical obstacle limiting condition is calculated from the flame volume of the vertical part and the flame volume under the non-limiting condition, the flame volume of which is a function of the size of the leakage hole and the hole-plate spacing, specifically
Wherein C is 1 Is a constant of 0.325, and,
the horizontal jet flame plume volume under unconstrained conditions is a function of the leak hole size and the unconstrained jet flame length, specifically
The horizontal jet fire length in the unrestricted condition is a function of the Froude number, in particular l lf /D＝23Fr 15 。
Froude number is a function of gas leakage rate and leakage hole equivalent diameter, fr = u j 2 /(gD)。
The gas horizontal leakage under the restriction of perpendicular barrier sprays fire, and the equivalent diameter need calculate the determination because of the leak hole shape is different, and circular leak hole equivalent diameter is r, and the equivalent diameter of rectangle leak hole is calculated through leak hole length and width, specifically is D =2 LW/(L + W).
Fig. 3 is a schematic diagram of a relationship between the height of a gas horizontal leakage injection fire along a vertical wall and the leakage rate under the limitation of a vertical obstacle according to an embodiment of the invention.
In the present application, FDS simulation is used to obtain the extension height of the horizontal fire along the vertical wall surface of each scene, and the relationship between the extension height of the flame and the leakage rate is plotted as shown in fig. 3.
According to the dimensionless heat release rate of the horizontal fire spray along the vertical wall surface of each scene, the relation between the dimensionless value of the extension height of the flame along the vertical wall surface and the dimensionless heat release rate is obtained by nonlinear fitting, and the prediction expression of the extension height of the horizontal fire spray along the vertical wall surface under the limitation of the vertical barrier is obtained in a simplified mode, namely the corresponding relation model of the dimensionless extension height of the horizontal fire spray under the limitation of the vertical barrier and the dimensionless heat release rate is provided by the application.
Fig. 4 is a schematic diagram of a relationship curve between a dimensionless extension height of a gas horizontal leakage injection fire and a dimensionless heat release rate under the limitation of a vertical obstacle in different scenarios according to an embodiment of the present invention. Referring to fig. 4, curve fitting is performed by using the relationship between the dimensionless value of the extension height of the flame along the vertical wall surface and the dimensionless heat release rate under different scenes.
And inputting the initial parameters into a preset model after obtaining the initial parameters, such as the initial parameters in the table 1, so as to obtain the predicted values of the flame extension height under each scene.
Based on a general inventive concept, embodiments of the present invention also provide a gas horizontal leakage injection fire height prediction apparatus.
The invention also provides equipment for predicting the height of the fuel gas horizontal leakage jet fire, which is used for realizing the embodiment of the method. Fig. 5 is a schematic structural diagram of a device for predicting the height of a horizontal leakage gas injection fire according to an embodiment of the present invention. As shown in fig. 5, the gas horizontal leakage jet fire height prediction apparatus of the present embodiment includes a processor 51 and a memory 52, and the processor 51 is connected to the memory 52. Wherein, the processor 51 is used for calling and executing the program stored in the memory 52; the memory 52 is used for storing a program for executing at least the gas level leakage jet fire height prediction method in the above embodiment.
The specific implementation of the device for predicting the height of the gas horizontal leakage jet fire provided by the embodiment of the present application may refer to the implementation of the method for predicting the height of the gas horizontal leakage jet fire of any of the above embodiments, and is not described herein again.
It is understood that the same or similar parts in the above embodiments may be mutually referred to, and the same or similar parts in other embodiments may be referred to for the content which is not described in detail in some embodiments.
It should be noted that the terms "first," "second," and the like in the description of the present invention are used for descriptive purposes only and are not to be construed as indicating or implying relative importance. In addition, in the description of the present invention, the meaning of "a plurality" means at least two unless otherwise specified.
Any process or method descriptions in flow charts or otherwise described herein may be understood as representing modules, segments, or portions of code which include one or more executable instructions for implementing specific logical functions or steps of the process, and alternate implementations are included within the scope of the preferred embodiment of the present invention in which functions may be executed out of order from that shown or discussed, including substantially concurrently or in reverse order, depending on the functionality involved, as would be understood by those reasonably skilled in the art of the present invention.
It should be understood that portions of the present invention may be implemented in hardware, software, firmware, or a combination thereof. In the above embodiments, the various steps or methods may be implemented in software or firmware stored in memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, any one or combination of the following techniques, which are known in the art, may be used: a discrete logic circuit having a logic gate circuit for implementing a logic function on a data signal, an application specific integrated circuit having an appropriate combinational logic gate circuit, a Programmable Gate Array (PGA), a Field Programmable Gate Array (FPGA), or the like.
It will be understood by those skilled in the art that all or part of the steps carried by the method for implementing the above embodiments may be implemented by hardware related to instructions of a program, which may be stored in a computer readable storage medium, and when the program is executed, the program includes one or a combination of the steps of the method embodiments.
In addition, functional units in the embodiments of the present invention may be integrated into one processing module, or each unit may exist alone physically, or two or more units are integrated into one module. The integrated module can be realized in a hardware mode, and can also be realized in a software functional module mode. The integrated module, if implemented in the form of a software functional module and sold or used as a separate product, may also be stored in a computer-readable storage medium.
The storage medium mentioned above may be a read-only memory, a magnetic or optical disk, etc.
In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.
Claims (7)
1. A method for predicting the height of a fuel gas horizontal leakage injection fire is applied to each scene under the limitation of a vertical obstacle, and comprises the following steps:
determining initial parameters of a gas leakage hole and environmental parameters of the gas leakage hole in a target scene to be predicted; wherein, gas leakage hole initial parameter includes: leak rate, leak hole shape, leak hole size, and hole-plate spacing; the environmental parameters of the gas leakage hole are as follows: ambient temperature and ambient density;
calculating the heat release rate of a fire source of gas leakage and the horizontal fire ejection length under the non-limited condition according to the initial parameters of the gas leakage hole and the environmental parameters of the gas leakage hole;
calculating the volume fraction of the fuel gas horizontal leakage injection fire along the vertical wall surface under the limitation of a vertical barrier according to the size of the leakage hole, the shape of the leakage hole and the horizontal injection fire length under the unlimited condition;
calculating the gas leakage dimensionless heat release rate of flame extending along the vertical wall surface according to the volume fraction of the gas horizontal leakage jet fire along the vertical wall surface under the restriction of the straight barrier, the heat release rate of the fire source, the environment density and the environment temperature;
inputting the gas leakage dimensionless heat release rate of the flame extending along the vertical wall surface into a prediction model which is constructed in advance, and obtaining a predicted value of the extension height of the gas horizontal leakage flame along the vertical wall surface under the limitation of a vertical obstacle; the preset model is a corresponding relation model of the dimensionless extension height of the gas horizontal leakage injection fire and the dimensionless heat release rate under the limitation of the vertical barrier.
2. The method of claim 1, wherein calculating a heat release rate of a fire source of the gas leakage and a horizontal fire length under an unrestricted condition according to the initial parameter of the gas leakage hole and the environmental parameter of the gas leakage hole comprises:
the leakage hole is rectangular in shape, and the size of the leakage hole comprises a long side L and a short side W;
calculating to obtain the equivalent diameter D =2 LW/(L + W) of the leakage hole according to the size of the leakage hole;
according to the leakage rate u j And the equivalent diameter D of the leakage hole, calculating to obtain a determined Froude number, fr = u j 2 /(gD)；
Calculating the horizontal jet fire length under the unrestricted condition according to the Froude number and the hole-plate spacing,
according to gas leakage rate u j Determining the heat release rate Q =18.61+29.1u of the fire source j 。
3. The method of claim 2, wherein the step of calculating the volume fraction of the gas horizontal leakage flame along the vertical wall surface under the limitation of the vertical obstacle according to the size of the leakage hole, the shape of the leakage hole and the length of the horizontal flame under the unrestricted condition comprises the following steps:
according to the size of the leakage hole, the flame volume under the unrestricted condition is determined:
according to the flame volume under the non-limited condition, determining the volume fraction of the gas horizontal leakage injection fire along the vertical wall surface under the limitation of the vertical barrier:
4. the method of claim 3, wherein calculating the gas leakage dimensionless heat release rate for the flame extending along the vertical wall from the volume fraction of the gas horizontal leakage jet fire along the vertical wall under the straight obstacle limit, the fire source heat release rate, the ambient density, and the ambient temperature comprises:
heat release according to fire sourceDischarge rate Q, ambient temperature T ∞ And ambient density ρ ∞ Determining the heat release rate of the dimensionless fire source:
calculating the gas leakage dimensionless heat release rate of the flame extending along the vertical wall surface according to the volume fraction of the gas horizontal leakage injection flame along the vertical wall surface under the limitation of the vertical barrier and the dimensionless fire source heat release rate:
5. the method according to claim 1, wherein the method for constructing the preset model comprises:
constructing a gas horizontal leakage jet fire scene under the limitation of a vertical barrier based on a prediction and evaluation target, wherein the scene comprises a gas leakage hole, an ignition source and the vertical barrier; the combustible gas is sprayed out of the leakage hole and then is ignited;
acquiring flame profiles under different initial parameters of the gas leakage holes and environmental parameters of the gas leakage holes to obtain a flame shape video; wherein, the initial parameter of gas leakage hole includes: leak rate, leak hole shape, leak hole size, and hole-to-plate spacing; the environmental parameters of the gas leakage hole are as follows: ambient temperature and ambient density;
calculating to obtain the corresponding gas leakage dimensionless heat release rate of flame extending along the vertical wall surface according to different initial parameters of the gas leakage hole and environmental parameters of the gas leakage hole;
for any gas horizontal leakage fire spraying scene under the limitation of a vertical barrier of gas leakage dimensionless heat release rate of flame extending along the vertical wall surface, processing a flame shape video corresponding to the gas horizontal leakage fire spraying scene under the limitation of the vertical barrier by adopting an Otsu method to obtain an extending height value of the flame along the vertical wall surface, and traversing all horizontal fire spraying scenes;
and carrying out nonlinear fitting according to the corresponding relation between the gas leakage dimensionless heat release rate of the flame extending along the vertical wall surface and the dimensionless value of the gas horizontal leakage jet fire height to obtain a preset model which is a corresponding relation model between the gas horizontal leakage jet fire dimensionless extension height and the dimensionless heat release rate under the limitation of a vertical barrier.
6. The method of claim 5, wherein the Otsu method is adopted to process a flame shape video corresponding to a gas horizontal leakage injection fire scene under the limitation of the vertical obstacle to obtain an extension height value of the flame along the vertical wall surface, and comprises the following steps:
simulating horizontal gas leakage fire injection under the limitation of vertical obstacles of each prediction scene by adopting fire dynamic simulation software to obtain a flame shape video of each scene;
and processing the flame shape video of each scene by adopting an Otsu method to obtain a flame pulsation probability picture, measuring the flame size in the picture by taking 50% of pulsation boundary as the flame boundary, and obtaining the extension height value of the flame along the vertical wall surface.
7. The gas horizontal leakage injection fire height prediction device is characterized by comprising a processor and a memory, wherein the processor is connected with the memory:
the processor is used for calling and executing the program stored in the memory;
the memory is used for storing the program, and the program is at least used for executing the gas horizontal leakage injection fire height prediction method of any one of claims 1-6.
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