CN113705062B - Smoke tube smoke screen shielding rate prediction method and computer storage medium - Google Patents
Smoke tube smoke screen shielding rate prediction method and computer storage medium Download PDFInfo
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Abstract
The method for predicting the smoke screen shielding rate of the smoke pipe comprises the following steps of calculating the lifting height of smoke emitted by the smoke pipe by using a Holland smoke lifting formula, further calculating the three-dimensional concentration distribution of the smoke screen of the smoke pipe by using a random walk particle model, and further realizing the calculation prediction of the smoke screen shielding rate, wherein the method specifically comprises the following steps: (1) Continuously emitting particles by the smoke tube by taking a set time step as a time interval, wherein N new particles are emitted at each time point, the emitted particles are accumulated to form a particle aerosol system, and the position coordinate of any particle in the particle aerosol system is obtained at the time t; (2) Selecting a certain point A at the t moment in the smoke screen, selecting n particles near the point A, and calculating to obtain the weighted concentration of each particle and the mass concentration of A; (3) And calculating the shielding rate of the smoke screen to light when the light radiation passes through the smoke screen by using the mass concentration of the smoke screen. The method is simple, is easier to realize on a medium-low configuration computer, and has higher reliability of the prediction result.
Description
Technical Field
The application belongs to the technical field of fluid simulation, and particularly relates to a smoke screen shielding rate prediction method for a smoke generating tube and a computer storage medium.
Background
In military affairs, the smoke screen refers to aerosol or similar system which is artificially generated and can effectively shield visible light and infrared targets or effectively attenuate electromagnetic wave radiation energy such as visible light, infrared light, laser, millimeter waves and the like in a certain time and space range. The smoke screen is an important means for resisting the photoelectric guided weapon under high-tech conditions, can attenuate visible light and infrared radiation of a target through the absorption and scattering effects of an aerosol system, effectively reduces the probability of finding the target, can manufacture a fake target by means of the infrared radiation of the smoke screen, and interferes the working loop of the photoelectric guided weapon of an enemy, so that the real target cannot be locked and tracked. Meteorological conditions have great influence on smoke screen diffusion, and the establishment of an optimal smoke screen layout scheme aiming at different meteorological environments is the key for exerting smoke screen efficiency.
The smoke screen simulation can quantitatively predict the influence of meteorological conditions on the using effect of the smoke screen, help a commander to optimize a smoke screen layout scheme, and improve the combat efficiency of the smoke screen. Common smoke simulation methods generally include a simulation method based on a physical prediction method and a simulation method based on Computational Fluid Dynamics (CFD) depending on a prediction mode.
The simulation method based on the physical prediction method generally adopts a Gaussian diffusion model to approximate the smoke concentration to normal distribution, and the standard deviation of the normal distribution is calculated by an empirical function. However, the gaussian diffusion model is used for researching the diffusion process in a fixed space, and the applicable conditions are that the ground is wide and flat, the property is uniform, the diffusion substance is stable and passive, the ground totally reflects the diffusion substance, the average flow field is straight and stable, and the average wind speed and the wind direction have no obvious time change. For the condition that a non-flat flow field or the wind speed is variable, the adaptability of the Gaussian diffusion model is poor. In addition, the high-temperature smoke sprayed from the smoke tube has obvious lifting phenomenon due to the density lower than that of the air, and the Gaussian diffusion model cannot simulate the lifting phenomenon of the smoke screen.
The CFD-based simulation method is based on three laws of thermodynamics, and numerical solutions of fluid motion are solved in an iteration mode. This type of simulation method is commonly used for professional fluid simulation, and smoke screen simulation is only one of the applications. The smoke screen simulation based on CFD can simulate complex and changeable wind fields, and can simulate the smoke screen diffusion process under different terrains by changing the modeling of a calculation area. However, the method needs a professional CFD solver for support, and the solver is difficult to integrate with other upper computer software. In addition, the solver has complex calculation iteration process, and the simulation of the medium and low configuration computer consumes too long time.
Disclosure of Invention
In view of the above, in one aspect, some embodiments disclose a method for predicting a smoke screen shielding rate of a smoke tube, wherein the smoke tube emits smoke, particles in the smoke gradually accumulate to form an aerosol system, the aerosol system forms a smoke screen, and the shielding rate of the smoke screen to light is predicted by the following method:
(1) Continuously emitting particles by the smoke tube at a set time step as a time interval, wherein N new particles are emitted at each time point, accumulating the particles emitted for multiple times to form a particle aerosol system, and calculating the position coordinates of any particle in the particle aerosol system at time t as (x (t), y (t), z (t)) according to the following formula:
(x(t),y(t),z(t))＝(x(t-τ),y(t-τ),z(t-τ))+l(τ)+(0,0,ΔH)
wherein x, y and z are coordinates of the particles in three directions of downwind, crosswind and vertical respectively; τ is a time step; (x (t- τ), y (t- τ), z (t- τ)) is the position coordinate of the particle at the last time point of time t; l (τ) is the displacement of the particle within the time step τ, and is calculated by:
l(τ)＝V(τ)·τ
wherein V (τ) is the particle velocity in the time step;
Δ H is the smoke lift height of the smoke screen, calculated by:
ΔH＝(1.5V s D+0.01Q h )/U
wherein, delta H is the lifting height of the smoke, U is the wind speed at the nozzle of the smoke tube, D is the diameter of the nozzle of the smoke tube, and V is s For the blowing speed of the chimney, Q h The heat release rate of the flue gas;
(2) Selecting a certain point A at the time t in the smoke screen, selecting n particles near the point A, and calculating the mass concentration q (r, t) of the point A according to the following formula:
wherein q is i (r i And t) is the weighted concentration of particles i, calculated according to the following formulaCalculating:
wherein i is a natural number from 1 to n; q (r, t) is the mass concentration of the point A in the smoke screen at the moment t; k is a constant, 1.5 is taken; q is the intensity of the emission source of the smoke tube, r i Is the distance between particle i and point a, calculated by:
wherein x is a ，y a ，z a Is the coordinate of the point A in three directions of downwind, crosswind and vertical, x i ，y i ，z i The coordinates of the particles i in the downwind direction, the crosswind direction and the vertical direction respectively;
(3) When light radiation passes through the smoke screen, the shielding rate of the smoke screen to light is eta, and is calculated by the following formula:
wherein alpha is e The mass extinction coefficient is adopted, lambda is the wavelength of light, and delta l is the optical path of light passing through the smoke screen; q (x, y, z) is the mass concentration of the smoke screen.
Further, some embodiments disclose methods for predicting smoke screen shielding rate of a smoking pipe by decomposing the particle velocity V (τ) in time steps into an average portion
And a pulsating part V' (τ) further decomposed into u (t), V (t), w (t) in x, y, z directions, respectively:
in the formula (I), the compound is shown in the specification,
the average speeds of the particles in the x direction, the y direction and the z direction at the moment t are respectively; u ' (t), v ' (t), w ' (t) are the pulse velocities of the particles in the three directions x, y, z at time t, respectively, which can be decomposed into a relevant part and a random part at different times:
u′(t+Δt)＝u′(t)R u (Δt)+σ u ·[1-R u 2 (Δt)] 0.5 ·L u
v′(t+Δt)＝v′(t)R v (Δt)+σ v ·[1-R v 2 (Δt)] 0.5 ·L v
wherein L is u 、L v 、L w The random numbers are standard normal distribution random numbers which are independent from each other in the x direction, the y direction and the z direction respectively; r u (Δt)、R v (Δt)、R w (Δ t) is the turbulence velocity correlation coefficient in x, y and z directions respectively, and is calculated by the following formula:
R u (Δt)＝exp(-Δt/T u )
R v (Δt)＝exp(-Δt/T v )
R w (Δt)＝exp(-Δt/T w )
wherein, T u 、T v 、T w The integral scale for turbulence in three directions is calculated by:
σ u 、σ v 、σ w the turbulence velocity variance in the three directions of x, y and z is calculated by the following formula:
σ u ＝2u * exp(-3fz/u * )
σ v ＝σ w ＝1.3u * exp(-2fz/u * )
wherein u is * The friction speed is 0.05-0.3 according to different terrains; z is the height of the mixed layer, and 2000 m, 1000 m and 500m are respectively taken as an unstable boundary layer, a neutral boundary layer and a stable boundary layer; f is a Coriolis constant with a value of 7.29e -5 。
Some embodiments disclose a method for predicting a smoke screen coverage of a smoking pipe, wherein the number n of particles in the smoke screen near point a is selected to be 10.
Some embodiments disclose a method for predicting smoke screen shielding rate of a smoke tube, and average speed of particles in three directions of x, y and z at time t
Equal to the average wind speed in the x, y and z directions.
In another aspect, some embodiments also disclose a computer storage medium containing computer-executable instructions that, when processed by a data processing apparatus, perform the method for predicting a smoke screen coverage rate of a smoking cartridge disclosed in the above embodiments.
The method for predicting the smoke screen shielding rate of the smoke pipe comprises the steps of calculating the lifting height of smoke emitted by the smoke pipe by using a Holland smoke lifting formula, calculating the three-dimensional concentration distribution of the smoke screen of the smoke pipe by using a random walk particle model, quickly and efficiently calculating the ion concentration in the smoke screen, and further realizing the calculation and prediction of the smoke screen shielding rate.
Drawings
FIG. 1 example 1 smoke tube smoke screen coverage simulation flow chart
FIG. 2 is a schematic diagram of a simulation result of a smoke screen shielding rate of a smoke generating tube in embodiment 1
Detailed Description
The word "embodiment" as used herein, is not necessarily to be construed as preferred or advantageous over other embodiments, including any embodiment illustrated as "exemplary". Unless otherwise indicated, the performance indicators tested in the examples herein were tested using methods routine in the art. It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure.
Unless defined otherwise, technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; other test methods and techniques not specifically mentioned in the present application are those commonly employed by those of ordinary skill in the art.
The terms "substantially" and "approximately" are used herein to describe small fluctuations. For example, they may mean less than or equal to ± 5%, such as less than or equal to ± 2%, such as less than or equal to ± 1%, such as less than or equal to ± 0.5%, such as less than or equal to ± 0.2%, such as less than or equal to ± 0.1%, such as less than or equal to ± 0.05%. Numerical data represented or presented herein in a range format is used merely for convenience and brevity and thus should be interpreted flexibly to include not only the numerical values explicitly recited as the limits of the range, but also to include all the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly recited. For example, a numerical range of "1 to 5%" should be interpreted to include not only the explicitly recited values of 1% to 5%, but also include individual values and sub-ranges within the indicated range. Thus, included in this numerical range are individual values, such as 2%, 3.5%, and 4%, and sub-ranges, such as 1% to 3%, 2% to 4%, and 3% to 5%, etc. This principle applies equally to ranges reciting only one numerical value. Moreover, such an interpretation applies regardless of the breadth of the range or the characteristics being described.
In this document, including the claims, all conjunctions such as "comprising," including, "" carrying, "" having, "" containing, "" involving, "" containing, "and the like are to be understood as being open-ended, i.e., to mean" including but not limited to. Only the connection words of 'composed of' 8230; '8230'; 'composed of' 8230 ';' are closed connection words.
In the following detailed description, numerous specific details are set forth in order to provide a better understanding of the present disclosure. It will be understood by those skilled in the art that the present application may be practiced without some of these specific details.
On the premise of no conflict, the technical features disclosed in the embodiments of the present application may be combined at will, and the obtained technical solution belongs to the content disclosed in the embodiments of the present application.
In some embodiments, the method of predicting the coverage of a smoker's smoke screen includes calculating the height of the high temperature smoke lift. The smoke tube belongs to a small and medium heating source, and the smoke lifting height can be calculated by using a Holland smoke lifting formula in the process of generating a smoke screen by emitting smoke. The smoke lift height Δ H of the smoke screen is calculated by the following formula (1):
ΔH＝(1.5V s D+0.01Q h )/U (1)
the method comprises the following steps of (1) wherein delta H is the lifting height of smoke, and the measurement unit is m; u is the wind speed at the nozzle of the smoke tube, and the measurement unit is m/s; d is the diameter of a nozzle of the smoke generating tube, and the measurement unit is m; v s The air injection speed of the smoke tube is measured in m/s; q h The heat release rate of the flue gas is shown in KJ/s.
The effective smoke screen produced by the smoke tube can reach hundreds of meters generally, the height can reach tens of meters, and compared with the size of the smoke screen, the smoke tube has small equipment volume and can be similar to a continuous point emission source. The effective smoke screen produced by a smoke tube is generally a small scale particle diffusion system. In the prior art, a smoke mass-random walk particle model is generally used for predicting diffusion of mesoscale pollutants, and the smoke mass-random walk particle model is applied to a small-scale particle diffusion system in the embodiment of the application, so that the ion diffusion in a smoke screen of a smoke tube is researched, and an unexpected good technical effect can be obtained. For example, based on a time sampling method, some embodiments may divide the process of continuously emitting smoke from the smoke tube to form the smoke screen into a series of discrete time points by using a set time step as a unit, where the time between two adjacent time points is the time step τ, and thus the process of continuously emitting smoke from the smoke tube may be approximated as a discrete process; generally, the smaller the time step, the closer the discrete process is to the continuous process.
Generally, the air-jet speed of the smoke tube is equal to the initial speed of smoke particles generated in the process of emitting smoke by the smoke tube. After the particles are emitted from the mouth of the smoker, they continue to move under the action of the air and the surrounding environment. In the discrete process at intervals of time steps, the particle velocity V (τ) in any time step can be considered to be the same.
As an alternative embodiment, the particle velocity V (τ) within a time step may be decomposed into an average velocity
And a pulsation velocity V' (τ), further decomposed into u (t), V (t), and w (t) in x, y, and z directions, respectively:
in the formula (2), the reaction mixture is,
the average speeds of the particles in the x direction, the y direction and the z direction at the moment t are respectively, and the measurement unit is m/s; u ' (t), v ' (t) and w ' (t) are the pulse velocities of the particles in the three directions of x, y and z at the time t respectively, the measurement unit is m/s, and the pulse velocities can be further decomposed into related parts and random parts at different times, see the following formula (3):
in formula (3), L u 、L v 、L w The random numbers are standard normal distribution random numbers which are independent from each other in the x direction, the y direction and the z direction, and are dimensionless; r is u (Δt)、R v (Δt)、R w (Δ t) is the turbulence velocity correlation coefficient in x, y and z directions, respectively, and is calculated by the following formula (4) in a dimensionless way:
R u (Δt)＝exp(-Δt/T u )
R v (Δt)＝exp(-Δt/T v ) (4)
R w (Δt)＝exp(-Δt/T w )
in the formula (4), T u 、T v 、T w Is the integral scale of turbulence in three directions, measured in s, calculated by the following equation (v):
in the formula (5), σ u 、σ v 、σ w The turbulence velocity variance in the three directions of x, y and z is measured in m/s, and is calculated by the following formula (6):
in the formula (6), u * The friction speed is measured, the measurement unit is m/s, and the value is 0.05-0.3 according to different terrains; z is the height of the mixed layer, the measurement unit is m, and 2000, 1000 and 500 are respectively taken as an unstable boundary layer, a neutral boundary layer and a stable boundary layer; f is a Coriolis force constant with a measurement unit of 1/s and a value of 7.29e -5 ；
Further, the sum of the component velocities u (t), V (t), and w (t) in the x, y, and z directions is V (τ).
As an optional embodiment, in the method for predicting the smoke screen shielding rate of the smoke generating tube, the average speed of the particles in the x, y and z directions at the time t is
Equal to the average wind speed in the x, y and z directions.
In the process of forming a smoke screen by emitting smoke by the smoke tube, the smoke tube can be set to continuously emit particles by taking a time step tau as a time interval, N new particles are emitted at each time point, and the particles emitted for multiple times are gradually accumulated to form a particle aerosol system; at a certain time t, the position coordinates of any particle in the particle aerosol system are (x (t), y (t), z (t)), and the measurement unit is (m, m, m), which can be calculated by the following formula (7):
(x(t),y(t),z(t))＝(x(t-τ),y(t-τ),z(t-τ))+l(τ)+(0,0,ΔH) (7)
in the formula (7), x, y and z respectively represent the coordinates of the particles in three directions of downwind, crosswind and vertical, and the coordinate measurement unit is m; τ is a time step; (x (t- τ), y (t- τ), z (t- τ)) is the position coordinate of the particle at the last moment in time t, and the measurement unit is (m, m, m); delta H is the lifting height of the smoke, and the measurement unit is m; l (τ) is the displacement of the particle within the time step τ, measured in m, and calculated by the following equation (8):
l(τ)＝V(τ)·τ (8)
in the formula (8), V (τ) is the particle velocity in the time step, and the measurement unit is m/s.
Based on the calculated determination of the position (x (t), y (t), z (t)) of each particle in the smoke screen, the initial conditions can be further combined, and finally the position distribution of the particle aerosol system at all time points can be calculated.
Based on the calculation results of the position distribution of all particles in the smoke screen, the mass concentration of any position in the smoke screen can be further obtained. In general, in a method for calculating the mass concentration of any point in a smoke screen, particles near the point need to be counted, the counted number of the particles is larger, and the mass concentration of the smoke screen is higher, but the method needs a sufficient number of particles to ensure that the obtained mass concentration has sufficient accuracy, if the number of the particles is too small, the mass concentration of the smoke screen at different positions jumps, which affects the accuracy of prediction calculation, and if the number of the particles is too large, the operation speed of a random walk model is seriously affected, which causes the smoke screen to be blocked or even have no response in the smoke screen prediction calculation process. The method adopted in the embodiment of the application is that a certain point A at the time t in the smoke screen is selected, n limited particles near the point A are selected, and the mass concentration q (r, t) of the point A is calculated according to the following formula (9):
in the formula (9), q (r, t) is the time t, the mass concentration of the point A in the smoke screen is measured in g/m 3 ；q i (r i And t) is a weighted concentration for each particle, calculated according to the following equation (10):
in the formula (10), k is a constant and is 1.5; q is the emission source intensity of the smoke tube, and the measurement unit is kg/s; r is i The distance between the particle and the point A is measured in m; i is a natural number from 1 to n;
wherein r is i The distance between the particle i and the point a is calculated by the following formula (11):
in formula (11), x a ，y a ，z a Is the coordinate of the point A in three directions of downwind, crosswind and vertical, x i ，y i ，z i The coordinates of the particles i in the downwind direction, the crosswind direction and the vertical direction respectively;
as an alternative embodiment the number n of particles in the smoke screen near point a is chosen to be 10.
When visible light, infrared light and other light rays are radiated through the smoke screen aerosol system, the visible light, the infrared light and other light rays are weakened by the scattering and absorption effects of the smoke screen aerosol system, and the action rule of the weakening process conforms to the Lambert-Beer law, namely the following formula (12):
in the formula (12), I is the radiation intensity after passing through the smoke screen, and the meterThe unit of the amount is W/cm 2 ；I 0 The measurement unit is W/cm for the radiation intensity before passing through the smoke screen 2 (ii) a q is the mass concentration of the smoke screen, and the measurement unit is g/m 3 (ii) a L is the optical path of visible light and infrared radiation passing through a smoke screen with the concentration of q, and the measurement unit is m; alpha is alpha e The mass extinction coefficient is measured in m 2 The extinction coefficient is related to the nature of the smoke agent, the size of the smoke screen particles, the radiant wave, etc.
The transmittance of infrared ray and visible light after passing through a certain distance in the smoke screen is the ratio of the radiation flux density before and after passing through the smoke screen, namely the following formula (13):
if the smoke aerosol is non-uniformly distributed, the transmittance t may be represented by formula (14):
spatially discretizing the above formula to yield formula (15):
the sum of the smoke shielding rate η and the transmittance t is 1, and therefore, the shielding rate η is calculated by the following formula (16):
in the formula (16), α e The mass extinction coefficient is measured in m 2 (ii)/g; λ is the wavelength of light; delta l is the optical path of light passing through the smoke screen, and the measurement unit is m; q (x, y, z) is the mass concentration of the smoke screen, and the measurement unit is g/m 3 . If the shading rate in the vertical direction is calculated, the integral direction is the y-axis direction of the coordinate system, if the shading rate in the horizontal direction is calculated,the integration direction is the x-axis direction or the z-axis direction of the coordinate system.
The technical details are further illustrated in the following examples.
Example 1
And (4) performing simulation calculation on the smoke screen shielding rate of the smoke generating tube by using a smoke screen shielding rate prediction method of the smoke generating tube.
Fig. 1 is a flowchart of a simulation of smoke screen coverage by a smoke screen coverage prediction method of a smoke generating tube in example 1. The simulation calculation process of the smoke screen shielding rate of the smoke tube comprises the following steps:
s101, inputting simulation parameters such as meteorological parameters, wherein the meteorological parameters comprise longitudinal wind speed, transverse wind speed, atmospheric vertical stability, ambient temperature and reference height; topographic parameters such as lower interface roughness; the performance parameters of the smoke tube, such as the application position of the smoke tube, the diameter of a smoke nozzle, the outlet speed, the outlet temperature, the particle diameter, the particle density, the smoke generation time and the like; simulation calculation parameters such as a test distance, a visible light path, a concentration test point and the like;
s102, generating n new particles;
s103, supplementing the generated N new particles into a smoke screen containing N particles to obtain a smoke screen containing N + N particles, wherein the number of the particles is a natural number from 1;
s104, calculating the lifting height delta H of the smoke screen by using the following formula (1):
ΔH＝(1.5V s D+0.01Q h )/U (1)
the method comprises the following steps of (1) wherein delta H is the lifting height of smoke, and the measurement unit is m; u is the wind speed at the nozzle of the smoke tube, and the measurement unit is m/s; d is the diameter of a nozzle of the smoke tube, and the measurement unit is m; v s The air injection speed of the smoke tube is measured in m/s; q h The heat release rate of the flue gas is shown, and the measurement unit is KJ/s;
s105, calculating the coordinates (x (T), y (T), z (T)) of the ith particle at the time T according to the following formula (7), wherein the measurement unit is (m, m, m):
(x(t),y(t),z(t))＝(x(t-τ),y(t-τ),z(t-τ))+l(τ)+(0,0,ΔH) (7)
in the formula (7), x, y and z respectively represent the coordinates of the particle i in three directions of downwind, crosswind and vertical, and the coordinate measurement unit is m; τ is a time step; (x (t- τ), y (t- τ), z (t- τ)) is the position coordinate of the particle i at the previous moment of the t moment, and the measurement unit is (m, m, m); delta H is the lifting height of the smoke, and the measurement unit is m; l (τ) is the displacement of the particle i in time step τ, and is measured in m, and is calculated by the following equation (8):
l(τ)＝V(τ)·τ (8)
s106, assigning the number i of the particles with the coordinates calculated to be i +1; if the value of i is not more than N + N, repeating the steps S104 and S105, calculating the coordinate of the next particle, if the value of i is more than N + N, ending the coordinate calculation, obtaining the coordinates of N + N particles in the smoke screen, and entering the step S107;
s107, screening n nearest particles near the point A;
s108, calculating the weighted concentration q of each particle to be screened by adopting the following formula (10) i (r i ,t)：
In the formula (10), k is a constant and is 1.5; q is the emission source intensity of the smoke tube, and the measurement unit is kg/s; r is i The distance between the particle and the point A is measured in m; i is a natural number from 1 to n;
wherein the distance r between the particle i and the point A i Calculated by the following formula (11):
in formula (11), x a ，y a ，z a Is the coordinate of the point A in three directions of downwind, crosswind and vertical, x i ，y i ，z i The coordinates of the particles i in the downwind direction, the crosswind direction and the vertical direction respectively;
s109, calculating the mass concentration q (r, t) of the point A by using the following formula (9):
in the formula (9), q (r, t) is the mass concentration of the point A in the smoke screen at the time t, and the measurement unit is g/m 3 ；
S110, calculating the point concentration of all the points of the simulated smoke screen according to S109 to obtain the three-dimensional concentration distribution of the simulated smoke screen;
s111, calculating the linear concentration of the smoke screen, and further calculating the smoke screen shielding rate, wherein the calculation formula is as follows (16):
in the formula (16), α e Is mass extinction coefficient, and the measurement unit is m 2 (ii)/g; λ is the wavelength of light; delta l is the optical path of light passing through the smoke screen, and the measurement unit is m; q (x, y, z) is the mass concentration of the smoke screen, and the measurement unit is g/m 3 (ii) a q (x, y, z) × Δ l is the line concentration;
s112, updating simulation calculation time;
s113, if the simulation calculation time is less than the simulation time set in the input parameters, repeating the step S102 and entering a re-simulation process; if the simulation calculation time is longer than the simulation time set in the input parameters, the simulation is finished.
Based on the method disclosed in embodiment 1, the inventor develops smoke tube smoke screen shielding rate prediction simulation software and carries out simulation calculation on the smoke tube smoke screen shielding rate. As an alternative embodiment, fig. 2 is a diagram illustrating a simulation result of the smoke screen shielding rate of the smoke generating tube. As shown on the right side of FIG. 2, the longitudinal wind speed is 1.5 m/s and the lateral wind speed is 0 m/s. Atmospheric vertical stability A, ambient temperature 26 ℃, reference height 2m, lower interface roughness 0.05, application position (0 m, 0 m), diameter of a smoke nozzle 0.1 m, outlet speed 2 m/s, outlet temperature 300 ℃, average particle diameter 5 micron, particle diameter variance 0.6 micron, particle density 1860 kg/cubic meter, smoke time 480 s; the test distance is 50 meters, the incident point (60 meters, 25 meters, 8 meters), the emergent point (60 meters, -25 meters, 8 meters), the test point (30 meters, 0 meters, 2.5 meters). The simulation results are shown in fig. 2.
In FIG. 2, the upper left side is a three-dimensional view of the smoke screen at a time point of 47.00 seconds, i.e., a view in the three coordinate axis directions, the upper view is a side view in the Y-axis direction, the middle view is a top view in the Z-axis direction, and the lower view is a front view in the X-axis direction, at which point concentration DND of test points (30 m, 0m, 2.5 m) is 0.22g/m 3 The transmittance TGL is 2.43 percent, the particle number Num is 6328, the Length of the smoke screen is 90.10m, and the width Height is 18.82m;
in fig. 2, the lower left side is a test point concentration curve, the ordinate is test point concentration, and the abscissa is simulation time, which represents the trend of the test point concentration changing along with the simulation time; in fig. 2, the lower right side is a test point light path transmittance curve, the ordinate is the shielding rate, and the abscissa is the simulation time, i.e., the trend of the smoke screen shielding rate changing with the simulation time. And in 0-47.00 seconds, along with the extension of the simulation calculation time, the concentration of the test point is gradually increased, the smoke screen shielding rate is gradually reduced, and the trends of the test point concentration and the smoke screen shielding rate accord with the smoke screen development evolution and light transmission rule.
The above embodiments may be implemented in various hardware, software code, or combinations of both. For example, an embodiment of the present invention may also be program code that executes a method of predicting a smoke mask rate of a smoking pipe in a Digital Signal Processor (DSP). The invention may also relate to a variety of functions performed by a computer processor, digital signal processor, microprocessor, or Field Programmable Gate Array (FPGA).
The processor described above may be configured according to the present invention to perform certain tasks by executing machine-readable software code or firmware code that defines certain methods disclosed herein. Software code or firmware code may be developed in different programming languages and in different formats or forms. However, the different code styles, types, and languages of software code and other types of configuration code that perform tasks in accordance with the present invention do not depart from the spirit and scope of the present invention.
According to the method for predicting the smoke screen shielding rate of the smoke pipe, the Howland smoke lifting formula is used for calculating the lifting height of smoke emitted by the smoke pipe, the random wandering particle model is used for calculating the three-dimensional concentration distribution of the smoke screen of the smoke pipe, the ion concentration in the smoke screen can be quickly and efficiently calculated, the smoke screen shielding rate is calculated and predicted, the calculation and prediction process is simple, the calculation and prediction can be easily realized on a medium-low configuration computer, the prediction result is high in reliability, and the method has a good application prospect in the smoke screen prediction aspect of small smoke screen continuous emission sources such as the smoke pipe.
The technical solutions and the technical details disclosed in the embodiments of the present application are only examples to illustrate the inventive concept of the present application, and do not constitute a limitation on the technical solutions of the present application, and all the conventional changes, substitutions, combinations, and the like made to the technical details disclosed in the present application have the same inventive concept as the present application and are within the protection scope of the claims of the present application.
Claims (5)
1. The method for predicting the smoke screen shielding rate of the smoke tube is characterized in that the smoke tube emits smoke, particles in the smoke accumulate to form an aerosol system, the aerosol system forms a smoke screen, and the shielding rate of the smoke screen to light is predicted by the following method:
(1) Continuously emitting particles by the smoke tube at a set time step as a time interval, wherein N new particles are emitted at each time point, the emitted particles are accumulated to form a particle aerosol system, and the position coordinate of any particle in the particle aerosol system at the time t is (x (t), y (t), z (t)), and is calculated by the following formula:
(x(t),y(t),z(t))＝(x(t-τ),y(t-τ),z(t-τ))+l(τ)+(0,0,ΔH)
wherein x, y and z are coordinates of the particles in three directions of downwind, crosswind and vertical respectively; τ is a time step; (x (t- τ), y (t- τ), z (t- τ)) is the position coordinate of the particle at the last time point of time t; l (τ) is the displacement of the particle within the time step τ, and is calculated by:
l(τ)＝V(τ)·τ
wherein V (τ) is the particle velocity in the time step;
Δ H is the smoke lift height of the smoke screen, calculated by:
ΔH＝(1.5V s D+0.01Q h )/U
wherein, delta H is the lifting height of the smoke, U is the wind speed at the nozzle of the smoke tube, D is the diameter of the nozzle of the smoke tube, and V is s For the blowing speed of the chimney, Q h The heat release rate of the flue gas;
(2) Selecting a certain point A at the time t in the smoke screen, selecting n particles near the point A, and calculating the mass concentration q (r, t) of the point A according to the following formula:
wherein q is i (r i And t) is the weighted concentration of particle i, calculated according to the following formula:
wherein i is a natural number from 1 to n; q (r, t) is the mass concentration of the point A in the smoke screen at the moment t; q. q.s i (r i And t) is the weighted concentration of the particle i at the time t; k is a constant, 1.5 is taken; q is the emission source intensity of the smoke tube; r is i The distance between particle i and point a is calculated by:
wherein x is a ，y a ，z a Is the coordinate of the point A in three directions of downwind, crosswind and vertical, x i ，y i ，z i The coordinates of the particles i in the downwind direction, the crosswind direction and the vertical direction respectively;
(3) When light radiation passes through the smoke screen, the shielding rate of the smoke screen to light is eta, and the shielding rate is calculated by the following formula:
wherein alpha is e In order to obtain the mass extinction coefficient, lambda is the wavelength of light, and delta l is the optical path of light passing through the smoke screen; q (x, y, z) is the mass concentration of the smoke screen.
2. The method of claim 1 wherein the particle velocity V (τ) in time steps is decomposed into an average component
And a pulsating part V' (τ) further decomposed into u (t), V (t), w (t) in x, y, z directions, respectively:
in the formula (I), the compound is shown in the specification,
the average speeds of the particles in the x direction, the y direction and the z direction at the moment t are respectively equal to the average wind speeds in the x direction, the y direction and the z direction; u ' (t), v ' (t), w ' (t) are the pulse velocities of the particles in the three directions x, y, z at time t, respectively, which can be decomposed into a relevant part and a random part at different times:
u′(t+Δt)＝u′(t)R u (Δt)+σ u ·[1-R u 2 (Δt)] 0.5 ·L u
v′(t+Δt)＝v′(t)R v (Δt)+σ v ·[1-R v 2 (Δt)] 0.5 ·L v
wherein L is u 、L v 、L w The random numbers are standard normal distribution random numbers which are independent from each other in the x direction, the y direction and the z direction respectively; r u (Δt)、R v (Δt)、R w (Δ t) is the turbulence velocity correlation coefficient in x, y and z directions respectively, and is calculated by the following formula:
R u (Δt)＝exp(-Δt/T u )
R v (Δt)＝exp(-Δt/T v )
R w (Δt)＝exp(-Δt/T w )
wherein, T u 、T v 、T w The integral scale for turbulence in three directions is calculated by:
σ u 、σ v 、σ w the variance of the turbulent velocity in the x, y and z directions is calculated by the following formula:
σ u ＝2u * exp(-3fz/u * )
σ v ＝σ w ＝1.3u * exp(-2fz/u * )
wherein u is * The friction speed is 0.05-0.3 according to different landforms; z is the height of the mixed layer, and 2000 m, 1000 m and 500m are respectively taken as an unstable boundary layer, a neutral boundary layer and a stable boundary layer; f is a Coriolis constant with a value of 7.29e -5 。
3. The method of predicting the smoke screen coverage of a smoker according to claim 1, wherein the number n of particles in the smoke screen near point a is selected to be 10.
4. The method of claim 2, wherein the average velocity of particles in x, y, and z directions at time t is determined by the method
Equal to the average wind speed in the x, y and z directions.
5. A computer storage medium containing computer executable instructions, wherein the computer executable instructions, when processed by a data processing apparatus, cause the data processing apparatus to perform the method of predicting a smoke screen coverage of a smoking cartridge of any one of claims 1 to 4.
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