A method, system and medium for simulating the detection of a vertically arranged road surface remote sensing device

Abstract

The application discloses a kind of simulation vertical arrangement's road surface remote sensing equipment detection method, system and medium, detection method includes: successively dividing A, B, C three continuous regions, using car is placed in B region relatively stationary and carries out physical modeling;Draw dynamic grid, for the influence of entry speed and vehicle speed is decoupled analysis;Carry out numerical simulation, based on large eddy simulation method simulation turbulence model, to obtain the instantaneous data of pollutant in exhaust gas;Utilize light source to emit ultraviolet and infrared light beam, and receive light through exhaust gas, to obtain the integral molar concentration of pollutant and the contour map of pollutant diffusion situation by calculation.The application realizes the processing of mass instantaneous data of pollutant in vehicle exhaust by simulating the vehicle, the concentration of pollutant under the working condition is obtained from the instantaneous data, so as to summarize the diffusion law of pollutant, and then help to improve the accuracy of remote sensing equipment in actual production.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of data measurement, and particularly relates to a method and system for detecting a simulated vertically arranged road surface remote sensing device, and a medium. BACKGROUND

[0002] Road surface remote sensing (RS) is a fast, non-invasive and economical monitoring method for diagnosing pollutant emissions during actual driving. This RS method has received extensive attention in recent years, which contains 2 arrangement modes (horizontal and vertical laser beams). By comparing the light attenuation of infrared beams, the concentrations of hydrocarbons (HC), carbon monoxide (CO) and carbon dioxide (CO2) in the plume can be measured. Nitrogen oxides (NO) can also be measured by ultraviolet beams. When a vehicle passes through the measurement site, the concentration ratios of pollutants (such as CO, HC and NO) to CO2 in the exhaust plume can be measured within 0.5 s. This horizontal beam may be affected by dust and vehicle splashes, as it is usually placed about 25.4 cm from the ground. The vertical arrangement can overcome the shortcomings of the horizontal arrangement, as its measurement device is placed at a higher position, which can avoid the influence of vehicle flow and pedestrians near the ground. In addition, the vertical arrangement can also take downward images of passing vehicles and their exhaust plumes through the dust-scanning method to provide information about the dispersion of emissions, which is very promising in remote sensing devices.

[0003] For law enforcement purposes, the identification of high-emission vehicles must be highly accurate, which is the main challenge faced by RS devices. Computational fluid dynamics (CFD) is an effective tool for improving the accuracy of RS, which can intuitively display detailed information about the transmission of pollutant emissions in the turbulent field behind the vehicle.

[0004] Studies have shown that exhaust emissions into the air will immediately diffuse and the concentration will decrease due to dilution. For a given plume, CO2 is used as a reference gas, and Q CO , Q HC , Q NO represent the concentration ratios of CO, HC, NO to CO2, i.e. Q CO = CO / CO2, Q HC = HC / CO2, Q NO = NO / CO2. Studies have shown that for a certain motor vehicle exhaust plume, Q CO , Q HC , Q NOThe initial stage (last about 1s) of the diffusion of the exhaust pipe and air is kept constant, so that the volume concentration of each pollutant in the exhaust gas can be calculated reversely, assuming that the engine air-fuel ratio is m, there is no excess air, the proportion of nitrogen and oxygen in the engine intake air is 79% and 21% respectively, and the fuel carbon-hydrogen ratio is fixed. Generally, the chemical composition of diesel can be regarded as C12H23, and the carbon-hydrogen ratio is very close to 1:2. Assuming that diesel is in CH2 equivalent, the combustion equation is:

[0005]

[0006] According to the atomic conservation in the combustion equation, and the definitions of Q CO , Q HC , Q NO , the dry basis volume concentration of each component can be derived as follows.

[0007]

[0008] In the formula, C CO2 , C CO , C HC , C NO are the volume concentrations of CO2, CO, HC and NO in the exhaust gas respectively.

[0009] The existing method has single applicability to motor vehicle working conditions. In actual vehicle driving, the air-fuel ratio changes constantly with different driving conditions, the engine combustion efficiency changes constantly, and the exhaust gas residual oxygen concentration also changes constantly. The applicability of the combustion equation assuming no excess oxygen is poor.

[0010] The method of the present application can directly obtain the diffusion data of the exhaust gas behind the diesel vehicle in actual driving process by dynamic mesh technology combined with numerical simulation, and then calculate the integral molar concentration of CO2, CO, HC and NO in the vehicle exhaust by a specific numerical processing method, which has wide applicability and conforms to the actual production. SUMMARY

[0011] The purpose of the present application is to overcome the above problems existing in the prior art, and to provide a simulation of vertically arranged road surface remote sensing equipment detection method, system and medium.

[0012] To achieve the above technical purposes and effects, the present application realizes the following technical solutions:

[0013] A simulation of vertically arranged road surface remote sensing equipment detection method, comprising:

[0014] Three continuous regions A, B and C are sequentially divided, and a vehicle is placed in the B region to be relatively static and physically modeled, and the B region moves forward according to the vehicle speed; wherein, an A-B interface is arranged between the A region and the B region, and a B-C interface is arranged between the B region and the C region;

[0015] A dynamic mesh is drawn based on the A-B interface and the B-C interface, for decoupling analysis of the influence of the inlet velocity and the vehicle speed;

[0016] An Euler method of a computational fluid software is used for numerical simulation, and a large eddy simulation method is used to simulate a turbulent flow model, so that transient data of pollutants in exhaust gas are obtained;

[0017] Ultraviolet and infrared light beams are emitted by a light source, and light passing through the exhaust gas is received, so that an integral molar concentration of pollutants and a contour map of pollutant diffusion are calculated.

[0018] Further, the large eddy simulation method uses a wall-adaptive local eddy viscosity model to capture transient turbulence.

[0019] Further, a pressure-implicit algorithm splitting method is used to solve pressure-velocity coupling.

[0020] Further, the A region and the C region are located in front of and behind the B region respectively, and as the B region moves forward, the grid of the A region closest to the B region gradually disappears, and the grid of the C region appears.

[0021] Further, the left and right two faces of the A region, the B region and the C region are coupled by setting a periodic boundary.

[0022] Further, the Euler method of the computational fluid software for numerical simulation includes mass, momentum, energy and species conservation equations, and the absolute standard of the four conservation equations is 10 -12 , and the formulas are as follows:

[0023]

[0024] Further, the formula for calculating the integral molar concentration of pollutants and the contour map of pollutant diffusion is as follows:

[0025]

[0026] Further, the calculation of the integral molar concentration of pollutants and the contour map of pollutant diffusion includes the following steps:

[0027] The molar concentration and grid height of the grid are extracted to calculate the integral;

[0028] The molar concentration and grid height in the same grid are multiplied to obtain a product;

[0029] Summing these products along each vertical line;

[0030] Averaging the integral values to eliminate the influence of time fluctuations;

[0031] Generating a contour plot in the x-z plane.

[0032] The application also provides a simulation vertical arrangement road surface remote sensing device detection system, comprising:

[0033] The physical modeling module is used for sequentially dividing the three continuous areas A, B and C, physically modeling the vehicle placed in the B area and relatively static, and moving the B area forward according to the vehicle speed; wherein, the A-B interface is arranged between the A area and the B area, and the B-C interface is arranged between the B area and the C area.

[0034] The grid drawing module is used for drawing a moving grid based on the A-B interface and the B-C interface, and decoupling analysis of the influence of the inlet velocity and the vehicle speed.

[0035] The numerical simulation module is used for numerical simulation by adopting the Euler method of the computational fluid software, simulating a turbulent flow model based on a large eddy simulation method, so as to obtain transient data of pollutants in the exhaust gas.

[0036] The pollution calculation module is used for emitting ultraviolet and infrared light beams by the light source, and receiving light passing through the exhaust gas, so as to calculate the integral molar concentration of the pollutants and the contour plot of the pollutant diffusion.

[0037] The application also provides a computer storage medium, which has a computer program stored thereon, and the computer program is executed to realize the detection method.

[0038] The application has the following beneficial effects:

[0039] 1. The application realizes mass transient data processing of pollutants in vehicle exhaust by simulating the driving vehicle, obtains the concentration of pollutants of the vehicle under the working condition from the transient data, and summarizes the pollutant diffusion law, thereby helping to improve the remote sensing device accuracy in actual production.

[0040] 2. The application estimates the emission concentration of each pollutant of the gasoline and diesel vehicle by using the linear regression analysis method.

[0041] 3. The application develops research on the remote sensing method emission factor by using the carbon balance method.

[0042] 4. The application corrects the concentration inversion algorithm of nitrogen oxides by using the weighted partial least squares method.

[0043] 5. The present application modifies the engine combustion equation by considering the influence of residual oxygen on the combustion equation, and estimates the emission factor by using the carbon balance method after the modification. BRIEF DESCRIPTION OF DRAWINGS

[0044] The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiments of the present application and together with the description serve to explain the present application. In the drawings:

[0045] Figure 1 is a flow chart of the method of the present application;

[0046] Figure 2 is a schematic diagram of the area division of the dynamic grid in the present application;

[0047] Figure 3 is a schematic diagram of the distribution of the vertical line of the vehicle wake area in the present application;

[0048] Figure 4 is a CO2 integrated molar concentration contour map at vehicle speeds of 30 km / h (a) and 90 km / h (b) in the present application;

[0049] Figure 5 is a system structure block diagram of the present application. DETAILED DESCRIPTION

[0050] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of the present application.

[0051] As shown in a simulated vertical arrangement of a road remote sensing device detection method, comprising: Figure 1 A, B, C three continuous areas are sequentially divided, and the vehicle is placed in the B area to be relatively static and physically modeled, and the B area moves forward according to the vehicle speed; wherein, an A-B interface is arranged between the A area and the B area, and a B-C interface is arranged between the B area and the C area;

[0052] The A-B interface and the B-C interface are used to draw a dynamic grid for decoupling analysis of the influence of the inlet velocity and the vehicle speed;

[0053] An Euler method of a computational fluid software is used for numerical simulation, and a large eddy simulation method is used to simulate a turbulent flow model, so as to obtain transient data of pollutants in the exhaust gas;

[0054]

[0055] ​The light source emits ultraviolet and infrared beams, and receives light passing through the exhaust gas, so as to calculate the integral molar concentration of the pollutants and the contour map of the diffusion of the pollutants.

[0056] The present application takes a Toyota Hiace car equipped with a 3.0L turbocharged diesel engine as an example. The overall length, width and height of the car are 4695mm, 1695mm and 1980mm respectively. The exhaust tail pipe is located on the left side of the vehicle, with a diameter of 104mm. As shown in Figure 2 The dynamic mesh is divided into three areas A, B and C. The vehicle is placed in the B area and is relatively static, and the B area moves forward according to the vehicle speed. The A area and the C area are located in front of and behind the B area respectively. The initial length of the A area and the C area is 200m and 2m respectively. As the B area moves forward, the mesh closest to the B area gradually disappears, and the mesh of the C area appears.

[0057] Since the time scale considered in this study is short, the chemical reaction source term in the energy equation and species equation is ignored. In addition to nitrogen (N2) and oxygen (O2) in the air, the present application only considers CO2, NO and water vapor (H2O), because the CO and HC emissions of diesel vehicles are relatively low. Large eddy simulation (LES) uses the wall-adaptive local eddy viscosity (WALE) model to capture transient turbulence. The pressure-velocity coupling is solved by the pressure-implicit operator splitting (PISO) method. The numerical simulation using the Euler method of the computational fluid software includes mass, momentum, energy and species conservation equations, and the absolute standard of the four conservation equations is 10 -12 , the formulas are as follows:

[0058]

[0059]

[0060] Table 1 shows the boundary conditions of each face in A, B and C. The main advantage of the dynamic mesh is that it can decouple the analysis of the effects of the inlet velocity and the vehicle speed. In addition, an interface boundary is also needed to establish the relationship between different areas. For example, the A-B interface is set by coupling the rear of the A area and the front of the B area, because the two faces are adjacent. Similar to the static mesh, the left and right two faces of the A, B and C areas are also coupled by setting the periodic boundary. Through the above dynamic mesh technology combined with the large eddy simulation method, the transient simulation results of the pollutants in the vehicle exhaust can be obtained.

[0061] Table 1 Boundary conditions of dynamic mesh

[0062]

[0063] The integral molar concentration of the pollutants and the contour map of the diffusion of the pollutants can be obtained by using the original specific integral method on the above results. x The light beams emitted by the light source are absorbed by CO2, CO, NO

[0064] The formula for calculating the integral molar concentration of the pollutants and the contour map of the diffusion of the pollutants is as follows:

[0065]

[0066] Figure 3 The uniform distribution of the vertical lines in the vehicle wake area is shown, and the integral process is divided into the following five steps:

[0067] The molar concentration and the grid height of the grid are extracted to calculate the integral;

[0068] The molar concentration and the grid height in the same grid are multiplied to obtain a product;

[0069] The products are summed along each vertical line;

[0070] The integral values are averaged in the range of 3.0-8.0s to eliminate the influence of time fluctuations;

[0071] The contour map is generated in the x-z plane.

[0072] As Figure 4 shown, the contour maps of the integral molar concentration of CO2 in the vehicle exhaust at vehicle speeds of 30km / h and 90km / h are drawn.

[0073] The second aspect of the present application also provides a simulation of a vertically arranged road surface remote sensing device detection system, comprising:

[0074] A physical modeling module is used to sequentially divide three continuous areas A, B and C, and the car is placed in the B area to be relatively stationary and physically modeled, and the B area moves forward according to the vehicle speed; wherein an A-B interface is arranged between the A area and the B area, and a B-C interface is arranged between the B area and the C area;

[0075] A grid drawing module is used to draw a moving grid based on the A-B interface and the B-C interface, and to decouple the analysis of the influence of the inlet velocity and the vehicle speed;

[0076] a numerical simulation module for numerical simulation by using Euler method of computational fluid software, simulating a turbulent flow model based on large eddy simulation method, so as to obtain transient data of pollutants in tail gas;

[0077] a pollution calculation module for emitting ultraviolet and infrared light beams by using a light source and receiving light passing through the exhaust gas, so as to calculate integral molar concentration of pollutants and contour map of pollutant diffusion.

[0078] The third aspect of the present application further provides a computer storage medium, which has a computer program stored thereon, and the computer program is executed to realize the above method. The storage medium can include: a U disk, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk, and various storage medium capable of storing program codes.

[0079] In the description of the present application, the description of the terms "one embodiment", "an example", "a specific example" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present application, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0080] The basic principles, main features and advantages of the present application are shown and described above. It should be understood by those skilled in the art that the present application is not limited by the above embodiments, and the above embodiments and descriptions in the specification are only illustrative of the principles of the present application. Without departing from the spirit and scope of the present application, various changes and improvements can be made to the present application, and these changes and improvements all fall within the scope of the present application.

Claims

1. A method for detecting a road surface remote sensing device arranged vertically, characterized in that, Comprise: Divide A, B, C three continuous area in turn, using the car is placed in B area relative static and carries out physical modeling, B area according to vehicle speed moves forward;Wherein, A area and B area between A-B interface are equipped, B area and C area between B-C interface are equipped; Based on A-B interface and B-C interface draw dynamic grid, for the influence of inlet velocity and vehicle speed decoupling analysis; Adopt the Euler method of computational fluid software to carry out numerical simulation, based on large eddy simulation method simulates turbulent flow model, so as to obtain the instantaneous data of pollutants in exhaust gas; Utilize light source to emit ultraviolet and infrared light beams, and receive the light through the exhaust gas, so as to calculate the integral molar concentration of pollutants and the contour map of pollutant diffusion situation; The numerical simulation was performed using the Euler method of the computational fluid software, including the mass, momentum, energy and species conservation equations, with an absolute standard of 10 -12 for the four conservation equations, and the formulas are as follows: The integral molar concentration of pollutants and the contour map of pollutant diffusion situation are calculated as follows:

2. The method of claim 1, wherein the method comprises: Large eddy simulation method adopts wall self-adaptive local vortex viscosity model to capture transient turbulence.

3. The method of claim 1, wherein the method comprises: The pressure-implicit operator splitting method is used to solve the pressure-velocity coupling.

4. The method of claim 1, wherein the method is used for detecting a road surface remote sensing device in a simulated vertical arrangement. A area and C area are located in front of and behind B area respectively, with the forward movement of B area, the grid of A area closest to B area gradually disappears, and the grid of C area appears.

5. The method of claim 1, wherein the method is used for detecting a road surface remote sensing device in a simulated vertical arrangement. The left and right two faces of A area, B area and C area are coupled by setting periodic boundary.

6. The method of claim 1, wherein the method is used for detecting a road surface remote sensing device in a simulated vertical arrangement. The integral molar concentration of pollutants and the contour map of pollutant diffusion situation are calculated as follows: Extract the molar concentration and grid height of the grid to calculate the integral; Multiply the molar concentration and grid height in the same grid to obtain a product; Sum the products along each vertical line; Average the integral values to eliminate the influence of time fluctuations; Generate contour map on x-z plane.

7. A simulation of a vertically arranged road surface remote sensing device detection system, utilizing the detection method of claim 1, characterized by, Comprise: Physical modeling module, for dividing A, B, C three continuous area in turn, using the car is placed in B area relative static and carries out physical modeling, B area according to vehicle speed moves forward;Wherein, A area and B area between A-B interface are equipped, B area and C area between B-C interface are equipped; Grid drawing module, based on A-B interface and B-C interface draw dynamic grid, for the influence of inlet velocity and vehicle speed decoupling analysis; Numerical simulation module, for adopting the Euler method of computational fluid software to carry out numerical simulation, based on large eddy simulation method simulates turbulent flow model, so as to obtain the instantaneous data of pollutants in exhaust gas; Pollution calculation module, for utilizing light source to emit ultraviolet and infrared light beams, and receive the light through the exhaust gas, so as to calculate the integral molar concentration of pollutants and the contour map of pollutant diffusion situation.

8. A computer storage medium having stored thereon a computer program, characterized in that: The computer program is executed to realize the detection method of any one of claims 1-6.

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