Fluent-based numerical simulation and experimental design method for shake of liquid in tank of tank truck

Abstract

The invention discloses a Fluent-based numerical simulation and experimental design method for shaking of liquid in a tank of a tank truck, and belongs to the technical field of numerical simulation of fluid dynamics (CFD). The method includes the steps that the hole opening position of the wave-proof plate serves as an independent variable, multiple hole opening position schemes are designed, liquid shaking related indexes are determined to serve as dependent variables, a geometric model is established according to the actual structure of a tank truck tank body, a fluid mechanics model and boundary conditions are set, a solver is configured, output parameters and numerical simulation initial values are set, and an experiment is executed. The liquid shaking process of a certain swash plate trepanning scheme is simulated, acting force data, namely shaking index data, between liquid shaking and the inner wall of the tank body is recorded, the advantages and disadvantages of each trepanning position scheme are evaluated based on the shaking index data, and the optimal scheme is determined. According to the method, a real object experiment is replaced by CFD numerical simulation, parameter setting is carried out, the experiment cost and the experiment risk are remarkably reduced, the experiment efficiency is improved, and data support can be provided for industry design.

Description

Technical Field

[0001] This invention relates to the field of numerical simulation technology of fluid dynamics (CFD), specifically to a numerical simulation and experimental design method for liquid sloshing inside a tank truck based on Fluent. Background Technology

[0002] As the primary means of road transporting hazardous chemicals, the driving safety of tank trucks has always been a major concern. Unlike ordinary solid cargo, the sloshing of liquids inside the tank generates significant fluid impact forces. Especially during vehicle braking, acceleration, or steering, these impact forces create periodic shocks to the front and rear ends of the tank, severely compromising the longitudinal and lateral stability of the entire vehicle. This is one of the main causes of traffic accidents such as skidding, fishtailing, and even rollovers.

[0003] Baffles are key internal structures for suppressing liquid sloshing. Their core function is to effectively reduce the overall kinetic energy of the liquid by dividing its volume, thereby reducing its impact torque on the tank. However, current Chinese design standards for baffles (such as GB 18564.1) mainly focus on macroscopic parameters such as dimensions, spacing, and installation strength, without providing unified and detailed technical specifications for their specific structural forms, especially the shape, size, and location of openings. This leads to a reliance on experience in baffle opening design during actual production, resulting in a degree of uncertainty. To meet process requirements such as cleaning, ventilation, and liquid connectivity, baffles must have openings, and circular or elliptical holes are widely used due to their ease of processing and weaker stress concentration effect. However, how the location of the openings (such as center, upper, lower, or offset left and right) affects the transient sloshing characteristics of the liquid, and thus the dynamic stability of the vehicle, remains a critical issue lacking systematic theoretical guidance.

[0004] To address the aforementioned issues, there is an urgent need for a Fluent-based numerical simulation and experimental design method for liquid sloshing inside tank trucks, which can solve the problems associated with traditional methods. Summary of the Invention

[0005] The purpose of this invention is to provide a numerical simulation and experimental design method for liquid sloshing inside a tank truck based on Fluent. By replacing physical experiments with CFD numerical simulation, it is easier to set parameters, significantly reduces experimental costs and risks, improves experimental efficiency, and can provide reliable data support for industry design.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A numerical simulation and experimental design method for liquid sloshing inside a liquid tanker truck based on Fluent includes: Step 1: Using the opening position of the baffle plate as the independent variable, design multiple opening position schemes and determine the liquid sloshing related indicators as the dependent variable; Step 2: Establish a geometric model based on the actual structure of the tanker truck, and set the fluid dynamics model and boundary conditions; Step 3: Configure the solver, set the output parameters and initial values ​​for the numerical simulation; Step 4: Perform the experiment to simulate the liquid sloshing process when a certain baffle plate opening scheme is used, and record the force data between the liquid sloshing and the inner wall of the tank, i.e., the sloshing index data. Step 5: Evaluate the advantages and disadvantages of each opening position scheme based on the shaking index data, and determine the optimal scheme.

[0007] Furthermore, the opening location scheme includes uniformly distributed openings, concentratedly distributed openings, and combinations of openings of different sizes and shapes.

[0008] Furthermore, the liquid sloshing-related indicators include the impact force, amplitude, and sloshing frequency on the tank wall.

[0009] Furthermore, in step 2, a geometric model is established based on the actual structure of the tank truck, and a fluid dynamics model and boundary conditions are set, specifically as follows: Based on the actual dimensions of the tanker truck, a geometric model of the tank was created using 3D modeling software, including the dimensions and shape of the tank, the position and size of the baffles, and the location of the openings. The VOF model is used as the fluid dynamics model, the liquid is set as an incompressible fluid, and its density and viscosity physical properties are set. The tank filling ratio can be set by configuring the liquid space coordinates in the area registration system. Select the solver, set the time step and number of iterations.

[0010] Furthermore, in step 3, the solver is configured, and the output parameters and initial values ​​for the numerical simulation are set, specifically as follows: A pressure-based solver combined with the PISO split algorithm was used to simulate the driving conditions of a liquid tanker truck by setting standard gravitational acceleration and time-varying longitudinal acceleration. Set the longitudinal acceleration function to simulate variable speed driving conditions; Set the liquid material type and its physical properties.

[0011] Furthermore, the formula for calculating the longitudinal acceleration is: 1) In the formula, Longitudinal acceleration, in m / s² 2 t represents time, measured in seconds (s).

[0012] Furthermore, the lateral acceleration function is: In the formula, IF is a conditional function, s is a time unit, and m is a length unit.

[0013] Furthermore, in step 5, the merits of each opening location scheme are evaluated based on the shaking index data, specifically as follows: The advantages and disadvantages of each opening position scheme are evaluated by assessing the longitudinal stress on the tank under vehicle acceleration or braking conditions, the amplitude of vibration when the vehicle enters a constant speed state, and the rate of amplitude decay.

[0014] In summary, the present invention has at least one of the following beneficial technical effects: 1. It improves the scientific nature and precision of baffle design, avoids the blindness of experience-based design, and establishes a scientific mapping relationship from design variables to performance indicators by taking the opening position as an independent variable and setting clear liquid sloshing evaluation indicators. This replaces the traditional trial-and-error approach that relies on the personal experience of engineers, and makes the design of baffle openings shift from "experience-driven" to "data-driven". 2. Significantly reduced R&D costs and time. Through high-precision computer simulation, multiple design schemes can be fully virtual tested and screened before physical prototype manufacturing, greatly reducing the number of expensive physical experiments, material waste and testing time, thereby achieving cost reduction and efficiency improvement. 3. This method can deeply reveal the intrinsic relationship between liquid sloshing and vehicle stability, effectively improving driving safety. It can not only evaluate the effect of the baffle plate on suppressing the sloshing amplitude, but also directly relate to the key mechanical parameters that affect the vehicle's braking performance and lateral stability, providing a theoretical basis and design guidance for fundamentally preventing accidents such as sideslip and fishtailing. 4. The experimental results are highly reliable and repeatable. By strictly controlling variables other than the opening position, the fairness of the experimental comparison is ensured. By calculating the average and standard deviation of multiple experimental data, the dispersion of the data is effectively evaluated, making the final optimal solution conclusion more robust and reliable. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the method flow of the present invention. Detailed Implementation

[0016] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0017] like Figure 1As shown, this invention provides a numerical simulation and experimental design method for liquid sloshing inside a tank truck based on Fluent, including: Step 1: Using the opening position of the baffle plate as the independent variable, design multiple opening position schemes and determine the liquid sloshing related indicators as the dependent variable; Step 2: Establish a geometric model based on the actual structure of the tanker truck, and set the fluid dynamics model and boundary conditions; Step 3: Configure the solver, set the output parameters and initial values ​​for the numerical simulation; Step 4: Perform the experiment to simulate the liquid sloshing process when a certain baffle plate opening scheme is used, and record the force data between the liquid sloshing and the inner wall of the tank, i.e., the sloshing index data. Step 5: Evaluate the advantages and disadvantages of each opening position scheme based on the shaking index data, and determine the optimal scheme.

[0018] In step 1, using the opening position of the baffle plate as the independent variable, multiple opening position schemes are designed, and liquid sloshing-related indicators are determined as the dependent variable, specifically: Using the location of the baffle plate openings as the independent variable in the experiment, and based on the actual size of the tanker truck and transportation requirements, a variety of representative opening location schemes were designed, such as uniformly distributed openings, concentratedly distributed openings, and combinations of openings of different sizes and shapes. Liquid sloshing-related indicators were used as the dependent variables in the experiment, including the impact force, amplitude, and sloshing frequency on the tank wall. By using the controlled variable method, all variables except the orifice position were kept constant in the experiment, such as the tanker's acceleration, road conditions, liquid type, and loading capacity. Only the orifice position was changed. The experiment was conducted on a professional experimental platform to simulate the liquid sloshing under different driving conditions. The force monitor function in Fluent software was used to accurately measure the relevant data. By comparing the changes in liquid sloshing indicators under different orifice position schemes, the advantages and disadvantages of each scheme were analyzed, providing a basis for subsequent optimization design.

[0019] In step 2, a geometric model is established based on the actual structure of the tank truck, and a fluid dynamics model and boundary conditions are set, specifically as follows: 1. Based on the actual structure of the tank truck, a geometric model of the tank body is established using 3D modeling software, including the size and shape of the tank body, as well as the position and size of the baffles. For the openings of the baffles, the openings at different positions are precisely set in the model according to the experimental design scheme. 2. The VOF model was used as the fluid dynamics model. In the model settings, the liquid was set as an incompressible fluid, and its physical properties such as density and viscosity were defined. In this experiment, water was selected as the medium, with a density of 998.2 kg / m³. 3 The viscosity is 0.001003 kg / m·s; 3. By using the regional register settings to transmit the liquid space coordinates, the tank filling ratio (liquid height) can be set. After the liquid space threshold is determined, the boundary conditions do not need to be set when simulating the liquid sloshing of the tank truck, as the system will automatically generate the boundary conditions.

[0020] In step 3, the solver is configured, and the output parameters and initial values ​​for the numerical simulation are set, specifically as follows: 1. Select a suitable solver and configure the model's solution settings, such as setting the time step and determining the number of iterations. 2. A pressure-based solver combined with the PISO split algorithm was selected. Standard gravitational acceleration and time-varying longitudinal acceleration were set to simulate the driving conditions of the liquid tanker truck, and the time step, total duration, and maximum number of iterations were determined. The formula for calculating the time-varying longitudinal acceleration is as follows: 1) In the formula, Longitudinal acceleration, in m / s² 2 t represents time, measured in seconds (s). 3. Force Field Parameter Settings: Open the task page dialog box, select transient in the time column according to the experiment type, and provide an initial excitation in the X direction that causes the liquid to slosh. Set the lateral acceleration that changes with time using a user-defined method; the function expression is: In the formula, IF is a conditional function, s is a unit of time, and m is a unit of length; it simulates the gradually increasing lateral acceleration of a liquid tanker truck when it turns, which becomes zero after 2 seconds, providing a lateral excitation in the longitudinal direction to cause the liquid to slosh. The gravitational acceleration in the Y direction is assumed to be -9.81 m / s². 2 There is no external force in the Z direction.

[0021] In step 4, an experiment is performed to simulate the liquid sloshing process under a certain baffle opening scheme. The force data between the liquid sloshing and the inner wall of the tank is recorded, i.e., the sloshing index data, specifically: 1. Import the existing liquid tanker truck liquid sloshing model (referring to the model established in steps 1 to 3, including the tank body, liquid and parameter settings, etc.) and set the boundary conditions; 2. Select a suitable solver and fluid dynamics model, and set the solution parameters, including time step, number of iterations, etc. 3. Set the driving conditions of the liquid tanker model to simulate various situations in the actual transportation process, record the changes in the liquid sloshing index during the vehicle's braking process, and observe the impact of liquid sloshing on the tank wall, recording the magnitude and distribution of the impact force. 4. Collect experimental data in real time and obtain data and images related to liquid sloshing, such as the distribution cloud map of sloshing amplitude and the curve of impact force on the tank wall.

[0022] In step 5, the advantages and disadvantages of each opening position scheme are evaluated based on the shaking index data, and the optimal scheme is determined, specifically as follows: The ability of the baffle plate to suppress liquid sloshing is evaluated from three aspects: the longitudinal force on the tank during vehicle acceleration or braking, the amplitude of the sloshing when the vehicle enters a constant speed state, and the rate of amplitude decay. The specific evaluation method is as follows: the merits of the solution are judged by analyzing the changes in the peak and amplitude of the longitudinal and lateral pressure on the inner wall of the tank during the liquid sloshing process. If the peak pressure is larger or the amplitude decays more slowly, the liquid sloshing indicates a greater impact on vehicle driving safety. The longitudinal pressure mainly affects the vehicle's braking performance and stability when stopped; the lateral pressure mainly affects the vehicle's lateral stability, such as rollover or lateral stability performance. The data such as sway amplitude, sway frequency, and impact force from multiple experiments under the corresponding opening position scheme are statistically analyzed. Then, the average value and standard deviation of each index are calculated. The average value reflects the overall level of liquid sway index under each scheme, while the standard deviation reflects the dispersion of the data. By comparing them horizontally, the optimal design scheme of the baffle in the corresponding transportation scenario can be obtained.

[0023] The present invention provides a specific embodiment of the steps, which specifically include: S1. Determine the research plan: Using the opening position of the baffle plate as the independent variable, design multiple opening position schemes, and determine the liquid sloshing-related indicators as the dependent variable; S2. Construct the tank model: Establish a geometric model based on the actual structure of the liquid tanker truck's tank; S3. Numerical Simulation Parameter Settings: Fluent software startup parameters (set counting accuracy, number of CPU cores and threads according to computer hardware configuration and simulation requirements); Task parameter settings (select a pressure-based solver and set force field parameters); S4. Create fluid and liquid model settings: Define liquid material type; liquid properties (density, viscosity, specific heat, etc.); simulation phase (liquid-gas two-phase state) and liquid viscosity model (turbulence model); liquid filling ratio in the tank; S5. Solution Method and Output Parameter Settings: Set the solution method and force monitor settings; S6. Initial conditions for data simulation: setting the liquid filling ratio and initial flow field values ​​in the tank; S7. Post-processing settings for calculation results: Create observation surface, set animation scene and parameters; S8. Operation and Data Acquisition: Execute the experiment and collect data, import the model and set the working conditions, simulate the liquid sloshing process, and record the sloshing index data. S9. Data Analysis and Solution Determination: Evaluate the merits of each opening location scheme based on the shaking index data, and determine the optimal scheme.

[0024] Embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0025] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0026] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0027] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0028] Contents not described in detail in this specification are prior art known to those skilled in the art. It is hereby indicated that the above description is intended to help those skilled in the art understand this invention, but does not limit the scope of protection of this invention. Any equivalent substitutions, modifications, improvements, or simplifications of the above descriptions that do not depart from the essential content of this invention fall within the scope of protection of this invention.

Claims

1. A numerical simulation and experimental design method for liquid sloshing in a tank truck based on Fluent, characterized in that, include: Step 1: Using the opening position of the baffle plate as the independent variable, design multiple opening position schemes and determine the liquid sloshing related indicators as the dependent variable; Step 2: Establish a geometric model based on the actual structure of the tanker truck, and set the fluid dynamics model and boundary conditions; Step 3: Configure the solver, set the output parameters and initial values ​​for the numerical simulation; Step 4: Perform the experiment to simulate the liquid sloshing process when a certain baffle plate opening scheme is used, and record the force data between the liquid sloshing and the inner wall of the tank, i.e., the sloshing index data. Step 5: Evaluate the advantages and disadvantages of each opening position scheme based on the shaking index data, and determine the optimal scheme.

2. The numerical simulation and experimental design method for liquid sloshing inside a tank truck based on Fluent, as described in claim 1, is characterized in that... The opening location scheme includes uniformly distributed openings, concentratedly distributed openings, and combinations of openings of different sizes and shapes.

3. The numerical simulation and experimental design method for liquid sloshing inside a tank truck based on Fluent, as described in claim 2, is characterized in that... The liquid sloshing-related indicators include the impact force, amplitude, and sloshing frequency on the tank wall.

4. The numerical simulation and experimental design method for liquid sloshing inside a tank truck based on Fluent, as described in claim 3, is characterized in that... In step 2, a geometric model is established based on the actual structure of the tank truck, and a fluid dynamics model and boundary conditions are set, specifically as follows: Based on the actual dimensions of the tanker truck, a geometric model of the tank was created using 3D modeling software, including the dimensions and shape of the tank, the position and size of the baffles, and the location of the openings. The VOF model is used as the fluid dynamics model, the liquid is set as an incompressible fluid, and its density and viscosity physical properties are set. The tank filling ratio can be set by configuring the liquid space coordinates in the area registration system. Select the solver, set the time step and number of iterations.

5. The experimental method for optimizing the opening position of the baffle plate of a liquid tanker truck based on CFD according to claim 4, characterized in that, In step 3, the solver is configured, and the output parameters and initial values ​​for the numerical simulation are set, specifically as follows: A pressure-based solver combined with the PISO split algorithm was used to simulate the driving conditions of a liquid tanker truck by setting standard gravitational acceleration and time-varying longitudinal acceleration. Set the longitudinal acceleration function to simulate variable speed driving conditions; Set the liquid material type and its physical properties.

6. The experimental method for optimizing the opening position of the baffle plate of a liquid tanker truck based on CFD according to claim 5, characterized in that, The formula for calculating the longitudinal acceleration is: （1） In the formula, Longitudinal acceleration, in m / s² 2 ; t represents time, measured in seconds (s).

7. The experimental method for optimizing the opening position of a baffle plate on a liquid tanker truck based on CFD, as described in claim 6, is characterized in that... The longitudinal acceleration function is: In the formula, IF is a conditional function, s is a time unit, and m is a length unit.

8. The experimental method for optimizing the opening position of the baffle plate of a liquid tanker truck based on CFD according to claim 7, characterized in that, In step 5, the merits of each opening location scheme are evaluated based on the shaking index data, specifically as follows: The advantages and disadvantages of each opening location scheme are evaluated by assessing the longitudinal and lateral forces on the tank under vehicle acceleration or braking conditions, the amplitude of vibration when the vehicle enters a constant speed state, and the rate of amplitude decay.

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