Integrated exhaust manifold GT-suite modeling and simulation method

Abstract

This invention provides a modeling and simulation method for an integrated exhaust manifold in GT-Suite. By simulating the actual exhaust valve flow coefficient test method under integrated exhaust manifold technology in GT-Suite, the exhaust valve flow coefficient is calculated through simulation and then substituted into the exhaust valve module of GT-Suite to perform integrated exhaust manifold modeling, thereby obtaining a usable integrated exhaust manifold simulation model and realizing engine simulation with integrated exhaust manifold technology.

Description

Technical Field

[0001] This invention relates to exhaust manifold simulation technology, belonging to the technical field of power component modeling. Background Technology

[0002] GT-Suite is an automotive simulation and analysis software developed by Gamma Technologies, Inc. in the United States. It is primarily used for analyzing vehicle design parameters, calculating fuel consumption and noise levels under various operating conditions, and can also be used for engine performance evaluation and cooling system performance evaluation. In the automotive industry, using GT-Suite software can significantly shorten design and development cycles and reduce production costs.

[0003] The main process for creating an exhaust manifold model in GT-Suite is generally as follows:

[0004] 1. The exhaust manifold physical model was processed using HyperMesh software, including extracting the inner surface, meshing, and converting it to STL format.

[0005] 2. Use the GEM3D tool to convert the STL format file into a 1D model and import it into GT-Suite.

[0006] 3. In GT-Suite, model the exhaust manifold according to the recommended exhaust manifold modeling method.

[0007] The file system provided by GT offers a modeling method for traditional exhaust passages (exhaust duct and exhaust manifold are separate). Since traditional exhaust passages are relatively straight and short, the flow loss caused by their shape and surface roughness can be considered together with the valve throttling effect. That is, the total flow loss characteristics of valves and exhaust passages are usually unified into the flow coefficient characteristics of the exhaust passages. In the GT model, this is described by the flow coefficient curve of the valve model, while the exhaust passage is simulated as a straight pipe that ignores friction. The exhaust manifold part at the exhaust passage outlet is modeled according to its specific geometric structure. The specific method is as follows: (1) The exhaust flow coefficient obtained from the experimental measurement is directly input into the GT-Suite exhaust valve module. (2) The 1D model in the above steps is subjected to internal surface friction treatment in GT-Suite, and the friction coefficient is set to 0. After completing the above two steps, a usable exhaust manifold simulation model is obtained, which can be further used for engine simulation analysis.

[0008] Integrated exhaust manifolds (where the exhaust passage and manifold are integrated into one unit) are a relatively recent technology, and there is no corresponding modeling method for them in GT-Suite. For engines using integrated exhaust manifold technology, the exhaust passage and manifold are integrated, resulting in a complex exhaust path structure and significantly longer dimensions than traditional exhaust passages. The throttling losses caused by the airflow path structure and friction are not suitable for continued unified consideration in the valve model; otherwise, the simulation calculations of the exhaust process (especially under heavy loads) will produce significant deviations, leading to large errors in the calculations of engine cylinder pressure and scavenging processes. In other words, directly inputting experimentally measured exhaust flow coefficients into the GT-Suite exhaust valve module will cause model distortion and render the model unusable. Summary of the Invention

[0009] This invention addresses the shortcomings of existing technologies by providing a modeling and simulation method for an integrated exhaust manifold in GT-Suite. The aim is to establish a method for modeling an integrated exhaust manifold in GT-Suite, with the key being the processing of the exhaust valve flow coefficient in the integrated exhaust manifold model to obtain a usable integrated exhaust manifold simulation model.

[0010] The technical solution of the present invention is as follows:

[0011] A modeling and simulation method for an integrated exhaust manifold GT-Suite, the method comprising the following steps:

[0012] S1. The physical model of the integrated exhaust manifold is processed using finite element software to obtain a format file;

[0013] S2. Use the GEM3D tool to convert the format file into a 1D model and import it into GT-Suite;

[0014] S3. Add boundary modules and valve structure modules to the 1D model to form an exhaust valve flow coefficient optimization model;

[0015] S4. Set the pressure and temperature in the boundary module according to the boundary set in the cylinder head air passage flow test.

[0016] Common methods for cylinder head intake manifold flow rate testing include the FEV method, the Ricardo method, and the AVL method. For example, the FEV method involves adjusting the valve lift from 1 mm to integer millimeters after the maximum valve lift, and testing the flow rate at different valve lifts with a pressure difference of 5 kPa.

[0017] S5. Model the valve structure and set three parameters: cylinder bore, valve lift / cylinder bore, and flow coefficient.

[0018] S6. Set up the heat transfer model for the integrated exhaust manifold.

[0019] S7. Add control signals to control the exhaust valve lift of each cylinder.

[0020] S8. Calculate the difference f(x) between the exhaust valve flow rate in the model and the measured exhaust valve flow rate, and use it as the optimization objective.

[0021] S9. Perform optimization, selecting the exhaust valve flow coefficient as the optimization variable, with the optimization principle being to minimize f(x).

[0022] S10. Obtain the exhaust valve flow coefficient for each cylinder under different valve lifts, and average the optimization results for each cylinder under the same valve lift.

[0023] S11. Substitute the optimization results into the integrated exhaust manifold model and calculate the flow rate of each cylinder under different valve lifts. If the absolute value of the relative difference between the simulated flow rate and the measured exhaust valve flow rate is ≤3%, the integrated exhaust manifold simulation model can be considered usable.

[0024] Furthermore, in S1, the integrated exhaust manifold physical model is processed by extracting the inner surface and meshing using HyperMesh / ANSYS software, and then converted into STL format.

[0025] Furthermore, in S3, a boundary module and a valve structure module are added to the 1D model according to the cylinder head air passage flow test method to form an exhaust valve flow coefficient optimization model.

[0026] Furthermore, in S6, when setting the heat transfer model of the integrated exhaust manifold, if the fixed wall temperature method is used, the solid surface temperature needs to be set to room temperature; if the wall solution method is used, the heat transfer boundary needs to be set to the ambient temperature during the test.

[0027] The advantages of this invention are as follows:

[0028] Currently, GT-Suite only offers traditional exhaust manifold modeling methods. If the measured exhaust valve flow coefficient is directly input into the GT-Suite exhaust valve module for integrated exhaust manifold modeling, the model will be distorted and unusable. This invention simulates the actual exhaust valve flow coefficient testing method in GT-Suite with integrated exhaust manifold technology. The exhaust valve flow coefficient is calculated through simulation and then substituted into the GT-Suite exhaust valve module for integrated exhaust manifold modeling. Specifically, in GT-Suite, the exhaust valve flow coefficient in the integrated exhaust manifold model is processed (steps S7-S10), with the key addition of control and optimization modules to simulate the actual intake manifold flow coefficient testing process, resulting in a usable integrated exhaust manifold simulation model. This establishes a new method for integrated exhaust manifold modeling, filling a gap in GT-Suite's integrated exhaust manifold modeling methods and having significant implications for engine simulation work with integrated exhaust manifold technology. Attached Figure Description

[0029] Figure 1 This is a flowchart of the integrated exhaust manifold GT-Suite modeling and simulation method in one embodiment of the present invention;

[0030] Figure 2.1 An integrated exhaust manifold 1D model in one embodiment of the present invention.

[0031] Figure 2.2 An optimization model for the flow coefficient of the exhaust valve in an integrated exhaust manifold.

[0032] Figure 2.3 Environment module settings.

[0033] Figure 2.4 Valve structure modeling in the GT model library.

[0034] Figure 2.5 Fixed wall temperature setting.

[0035] Figure 2.6.1 “SignalGenerator” signal module 1 settings.

[0036] Figure 2.6.2 “SignalGenerator” signal module 2 settings.

[0037] Figure 2.7 The “MathEquation” module.

[0038] Figure 2.8 "optimizer" Detailed Implementation

[0039] The present invention will be further described below with reference to specific accompanying drawings and embodiments.

[0040] In one embodiment of this application, the integrated exhaust manifold GT-Suite modeling and simulation method of this application is specifically illustrated by modeling the integrated exhaust manifold of a four-cylinder engine. See [link to relevant documentation]. Figure 1 The modeling steps include:

[0041] S1. The integrated exhaust manifold physical model was processed by extracting the inner surface, meshing, etc., using HyperMesh software, and then converted into STL format.

[0042] S2. Use the GEM3D tool to convert the STL format file into a 1D model and import it into GT-Suite.

[0043] In this step, the piping uses the "Multiple-Bends" module, and the branching pipes use the "Flow Split" module. Two points should be noted:

[0044] 1) The branch pipe at the exhaust outlet (e.g.) Figure 2.1 In “ex-fs-1”, the expansion diameter 3,2 is set to √2 / 2 times the expansion diameter 1;

[0045] 2) The surface roughness of the pipeline is set according to the material properties, and the friction coefficient is set to the default Def.

[0046] S3. Based on the cylinder head intake port flow test method, the imported integrated exhaust manifold 1D model (such as...) Figure 2.1 Add boundary modules and valve structure modules to form an exhaust valve flow coefficient optimization model (such as...). Figure 2.2 ).

[0047] S4. Set the pressure and temperature in the boundary module according to the cylinder head air passage flow test boundary, such as... Figure 2.3 For boundary module 2, the ambient temperature is set to 298K and the pressure is set to 105Kpa. For boundary module 1, the ambient temperature is set to 298K and the pressure is set to 100Kpa.

[0048] S5. In the GT model library, the valve structure is modeled using the "ValveActuLiftCdConn" module, and the three parameters—cylinder bore, valve lift / bore, and flow coefficient—are set within the module, such as... Figure 2.4 For example, the cylinder bore is set to 73.5mm, and the valve lift / cylinder bore ratios are 1 / 73.5, 2 / 73.5, 3 / 73.5... 9 / 73.5, respectively. The exhaust valve flow coefficient is named as the variable [cdv].

[0049] S6. Set the heat transfer model for the integrated exhaust manifold piping, using a fixed wall temperature method, and set the solid surface temperature to ambient temperature (25℃). Figure 2.5 As shown.

[0050] S7. Add a "SignalGenerator" control signal to control the exhaust valve lift of each cylinder, such as... Figures 2.6.1-2.6.2 As shown. The model currently optimizes the exhaust valve flow coefficient of cylinder 1, and the valve lift parameter [lift] of cylinder 1 is set from 1mm to 9mm (the valve lift is consistent with the cylinder head air passage flow test), while the valve lift of cylinders 2, 3 and 4 is 0.

[0051] S8. Add the "MathEquation" module, and write "=abs(massflow-[target])" to calculate the difference f(x) between the exhaust valve flow rate in the model and the measured exhaust valve flow rate, and use it as the optimization objective. Figure 2.7 As shown.

[0052] S9. Optimize using the "Direct Optimizer" module built into GT-Suite. The optimization variable is the exhaust valve flow coefficient [cdv] (cdv definition is in step S5). The optimization principle is to minimize f(x). Figure 2.8 .

[0053] S10. After optimization, the flow coefficients of each cylinder under different valve lifts were obtained. Under the same valve lift, the optimization results of each cylinder were averaged to obtain the results. The simulated values ​​of the flow coefficients under different valve lifts are shown in Table 1 below:

[0054]

[0055] S11. Substitute the optimization results into the integrated exhaust manifold model to calculate the flow rate of each cylinder under different valve lifts. The flow rate deviation results are shown in Table 2 below:

[0056]

[0057] Determine the absolute value of the relative difference between the simulated flow rate and the measured exhaust valve flow rate. If the absolute value of the difference is ≤3%, the result meets the requirements, indicating that the integrated exhaust manifold model can be further used for engine performance simulation calculations. Otherwise, return to step S9 and perform optimization again.

[0058] It should be understood that the various forms of processes shown above can be used to rearrange, add, or delete steps. For example, the steps described in this application can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution disclosed in this application can be achieved, and this is not limited herein.

[0059] The specific embodiments described above do not constitute a limitation on the scope of protection of this application. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A modeling and simulation method for an integrated exhaust manifold GT-Suite, characterized in that, Includes the following steps: S1. The physical model of the integrated exhaust manifold is processed using finite element software to obtain a format file; S2. Use the GEM3D tool to convert the format file into a 1D model and import it into GT-Suite; S3. Based on the cylinder head intake port flow test method, add boundary modules and valve structure modules to the 1D model to form an exhaust valve flow coefficient optimization model; S4. Set the pressure and temperature in the boundary module according to the boundary set in the cylinder head air passage flow test; S5. Model the valve structure and set three parameters: cylinder bore, valve lift / cylinder bore, and flow coefficient; S6. Set up the heat transfer model for the integrated exhaust manifold. When setting up, if the fixed wall temperature method is used, the solid surface temperature should be set to room temperature. If the wall solution method is used, the heat transfer boundary should be set to the ambient temperature during the test. S7. Add control signals to control the exhaust valve lift of each cylinder; S8. Calculate the difference f(x) between the exhaust valve flow rate in the model and the measured exhaust valve flow rate, and use it as the optimization objective; S9. Perform optimization, selecting the exhaust valve flow coefficient as the optimization variable, with the optimization principle being to minimize f(x); S10. Obtain the exhaust valve flow coefficient for each cylinder under different valve lifts, and average the optimization results for each cylinder under the same valve lift. S11. Input the optimization results into the integrated exhaust manifold model and calculate the flow rate of each cylinder under different valve lifts. If the absolute value of the relative difference between the simulated flow rate and the measured exhaust valve flow rate is less than the set standard, the integrated exhaust manifold simulation model can be considered usable.

2. The integrated exhaust manifold GT-Suite modeling and simulation method according to claim 1, characterized in that, In S1, the integrated exhaust manifold physical model is extracted for internal surface and mesh generation using HyperMesh / ANSYS software, and then converted into STL format.

3. The integrated exhaust manifold GT-Suite modeling and simulation method according to any one of claims 1-2, characterized in that, In S5, the ValveActuLiftCdConn module is selected from the GT model library to model the valve structure.

4. The integrated exhaust manifold GT-Suite modeling and simulation method according to any one of claims 1-2, characterized in that, In S7, the exhaust valve lift of each cylinder is controlled by adding a SignalGenerator control signal.

5. The integrated exhaust manifold GT-Suite modeling and simulation method according to any one of claims 1-2, characterized in that, In S8, the difference f(x) between the exhaust valve flow rate in the model and the measured exhaust valve flow rate is calculated by adding the MathEquation module.

6. The integrated exhaust manifold GT-Suite modeling and simulation method according to any one of claims 1-2, characterized in that, In S9, optimization is performed using the Direct Optimizer module.

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