CN114676525A - Simulation prediction method and system for heat release of engine water jacket - Google Patents
Simulation prediction method and system for heat release of engine water jacket Download PDFInfo
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Abstract
The embodiment of the application discloses a method and a system for simulating and predicting the heat release of an engine water jacket, wherein the method comprises the following steps: acquiring an exhaust flow boundary, an in-cylinder temperature distribution boundary and a convective heat transfer coefficient of gas and a cylinder body and a cylinder cover based on the water temperature of an engine, the temperature of an intake manifold and preset combustion parameters; acquiring the flow of cooling liquid at each inlet and outlet of the water jacket; and predicting the heat release of the engine water jacket based on the exhaust flow boundary, the in-cylinder temperature distribution boundary, the convective heat transfer coefficient of the gas and the cylinder body and the cylinder cover and the flow of cooling liquid at each inlet and outlet of the water jacket.
Description
Technical Field
The application relates to the technical field of engines, in particular to a method and a system for simulating and predicting the heat release of an engine water jacket.
Background
The simulation prediction method for the heat release of the engine water jacket is mainly suitable for the situation that in the engine development process, an entity prototype is not manufactured in a trial mode, the heat release data of the engine under a characteristic working condition needs to be estimated and predicted so as to be loaded on a whole vehicle to develop a corresponding cooling heat balance system, and the related technology for predicting the heat release data of the engine water jacket is not available at present.
Disclosure of Invention
In order to solve the technical problem, the embodiment of the application provides a simulation prediction method and system for the heat release of an engine water jacket.
The technical scheme of the embodiment of the application is realized as follows:
in a first aspect, an embodiment of the present application provides a simulation prediction method for engine water jacket heat release, where the method includes:
acquiring an exhaust flow boundary, an in-cylinder temperature distribution boundary and a convective heat transfer coefficient of gas and a cylinder body and a cylinder cover based on the water temperature of an engine, the temperature of an intake manifold and preset combustion parameters;
acquiring the flow of cooling liquid at each inlet and outlet of the water jacket;
and predicting the heat release of the engine water jacket based on the exhaust flow boundary, the in-cylinder temperature distribution boundary, the convective heat transfer coefficient of the gas and the cylinder body and the cylinder cover and the flow of cooling liquid at each inlet and outlet of the water jacket.
In a second aspect, an embodiment of the present application provides an engine water jacket heat release amount simulation prediction system, where the system includes:
a simulation module: the device is used for acquiring an exhaust flow boundary, an in-cylinder temperature distribution boundary and a convective heat transfer coefficient of gas and a cylinder body and a cylinder cover based on the water temperature of an engine, the temperature of an intake manifold and preset combustion parameters; acquiring the flow of cooling liquid at each inlet and outlet of the water jacket; and predicting the heat release of the engine water jacket based on the exhaust flow boundary, the in-cylinder temperature distribution boundary, the convective heat transfer coefficient of the gas and the cylinder body and the cylinder cover and the flow of cooling liquid at each inlet and outlet of the water jacket.
The technical scheme provided by the embodiment of the application can predict the heat release information of the engine at the initial development stage, so that the heat balance development work of the whole vehicle is developed as early as possible, the heat balance examination test is achieved at one time, and the repeated design change of the whole vehicle caused by the large deviation between the early rough predicted heat release and the test result of an engine prototype is avoided.
Drawings
FIG. 1 is a first schematic flow chart of a simulation prediction method for heat release of an engine water jacket according to an embodiment of the present application;
FIG. 2 is a second flowchart illustrating a simulation and prediction method for heat release of an engine water jacket according to an embodiment of the present application;
FIG. 3 is a schematic diagram of an engine water jacket heat release simulation prediction system provided in an embodiment of the present application.
Detailed Description
Technical solutions in the embodiments of the present application will be described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are some embodiments of the present application, but not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
It should be noted that, in the embodiment of the present application, the term "and/or" is only one kind of association relationship describing an associated object, and indicates that three relationships may exist, for example, a and/or B may indicate: a exists alone, A and B exist simultaneously, and B exists alone. In addition, in the embodiment of the present application, the character "/" generally indicates that the preceding and following related objects are in an "or" relationship.
In the description of the embodiments of the present application, the term "correspond" may indicate that there is a direct correspondence or an indirect correspondence between the two, may also indicate that there is an association between the two, and may also indicate and be indicated, configure and configured, and so on.
To facilitate understanding of the technical solutions of the embodiments of the present application, the following describes related arts of the embodiments of the present application:
mean Effective Pressure (IMEP): the indicating work emitted by unit cylinder working volume is called average indicating pressure
Indicated Fuel Consumption (ISFC): specific fuel consumption, i.e. specific fuel consumption, is the mass of fuel consumed (in g) in 1h per 1kw of power commanded by the engine, and is expressed in ge in g/(kw.h).
So that the manner in which the features and aspects of the present application can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings.
Fig. 1 is a schematic implementation flow diagram of a first method for simulating and predicting engine water jacket heat release according to an embodiment of the present disclosure, and as shown in fig. 1, the embodiment of the present disclosure provides a method for simulating and predicting engine water jacket heat release, where the method includes:
and 101, acquiring an exhaust flow boundary, an in-cylinder temperature distribution boundary and a convection heat transfer coefficient of gas and a cylinder body and a cylinder cover based on the water temperature of the engine, the temperature of an intake manifold and preset combustion parameters.
The exhaust flow boundary, the in-cylinder temperature distribution boundary and the convective heat transfer coefficient of the gas and the cylinder body and the cylinder cover can be obtained through the iterative process of the thermodynamic performance simulation and the iterative process of the combustion system simulation, and when the thermodynamic performance simulation and the combustion system simulation are stable in iteration, the thermodynamic performance simulation outputs the exhaust flow boundary and the convective heat transfer coefficient of the combustion system output gas and the cylinder body and the cylinder cover. Whether the iterative process of the thermodynamic simulation and the iterative process of the combustion system simulation converge or not can be judged through the IMEP and the ISFC of the thermodynamic simulation and the combustion system simulation, and when the IMEP and the ISFC converge, the iterative process of the thermodynamic simulation and the iterative process of the combustion system simulation converge.
Specifically, each iteration process of the thermodynamic performance simulation comprises the following steps: and performing thermodynamic performance simulation based on the water temperature of the engine, the temperature of the intake manifold and the combustion parameters, and outputting transient intake air flow and a pressure boundary. In the first iteration process, thermodynamic performance simulation can be carried out based on the water temperature of the engine, the temperature of an intake manifold and preset combustion parameters, and transient intake air flow and a pressure boundary are output; each iteration process of the combustion system simulation comprises the steps of carrying out combustion system simulation based on transient intake air flow and pressure boundary output by thermodynamic performance simulation, and outputting combustion parameters. The combustion parameters include: cylinder pressure curves, CA10, CA50, CA90, where CA10, CA50, and CA90 respectively indicate crank angles corresponding to 10%, 50%, and 90% of fuel burned during combustion.
Based on this, the method for simulating and predicting the heat release of the engine water jacket according to another embodiment of the present application, which obtains the exhaust flow, the temperature boundary, the in-cylinder temperature distribution boundary, and the convective heat transfer coefficient between the gas and the cylinder head based on the engine water temperature, the intake manifold temperature, and the preset combustion parameter, includes:
performing an iterative process of thermodynamic performance simulation and an iterative process of combustion system simulation until IMEP and ISFC of the thermodynamic performance simulation and the combustion system simulation converge; acquiring an exhaust flow boundary, an in-cylinder temperature distribution boundary and a convective heat transfer coefficient of gas and a cylinder body and a cylinder cover based on the converged thermodynamic performance simulation output and the combustion system simulation output;
wherein each iteration process of the thermodynamic performance simulation comprises: performing thermodynamic performance simulation based on the water temperature of the engine, the temperature of an intake manifold and combustion parameters, and outputting transient intake air flow and a pressure boundary; in the first iteration process, the combustion parameter is a preset combustion parameter; in a non-first iteration process, the combustion parameters are combustion parameters output by the combustion system in a simulation mode;
each iteration process of the combustion system simulation comprises: and simulating a combustion system based on the transient intake air flow and the pressure boundary output by the thermodynamic performance simulation, and outputting combustion parameters.
Furthermore, thermodynamic performance simulation can be completed based on specific simulation software, such as GT-Power and AVL-Boost, and the method is used for analyzing the working state of the engine, constructing an engine thermodynamic model according to the geometric parameters of the engine and the performance data of parts such as a supercharger, setting combustion parameters, performing thermodynamic simulation on the engine, and taking transient pressure, flow and temperature data of the last cycle after the working condition is stable in iteration (the cyclic fluctuation of torque, intake pressure and exhaust temperature is less than 0.1%). The transient intake air flow and pressure boundary refers to the data of the mass flow of fresh gas entering the cylinder as a function of the crankshaft angle (720 crank angle per cycle) at a characteristic engine operating condition (speed, torque). For engine thermodynamic performance simulation, a knock prediction function is required, so that the influence of the temperature of an intake manifold and the temperature of engine water on engine knock needs to be considered when simulation analysis is carried out. Here, the geometric parameters are cylinder diameter, stroke, connecting rod length, piston offset, intake and exhaust manifold shape, etc
For combustion system simulation, it can be done based on specific simulation software, such as AVL-Fire, convert. According to the method, a combustion system simulation model is constructed according to the numerical models of a cylinder cover, a cylinder body, a piston and a valve of an engine, transient intake air flow and intake pressure boundary data are input, an ignition advance angle is set, numerical simulation prediction of a combustion process is carried out, and combustion process data such as a cylinder pressure curve, CA10, CA50 and CA90 are derived according to an analysis result. And meanwhile, the results of the gas temperature and the convective heat transfer coefficient of the contact surface of the cylinder body, the cylinder cover and the combustion gas are derived.
Whether the IMEP and the ISFC of the thermodynamic simulation and the combustion system simulation are converged can be judged through the following mode, the increase rate or the decrease rate of the IMEP value of the combustion system simulation in the current iteration process compared with the IMEP value of the thermodynamic simulation is compared with a preset second threshold, the increase rate or the decrease rate of the ISFC value of the combustion system simulation in the current iteration process compared with the ISFC value of the thermodynamic simulation is compared with the preset second threshold, and if the increase rate or the decrease rate is smaller than or equal to the preset second threshold, the IMEP and the ISFC of the thermodynamic simulation and the combustion system simulation are converged.
Based on this, an embodiment of the present application provides a method for predicting engine water jacket heat release amount simulation, where IMEP and ISFC of the thermodynamic performance simulation and the combustion system simulation converge, including:
and respectively comparing the increase rate or the decrease rate of the IMEP of the combustion system simulation in the current iteration process compared with the IMEP of the thermodynamic performance simulation and the ISFC of the combustion system simulation in the current iteration process compared with the ISFC of the thermodynamic performance simulation with a preset second threshold, and if the increase rate or the decrease rate of the IMEP of the combustion system simulation in the current iteration process compared with the ISFC of the thermodynamic performance simulation is less than or equal to the preset second threshold, the IMEP and the ISFC of the thermodynamic performance simulation and the combustion system simulation are converged.
In an embodiment of the present application, the preset second threshold is 3%.
And 102, acquiring the flow of the cooling liquid of each inlet and outlet of the water jacket.
Here, the flow rate of the coolant at each inlet/outlet of the water jacket can be obtained by a cooling system simulation.
Based on this, the method for predicting the heat release of the engine water jacket provided in an embodiment of the present application includes:
and (5) simulating a cooling system to obtain the flow of the cooling liquid at each inlet and outlet of the water jacket.
Specifically, the simulation of the cooling system is a simulation work in the engine development, and can be based on specific simulation software, such as GT-Power, Flowmaster, and can also be calculated by tool balancing such as excel. A cooling system pipeline constructs a cooling system simulation model according to an entity digital model, the flow resistance and the water pump performance of parts adopt flow-pressure drop curve data measured in tests, and the cooling flow passing through each part at different engine rotating speeds is obtained through simulation analysis.
And 103, predicting the heat release of the engine water jacket based on the exhaust flow boundary, the temperature distribution boundary in the cylinder, the heat convection coefficient of the gas and the cylinder cover of the cylinder body and the flow of cooling liquid at each inlet and outlet of the water jacket.
Specifically, when the temperature distribution boundary of the cylinder body and the cylinder head input into the water jacket CFD simulation converges, a statistical result of the solid surface heat exchange power of the water jacket CFD simulation, namely a heat release result of the engine water jacket, is obtained based on the output of the converged water jacket CFD simulation.
Further, each iteration process of the water jacket CFD simulation includes: performing water jacket CFD simulation based on the flow of the cooling liquid at each inlet and outlet of the water jacket and the temperature distribution boundary of the cylinder body and the cylinder cover obtained in the step 102, and outputting the temperature distribution of the cooling liquid and the convective heat transfer coefficient of the cooling liquid and the cylinder body and the cylinder cover; in the first iteration process, the temperature distribution boundary of the cylinder body and the cylinder cover is a preset temperature distribution boundary of the cylinder body and the cylinder cover; in a non-first iteration process, the temperature distribution boundary of the cylinder body and the cylinder cover is a temperature distribution boundary of the cylinder body and the cylinder cover output by the simulation of a temperature field of the cylinder body and the cylinder cover; the process of each iteration of the simulation of the temperature field of the cylinder body and the cylinder cover comprises the following steps: and simulating a temperature field of the cylinder body and the cylinder cover based on the exhaust flow boundary, the temperature distribution boundary in the cylinder, the convective heat transfer coefficient of the gas and the cylinder body and the cylinder cover, the temperature distribution of the cooling liquid and the convective heat transfer coefficient of the cooling liquid and the cylinder body and the cylinder cover, and outputting the temperature distribution boundary of the cylinder body and the cylinder cover.
Based on this, an engine water jacket heat release simulation prediction method provided in another embodiment of the present application, which predicts the engine water jacket heat release based on the exhaust flow boundary, the in-cylinder temperature distribution boundary, the convective heat transfer coefficient between the gas and the cylinder block and the cylinder cover, and the flow rates of the cooling liquid at the respective inlets and the outlets of the water jacket, includes:
carrying out an iterative process of water jacket CFD simulation and an iterative process of cylinder body and cylinder cover temperature field simulation until the temperature distribution boundary of the cylinder body and cylinder cover input into the water jacket CFD simulation converges; and acquiring a solid surface heat exchange power statistical result of the water jacket CFD simulation, namely an engine water jacket heat release result, based on the output of the converged water jacket CFD simulation.
Wherein each iteration process of the water jacket CFD simulation comprises: performing CFD simulation on the water jacket based on the flow of the cooling liquid at each inlet and outlet of the water jacket and the temperature distribution boundary of the cylinder body and the cylinder cover, and outputting the temperature distribution of the cooling liquid and the convective heat transfer coefficient of the cooling liquid and the cylinder cover; in the first iteration process, the temperature distribution boundary of the cylinder body and the cylinder cover is a preset temperature distribution boundary of the cylinder body and the cylinder cover; in a non-first iteration process, the temperature distribution boundary of the cylinder body and the cylinder cover is the temperature distribution boundary of the cylinder body and the cylinder cover which is output by the simulation of a temperature field of the cylinder body and the cylinder cover;
the simulation of the temperature field of the cylinder body and the cylinder cover comprises the following iterative processes: and simulating a cylinder body and cylinder cover temperature field based on the exhaust flow boundary, the in-cylinder temperature distribution boundary, the convective heat transfer coefficient of the gas and the cylinder body and the cylinder cover, the coolant temperature distribution and the convective heat transfer coefficient of the coolant and the cylinder body and the cylinder cover, and outputting the cylinder body and cylinder cover temperature distribution boundary.
For water jacket CFD simulation, the simulation can be completed based on specific simulation software, such as STAR-CCM +, a cold water jacket model is constructed according to a digital model of an engine cylinder body and a cylinder cover, flow boundaries of inlets and outlets of a water jacket are set according to flow results of cooling system simulation, cooling liquid pressure and temperature boundaries of an outlet of the water jacket are set according to analysis results of the cooling system, and flow field distribution of cooling liquid in the water jacket and convective heat transfer coefficients and cooling liquid temperature distribution of a contact surface of the cooling liquid and the cylinder cover are obtained through simulation.
For temperature field simulation, this can be done based on specific simulation software, such as Abaqus. A temperature field simulation model is constructed according to the digifax of the engine cylinder body and the cylinder cover, grids are divided, the temperature, the pressure and the convective heat transfer coefficient of the contact surface of the cylinder body, the cylinder cover and the air side are input according to the simulation result of the combustion system, meanwhile, the temperature, the pressure and the convective heat transfer coefficient of the contact surface of the cylinder body, the cylinder cover and the cooling liquid are input according to the CFD simulation result of the cooling water jacket, the heat transfer process of the solid part of the cylinder body and the cylinder cover is calculated, and the wall surface temperature and the temperature distribution result of the cylinder body and the cylinder cover are obtained.
Whether the temperature distribution boundary of the cylinder body and the cylinder cover input into the water jacket CFD simulation is converged can be judged in the following mode, the increasing rate or the decreasing rate of the temperature distribution boundary of the cylinder body and the cylinder cover input into the water jacket CFD simulation in the current iteration process compared with the temperature distribution boundary of the cylinder body and the cylinder cover input into the water jacket CFD simulation at the last time is compared with a preset first threshold, and if the increasing rate or the decreasing rate is smaller than or equal to the preset first threshold, the temperature distribution boundary of the cylinder body and the cylinder cover is converged.
Based on this, the method for predicting the simulation of the heat release of the engine water jacket provided in an embodiment of the present application, where the boundary of the temperature distribution of the cylinder head of the cylinder block input with the CFD simulation of the water jacket converges, includes:
comparing the increasing rate or the decreasing rate of the temperature distribution boundary of the simulated cylinder body and the cylinder cover, which is input with the water jacket CFD in the current iteration process, compared with the temperature distribution boundary of the simulated cylinder body and the cylinder cover, which is input with the water jacket CFD last time, with a preset first threshold, and if the increasing rate or the decreasing rate is smaller than or equal to the preset first threshold, the temperature distribution boundary of the cylinder body and the cylinder cover is converged.
The in-cylinder temperature distribution boundary refers to a temperature distribution boundary of in-cylinder gas in a cylinder and a cylinder cover, and the cylinder and cylinder cover temperature distribution boundary refers to a temperature distribution boundary of cooling liquid in the cylinder and cylinder cover
According to the simulation prediction method for the heat release of the water jacket of the engine provided by the embodiment of the application, the analysis precision is improved and the accuracy of the heat release prediction of the water jacket is ensured through complete boundary mapping and multi-round iterative analysis. In addition, the scheme introduces the boundary of the temperature of the intake manifold and the water temperature of the engine, fully considers the influence of environmental factors on the heat release of the engine, is suitable for predicting the heat release under wider environmental conditions, and realizes the function of predicting and analyzing the heat release of the water jacket of the engine.
In another embodiment of the present application, the preset first threshold is 3%.
Fig. 2 is a schematic flow chart of an implementation of a simulation prediction method for engine water jacket heat release according to another embodiment of the present application, and as shown in fig. 2, the simulation prediction method for engine water jacket heat release according to this embodiment includes the following steps:
step 201: performing thermodynamic performance simulation according to the geometric structure and the performance target of the engine, wherein the simulation task needs to have a knock prediction function, and the influence of the temperature of an intake manifold and the temperature of water of the engine on the engine knock is considered during analysis; and (4) simulating and outputting transient flow and pressure boundaries of all the air inlet and exhaust passages in each engine cycle period by thermodynamic performance.
Step 202: the simulation of the combustion system takes the transient intake air flow and the pressure boundary as input to carry out simulation and outputs combustion parameters.
Step 203: and the thermodynamic performance simulation updates the combustion parameters for simulation according to the combustion simulation result, and updates the transient flow and the pressure boundary of the air inlet and exhaust passage again.
Step 204: and (5) simulating and updating the transient intake air flow and pressure boundary by the combustion system, and simulating again.
Step 205: comparing IMEP and ISFC of thermodynamic performance simulation and combustion system simulation, judging that iteration is not converged if the deviation is more than 3%, and returning to step 203; the deviation is less than or equal to 3 percent and is regarded as iterative convergence, the combustion system simulates and outputs the temperature distribution boundary in the cylinder and the heat convection coefficient of the gas and the cylinder cover of the cylinder body, and the thermodynamics simulates and outputs the exhaust flow boundary.
Step 206: and (5) simulating an engine cooling system, and analyzing to obtain the flow of the cooling liquid at each inlet and outlet of the water jacket.
Step 207: and (4) performing CFD simulation on the water jacket, inputting the flow boundary of the cooling system, estimating the temperature boundary of the input cylinder body and the cylinder cover, and analyzing to obtain the temperature distribution of the cooling liquid and the convective heat transfer coefficient of the cooling liquid and the cylinder cover.
Step 208: and simulating a temperature field of the cylinder body and the cylinder cover according to the temperature distribution boundary in the cylinder and the convective heat transfer coefficient between the gas and the cylinder body and the cylinder cover output by the combustion system simulation, the exhaust flow boundary output by the thermodynamic simulation and the temperature distribution of the cooling liquid output by the water jacket CFD analysis and the convective heat transfer coefficient between the cooling liquid and the cylinder body and the cylinder cover to obtain the temperature distribution boundary of the cylinder body and the cylinder cover.
Step 209: and (4) the CFD of the water jacket takes the temperature distribution boundary mapping of the cylinder body and the cylinder cover analyzed by the temperature field as input, and the simulation is carried out again.
Step 210: comparing the temperature distribution of the cylinder body and the cylinder cover adopted by the CFD input of the water jacket twice, judging that the deviation is more than 3 percent, and returning to the step 208 if the deviation is not converged; and the deviation is less than or equal to 3%, the iteration convergence is considered, and the statistical result of the solid surface heat exchange power of the CFD of the water jacket is output, namely the heat release result of the water jacket of the engine.
In order to implement the method for replacing advertisement programs in real time according to the application embodiment of the present application, the embodiment of the present application further provides an engine water jacket heat release policy prediction system 300; fig. 3 is a schematic structural diagram of an engine water jacket heat release quantity guideline prediction system 300 according to an embodiment of the present application, and as shown in fig. 3, the engine water jacket heat release quantity guideline prediction system 300 according to the embodiment of the present application includes:
the simulation module 301: the device is used for acquiring an exhaust flow boundary, an in-cylinder temperature distribution boundary and a convective heat transfer coefficient of gas and a cylinder body and a cylinder cover based on the water temperature of an engine, the temperature of an intake manifold and preset combustion parameters; acquiring the flow of cooling liquid at each inlet and outlet of the water jacket; and predicting the heat release of the engine water jacket based on the exhaust flow boundary, the in-cylinder temperature distribution boundary, the convective heat transfer coefficient of the gas and the cylinder body and the cylinder cover and the flow of cooling liquid at each inlet and outlet of the water jacket.
In other embodiments of the present application, the simulation module 301 is specifically configured to perform an iterative process of thermodynamic performance simulation and an iterative process of combustion system simulation until IMEP and ISFC of the thermodynamic performance simulation and the combustion system simulation converge; acquiring an exhaust flow boundary, an in-cylinder temperature distribution boundary and a convective heat transfer coefficient of gas and a cylinder body and a cylinder cover based on the output of the converged thermodynamic performance simulation and the output of the combustion system simulation; wherein each iteration process of the thermodynamic performance simulation comprises: performing thermodynamic performance simulation based on the water temperature of the engine, the temperature of an intake manifold and combustion parameters, and outputting transient intake air flow and a pressure boundary; in the first iteration process, the combustion parameter is a preset combustion parameter; in a non-first iteration process, the combustion parameters are combustion parameters output by the combustion system in a simulation mode; each iteration process of the combustion system simulation comprises: and simulating a combustion system based on the transient intake air flow and the pressure boundary output by the thermodynamic performance simulation, and outputting combustion parameters.
In other embodiments of the present application, the simulation module 301 is specifically further configured to perform cooling system simulation to obtain the flow rates of the cooling liquid at the respective inlets and outlets of the water jacket.
In other embodiments of the present application, the simulation module 301 is further specifically configured to perform an iterative process of water jacket CFD simulation and an iterative process of cylinder block and cylinder head temperature field simulation until a boundary of a cylinder block and cylinder head temperature distribution input to the water jacket CFD simulation converges; based on the output of the water jacket CFD simulation after convergence, obtaining a statistical result of the solid surface heat exchange power of the water jacket CFD simulation, namely a heat release result of the engine water jacket; wherein each iteration process of the water jacket CFD simulation comprises: performing CFD simulation on the water jacket based on the flow of the cooling liquid at each inlet and outlet of the water jacket and the temperature distribution boundary of the cylinder body and the cylinder cover, and outputting the temperature distribution of the cooling liquid and the convective heat transfer coefficient of the cooling liquid and the cylinder cover; in the first iteration process, the temperature distribution boundary of the cylinder body and the cylinder cover is a preset temperature distribution boundary of the cylinder body and the cylinder cover; in a non-first iteration process, the temperature distribution boundary of the cylinder body and the cylinder cover is the temperature distribution boundary of the cylinder body and the cylinder cover which is output by the simulation of a temperature field of the cylinder body and the cylinder cover; each iteration process of the simulation of the temperature field of the cylinder body and the cylinder cover comprises the following steps: and simulating a cylinder body and cylinder cover temperature field based on the exhaust flow boundary, the in-cylinder temperature distribution boundary, the convective heat transfer coefficient of the gas and the cylinder body and the cylinder cover, the coolant temperature distribution and the convective heat transfer coefficient of the coolant and the cylinder body and the cylinder cover, and outputting the cylinder body and cylinder cover temperature distribution boundary.
In other embodiments of the present application, the convergence of the temperature distribution boundary of the cylinder block and the cylinder head of the input water jacket CFD simulation includes: comparing the increase rate or the decrease rate of the temperature distribution of the simulated cylinder body and the cylinder cover, compared with the temperature distribution of the simulated cylinder body and the cylinder cover, input with the water jacket CFD last time in the current iteration process, with a preset first threshold, and if the increase rate or the decrease rate is smaller than or equal to the preset first threshold, converging the temperature distribution boundary of the cylinder body and the cylinder cover.
In other embodiments of the present application, the IMEP and ISFC convergence of the thermodynamic performance simulation and combustion system simulation, comprising: and respectively comparing the increase rate or the decrease rate of the IMEP of the combustion system simulation in the current iteration process compared with the IMEP of the thermodynamic performance simulation and the ISFC of the combustion system simulation in the current iteration process compared with the ISFC of the thermodynamic performance simulation with a preset second threshold, and if the increase rate or the decrease rate of the IMEP of the combustion system simulation in the current iteration process compared with the ISFC of the thermodynamic performance simulation are less than or equal to the preset second threshold, converging the IMEP and the ISFC of the thermodynamic performance simulation and the combustion system simulation.
Those skilled in the art will appreciate that the functions implemented by each unit in the engine water jacket heat release amount simulation prediction system shown in fig. 3 can be understood by referring to the related description of the foregoing method. The functions of the units in the engine water jacket heat release amount simulation prediction system shown in fig. 3 can be realized by a program running on a processor, and can also be realized by a specific logic circuit.
Those of ordinary skill in the art will appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware or combinations of computer software and electronic hardware. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the implementation. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present application.
It is clear to those skilled in the art that, for convenience and brevity of description, the specific working processes of the above-described systems, apparatuses and units may refer to the corresponding processes in the foregoing method embodiments, and are not described herein again.
In the several embodiments provided in the present application, it should be understood that the disclosed system, apparatus and method may be implemented in other ways. For example, the above-described apparatus embodiments are merely illustrative, and for example, the division of the units is only one logical division, and other divisions may be realized in practice, for example, a plurality of units or components may be combined or integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or units, and may be in an electrical, mechanical or other form.
The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.
In addition, functional units in the embodiments of the present application may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit.
The functions, if implemented in the form of software functional units and sold or used as a stand-alone product, may be stored in a computer readable storage medium. Based on such understanding, the technical solutions of the present application or portions thereof that substantially contribute to the prior art may be embodied in the form of a software product, which is stored in a storage medium and includes several instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the steps of the methods described in the embodiments of the present application. And the aforementioned storage medium includes: various media capable of storing program codes, such as a usb disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk, or an optical disk.
The above description is only for the specific embodiments of the present application, but the scope of the present application is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present application, and shall be covered by the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.
Claims (10)
1. An engine water jacket heat release amount simulation prediction method is characterized by comprising the following steps:
acquiring an exhaust flow boundary, an in-cylinder temperature distribution boundary and a convective heat transfer coefficient of gas and a cylinder body and a cylinder cover based on the water temperature of an engine, the temperature of an intake manifold and preset combustion parameters;
acquiring the flow of cooling liquid at each inlet and outlet of the water jacket;
and predicting the heat release of the engine water jacket based on the exhaust flow boundary, the in-cylinder temperature distribution boundary, the convective heat transfer coefficient of the gas and the cylinder body and the cylinder cover and the flow of cooling liquid at each inlet and outlet of the water jacket.
2. The engine water jacket heat release quantity simulation prediction method according to claim 1, wherein acquiring an exhaust flow boundary, an in-cylinder gas temperature distribution boundary and a convective heat transfer coefficient of gas and a cylinder block and a cylinder cover based on an engine water temperature, an intake manifold temperature and a preset combustion parameter comprises:
performing an iterative process of thermodynamic performance simulation and an iterative process of combustion system simulation until IMEP and ISFC of the thermodynamic performance simulation and the combustion system simulation converge; acquiring an exhaust flow boundary, an in-cylinder temperature distribution boundary and a convective heat transfer coefficient of gas and a cylinder body and a cylinder cover based on the converged thermodynamic performance simulation output and the combustion system simulation output;
wherein each iteration process of the thermodynamic performance simulation comprises: performing thermodynamic performance simulation based on the water temperature of the engine, the temperature of an intake manifold and combustion parameters, and outputting transient intake air flow and a pressure boundary; in the first iteration process, the combustion parameter is a preset combustion parameter; in a non-first iteration process, the combustion parameters are combustion parameters output by the combustion system in a simulation mode;
each iteration process of the combustion system simulation comprises: and simulating a combustion system based on the transient intake air flow and the pressure boundary output by the thermodynamic performance simulation, and outputting combustion parameters.
3. The engine water jacket heat release quantity simulation prediction method according to claim 2, wherein the acquiring of the flow quantity of the coolant at each inlet and outlet of the water jacket includes:
and (5) simulating a cooling system to obtain the flow of the cooling liquid at each inlet and outlet of the water jacket.
4. The engine water jacket heat release amount simulation prediction method according to claim 3, wherein the prediction of the engine water jacket heat release amount based on the exhaust flow rate boundary, the in-cylinder temperature distribution boundary, the convective heat transfer coefficient of the gas and the cylinder head, and the flow rates of the coolant at the respective inlets and outlets of the water jacket, comprises:
carrying out an iterative process of water jacket CFD simulation and an iterative process of cylinder body and cylinder cover temperature field simulation until the temperature distribution boundary of the cylinder body and cylinder cover input into the water jacket CFD simulation converges; based on the output of the water jacket CFD simulation after convergence, obtaining a statistical result of the solid surface heat exchange power of the water jacket CFD simulation, namely a heat release result of the engine water jacket;
wherein each iteration process of the water jacket CFD simulation comprises: performing CFD simulation on the water jacket based on the flow of the cooling liquid at each inlet and outlet of the water jacket and the temperature distribution boundary of the cylinder body and the cylinder cover, and outputting the temperature distribution of the cooling liquid and the convective heat transfer coefficient of the cooling liquid and the cylinder cover; in the first iteration process, the temperature distribution boundary of the cylinder body and the cylinder cover is a preset temperature distribution boundary of the cylinder body and the cylinder cover; in a non-first iteration process, the temperature distribution boundary of the cylinder body and the cylinder cover is the temperature distribution boundary of the cylinder body and the cylinder cover which is output by the simulation of a temperature field of the cylinder body and the cylinder cover;
the simulation of the temperature field of the cylinder body and the cylinder cover comprises the following iterative processes: and simulating a cylinder body and cylinder cover temperature field based on the exhaust flow boundary, the in-cylinder temperature distribution boundary, the convective heat transfer coefficient of the gas and the cylinder body and the cylinder cover, the coolant temperature distribution and the convective heat transfer coefficient of the coolant and the cylinder body and the cylinder cover, and outputting the cylinder body and cylinder cover temperature distribution boundary.
5. The engine water jacket heat release simulation prediction method according to claim 4, wherein the convergence of the cylinder head temperature distribution boundary of the input water jacket CFD simulation comprises:
comparing the increase rate or the decrease rate of the temperature distribution of the simulated cylinder body and the cylinder cover, compared with the temperature distribution of the simulated cylinder body and the cylinder cover, input with the water jacket CFD last time in the current iteration process, with a preset first threshold, and if the increase rate or the decrease rate is smaller than or equal to the preset first threshold, converging the temperature distribution boundary of the cylinder body and the cylinder cover.
6. The engine water jacket heat release simulation prediction method of any one of claims 2-5, wherein the IMEP and ISFC of the thermodynamic performance simulation and combustion system simulation both converge, comprising:
and respectively comparing the increase rate or the decrease rate of the IMEP of the combustion system simulation in the current iteration process compared with the IMEP of the thermodynamic performance simulation and the ISFC of the combustion system simulation in the current iteration process compared with the ISFC of the thermodynamic performance simulation with a preset second threshold, and if the increase rate or the decrease rate of the IMEP of the combustion system simulation in the current iteration process compared with the ISFC of the thermodynamic performance simulation is less than or equal to the preset second threshold, the IMEP and the ISFC of the thermodynamic performance simulation and the combustion system simulation are converged.
7. An engine water jacket heat release simulation prediction system, characterized in that the system comprises:
a simulation module: the device is used for acquiring an exhaust flow boundary, an in-cylinder temperature distribution boundary and a convective heat transfer coefficient of gas and a cylinder body and a cylinder cover based on the water temperature of an engine, the temperature of an intake manifold and preset combustion parameters; acquiring the flow of cooling liquid at each inlet and outlet of the water jacket; and predicting the heat release of the engine water jacket based on the exhaust flow boundary, the in-cylinder temperature distribution boundary, the convective heat transfer coefficient of the gas and the cylinder body and the cylinder cover and the flow of cooling liquid at each inlet and outlet of the water jacket.
8. The engine water jacket heat release amount simulation prediction system according to claim 7,
the simulation module is specifically used for performing an iterative process of thermodynamic performance simulation and an iterative process of combustion system simulation until IMEP and ISFC of the thermodynamic performance simulation and the combustion system simulation converge; acquiring an exhaust flow boundary, an in-cylinder temperature distribution boundary and a convective heat transfer coefficient of gas and a cylinder body and a cylinder cover based on the converged thermodynamic performance simulation output and the combustion system simulation output; wherein each iteration process of the thermodynamic performance simulation comprises: performing thermodynamic performance simulation based on the water temperature of the engine, the temperature of an intake manifold and combustion parameters, and outputting transient intake air flow and a pressure boundary; in the first iteration process, the combustion parameter is a preset combustion parameter; in a non-first iteration process, the combustion parameters are combustion parameters output by the combustion system in a simulation mode; each iteration process of the combustion system simulation comprises: and simulating a combustion system based on the transient intake air flow and the pressure boundary output by the thermodynamic performance simulation, and outputting combustion parameters.
9. The engine water jacket heat release amount simulation prediction system according to claim 8,
the simulation module is specifically used for simulating a cooling system and acquiring the flow of cooling liquid at each inlet and outlet of the water jacket.
10. The engine water jacket heat release amount simulation prediction system according to claim 9,
the simulation module is specifically used for carrying out an iterative process of water jacket CFD simulation and an iterative process of cylinder body and cylinder cover temperature field simulation until the temperature distribution boundary of the cylinder body and cylinder cover input into the water jacket CFD simulation converges; based on the output of the water jacket CFD simulation after convergence, obtaining a statistical result of the solid surface heat exchange power of the water jacket CFD simulation, namely a heat release result of the engine water jacket; wherein each iteration process of the water jacket CFD simulation comprises: performing CFD simulation on the water jacket based on the flow of the cooling liquid at each inlet and outlet of the water jacket and the temperature distribution boundary of the cylinder body and the cylinder cover, and outputting the temperature distribution of the cooling liquid and the convective heat transfer coefficient of the cooling liquid and the cylinder cover; in the first iteration process, the temperature distribution boundary of the cylinder body and the cylinder cover is a preset temperature distribution boundary of the cylinder body and the cylinder cover; in a non-first iteration process, the temperature distribution boundary of the cylinder body and the cylinder cover is the temperature distribution boundary of the cylinder body and the cylinder cover which is output by the simulation of a temperature field of the cylinder body and the cylinder cover; the simulation of the temperature field of the cylinder body and the cylinder cover comprises the following iterative processes: and simulating a temperature field of the cylinder body and the cylinder cover based on the exhaust flow boundary, the temperature distribution boundary in the cylinder, the convective heat transfer coefficient of the gas and the cylinder body and the cylinder cover, the temperature distribution of the cooling liquid and the convective heat transfer coefficient of the cooling liquid and the cylinder body and the cylinder cover, and outputting the temperature distribution boundary of the cylinder body and the cylinder cover.
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