Simulations Of 3-D Transient Heat Transfer Of Multi-Components Coupling System In Combustion Chamber

A 3-D numerical analysis model of transient heat transfer among the multi-components coupling system in combustion chamber of internal combustion engine has been developed successfully in the paper. The model includes cyclic transient heat transfer of the 3-D moving piston assembly-liner coupling system and the piston-liner-gasket-head-valves coupling system. And the simulation software of transient heat transfer model of the multi-components coupling system has been also developed successfully. The model and the software will be important analysis tools to study the whole engine heat transfer, heat balance and heat loads in internal combustion engine.During the development of the multi-components coupling system transient heat transfer model ,some work has been finished as follows : the deduction of the mathematical formula; the analysis of the physics model; the establishment of the FEA model; the development of the computational program; the evaluation of the result; the verification and application of the model, etc.1) Developed the transient heat transfer model of the coupling 3-D moving piston assembly-liner system. With hypothesizing the lubricant film as 1-D thermal resistances and applying the direct coupled-field analysis method, the heat transfer relation among the moving components is established. In the model, the effect of friction heat generated on the piston ring/liner interfaces is also taken into account. A 3-D hydrodynamic mixed lubrication model has been employed to calculate the lubricant film thickness and the friction heat which varies with crank angle and circumferential direction. To reflect the influence of the different material property on the temperature distributions, the piston ring assembly, the piston, the liner and the cylinder body are meshed respectively in the model. The transient temperature waves on the surface of the piston rings are also obtained.2) Based on the model of 3-D moving piston assembly-liner coupling system, the transient heat transfer model of multi-components coupling system of the internal combustion chamber is also developed. The model includes almost all components in combustion chamber, such as piston assembly, cylinder liners, cylinder head gaskets, cylinder heads, intake valves and exhaust valves, etc. With two different coupling heat transfer modes-----one is the lubricant film conduction between two moving components, another is the contact conduction between two immovable solid components------and the direct coupled-field analysis method, the heat transfer relation among the components is established. The result dedicates the transient heat transfer process between the valve head and valve seat. The effect of cylinder head gaskets on heat transfer among the components is also studied.3) Developed the numerical simulation computational software of the multi- components coupling system transient heat transfer model. By establishing the standard data format, the preprocessor and the post-processor of the main computational program have been connected smoothly. The data structure of spare matrix is applied to save the whole temperature stiffness matrix of the coupling system model to reduce the time of calculation and the quantity of used memory.4) Applied the developed software to study the transient heat transfer process of the 3-D moving piston assembly-liner coupling system and the piston-liner/cylinder- gasket-head-valves coupling system for LJ377MV gasoline engine. The results provide a basis of the improvement and optimum design for the engine.5) Adopted two kinds of methods to verify the heat transfer model and the software of the multi-components coupling system. one is comparison between the developed software and the commercial FEA software on a simple coupling heat transfer example. Another is comparison and contrast between the simulation result and the experimental result on the CUB100 gasoline engine.The heat transfer of internal combustion engine is very complex, whose heat transfer process couples with many physics fields. So, the discrete theories, the developed software and the model in the paper are the most important parts in the heat transfer of the complete model simulation research and the bases of the virtual design for the internal combustion engine.