Combustion chamber components(cylinder head,cylinder liner,piston assembly and oil film) are treated as a coupled body.Based on the three-dimensional numerical simulation of heat transfer of the coupled body,a coupled three-dimensional calculation model for the in-cylinder working process and the combustion chamber components was built with domain decomposition and boundary coupling method,in which the coupled three-dimensional simulation of in-cylinder working process and the combustion chamber components was adopted.The simulation was applied in the influence investigation of the space non-uniformity in heat transfer among combustion chamber components on the generation of in-cylinder emissions.The results show that the space non-uniformity in heat transfer among the combustion chamber components has great influence on the generation of in-cylinder NOx emissions.The heat transfer space non-uniformity of combustion chamber components has little effect on soot formation,and far less effect on soot formation than on NOx.Under two situations of different wall temperature distributions,the soot in cylinder is different by 1.3% when exhaust valves are open.
To make heat conduction equation embody the essence of physical phenomenon under study,dimensionless factors were introduced and the transient heat conduction equation and its boundary conditions were transformed to dimensionless forms.Then,a theoretical solution model of transient heat conduction problem in one-dimensional double-layer composite medium was built utilizing the natural eigenfunction expansion method.In order to verify the validity of the model,the results of the above theoretical solution were compared with those of finite element method.The results by the two methods are in a good agreement.The maximum errors by the two methods appear when τ(τ is nondimensional time) equals 0.1 near the boundaries of ξ =1(ξ is nondimensional space coordinate) and ξ =4.As τ increases,the error decreases gradually,and when τ =5 the results of both solutions have almost no change with the variation of coordinate ξ.
