Simplification Of Combustion Reaction Mechanism Based On Computational Singular Perturbation Method And The Application

Energy saving and emission control have become the main topic of currant automobile industry,and the research of combustion behavior of fuel is the key point for energy saving and emission control.The detailed chemical kinetic mechanisms of the fuel of internal combustion engine contain a lot of species and elementary reactions,so that the numerical simulation of internal combustion engine working process is hard to execute,but the extremely simplified reaction mechanism can’t make a perfect description for the combustion process.So the simplification for the detail reaction mechanisms has become very important.The traditional simplification method for detailed mechanisms need higher requirements for researchers’ knowledge reserves of chemical kinetic and research experience,the simplification result will be influenced by the researchers’ subjective factor.Computational Singular Perturbation method based on mathematical theory to divide the reaction system into fast and slow mode,so that make the detailed mechanism more simplifier than before.This article used matlab to compile computer program for the simplification of detail mechanisms with the theory of CSP-method.Using this program to simplify the methane/air detailed combustion mechanism,36 species and 31 reactions were obtained.By comparing the reduced mechanism and detailed mechanism to verify the reliability of the reduced mechanism.Chose iso-octane and n-heptane as the simulated fuel of gasoline.The detailed mechanism contains 980 species and 4792 reactions which comes from ANSYS company’s experimental result.At first,used the DRG-method to obtain 106 species and525 reactions skeletal mechanism.Comparison and analysis was done between detailed and skeletal mechanisms.Then 31 species and 78 reactions reduced reaction model was generated by CSP –method on the skeletal mechanism,and verified the correctness of reduced mechanism used SI_engine reactor of Chemkin-pro.Used the reduced mechanism based on CSP-method,PRF combustion model and single step empirical combustion model to couple with the internal combustion engine3-dimensional model,calculated the engine’s working process.Compared different mechanisms calculation result with experimental result.The comparison result shows:the reduced mechanism based on CSP-method and PRF combustion model could get more accurate result but the calculation time of PRF combustion model was the most.The calculation result of single step empirical combustion model was inaccurate but the calculation time was much less than others.So use the reduced mechanism based on CSP-method to the numerical simulation of internal combustion engine could get accurate result and less time consuming.