Parameter Optimization Of KH-RT Breakup Model Based On Genetic Algorithm

The 21st century is a century of energy,and the effective use of energy is the goal people pursue.As the most important heat engine,internal combustion engine are especially necessary to improve its efficiency.Fuel atomization is an important part of the combustion process of internal combustion engines.The quality of fuel atomization directly determines the efficiency of engines.Therefore,it is very important to numerically simulate the fuel atomization process.The process of fuel atomization is very complicated.After years of development,many atomization model have appeared in different forms.The existing Kelvin-Helmholtz-Rayleigh-Taylor(KH-RT)model is the most widely used model among various atomization models.The KH-RT model do a good simulation of the spray atomization process.The spray penetration and spray shape are basically correct.However,five model constants that are very important for simulation mainly depends on experience.A large amount of time is used to adjust the model constants during the application of the model.In this paper,a large number of different spray penetration and spray physical conditions are studied.The genetic algorithm is used to fit the model constants,and the important constants CRT and Cb are selected from the obtained results.The genetic algorithm has a huge advantage in optimizing the model constants.The genetic algorithm does not need to understand the internal principles but provide good optimization for the black box problem.The parallel calculation of multi-objective optimization through genetic algorithm greatly saves the calculation time and the model constant can be optimized quickly.Then the empirical formula of KH-RT atomization model constant is fitted according to physical conditions.The results predicted by the empirical formula are brought into the computational fluid dynamics(CFD)model for calculation,and the calculation results are compared with the results obtained in experiments.The evaluation is made from the aspects of spray penetration,spray shape,spray particle diameter,and the like.The validity of the empirical formula for determining the parameters of the KH-RT model under high-temperature and high-pressure operating conditions in diesel engine is confirmed.By comparing with the empirical formula of spray penetration summarized by the previous studies,the empirical formula for determining model constants proposed in this paper is verified,and it is confirmed that the method of this paper can improve the accuracy of the spray model.