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The combustion efficiency of a diesel engine depends not only on spray characteristics but also on fuel-air mixing characteristics.Based on the original spray model,a new spray model is established in this paper to accurately predict the diesel spray,and then a multi-component evaporation model is added into it.The model takes the influence of component concentration gradient and species on its evaporation rate in the liquid phase into account.This paper studies the spray characteristics (spray penetration,spray angle and spray morphology) and fuel-air mixing characteristics (spray area,spray volume and air entrainment mass) using the spray model,and the results are compared with the experimental results.The comparison shows that the simulated spray penetration and spray angle are close to the experimental results with the average deviations less than 3％.Moreover,this paper studies the spray area,spray volume and air entrainment using empirical formula under different conditions.And the maximum deviations of the spray volume,spray area and air entrainment mass are less than 5％ as compared with the test values.Overall,this spray model can predict the diesel spray characteristics and fuel-air mixing characteristics under high injection pressure accurately.