a b s t r a c tIn order to improve the precision of quasi-dimensional combustion model for predicting diesel engine performance and promote the real time operating performance of the simulation model, a new phase-divided spray mixing model is proposed and the quasi-dimensional combustion model of diesel engine working process is developed. The software MATLAB/Simulink is utilized to build the quasi-dimensional combustion model of diesel engine working process, and the performance for diesel engine is simulated. The simulation results agree with experimental data quite well. The comparisons between them show that the relative error of power and brake specific fuel consumption is less than 2.8% and the relative error of nitric oxide and soot emissions is less than 9.1%. By utilization of this simulation model with personal computer, the average computational time for one diesel engine working process is 36 s, which presents good real time operating performance of the model. At the same time, the influence of parameters in calculation of air entrainment on prediction precision of diesel engine's simulation model is analyzed.

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In order to improve the precision of quasi-dimensional model for predicting diesel engine performance, three kinds of air entrainment period in quasi-dimensional model for diesel engine working process is developed in this research. The software MATLAB/Simulink is utilized to build the quasi-dimensional model for diesel engine and different kinds of air entrainment period effect on the performance prediction of diesel engine are simulated. The simulation results show that the relative errors of diesel engine performance between three methods are obvious different at rated working condition. It can be concluded that the proper method to calculate air entrainment period must be selected to improve performance prediction precision of simulation model.

Abstract. In order to satisfy the validity demand of quasi-dimensional combustion model for predicting diesel engine performance, a new phase-divided spray mixing model is proposed in this work. The software MATLAB/Simulink is utilized to build the quasi-dimensional combustion model of diesel engine working process, and the performance for diesel engine is simulated. The comparisons between calculated results and experimental data show that the relative error of power and brake specific fuel consumption is less than 2.3%, and the relative error of nitric oxide and soot emissions is less than 5.8%. The good agreement between experimental results and calculated results indicates that the quasi-dimensional model of diesel engine working process which is based on the phase-divided spray mixing model is reliable for predicting power, fuel consumption and emissions of diesel engine.