Development of a simplified model for droplet vaporization

Abstract

Droplet vaporization is an essential sub-process of fuel spray in diesel engines, which has important effects on combustion and emissions performance. Development of a simplified droplet vaporization model is necessary to simulate gas mixture formation in cylinder for lower computational costs, and it is also applicable in practical multi-dimension spray calculations for diesel engines. An empirical exponential equation is introduced in this paper to approximate the internal temperature profile of droplet instead of solving the partial differential equation for temperature distribution. Results indicate that the computational cost has been reduced by almost thirty percent in total. Also, the concept of effective diffusion is introduced by using an enlarged diffusivity to take account of the effect of internal circulations inside droplets. The calculated result of the simplified evaporation model has been compared with that of the infinite diffusivity model and one-dimensional model respectively. It shows that the calculation precision of the simplified model is among those two models.