Analysis of diesel spray structure using a hybrid model

Abstract

This study proposes a hybrid model that consists of modified Taylor Analogy Breakup (TAB) model and a Discrete Vortex Method (DVM). In this study the simulation is divided into three steps. The first step is to analyze the breakup of the injected fuel droplets by using a modified TAB model. The second step is based on Siebers’ theory of liquid length, which is an analysis of spray evaporation. The liquid length analysis for injected fuel is used to connect both the modified TAB model and the DVM. The final step is to reproduce the ambient gas flow and the inner vortex flow of the injected fuel by using the DVM. In order to examine this hybrid model, we performed an experiment involving a free evaporating fuel spray at the early injection stage within an environment similar to that found inside of an engine cylinder. The numerical results were calculated by using the present hybrid model and compared to the experimental results. The calculated results of the gas jet flow that were determined through the DVM corresponded well with the experimental results for a downstream evaporative spray. It is also confirmed that an ambient gas flow occupies the downstream region of a diesel spray.