Study of behavior characteristics of diesel fuel spray according to breakup models

Abstract

The atomization of the injection fuel in the diesel engine directly affects on the combustion process of engine, and as a result, it is the main factor that determines the operating performance of the engine. In this study, the breakup process of the droplets by the atomization of the injected was investigated, using the breakup models (Reitz&Diwakar, CAB, ETAB and TAB) included in the commercial numerical analysis program. In order to select the optimum model for the droplet breakup interpretation, the results of spray tip penetration, Sauter mean diameter (SMD) and momentum length obtained as each breakup model were compared with the experimental data. In the case of changing of the spray tip penetration as the research results, TAB model was measured the shorter compared to the experimental measurements, and other models showed the similarity with the experimental value. In the case of SMD analysis, the use of Reitz&Diwakar model showed the best results. In addition, the frequency of breakup which is the microscopic spray behavior characteristics considering the impact of the coefficient of contraction in the nozzle was investigated in order to determine the diameter of initial particle in the fuel injection necessary to the numerical analysis. As a result, it was found that there is suitable initial droplet diameter in numerical analysis, in the case of nozzle-hole diameter 0.12mm of this study, it was the most appropriate that the diameter of the initial particle for the numerical analysis is about 0.06mm.

Keywords

• breakup
• common-rail system
• cfd
• internal combustion engine
• spray