직접분사 디젤엔진의 연소실내 분무연소 측정을 통한 설계기술 개발

Abstract

Spray characteristics of diesel fuel injection is one of the most important factors in diesel combustion and pollutant emissions especially in HSDI (High Speed Direct Injection) diesel engines where the interval between the onset of combustion and the evaporation of atomized fuel is relatively short. An investigation into different spray characteristics of different holes of two VCO nozzles was performed and its results were compared to standard sac nozzle. The global characteristics of spray, including spray angle, spray tip penetration, and spray pattern were measured from the spray images which were frozen by a spark light source. For better understanding of spray behavior, SMD of the fuel spray from one of the multi hole nozzle is measured with back light photography while the sprays from the other holes are covered by a purpose built nozzle cap. The investigation manifestly reveals, at the beginning of injection the different spray patterns produced by each VCO nozzle can be identified as three distinct types with their own macroscopic characteristics.