3D MODELING STUDY OF SPRAY CHARACTERISTICS OF SIMPLEX PRESSURE-SWIRL ATOMIZERS WITH VARIOUSORIFICE AND SWIRL CHAMBER GEOMETRYIES

To improve the fuel consumption and exhaust emission for gasoline engines, GasolineDirect Injection (GDI) system was spotlighted to solve above requirements. Mixturepreparation strategy is intimately related to the fuel injection system. At high strength ofswirling motion in pressure swirl atomizers, an air core will appear inside of the atomizer.Thus, a two-phase flow will be present inside of the atomizer. In this study, the volume-offluid(VOF) method is used to simulate the internal flow of pressure-swirl atomizers. In orderto investigate the effects of orifice geometry and swirl angle on flow characteristics of simplexpressure-swirl injectors, several three-dimensional simulations were done. The effects oflength to diameter ratio of the orifice, orifice diameter and swirl angle have been studied onthe atomization characteristics such as spray cone angle and discharge coefficient. It wasobserved that by increasing the orifice diameter and orifice length to diameter ratio, and alsoby decreasing the swirl angle, the spray cone angle decreases. However the dischargecoefficient increases. Monitoring the rate of the variations leads to an approach for optimizedgeometry of simplex pressure-swirl atomizers.

Keywords:

Gasoline direct injection , Simplex pressure swirl atomizer , Volume-of-fluid , Spray cone angle , Discharge coefficient , orifice geometry , Swirl angle