Study of Liquid and Vapor Phases of a GDI Spray

ABSTRACT

Gasoline direct injection (GDI) systems have become dominant in passenger cars due to their flexibility in the fuel managing and the consequent advantages in the fuel economy. With the increasingly stringent emission regulations and concurrent requirements for enhanced engine thermal efficiency, a comprehensive characterization of the fuel spray behavior has become essential. Characteristics of free-evolving and impinging spray of iso-octane fluid, using a GDI injector from the Engine Combustion Network (ECN) circuit, were investigated by a hybrid Mie-scattering and schlieren optical technique. The experiments provided the spatial distribution and time-resolved evolution of the free, as well as the post-impingement, characteristics of the spray under various operating conditions. A customized processing algorithm, able to catch the contours of both liquid and vapor/atomized phases, was used to extract the diffusion and evaporation parameters that characterized the fuel spray. Aim of this study is a detailed understanding of a GDI spray evolution under engine-like conditions, by studying both the liquid and the vapor phases as the ambient and injection conditions varies in a controlled environment.

KEYWORDS:

• Liquid–vapor phase
• flash boiling
• imaging diagnostics
• impacting spray