ID 382

Fuel distribution of a GDI spray impacting on a heated wall: liquid and vapour phase

 

Abstract:

The impingement of liquid fuel on combustion chamber walls is one of the major drawback in GDI engines because of its increasing in HC emissions and the effects on the combustion process. In the spray wall-guided configuration, an increasing attention is focused on the film deposit evolutions and their role in the soot formation. The temperature of the wall surface is identified as an important parameter affecting the outcome of the fuel after impact. Hence, the necessity of detailed understanding of the spray-wall impingement processes and their effects on the fuel distribution. Aim of this study is a detailed understanding of the interaction between fuel and a flat wall under engine-like conditions, observing both the liquid and the vapour phases as the surface temperature varied in a controlled environment (room to 573 K). Iso-octane was injected by an eight-hole direct-injection gasoline injector, from the Engine Combustion Network (ECN), and investigated at atmospheric backpressure and room gas temperature. Simultaneous Mie scattering and schlieren images were captured in cycle-resolved mode to perform a visual tracking of the interaction process for both liquid and vapour phases. The experiments provided the spatial distribution and time-resolved evolution of the impact, as well as the post-impingement spray characteristics under various operating conditions. A customized algorithm, able to catch the contours of the liquid phase and the vapor/atomized zone, was used to extract the diffusion and evaporation parameters that characterized the impingement of the fuel.