Characteristics and mechanism of the shift in condition- and time-dependent spray patterns induced by oxygenated fuel addition

Abstract

As renewable energy sources, ethanol and butanol are usually added to fuels to reduce the fossil fuel consumption and soot emissions. Gasoline direct injection with multi-hole injectors provides accurate plume control, enabling ejection toward the desired location, while spray pattern shift leads to deviation in the injection direction. The spray shift needs to be modulated to realize the desired spray pattern, which is complicated by oxygenated fuel addition. To illustrate the shift induced by oxygenated fuel addition, numerical simulations and experimental studies were performed. The macroscopic and microscopic characteristics of the spray under various operating conditions were obtained via the diffuse backlight illumination and phase Doppler anemometry methods and the simulation of the internal three-phase flow. Moreover, typical single-component and binary fuels were employed to define the general envelope of the multi-component nature for auxiliary analysis. The shift in condition- and time-dependent spray patterns under both flashing and non-flashing conditions were illustrated. The spray morphologies were characterized by rectangular- and trapezoid-like trends. The addition of oxygenated fuels resulted in a smoother trend due to the change of the vapor pressure and surface tension of the mixed fuel. Moreover, it resulted in the variation of the critical width, which is crucial for the spray pattern shift. Additionally, the correlation between the critical width and ambient pressure was obtained. For the non-flashing spray, the internal flow and jet instabilities both influenced the spray width, and the correlation between gas ingestion and turbulence characteristics was obtained. This study aimed to provide guidance for better utilization of oxygenated fuels.