Microscopic and Macroscopic Spray Characteristics of GDI Injector Using Gasohol Fuels at Various Injection Pressures

The development of advanced gasoline direct injection (GDI) injector requires in-depth investigations of macroscopic and microscopic spray characteristics. Over the years, GDI injectors have undergone exponential improvement to be able to deliver fuel at high injection pressure. High fuel injection pressure (FIP) leads to superior fuel atomization, and consequently superior fuel-air mixing. Present investigations aim to improve our fundamental knowledge of the furl-air mixture preparation mechanisms of different test fuels. Experiments were conducted to study spray breakup of GDI injector. This study focuses on the spray investigations using Phase Doppler Interferometry (PDI) for the measurement of various spray related studies such as determination of arithmetic mean diameter (AMD), sauter mean diameter (SMD) and spray droplet velocity distributions. Gasohol mixtures (methanol and ethanol blended with gasoline) have been used as test fuels to investigate microscopic and macroscopic spray characteristics of these fuels injected from the GDI injector. The investigations were carried out at five different FIPs (40, 80, 120, 160, 200 bar). Macroscopic spray visualization was done using a high speed CCD camera at varying FIPs. It was found that spray penetration length increased with increasing FIP. Spray droplet size distribution decreased and spray droplets velocity distribution increased with increasing FIP. These results predicted behavior of GDI injector for mixture preparation at various FIPs for these two gasohols vis-à-vis baseline gasoline.