Macroscopic and Microscopic Study of Effect of Fuel Properties on Flash Boiling Spray with Isooctane-Ethanol Fuel Blends 2019-01-0274
Flash boiling spray has drawn many attentions recently due to the ability of enhancing atomization, vaporization and providing better fuel/air mixture for a gasoline direct injection engine. However, the impact of fuel properties on multi-component spray under flash boiling condition has not been fully discovered. In this study, isooctane, ethanol and the mixture of two have been chosen as the fuels. Diffused back-illumination (DBI) imaging technique and Phase Doppler Anemometry (PDA) have been applied to study both macroscopic and microscopic characteristics of multi-component flash boiling spray under various ambient pressures. Comparisons between single component and binary fuel mixture flash boiling sprays have been performed in order to study how the fuel properties affect spray structure as well as atomization and vaporization processes. Due to the different boiling points and saturation pressures between each fuel component, lighter component can reach flash boiling condition earlier than the less volatile one, which could lead to partial flash boiling. Six ambient pressures from 10 kPa to 100 kPa have been chosen to study how partial flash boiling phenomenon affected the spray morphology and microscopic characteristics. Liquid penetration length, droplet size and velocity have been used to quantitatively analyze the flash boiling spray behavior. Spray collapse and interaction with ambient gas have also been investigated.
Junhao Yan, Tairan Chen, Suya Gao, Timothy Lee, Erick Diaz, Chia-Fon Lee
Univ of Illinois at Urbana-Champaign, Beijing Institute of Technology