Abstract:

Flash boiling spray， as a form of phase-changing spray， plays an important role in the combustion of alternative fuels and zero-carbon fuels. However， most of the current researches focus on the spray morphologies， and there are few studies on the fundamental combustion mechanism. Therefore， the constant volume combustion chamber （CVCC） is used in this paper to analyze the atomization and combustion process of flash boiling spray under lean conditions， focusing on the characteristics of flash boiling spray， mixture ignition and flame kernel development， flame propagation and heat release characteristics. The results show that flash boiling spray can effectively reduce ignition delay and increase flame propagation speed， which is beneficial to energy conversion thus achieving higher heat release rate and larger cumulative heat release. Moreover， the flame front shape of flash boiling combustion is more regular， which suggests more stable flame propagation which is helpful to improve engine thermal efficiency as well as combustion stability under lean burn conditions.

Key words: flash boiling spray, lean burn, constant volume combustion chamber, high-speed color imaging