Fundamental Study on Lean Spontaneous Ignition Combustion with Direct Injection

Abstract

In order to obtain strategies for controlling ignition timing and heat release rate in direct-injection PCCI combustion, a fundamental study was carried out using a constant volume vessel. Effects of injection quantity, injection pressure, nozzle orifice diameter and ambient oxygen concentration were investigated under PCCI-like ambient conditions. The results show that a low oxygen concentration reduces increase in peak heat release by increase in injection pressure and equivalence ratio. Enhanced mixing causes rapid heat release at higher overall equivalence ratios and an usual oxygen concentration ; however, it brings about delayed and reduced heat release at lower overall equivalence ratios or a lower oxygen concentration.