To study the effects of ambient temperature,methane premix time,and pilot fuel injection pressure on the ignition and combustion characteristics of methane premixture ignited by pilot-injected n-hexadecane,a visual-ization experiment was performed on a constant volume optical testing system using high-speed photography and shadow shooting method.The results revealed that with increasing ambient temperature,the delay period of pilot fuel ignition was shortened,the development of methane flame was accelerated,and the premixture outside the main combustion area ignited locally.When the methane premix time was short,more soot was formed,and the flame development rate decreased with increasing premix time.When the premix time was long,the flame develop-ment rate tended to be stable.Moreover,with increasing pilot fuel injection pressure,the flame penetration length of the pilot fuel increased,the ignition delay period shortened,the initial ignition position moved,and the flame development rate increased.
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