| OPTICAL STUDY ON SPRAY AND TWO-STAGE IGNITION
CHARACTERISTICS FOR DIESEL SPRAY UNDER LOW AMBIENT
TEMPERATURE AND DENSITY CONDITIONS |
| Yikai Li 1, Zefeng Xue 1, Zhongjie Shi 1,2, Haiyan Chen 1, Weiwei Lv 1,2 |
1School of Mechanical Engineering, Beijing Institute of Technology
2Testing Service Center of Xishan Campus, Experimental Center of Vehicles, Beijing Institute of Technolog |
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| ABSTRACT |
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Poor atomization and ignition difficulty due to the deterioration of environmental conditions restrict the coldstart
performance of diesel engine. To investigate how the ambient and injection parameters affect diesel ignition characteristics
at low temperature and density, liquid spray development was measured by back-illumination method; vapor spray and ignition
process were visualized using high-speed shadowgraph method in constant volume combustion chamber. The results showed
that liquid-vapor penetration and two-stage ignition delay have different sensitivities to variables: the variation of ambient
density greatly affects the spray development while ambient temperature is the most significant parameter affecting ignition
delay. Additionally, the change of injection pressure cannot cause significant change of both liquid penetration length and low
temperature ignition, but increasing injection pressure promoted the vapor penetration length downstream development. Based
on the data obtained, the empirical formulation in the form of power function was fitted for the stable stage of liquid penetration
length, which proposed a reference for comparing the liquid phase development characteristics of diesel spray. Similarly, revise
the Arrhenius-type ignition delay prediction formula and the correction coefficient K ( and ) was optimized
quantitatively instead of fixed values, provides a preliminary theoretical basis for subsequent diesel spray model. |
| Key Words:
Low temperature, Spray characteristics, Two-stage ignition, Penetration length, Ignition delay, Formula
optimization |
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Corresponding Author.
Zhongjie Shi , Email. 
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