柴油十六烷值测定过程中的燃烧模拟研究

摘要

以计算流体力学、计算传热学、化学动力学等理论研究为基础,建立FCD-Ⅱ型柴油十六烷值机气缸内燃料雾化、传质数学模型,对气缸内燃烧过程中的温度流场、压力流场、速度流场分布进行模拟仿真分析.结果表明:在恒定风量条件下,随着气缸内空气的压缩,缸内温度、压力升高,在上止点(360°转角)的压缩温度可满足燃料压燃条件;在风量表读数从200增加到800时,压缩终止温度从426 ℃上升到503 ℃,可满足燃料着火性质的要求;在燃烧阶段,温度流场、压力流场和速度流场的变化受气缸内局部区域燃料燃烧特性的影响,局部区域燃料的剧烈燃烧导致温度、压力和空气速度急剧增加并传递到其它区域,促进其它区域燃料的燃烧,使温度流场、压力流场和速度流场处于瞬时变化中.%By the computational fluid dynamics,computational heat transfer and chemical kinetics,a model for pulverization and mass transfer of diesel fuel in FCD-II cetane number machine was established to simulate the changes of combustion parameters of temperature,pressure and speed of airflow in the engine.The results indicate that the temperature and pressure of air due to being compressed is high enough to ignite the fuel at the top dead center(360° angle position) in the case of invariable air volume.When the reading value of the air flow meter is increased from 200 to 800,the compression terminal temperature rises from 426 ℃ to 503 ℃,high enough to ignite the fuel.During fuel combustion,the parameters are increased sharply by rapid combustion in local region in the cylinder and transferred to other regions,resulting in instantaneous variations of temperature,pressure and air speed in cylinder.