摘要
以柴油机后燃期颗粒的初期碰撞凝并过程为研究对象,在KF模型基础上,通过结合矩方法和颗粒尺寸分布模型,建立了柴油机颗粒碰撞凝并数学模型.探讨了柴油机燃烧过程中,自由分子区中的初级颗粒碰撞频率、凝并速率和剩余表面积的变化规律以及对颗粒尺寸生长的影响作用.结果表明:随着滞留时间增长,初级颗粒的碰撞频率逐渐降低;颗粒粒径分散性的增加能够提高碰撞频率;在同一粒径下,随着凝并特征时间增加,凝并速率明显降低;当粒径小于12.6,nm时,凝并速率对凝并特征时间变化的敏感性较高;初始凝并特征时间越大,表面积减小越慢;颗粒表面积随着滞留时间的增加而减小.
Initial collision and coalescence process of particles during post-combustion period in diesel engine was studied on the basis of collision and coalescence mathematical model, in which the KF model was coupled with moment method and particle size distribution model. Principles in collision frequency, coalescence rate and excess surface area of primary particles in free molecular regime and their impacts on particle growth in combustion period were studied. It was observed that collision frequency dropped gradually with the residence time prolonging. Increasing the dispersion of particle diameters improves the collision frequency. With the increase of coalescence characteristic time, it demonstrated an obvious decline of coalescence rate under the same diameter. For the particles whose diameters are smaller than 12.6 nm, it showed high sensitivity between the coalescence rate and coalescence characteristic time. The decline speed of particle surface area decreased with raises of initial coalescence characteristic time. Particle surface area decreased substantially with the growth of the residence time. © 2015, Chinese Society for Internal Combustion Engines. All right reserved.
出处
《内燃机学报》
EI
CAS
CSCD
北大核心
2015年第6期496-501,共6页
Transactions of Csice
基金
国家自然科学基金资助项目(51376083)
江苏省高校自然科学基金重点资助项目(10KJA470009)
江苏省2013年研究生创新计划资助项目(CXZZ13_0672)
关键词
柴油
颗粒
碰撞
凝并
粒径
Coalescence
Combustion
Diesel engines
Diesel fuels
Fuels
Method of moments
Particle size analysis
Particles (particulate matter)
Residence time distribution
