柴油机排气阶段颗粒碰撞过程动力学特征分析

doi:10.13229/j.cnki.jdxbgxb20190938

摘要/Abstract

摘要：

为探究柴油机排气阶段颗粒碰撞过程的动力学特征，采用离散单元动力学软件EDEM和Fluent耦合，基于相似理论，建立了柴油机排气阶段颗粒碰撞仿真模型。针对柴油机不同排气压差、气体流速的碰撞过程进行仿真，分析了碰撞过程中颗粒的角速度、湍动能、转矩、碰撞刮擦力等碰撞动力学参数的变化规律。结果表明：当流速一定、粒径相同、排气压差由0.188 MPa增大到0.268 MPa时，碰撞刮擦力中的法向作用力与切向作用力分别增加了1.5倍和1.7倍，平均旋转湍动能由2.26×10^-9 J增加到3.52×10^-9 J。当压差一定、粒径相同、气体流速由5.65 m/s增大到6.78 m/s时，碰撞刮擦力中的法向作用力与切向作用力分别增加50.5%和45.5%，颗粒的平均角速度由7.87×10⁵ rad/s增大到10.85×10⁵ rad/s。本文研究结果可为降低柴油机颗粒排放和提高柴油机捕集器（DPF）的捕集效率提供依据。

关键词: 动力机械工程, 柴油机, 排气阶段, 颗粒, 碰撞, 动力学

Abstract:

In order to explore the dynamic characteristics of particle collision in diesel engine exhaust phase， a simulation model of particle collision was established by coupling discrete element dynamics software EDEM with Fluent based on similarity theory. The collision process of diesel engine with different exhaust pressure difference and flow velocity were simulated. The effects of collision dynamics parameters such as angular velocity， rotational turbulent kinetic energy， torque and collision scraping force on the diesel engine during collision were analyzed. The results show that the normal force and tangential force increase by 1.5 and 1.7 times respectively when the velocity of flow is constant， the particle size is the same and the exhaust pressure difference increases from 0.188 MPa to 0.268 MPa， and the average rotational turbulent kinetic energy increases from 2.26×10^-9 J to 3.52×10^-9 J. When the pressure difference is constant， the particle size is the same and the gas flow rate increases from 5.65 m/s to 6.78 m/s， the normal force and tangential force increase by 50.5% and 45.5% respectively， and the average angular velocity of particles increases from 7.87×10⁵ rad/s to 10.85×10⁵ rad/s. The research results can provide a basis for improving diesel particulate filter （DPF） capture efficiency.

Key words: power machinery engineering, diesel engine, exhaust stage, particle, collision, dynamics

中图分类号:

TK421

王忠,李游,张美娟,刘帅,李瑞娜,赵怀北. 柴油机排气阶段颗粒碰撞过程动力学特征分析[J]. 吉林大学学报(工学版), 2021, 51(1): 39-48.

Zhong WANG,You LI,Mei-juan ZHANG,Shuai LIU,Rui-na LI,Huai-bei ZHAO. Analysis on particle collision dynamics parameters in diesel exhaust stage[J]. Journal of Jilin University(Engineering and Technology Edition), 2021, 51(1): 39-48.

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颗粒	粒径/nm	质量密度/(kg·m^-3)	温度/K	相似指标/R
原型	100	1200	1000	0.83~0.90
模型	1.0×10⁵	310	683
	1.5×10⁵	232	625
	2.0×10⁵	165	565
	2.5×10⁵	101	503

转速/ (r?min^-1)	各特征转角活塞上行速度/(m?s^-1)
转速/ (r?min^-1)	180 °CA	270 °CA	360 °CA
3000	0	11.30	0
3300	0	12.44	0
3600	0	13.56	0

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