TBD234柴油机有害物生成过程仿真研究

针对舰用TBD234柴油机燃烧室结构及共轨喷射条件下的工作特点,确立标定工况下的燃烧、NOx生成和炭烟生成模型,并合理修正了模型参数。利用CFD软件对其燃烧过程进行仿真计算,得到全过程的有害物组分浓度分布结果。结果显示NOx生成主要受燃烧温度和混合气浓度的影响,炭烟主要产生于浓混合气且贫氧的区域。从NOx和炭烟结果的对比发现二者分布区域形成互补关系,反映出控制NOx和控制炭烟的矛盾。仿真结果与实际情况较好吻合,从而验证了仿真参数选取的有效性。

Simulation Research on Emission Generation Progress of TBD234 Diesel Engine

Aiming at the special chamber structure and common-rail injection characteristics of TBD234 diesel engine used on ship,the paper establishes three models as follows: combustion model,NOx and soot generation model,and modifies the parameters of these models.The combustion process was simulated by the CFD software and it acquires the density distributing results of harmful emission for the whole process.It shows that the fuel does not symmetrical distributed in the engine cylinder,and there has a direct relationship between combustion and gas distribution,the generation of NOx is mainly affected by combustion temperature and density of mixture gas,soot mainly generated in the field of thick mixture gas and poor oxygen.From the contract of NOx and soot simulation result,it found that their distributing field are reciprocally for each other,accordingly it validates the conflict relationship between NOx control and soot control.The simulation results inosculate commendably with actual cases,so it can considering that the selecting of simulation parameters is effectual.