EFFECT OF TURBULENCE DERIVED FROM INITIAL COMBUSTION OF INTERMITTENT SPRAY COMBUSTION ON MIXING AND CHEMICAL REACTION

间歇喷雾燃烧初燃湍流对混合和化学反应的影响

基本信息

批准号：
10650221
负责人：
YAMANE Koji
金额：
$ 1.92万
依托单位：
THE UNIVERSITY OF SHIGA PREFECTURE
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 1999
项目状态：
已结题

项目摘要

The multidimensional engine simulation code, FREC-3D(CI), has been used to elucidate the effects of injection rate and split injection on diesel combustion, NO, and soot emissions. The combustion submodel has been updated, including the ignition submodel previously based on a one-step global mechanism. In-cylinder NO and soot formations were predicted by a Zeldovich mechanism with a partial equilibrium assumption and Morel's soot formation with an oxidation submodel, respectively. In result, computations give good agreement between measured and predicated trends of in-cylinder pressure, and rate of heat release, and a trade-off relationship between NO and soot emissions at pilot injection with high pressure injection. Computations also show that a high turbulence kinetic energy caused by a higher initial combustion is retained at the late combustion stage after fuel injection, and promotes the soot oxidation process.Experimental data suggests the roll of initial combustion on character … More istics of exhaust emissions. The experiment were carried out to change the initial combustion by using different nozzle orifice diameters and the electromagnetic controlled spool acceleration type injection system. It is found that smoke and NOx concentrations at smaller nozzle orifice diameter, I.e., dィイD2NィエD2 = 0.08mm, are higher than at bigger one, i.e., dィイD2NィエD2 = 0.14mm. The initial rate of heat release at dィイD2NィエD2 = 0.14mm is higher than that at dィイD2NィエD2 = 0.08mm. This means that the smaller orifice decreases the ignition delay at same injection pressure and controls rapid combustion at the initial stage. In generally, soot is formed at the late combustion stage. At late combustion stage, fuel injection is already terminated, so that combustion and spray at the initial stage have an influence on combustion at the late stage. So, the mixing by turbulence at late combustion stage is one key of important parameters for reduction of smoke, i.e., spray penetration, spray interaction by swirl, turbulent mixing of air and fuel, etc. The experimental results suggest that higher initial rate of heat release will enhance the mixing of soot and oxygen at late combustion stage. Less

多维发动机仿真代码 FREC-3D(CI) 已用于阐明喷射率和分次喷射对柴油燃烧、NO 和碳烟排放的影响。燃烧子模型已更新，包括以前基于的点火子模型。缸内 NO 和烟灰的形成分别通过具有部分假设平衡的 Zeldovich 机制和具有氧化子模型的 Morel 烟灰形成进行了预测。结果，计算给出了良好的结果。缸内压力和热释放率的测量趋势与预测趋势之间的一致性，以及高压喷射引燃喷射时 NO 和碳烟排放之间的权衡关系，计算还表明，较高的湍流动能会导致较高的湍流动能。燃油喷射后的燃烧后期保留了初始燃烧，并促进了碳烟氧化过程。实验数据表明初始燃烧对废气排放特性的影响。通过使用不同的方法来改变初始燃烧。喷嘴孔直径和电磁控制阀芯加速型喷射系统的研究发现，较小喷嘴孔直径（即 D2 = 0.08mm）时的烟气和 NOx 浓度高于较大喷嘴孔直径（即 d D2N D2 = 0.14mm）。 D2N 时的初始放热速率 D2 = 0.14mm高于D2NieD2=0.08mm，这意味着在相同喷射压力下，较小的孔口减少了点火延迟，并且控制了初期的快速燃烧。在此阶段，燃油喷射已经终止，初期的燃烧和喷雾对后期的燃烧有影响，因此燃烧后期的湍流混合是关键之一。减少烟雾的重要参数，即喷雾穿透力、涡流喷雾相互作用、空气和燃料的湍流混合等。实验结果表明，较高的初始放热率将增强燃烧后期烟灰和氧气的混合。较少的