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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

多维发动机模拟程序FREC-3D（CI），已被用来阐明喷射率和分流喷射对柴油机燃烧，NO和碳烟排放的影响。燃烧子模型已被更新，包括点火子模型先前的基础上的一步全球机制。缸内NO和碳烟的形成分别由Zeldovich机制与部分平衡假设和Morel的碳烟形成与氧化子模型预测。结果表明，在高压喷射条件下，缸内压力、放热率的实测值与预测值之间具有较好的一致性，并且在预喷射条件下，NO和碳烟排放之间存在着一种折衷关系。计算结果还表明，较高的初始燃烧引起的较高湍流动能在喷油后的燃烧后期得以保留，并促进了碳烟的氧化过程，实验数据表明了初始燃烧的性质 ...更多信息废气排放量。采用不同的喷孔直径和电磁控制阀芯加速式喷油系统，进行了改变初始燃烧的试验。结果表明，在较小的喷嘴孔径下，d φ D2 N φ D2 = 0.08mm，均高于较大的一个，即，d直径D2 N直径D2 = 0.14mm。初始放热速率d_（2N）_（2D）= 0.14mm时大于d_（2N）_（2D）= 0.08mm时。这意味着在相同的喷射压力下，较小的喷孔减小了点火延迟期，并控制了初始阶段的快速燃烧。通常，碳烟在燃烧后期形成。在燃烧后期，燃料喷射已经终止，使得初期的燃烧和喷雾对后期的燃烧有影响。因此，燃烧后期的湍流掺混是降低烟度的重要参数之一，试验结果表明，较高的初始放热速率有利于燃烧后期碳烟与氧的混合。少