将DPK点火模型和单步燃烧模型集成在KⅣA-3V中，构建汽油机MAP研究的多维模型。对汽油机工作过程进行数值模拟，并以动力性、经济性和指示功为控制条件，结合试验数据对点火提前角和喷油脉宽进行优化。研究表明：用多维模型模拟的方法生成的MAP可以作为电喷汽油机的初始MAP。

建立了三效催化转化器载体单个孔道内的二维流场模型,并且加入了详细化学反应机理,该机理考虑了8种气体组分和23种表面物质,共有61个基元反应。用计算流体力学软件对反应流进行了数值模拟,得到转化率随温度的变化情况,与试验值吻合良好。并且对模拟得到的气体组分的质量分数分布图进行了分析,得到了流场与催化剂表面化学性质之间的关系,对如何提高三效催化转化器转化率具有重要的参考价值。

提出了研究碳烟的生成和氧化历程及工作条件影响的方法 。将 Surovikin 碳烟生成模型和 Nagle 碳烟氧化模型集成在 ICFD2CN 源程序中构建多维模型 ,采用数值循环模拟的方法 ,根据不同的工作条件计算碳烟的生成和氧化历程 。结合试验数据分析和比较进气温度 、空燃比 、负荷 、转速和喷油提前角对碳烟生成和氧化历程的影响 。研究表明 :用数值模拟的方法反映了 1137 柴油机碳烟的生成和氧化历程以及设计参数对碳烟的生成和氧化的影响规律 ,对柴油机的设计具有参考价值 。

研究了天然气发动机关键参数对敲缸趋势的影响。将自点火和两步湍流燃烧两个子模型集成在发动机缸内流体动力学多维模型程序KIVA23V中,采用数值计算与试验相结合的方法修正多维模型,然后调整操作条件使发动机处于敲缸状态,解析点火提前角、压缩比、涡流比和等价率四个参数对敲缸时刻(KOCA)和敲缸强度(KI)的影响。研究表明:压缩比下降,敲缸强度明显下降。点火提前角增大,敲缸时刻提前,并且敲缸强度增加。当等价率从0.72增加到0.78,敲缸强度增加,敲缸时刻提前;而当等价率从0.78到0.92,敲缸强度增加,发生时刻反而推后。当涡流比从0.0到2.0变化时,敲缸时刻提前;而从2.0到3.11,敲缸时刻反而推后。压缩比对敲缸趋势影响最大,其次是等价率,相比之下,点火提前角和涡流比的影响较小

研究的柴油机微粒捕集器采用目前应用最为广泛的壁流式蜂窝陶瓷作为过滤体 ,根据其结构对称性和内部流动数学模型 ,建立了稳态层流的过滤体内部流动 CFD 仿真模型 ,并运用离散格式分离求解器进行求解 。仿真计算与试验验证表明模型能准确反映过滤体内部流动特性 。

A multidimensional numerical simulation method was developed to analyze air/fuel premixing, stratified combustion and NOx emission formation in a gasoline direct injection (GDI) engine. Firstly, many sub models were integrated into one Computational Fluid Dynamics (CFD) code: ICFD-CN, such as Sarre nozzle flow, Kelvin–Helmholtz (KH) dynamic jet model, Taylor-Analogy Breakup (TAB) model, Rayleigh–Taylor (RT) droplet breakup model, Lefebvre fuel vaporization model, Liu droplet drag & distortion model, Gosman turbulence & droplet dispersion model, O’rourke wall film model, O’rourke and Bracco droplet impinging & coalescence model, Stanton spray/wall impinging model, the Discrete Particle Ignition Kernel(DPIK)ignition model, the single step combustion and the patulous Zeldovich model for NOx generation mechanism. The integrated CFD code was then calibrated against experimental data in a gasoline direct injection engine for several engine operating conditions. Afterwards it was applied to investigate the influences on air/fuel premixing, stratified combustion as well as NOx emission formation of various combustion chamber designs Simulation results indicate that the distribution of air/fuel mixture becomes more and more uniform before ignition occurs, because of the elevated air/fuel mixture velocity and enhanced swirl level, in the range of combustion chamber bowl offsets changing from 0.0 cm to 1.7 cm with a step of about 0.25 cm. This, in turn, leads to shorter ignition delay, slower combustion, lower in-cylinder peak temperature and stronger heat transfer between the burnt and un-burnt zones. It is recommend that the best combustion chamber bowl offset should be from 0.5 cm to 1.0 cm, based on the compromise between NOx emission and un-burnt fuel (evaporated and liquid gasoline) mass. The 3D simulation model developed in this study is capable to provide detailed insights of all stages of the in-cylinder processes, including air motion, air/fuel mixing, combustion and emission formation. It is proven that the simulation approach and results very helpful in providing design guidelines and optimizing for the combustion chamber shape design.

This paper describes an improved mathematical model to study the emission conversion effectiveness of a three-way catalytic converter, which employed detailed chemical reaction mechanism. The model also accounts for adsorption/release of oxygen in the catalyst monolith under non-stoichiometric A/F conditions. A commercial CFD code FLUENT was utilized to solve the governing equations for flow and pressure drop and to simulate the transient process in a three-way catalytic converter in a multi-dimensional manner. A comparison between simulation results and experimental data for a three-way catalyst was conducted and a good agreement was observed. Based on the improved model, some geometric parameters were studied for an elliptic monolith catalyst, which are widely used in today’s converter systems because of its advantages in packaging. Simulation results show that, in general, decreasing the ellipse ratio, i.e. the ratio of the major over the minor axis length, has favorable effect on catalyst conversion efficiency. However the significance of improvement depends on the ellipse ratio itself: if the ellipse ratio is large, the effect is strong when reducing it; as the ratio is approaching to 1, the improvement becomes less and less significant. On the other hand, increasing the converter length also improves the catalyst conversion performance, so does the increase in the cross-sectional area. For a fixed converter volume: the performance of a short catalyst with large cross-sectional area is generally not as good as the one with longer length but smaller cross-section area. For a fixed void fraction of the catalyst, a catalyst with higher cell density but thinner wall thickness, because of its increased surface area, is generally more effective than the one with lower cell density but thicker wall thickness. The improved CFD model and simulation results are proven capable of providing guidelines for practical design improvements to meet the increasingly stringent emission legislations.

A 2-D gas-particle two-phase flow model has been developed to study the flow characteristics in a single channel of a honeycomb ceramic diesel particulate filter. A particle source in cell (PSIC) algorithm is used to calculate the gas-particle two-phase flow. Firstly, the gas-phase flow field alone (without taking into account of the particle-phase) is solved for estimation of gas velocity and pressure fields in the Euler coordinate. Secondly, the particle-phase is added in and particles tracked down in the Lagrange coordinate. Thirdly, the particle source which acts on the gas-phase cell is calculated and added to the gas-phase equations. Fourthly, the gas-phase equations with the particle source are solved again. Lastly, the above process is iterated until the flow field is convergent. Taking the above-mentioned approach, the gas-particle two-phase flow characteristic is simulated using FLUENT. The simulation results are in good agreement with experiment data. After the models being calibrated, the influences on particle movement traces of the exhaust gas entry velocity, particulate matter concentration and porous wall thickness are studied and presented. The work conducted provides an important reference to further studies on gas-particle two-phase flow and combustion characteristics during the cake filtration process and the regeneration process.