Developmental Research on Computer Aided Analysis and Design of an Engine Combustion System

为了获得混合气形成的基本知识，对燃油喷雾中的燃油蒸气浓度进行了定量分析，这是开发柴油机燃烧模拟程序所必需的。为此，开发了对纹影和阴影摄影所拍摄的喷雾图像进行处理的技术，并将其应用于高压高温环境下的轴对称喷雾。将该图像处理技术与计算机层析变换程序相结合，分析了横向气流中变形的喷雾的内部结构。将分析得到的信息整合到柴油机燃烧模拟程序中，该程序由气流子程序和混合气形成与燃烧子程序组成。短句来源考虑到计算成本和精度，采用两区模型，计算了活塞空腔半径内外区域的旋流角速度，计算了活塞空腔半径内外区域的旋流角速度。混合气形成与燃烧子程序的主要考虑是寻找与旋流相匹配的喷油参数和燃烧室参数，并对超旋流现象进行预测。在柱面坐标系下，用非均匀矩形固体单元对燃烧室进行了映射。采用有限差分技术对燃料蒸气浓度、燃烧产物浓度和气体焓守恒方程进行离散化。通过数值求解这些守恒方程，得到了燃料蒸气浓度、燃烧产物浓度和气体温度的空间分布。将计算结果与激光多普勒测速仪测得的角速度和在高速燃烧膜中观察到的火焰行为进行比较，证明了该模拟程序的潜力。少

A quantitative analysis of fuel vapor concentration in a fuel sprayh was made for obtaining fundamental knowledge of mixture formation which was necessary for the development of a sumulation program of diesel engine combustion. For this purpose, the technique for processing the spray image taken by the schlieren and shadow photography was developed, and applied to the axisymmetric spray in a high-pressure and high-temperature atmosphere. Internal structure of the spray distorted in a cross air flow was analyuzed by combining this image processing technique with the program for the computed tomographic transformation. Several informations obtained through these analysed were incorporated into the simulation program of the diesel engine combustion, which was composed of an air flow sub-program, and a mixture formation and combustion sub-program. The air flow sub-program was created for mainly predicting the swirling air flow during a compression stroke, especially at fuel injection timin … More g. Taking the computational cost and accuracy of into consideration, a two-zone model was adopted, and the angular velocities of the swirling air flow in the zones inside and outside the piston cavity radius were computed. The principle consideration of the mixture formation and combustion sub-program was to find the injection and combustion chamber parameters matching with the swirling air flow, and to predict the over-swirl phenomenon. The comubustion chamber was mapped with non-uniform rectangular soulid cells in cylindrical coordinates. The conservation equations for fuel vapor concentration, combustion product concentration and gas enthalpy were discretized in a finite difference technique. By numerically solving these conservation equations, the spatial distributions of fuel vapor concentration, combustion product concentration and gas temperature were obtained. The comparison between the computed result, and the angular velocity measured with the laser doppler velocimeter and fthe flame behavior observed in a high-speed combustion movie, demonstrates the potential of this simulation program. Less