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A Study on Combustion in Reciprocating Internal Combustion Engines by Computational Fluid Dynamic Approach

计算流体动力学方法研究往复式内燃机燃烧

基本信息

批准号：
63460098
负责人：
IKEGAMI Makoto
金额：
$ 4.42万
依托单位：
KYOTO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1988
资助国家：
日本
起止时间：
1988 至 1989
项目状态：
已结题

项目摘要

The in-cylinder flows and combustion in reciprocating internal combustion engines were described by a numerical fluid dynamic method, to enable prediction of effects of various parameters such as combustion-chamber shape, ignition, injection, and gas flows. A special caution was paid to select simple but adequate submodels for turbulence, spray, and chemical reactions. The simulation programs thus developed was applied to various problems. The following results were obtained.1. To allow the computer simulation at combustion chambers with arbitrary geometries, a new algorithm was proposed such that used finite element concept only for computational cells adjacent to wall boundaries, the remaining grid cells relying on an ordinary finite difference scheme in an orthogonal coordinate system. The proposed method was applied to elucidate flows and combustion in a reentrant chamber of a diesel engine.2. Turbulence near the region of flame front in a spark-ignition engine was directly measured by a laser homodyne method. The obtained results show that there is only a little production of turbulence in the flame zone, because of the laminarization at increased temperature.3. The effect of the top clearance in a deep-bowl direct-injection diesel engine was assessed based on the computer simulation. At a smaller clearance, unburnt outflow of the mixture from the bowl into the clearance space is suppressed in earlier stages of burning, and as a result unburnt raw fuel is less than at bigger clearance.4. Heat flux through the combustion-chamber walls of diesel engines was predicted. The predicted heat flux was in good agreement with that by the empirical correlations between the Nusselt and Reynolds numbers, once a thin deposit layer on the surface was assumed.

通过数值流体动力学方法描述了往复式内燃机的缸内流动和燃烧，以便能够预测燃烧室形状、点火、喷射和气流等各种参数的影响。特别注意选择简单但足够的湍流、喷雾和化学反应子模型。由此开发的模拟程序应用于各种问题。得到如下结果： 1．为了允许对任意几何形状的燃烧室进行计算机模拟，提出了一种新算法，仅对与壁边界相邻的计算单元使用有限元概念，其余网格单元依赖于正交坐标系中的普通有限差分格式。该方法被应用于阐明柴油机凹腔内的流动和燃烧。 2．通过激光零差法直接测量火花点火发动机火焰前锋区域附近的湍流。结果表明，由于温度升高导致层流化，火焰区仅产生很少的湍流。 3．基于计算机模拟评估了深碗直喷柴油机顶部间隙的影响。在间隙较小的情况下，在燃烧的早期阶段，未燃烧的混合物从转筒流入间隙空间的流出受到抑制，因此未燃烧的原燃料比间隙较大时要少。 4．预测了通过柴油发动机燃烧室壁的热通量。一旦假设表面有薄沉积层，预测的热通量与努塞尔数和雷诺数之间的经验相关性非常一致。