大加速度场中层流扩散火焰流场的数值计算

通过对大加速度场中层流燃烧室流场的数值计算，建立了大加速度场中二维层流燃烧的数学模型，对控制方程组进行离散，采用SIMPLE算法和交错网格设计并调试程序。在调试成功的程序上对甲烷和空气在大加速度场中的扩散燃烧过程进行了数值模拟。计算结果表明，沿燃烧室轴线方向的均匀大加速度场会对扩散火焰的速度场和温度场等产生明显影响。一方面使得燃料与空气的扩散混合过程得到强化，扩散火焰的形状变短变粗，火焰面温度升高．因而能够提高其燃烧速度；另一方面，由于浮力作用驱动高温气流的流动方向与燃料射流的方向相反，将形成一种不稳定的流场结构，并同时诱发燃烧过程的不稳定。

Numerical Calculation of Laminar Flow Field of a Diffusion Flame in a High Acceleration Field

A numerical calculation method is proposed for calculating the laminar flow field of a combustor in a high acceleration field and a mathematical model for two-dimensional laminar flow combustion in the high acceleration field was set up. A control equation group was discretised. A SIMPLE algorithm and a staggered grid design were adopted and the relevant program was debugged. On the basis of the successfully debugged program a numerical simulation of the diffusion combustion process was performed of methane and air in the high acceleration field. The results of the calculation indicate that the uniform and high acceleration field along the axis of the combustor will exercise a significant influence on the velocity and temperature fields of the diffusion flame. On the one hand, it has intensified the diffusion mixing process of the fuel and air, resulting in a length-reduction and thickening of the diffusion flame shape and a rise in flame surface temperature and thus enhancing its combustion speed. On the other hand, due to a floating force action the high-temperature air flow will assume a direction opposite to that of the fuel jet flow, which would produce a unstable flow field structure, triggering a unstable combustion process.