非正交贴体网格体系模拟炉内燃烧过程

开发了贴体曲线坐标系下煤粉燃烧全过程模拟程序,可在任意3-d贴体曲线坐标系下进行炉内气固流动,化学反应和辐射传热等完整的燃烧过程模拟。对某台670 t/h锅炉,采用了一种新的贴体曲线网格体系,其一族网格线从燃烧器喷口向外呈放射状展开,最外侧贴于炉膛壁面,燃烧器以上网格线扭转角度逐渐变化,至炉膛上部与壁面平行。计算结果与采用常规直角网格体系的结果相比,伪扩散误差明显减小,燃烧参数分布趋势接近实际分布。

COMPREHENSIVE MODELING OF COAL COMBUSTION IN BOILER FURNACE USING NON-ORTHOGONAL BODDY-FITTED MESH

A comprehensive coal combustion model is developed in non-orthogonal body-fitted coordinate (NOBFC). In this model, CFD method was employed to describe the turbulent flow while the Eulerian-Lagrangian method was used to treat the gas-solid two-phase flow and discrete ordinate method to radiation heat transfer. Special attentions were paid to numerical methods, especially to those that can reduce diffusion error in CFD solution for tangentially fired boiler. For the case of 670 t/h boiler, the meshes were generated to adapt the flow pattern in the burner region where the horizontal gridlines was set out from the burner and converged together in the opposite one. The horizontal grid pattern above the burner region is varied with the height, while at the upper furnace, the gridlines is parallel to the furnace walls. The geometrical boundaries of the furnace are well fitted by the meshes. It is evident that numerical diffusion error is smaller than that of the calculation based on Cartesian coordinate, and the prediction of combustion parameters is reasonably close to realistic