锅炉烟气走廊三维流动特性数值计算

The 3-Dimensional Numerical Simulation of the Fluid Field in Boiler Flue Passage

对锅炉烟气走廊的三维流场进行了计算机模拟计算。采用k-ε模型模拟烟道内烟气走廊的气体流动；将尾部受热面处理为多孔介质；几何拓扑结构采用多块结构，以减少计算机内存的浪费；采用贴体坐标系来描述复杂的几何边界；采用基于交错网格的网格系统；对于控制方程的对流项的离散，采用混合差分（HDS）格式；求解方程使用SIMPLE算法。同时，考虑到孔隙的不连续导致速度的不连续和压力场的不连续，方程求解采用改进的Rhie－Chow法。给出了锅炉尾部烟道内流场速度、温度、湍动能及其耗散率的分布，分析了尾部烟道不均匀流场形成的原因。计算结果与实验吻合得很好。为烟气走廊影响尾部受热面寿命、减少磨损等问题而采取措施提供了理论依据。

The 3-D numerical simulation of the fluid field in boiler flue passage is made in this paper. The rear heating surface is made into porous medium. The multiblock grid methodology involving the use of an unstructured set of block is applied, and the body-fitted grid specifies the geometric boundary in the smulation. the methods of discretization of diffusion terms and source terms in the control equ ations are Central Differencing (CDS), and the methods of discretization of advection terms in the con trol equations are Hybrid Differencing (HDS). The computing method is SIMPLE. Discontinuities in po rosity cause discontinuities in velocity sield due to mass continuity, and these in turn cause discon tinuities in the pressure field due to Bernoulli's law, so the improved Rhie-Chow interPolation method is used. the computation results that describe distribution of the velocity and turbulence kinetic energy and turbulence dissipation rate are good in accord with phenomena in prototypes. The simulation re sults can be used for decreasing conzection heating surface wear etc. in the boiler flue passage.