梭式窑空气动力模型中紊流流动与对流传热的数值模拟研究

为深入了解梭式窑对流换热规律和产生换热不均匀的原因，利用CFD软件FLUENT^TM 5.4.8，构造了非保形结构化－非结构化混合网格，采用标准紊动能－紊动能耗散率（K－ε）模型，对梭式窑空气动力模型内部紊流流动与传热进行了数值模拟研究。得出了烧嘴射流的发展过程以及烟气速度场和温度场的分布特征。分析了料垛之间以及料垛局部换热的不均匀分布特征和成因。结果表明：外围料垛换热较强、内部料垛换热较弱，造成料垛间换热不均匀。料垛间隙的周期性分布导致料垛周向换热不均匀，三层烧嘴作用范围不同导致料垛纵向换热不均匀，有关数值模拟结果与文献实验数据符合较好。在此基础上，提出了调整料垛码法、烧嘴位置和流量匹配等改善对流换热均匀性的措施，并给出了调整原则。

NUMERICAL SIMULATION OF TURBULENT FLOW AND CONVECTIVE HEAT TRANSFER IN AIR DYNAMIC MODEL OF SHUTTLE KILN

By using the CFD software FLUENT TM 5.4.8, the turbulent flow and heat transfer in an air dynamic model of shuttle kiln were numerically investigated to pursue a better insight into the problem of convective heat transfer non_uniformity in the kiln. The complex simulation domain was formed by a non_conformal structural-unstructural hybrid grid scheme. The standard model was used to simulate the turbulent flow and heat transfer. The development of gas jet streams as well as velocity and temperature fields was illustrated. Several heat transfer coefficients and non_uniformities were defined to evaluate the convective heat transfer non_uniformity among stacks and local parts of each stack. The results indicate that the global heat transfer coefficients of the peripheral stacks are higher than those of the internal ones, which results in the non_uniformity among stacks. The numerical results of the furnace global heat transfer coefficient and the non_uniformity are in close agreement with the experimental data in the literature. A periodical distribution of the peripheral heat transfer coefficients is formed due to the periodicity of the flow channel size around each stack, which results in the peripheral non_uniformity. The nozzles in the top and mid layers influence a larger domain than those in the bottom layer. The stack peripheral averaged heat transfer coefficient decreases from bottom to top, which induces the longitudinal non_uniformity. The stack global non_uniformity is a colligation of both the peripheral and the lateral non_uniformity. The suggestions are made for the arrangement of the stacks and nozzles as well as the nozzle flow rate to improve convective heat transfer uniformity.