Abstract

Multiflue stacks are finding ever increasing application at thermal power stations (TPS) in recent years. Until the present time, the opinion has prevailed that multiflue stacks at the same emission parameters offer lower floating-up height of flue gases than single-flue stacks do. Hence, they must be higher or be provided with devices making a single flume, such as common hoods, or due to a concentric slope of the outlet section of the stack flues. However, the research tools used up until now had poorer capabilities as compared to those implemented in the ANSYS Fluent software package. The process of combining jets outflowing from individual flues of a four-flue stack is studied and analyzed using the ANSYS Fluent package. Much attention is given to the selection of a proper turbulence model and its verification against generally accepted theoretical and experimental data. This revealed the effect of rapprochement of the jets’ axis from individual parallel flues similar to the Coanda effect. Comparison of the characteristics of cross sections in a combined plume from a four-flue stack and a plume from a single-flue stack having the same outflow parameters and the distance from the stack mouth, as well as using them as initial data for calculating the trajectory of the smoke plume, showed a good agreement of these trajectories. Selection of a turbulence model and a calculation scheme suitable for the considered conditions is rather complicated, as it is determined not only by physical and geometric parameters but also by the required model accuracy and available computer and time resources. Solutions are presented that are obtained using the ANSYS Fluent package in analyzing jet flows with a scale of approximately 100 m, and a procedure for selecting a turbulence model for a nonisothermal jet is described.

中文翻译：

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火力发电厂四烟囱烟气初始部分的建模

摘要

近年来，多烟道烟囱正在火力发电厂（TPS）上得到越来越多的应用。直到目前，仍存在这样一种观点，即在相同排放参数下的多烟道烟囱提供的烟道气漂浮高度比单烟道烟道更低。因此，它们必须更高或者配备有制造单个水槽的装置，例如通用罩，或者由于烟囱烟道出口部分的同心斜率。但是，与ANSYS Fluent软件包中实现的工具相比，到目前为止使用的研究工具的功能较差。使用ANSYS Fluent软件包研究和分析了从四烟道烟囱的各个烟道流出的喷射流的组合过程。人们对选择合适的湍流模型及其针对普遍接受的理论和实验数据的验证给予了极大的关注。这揭示了来自单个平行烟道的喷射轴线和解的效果类似于柯恩达效应。比较具有相同流出参数和到烟囱口的距离的四烟囱和单烟囱的组合烟流中横截面的特性，并将它们用作计算烟气量的初始数据烟羽的轨迹，显示出这些轨迹的良好一致性。选择适合所考虑条件的湍流模型和计算方案相当复杂，因为它不仅取决于物理和几何参数，还取决于所需的模型精度以及可用的计算机和时间资源。提出了使用ANSYS Fluent软件包获得的解决方案，用于分析规模约为100 m的射流，并介绍了为非等温射流选择湍流模型的过程。