Recent Progress In A Hybrid-Grid CFD Solver For Turbomachinery Flows
Recent Progress In A Hybrid-Grid CFD Solver For Turbomachinery Flows
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涡轮机械流动混合网格 CFD 求解器的最新进展
DOI：
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发表时间：
2010
期刊：
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通讯作者：
E. Kügeler
中科院分区：
文献类型：
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作者：
K. Becker;Kathrin Heitkamp;E. Kügeler
近年来，随着计算机技术的进一步发展，先进的计算流体动力学（CFD）程序已经能够分析涡轮机械复杂的三维流动特性。目前，大多数规则形状的构件都可以采用高质量的结构化网格进行网格划分。然而，对于某些零件或区域，例如壳体处理或冷却剂通道，即使应用多块拓扑，结构化网格的生成也是非常困难的。在这些情况下，必须引入非结构化网格。因此，一个混合结构化/非结构化求解器应该支持在同一建模网格拓扑结构。
本文介绍了最近的进展，在发展的混合计算流体动力学求解器方面的过渡建模。在低压涡轮中，由于普遍的低雷诺数，通常会遇到层流边界层。一方面，与湍流边界层相比，它们产生更少的损失。另一方面，它们对流动分离更敏感，导致更高的总损失。因此，CFD求解器中必须包含适当的过渡模型，以便能够定量预测总损失。CFD代码现在能够再现传输现象和过渡效应，而不管所使用的网格拓扑结构。为了验证和证明这些改进的有效性，介绍了两种试验情况，一种是用于非定常分析的三维平面涡轮机叶栅，另一种是用于非定常分析的二维涡轮机叶型。
In recent years, further developments in the computer technology have led to advanced CFD codes being able to analyze complex three-dimensional flow behavior of turbo-machines. At present, most components in regular shape can be meshed with high-quality structured grids. However, the generation of structured grids is very difficult for some parts or areas, such as casing treatments or coolant channels, even if multi-block topologies are applied. In these cases, unstructured grids have to be introduced. Therefore, a hybrid structured/unstructured solver should be favored supporting both grid topologies in the same modeling.
This paper presents recent progress in the development of the hybrid CFD solver with regard to the transition modeling. In low pressure turbines, laminar boundary layers are usually encountered due to the prevalent low Reynolds numbers. On the one hand, they produce fewer losses in comparison with turbulent boundary layers. On the other hand, they are more sensitive to flow separation leading to higher overall losses. Therefore, appropriate transition models have to be included in the CFD solver to be able to predict the overall losses quantitatively. The CFD code is now able to reproduce transport phenomena and the transitional effects regardless of the used grid topology. To validate and demonstrate the efficiency of the advancements, two test cases are introduced, a three-dimensional planar turbine cascade and two-dimensional turbine profile for unsteady analysis.