Heat Transfer in 3D-Vane-Passages - Systematic Generation and Investigation of Contoured Vane-Endwall Geometries for Turbomachines Using the Ice Formation Method

3D-Schaufelkanälen的研究项目Wärmeübergang已经设计了4年。目前的提案是项目第二阶段（第三和第四年）的提案。在最初的2年中，考虑到叶片端壁上的传热减少，冰形成方法被成功地用于创建新型叶片端壁配置。可以发现端壁配置，与非轮廓端壁相比，其显示出降低的整体热传递高达11%。项目第二阶段的调查将显示进一步改进的潜力。将更详细地研究瞬时冰增长的各个方面。将澄清的是，在冰层的生长期间是否已经形成其他感兴趣的拓扑结构，其特征在于压力损失和/或热传递行为的局部最优。为此，在稳态之前的多个时间点的轮廓将进行实验研究和分析的熵产生率，传热和压力损失。为了确定优化过程中不同的初始条件如何影响其结果，将以这些冰轮廓作为初始几何形状进行数值优化。由于叶栅前后的区域明显地影响端壁处的热传递，因此冷却区域将扩展到这些区域。因此，提供了更多的自由度，并开发了拓扑结构，不仅在叶片之间的区域中，而且在向上和下游部件的过渡区域中进行了优化。实验生成的冰轮廓将被用作初始几何形状的数值优化与多个目标函数和由此产生的轮廓将被分析。将数值研究扩展到燃气涡轮机的具体条件，应确保所得轮廓不仅具有学术意义，而且还可用于真实的应用。此外，还将研究通过叶片前的槽额外注入冷却液的端壁轮廓，以了解注入对冰拓扑结构的影响以及形成的轮廓。当这些拓扑用作数值优化过程的初始几何形状时。通过对本项目中生成的所有端壁轮廓进行总结性检查，应确定端壁轮廓的改进拓扑元素，并给出端壁轮廓的建议。这些建议允许生成未来的端壁轮廓，更好地适应各自的应用。例如，使用用于最小热传递的端壁轮廓显著地减少了所需的冷却空气，并因此导致部件的寿命延长和涡轮机的更高的热效率。

The research project Wärmeübergang in 3D-Schaufelkanälen, has been designed for 4 years. The present proposal is now for the second phase (3rd and 4th year) of the project. In the first 2 years, the ice formation method was successfully used for the creation of novel vane-endwall configurations considering the heat transfer reduction on the vane endwall. Endwall configurations could be found, that show reduced integral heat transfer up to 11% compared to an uncontoured endwall. Investigations in the second phase of the project will depict further potential for improvement. Aspects of the transient ice growth will be investigated in more detail. It will be clarified, whether during the growth of the ice layer other interesting topologies will already be formed, which feature local optima in pressure loss and/or heat transfer behavior. For that purpose, contours at multiple points in time prior to the steady state will experimentally be investigated and analyzed in terms of entropy production rates, heat transfer, and pressure loss. In order to determine how different initial conditions in the optimization process affect its results, numerical optimizations will be conducted with these ice contours as initial geometries. Since it has become apparent that also the regions in front of and behind the cascade considerably influence the heat transfer at the endwall, the cooled area will be extended to these regions. Thereby, more degrees of freedom are provided and topologies are developed, that are optimized not only in the region between the vanes but also in the transition regions to the up- and downstream components. The experimentally generated ice contours will be used as initial geometries for numerical optimizations with multiple goal functions and the resulting contours will be analyzed. An expansion of the numerical investigations to gas turbine specific conditions shall guarantee that resulting contours are not only of academic interest but will also be useful for real applications.Furthermore, endwall contouring with additional injection of cooling fluid through a slot in front of the vanes will be investigated in order to see what kind of influence the injection has on the ice topology and what kind of contours develop, when these topologies are used as initial geometries for the numerical optimization process. By the use of a concluding inspection of all endwall contours generated in this project, improved topology elements for endwall contouring shall be identified and recommendations for the contouring of endwalls will be given. These recommendations allow to generate future endwall contours, which are better adapted to the respective application. For example, the use of an endwall contour for minimum heat transfer reduces the required cooling air noticeably and therefore leads to enhanced life time of the components and to a higher thermal efficiency of the turbine.