The segmented thermal barrier coatings (TBCs) with vertical cracks have similar thermal insulation properties to layered coatings prepared by atmosphere plasma spraying (APS), and have similar mechanical properties to columnar coatings prepared by electron beam physical deposition (EB-PVD), which are very suitable for gas turbines with frequent start-up and variable load. Vertical cracks in the segmented APS-TBCs change the surface morphologies and internal microstructures, so it is necessary to study the internal heat transfer performance of the coating and the conjugate heat transfer characteristics between the TBCs and the cooling film. In this work, the numerical reconstruction models of TBCs with different crack lengths and openings were obtained based on the optimized quartet structure generation set (QSGS) method. By using the double distribution function lattice Boltzmann method (DDF-LBM), the temperature distribution of the coating, the conjugate heat transfer between TBCs and the cooling film and the flow characteristics of the cooling film were studied. The results showed that the vertical cracks with diverse sizes have significant effects on the coating-film cooling system, on which the crack opening has a greater effect. The temperature non-uniformity coefficient shows bimodal distribution in TBCs and the highest temperature is located at the crack center on the coating surface, which can easily lead to local hot spots near crack tips and further result in an acceleration of coating structure's fatigue failure. Meanwhile, the presence of cracks strengthens the interfacial convection heat transfer characteristics. The convection heat transfer coefficient change rate goes up 10% with the crack opening widens. Correspondingly, the greater deformation of the cooling film streamline and value of the vertical velocity are generated under the pre-existing larger size cracks. The results can provide us a powerful guide for the design of advanced coating structures and a strong foundation for a better understanding of the failure behavior of segmented TBCs.

具有垂直裂纹的分段式热障涂层（TBC）具有与通过大气等离子喷涂（APS）制备的层状涂层相似的绝热性能，并且具有与通过电子束物理沉积（EB-PVD）制备的柱状涂层相似的机械性能。非常适用于频繁启动和可变负载的燃气轮机。分段的APS-TBC中的垂直裂纹会改变表面形态和内部微观结构，因此有必要研究涂层的内部传热性能以及TBC与冷却膜之间的共轭传热特性。在此工作中，基于优化的四方结构生成集（QSGS）方法，获得了不同裂纹长度和开口的TBC数值重建模型。采用双分布函数格子玻尔兹曼方法（DDF-LBM），研究了涂层的温度分布，TBC与冷却膜之间的共轭传热以及冷却膜的流动特性。结果表明，不同尺寸的垂直裂纹对涂膜冷却系统影响显着，裂纹开口影响更大。温度不均匀系数在TBC中显示双峰分布，最高温度位于涂层表面的裂纹中心，这很容易导致裂纹尖端附近出现局部热点，并进一步加速了涂层结构的疲劳破坏。同时，裂纹的存在增强了界面对流换热特性。对流传热系数的变化率随着裂纹开口的扩大而增加了10％。相应地，在预先存在的较大尺寸的裂纹下产生了冷却膜流线的较大变形和垂直速度的值。结果可为我们提供高级涂层结构设计的有力指南，并为更好地了解分段式TBC的失效行为奠定坚实的基础。