Abstract The detection of laminar–turbulent transition in aerodynamics is very important, however, it can be extremely challenging, especially for unsteady flows or moving surfaces. To understand and control transition effects and associated friction losses on aerodynamic components, optical methods have been developed as they potentially do not disturb transition processes. Temperature Decline Thermography (TDT) was recently introduced to visualize boundary layer phenomena on surfaces exposed to flow. The technique is based on transient infrared thermography with active heating, offering high spatial resolution and precise transition detection in stationary systems. However, to improve the efficiency of modern aircraft engines, transition detection on rotating blades is of particular importance. In this study, TDT was enhanced and qualified for use on rotating blades in gas turbines. For the first time, a proof of concept is provided for flow visualization on stationary vanes and rotating blades under realistic flow conditions. Despite the limited optical access in a turbine rig, it was possible to visualize the near-wall traces of boundary layer transitions, separation and vortex systems with high spatial resolution and low measurement uncertainty. The application of TDT in turbomachinery allows for a deeper understanding of flow phenomena and enables validation and support of numerical models for the development of highly efficient gas turbines. Graphic abstract

中文翻译：

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旋转涡轮叶片层流-湍流转变的可视化

摘要 空气动力学中层流-湍流转变的检测非常重要，然而，它可能极具挑战性，特别是对于非定常流动或运动表面。为了理解和控制空气动力学部件上的过渡效应和相关的摩擦损失，已经开发了光学方法，因为它们可能不会干扰过渡过程。最近引入了温度下降热成像 (TDT) 来可视化暴露于流动的表面上的边界层现象。该技术基于具有主动加热功能的瞬态红外热成像，可在固定系统中提供高空间分辨率和精确的过渡检测。然而，为了提高现代飞机发动机的效率，旋转叶片的过渡检测尤为重要。在这项研究中，TDT 得到了增强，可用于燃气轮机的旋转叶片。这是第一次为在真实流动条件下固定叶片和旋转叶片上的流动可视化提供了概念验证。尽管涡轮钻机中的光学通路有限，但还是可以以高空间分辨率和低测量不确定性来可视化边界层过渡、分离和涡流系统的近壁轨迹。TDT 在涡轮机械中的应用可以更深入地了解流动现象，并能够验证和支持用于开发高效燃气轮机的数值模型。图形摘要 尽管涡轮钻机中的光学通路有限，但还是可以以高空间分辨率和低测量不确定性来可视化边界层过渡、分离和涡流系统的近壁轨迹。TDT 在涡轮机械中的应用可以更深入地了解流动现象，并能够验证和支持用于开发高效燃气轮机的数值模型。图形摘要 尽管涡轮钻机中的光学通路有限，但还是可以以高空间分辨率和低测量不确定性来可视化边界层过渡、分离和涡流系统的近壁轨迹。TDT 在涡轮机械中的应用可以更深入地了解流动现象，并能够验证和支持用于开发高效燃气轮机的数值模型。图形摘要 TDT 在涡轮机械中的应用可以更深入地了解流动现象，并能够验证和支持用于开发高效燃气轮机的数值模型。图形摘要 TDT 在涡轮机械中的应用可以更深入地了解流动现象，并能够验证和支持用于开发高效燃气轮机的数值模型。图形摘要