Abstract The helicopter group at the DLR in Gottingen has been actively involved in the development of measurement techniques for unsteady flows, particularly as they apply to the problems found in unsteady rotor blade aerodynamics. This includes the development and validation of new techniques for the detection of dynamically moving boundary layer transition, and for the detection of dynamic stall and other transient flow separation events. These new techniques include pressure sensor analysis, differential infrared thermography, local infrared thermography and the automated analysis of hot-film data. Particle image velocimetry (PIV) and background oriented schlieren (BOS) have been used for the analysis of the unsteady off-body flow, and synchronised PIV-BOS-pressure measurements have allowed direct comparisons between different methods. The Lagrangian volumetric PIV variant, shake-the-box, has been used to analyse secondary vortex structures in the vortex wake. This review article will give an overview of the advances in that group, as well as placing their activities in the context of international advances in these areas.

中文翻译：

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非定常直升机旋翼流动测量技术综述

摘要 哥廷根 DLR 的直升机小组一直积极参与非定常流测量技术的开发，特别是当它们应用于非定常转子叶片空气动力学中发现的问题时。这包括开发和验证用于检测动态移动边界层过渡以及用于检测动态失速和其他瞬态流分离事件的新技术。这些新技术包括压力传感器分析、差分红外热成像、局部红外热成像和热膜数据的自动分析。粒子图像测速 (PIV) 和背景导向纹影 (BOS) 已用于分析不稳定的离体流动，同步 PIV-BOS 压力测量允许在不同方法之间进行直接比较。拉格朗日体积 PIV 变体，即摇箱，已被用于分析涡流尾流中的次级涡流结构。这篇评论文章将概述该群体的进步，并将他们的活动置于这些领域的国际进步背景下。