In the framework of the AIM project the near field of the blade tip vortex of a full-scale helicopter in simulated hover flight was investigated by combining three-component Particle Image Velocimetry and Background Oriented Schlieren measurements. The velocity field measurements in the range of wake ages of \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\uppsi _{\mathrm{{v}}}={1}^\circ }$$\end{document} to \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${30}^\circ $$\end{document} in azimuth provided a reference for a quantitative analysis of the Schlieren results yielding vortex core density estimates. Ongoing vortex roll-up was observed at \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\uppsi _{\mathrm{{v}}}={1}^\circ }$$\end{document} while considerable aperiodicity was persistent thereafter. The vortex parameters for \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\uppsi _{\mathrm{{v}}}>{1}^\circ }$$\end{document} were consistent with the Scully vortex model. The particular challenges of full-scale, outdoor testing, especially the limited spatial resolution and aperiodicity effects, resulted in elevated measurement uncertainty as compared to sub-scale experiments.
Towards In-Flight Measurements of Helicopter Blade Tip Vortices
Research Topics in Aerospace
2013-02-14
15 pages
Article/Chapter (Book)
Electronic Resource
English
Particle Image Velocimetry , Particle Image Velocimetry Measurement , Particle Image Velocimetry Data , Main Rotor , Interrogation Window Size Engineering , Aerospace Technology and Astronautics , Engineering Fluid Dynamics , Applied and Technical Physics , Engineering Thermodynamics, Heat and Mass Transfer , Vibration, Dynamical Systems, Control
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