Flow Visualizations and Extended Thrust Time Histories of Rotor Vortex Wakes in Descent
Abstract:An experimental study was performed on a three‐bladed rotor model in two water tanks. Blade pitch, rotational velocity, descent angle, and descent speed were varied to simulate a wide range of rotorcraft operating states, focusing on cases where the rotor was operating in vortex ring state. Flow visualization used flow markers injected tangentially from the blade tips to mark vortex cores, showing the development of shortwave and longwave instabilities on the helical vortices in the wake. Strain gages recorded transient loads, allowing a correlation between rotor thrust and wake development. Chord Reynolds numbers were of order 10
Document Type: Research Article
Affiliations: University of California Berkeley, Berkeley, CA 94720-1740
Publication date: 2005-07-01
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