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Dynamical characteristics of the tip vortex from a four-bladed rotor in hover

Dynamical characteristics of the tip vortex from a four-bladed rotor in hover Dynamical characteristics of tip vortices shed from a 1 m diameter, four-bladed rotor in hover are investigated using various aperiodicity correction techniques. Data are acquired by way of stereo-particle image velocimetry and comprises measurements up to 260° vortex age with 10° offsets. The nominal operating condition of the rotor corresponds to Re c  = 248,000 and M = 0.23 at the blade tip. With the collective pitch set to 7.2° and a rotor solidity of 0.147, blade loading (C T/σ) is estimated from blade element momentum theory to be 0.042. The findings reveal a noticeable, anisotropic, aperiodic vortex wandering pattern over all vortex ages measured. These findings are in agreement with recent observations of a full-scale, four-bladed rotor in hover operating under realistic blade loading. The principal axis of wander is found to align itself perpendicular to the slipstream boundary. Likewise, tip vortices trailing from different blades show a wandering motion that is in phase instantaneously with respect to one another, in every direction and at every wake age in the measurement envelope. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Experiments in Fluids Springer Journals

Dynamical characteristics of the tip vortex from a four-bladed rotor in hover

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References (44)

Publisher
Springer Journals
Copyright
Copyright © 2013 by Springer-Verlag Berlin Heidelberg
Subject
Engineering; Engineering Fluid Dynamics; Fluid- and Aerodynamics; Engineering Thermodynamics, Heat and Mass Transfer
ISSN
0723-4864
eISSN
1432-1114
DOI
10.1007/s00348-013-1600-9
Publisher site
See Article on Publisher Site

Abstract

Dynamical characteristics of tip vortices shed from a 1 m diameter, four-bladed rotor in hover are investigated using various aperiodicity correction techniques. Data are acquired by way of stereo-particle image velocimetry and comprises measurements up to 260° vortex age with 10° offsets. The nominal operating condition of the rotor corresponds to Re c  = 248,000 and M = 0.23 at the blade tip. With the collective pitch set to 7.2° and a rotor solidity of 0.147, blade loading (C T/σ) is estimated from blade element momentum theory to be 0.042. The findings reveal a noticeable, anisotropic, aperiodic vortex wandering pattern over all vortex ages measured. These findings are in agreement with recent observations of a full-scale, four-bladed rotor in hover operating under realistic blade loading. The principal axis of wander is found to align itself perpendicular to the slipstream boundary. Likewise, tip vortices trailing from different blades show a wandering motion that is in phase instantaneously with respect to one another, in every direction and at every wake age in the measurement envelope.

Journal

Experiments in FluidsSpringer Journals

Published: Oct 4, 2013

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