Helical self-similarity of tip vortex cores

The present work investigates local flow structures and the downstream evolution of the core of helical tip vortices generated by a three-bladed rotor. Earlier experimental studies have shown that the core of a helical tip vortex exhibits a local helical symmetry with a simple relation between the a...

Full description

Saved in:
Bibliographic Details
Published in:Journal of fluid mechanics 2019-01, Vol.859, p.1084-1097
Main Authors: Okulov, Valery L., Kabardin, Ivan K., Mikkelsen, Robert F., Naumov, Igor V., Sørensen, Jens N.
Format: Article
Language:English
Subjects:
Aerodynamics
Aircraft components
Aircraft industry
Combustion chambers
Computational fluid dynamics
Cyclone separators
Evolution
Flow structures
Fluid flow
JFM Papers
Local flow
Measurement techniques
Scaling
Self-similarity
Separators
Similarity
Studies
Symmetry
Velocity
Vortex generators
Vortices
Wing tip vortices
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:The present work investigates local flow structures and the downstream evolution of the core of helical tip vortices generated by a three-bladed rotor. Earlier experimental studies have shown that the core of a helical tip vortex exhibits a local helical symmetry with a simple relation between the axial and azimuthal velocities. In the present study, a self-similarity scaling argument further describes the downstream development of the vortex core. Self-similarity has up to now only been investigated for longitudinal vortices and it is the first time that helical vortices have become the subject of such an analysis. Combining symmetry arguments from previous studies on helical vortices with novel experiments and knowledge regarding the self-similarity evolution of the core of longitudinal vortices, a new model describing what is referred to as ‘helical self-similarity’ is proposed. The generality of the model is verified and supported by experimental data. The proposed model is important for fundamental understanding of the behaviour of helical vortices, with a range of applications in both industry and nature. Examples of this are tip vortices behind aerodynamic devices, such as vortex generators, and fixed and rotary aircraft, and in combustion chambers and cyclone separators.
ISSN:0022-1120
1469-7645
DOI:10.1017/jfm.2018.850