Advance Ratio Effects on the Dynamic-stall Vortex of a Rotating Blade in Steady Forward Flight

Abstract

The effect of advance ratio on the flow structures above a rotor blade in dynamic stall is studied using stereoscopic particle image velocimetry. The dynamic stall vortex shows a significant velocity component in its core, implying a helical structure progressing radially outboard. The radial velocity attenuates at outboard locations, in contrast to the expected increase with centripetal acceleration. This attenuation is accompanied by an increase in unsteadiness of the vortex. The unsteadiness shows a low-frequency cycle-to-cycle variation despite steady freestream conditions and blade tracking. Proper orthogonal decomposition analysis of the dominant flow mode confirms the unsteady behavior of the leading-edge vortex. The dependence on advance ratio is used to relate the stability of the dynamic-stall vortex to Coriolis effects.

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Document Details

Document Type
Technical Report
Publication Date
Aug 06, 2014
Accession Number
ADA617336

Entities

People

  • Narayanan Komerath
  • Vrishank Raghav

Organizations

  • Georgia Tech Research Corporation

Tags

Communities of Interest

  • Air Platforms
  • Energy and Power Technologies

DTIC Thesaurus Topics

  • Boundary Layer
  • Energy Levels
  • Flow Fields
  • Fluid Dynamics
  • Fluid Mechanics
  • Helicopter Rotors
  • Layers
  • Leading Edges
  • Measurement
  • Particle Image Velocimetry
  • Radial Flow
  • Radial Velocity
  • Reynolds Number
  • Stratified Fluids
  • Three Dimensional
  • Turbulent Mixing
  • Wind Turbines

Fields of Study

  • Physics

Readers

  • Aerospace Engineering
  • Brain and Cognitive Science; Experimental Psychology; Cognitive Neuroscience
  • Fluid Mechanics and Fluid Dynamics.