Flow Visualization Studies of the Mach Number Effects on the Dynamic Stall of an Oscillating Airfoil

Abstract

Compressibility effects on the dynamic stall of a NACA 0012 airfoil undergoing sinusoidal oscillatory motion were studied using a stroboscopic schlieren system. Schlieren pictures and some quantitative data derived from them are presented and show the influence of freestream Mach number and reduced frequency on the dynamic-stall vortex. This study shows that a dynamic stall vortex always forms near the leading edge and convects on the airfoil upper surface at approximately 0.3 times the free stream velocity for all cases studied. The results also demonstrate that initiation of the dynamic stall vortex is delayed to higher angles of attack with increased reduced frequency, but that dynamic stall occurs at lower angles of incidence with increasing Mach numbers.

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Document Details

Document Type
Technical Report
Publication Date
Jan 12, 1989
Accession Number
ADA205029

Entities

People

  • L. W. Carr
  • Muguru S. Chandrasekhara

Organizations

  • Naval Postgraduate School

Tags

Communities of Interest

  • Air Platforms
  • Materials and Manufacturing Processes

DTIC Thesaurus Topics

  • Aeronautics
  • Aircrafts
  • Boundary Layer
  • Compressive Properties
  • Convection
  • Flow Fields
  • Flow Visualization
  • Fluid Dynamics
  • Fluid Flow
  • Fluid Mechanics
  • Frequency
  • Hydrodynamics
  • Light Sources
  • Mach Number
  • Photographs
  • Physics Laboratories
  • Turbulent Mixing

Fields of Study

  • Physics

Readers

  • Aerodynamics/Aeronautics.
  • Fluid Mechanics and Fluid Dynamics.