Accession Number:

ADA222202

Title:

Flow Visualization of Dynamic Stall on an Oscillating Airfoil

Descriptive Note:

Master's thesis,

Corporate Author:

NAVAL POSTGRADUATE SCHOOL MONTEREY CA

Personal Author(s):

Report Date:

1989-09-01

Pagination or Media Count:

116.0

Abstract:

Stroboscopic schlieren photography was used to investigate the effects of compressibility, reduced frequency, and amplitude on the dynamic stall of a NACA 0012 airfoil subjected to sinusoidal oscillation. The Mach number was varied from M at infinity 0.25 to M at infinity 0.45 corresponding to a Reynolds number variation of Re 450,000 to Re 810,000 the reduced frequency was varied from k 0.025 to k 0.10. Oscillation amplitudes of alpha sub m 5 deg and alpha sub m 10 deg were compared. Schlieren photographs are presented, which document the dynamic stall vortex formation, convection, and shedding sequence for various experimental conditions. Additionally, a preliminary examination of the flow reattachment process was conducted. Data derived from the photographs indicates that increasing the compressibility causes dynamic stall to occur at lower angles of attack while, increasing the reduced frequency andor the oscillation amplitude effectively delays dynamic stall effects to a higher angle of attack. Flow reattachment is sensitive to both Mach number and reduced frequency for low values of these parameters when either the Mach number or reduced frequency is sufficiently high, the reattachment process stabilizes. jhd

Subject Categories:

  • Aerodynamics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE