Accession Number : ADA331903

Title :   Experimental and Computational Analysis of Separation Bubble Behavior for Compressible Steady and Oscillatory Flows Over a NACA 0012 Airfoil (M=0.3, Re=540,000)

Descriptive Note : Doctoral thesis

Corporate Author : NAVAL POSTGRADUATE SCHOOL MONTEREY CA

Personal Author(s) : Van Dyken, Robert D.

PDF Url : ADA331903

Report Date : MAR 1997

Pagination or Media Count : 202

Abstract : In this thesis, the separation bubble behavior and its effect on the steady and dynamic stall characteristics of a thin airfoil in a compressible flow at a transitional Reynolds number was studied. For such flows, laminar separation occurs near the airfoil leading edge, but turbulent reattachment occurs within a short distance downstream, forming a separation bubble in the underlying region. Two experimental techniques, point diffraction interferometry (PDI) and laser doppler velocimetry (LDV), were used to acquire detailed flowfield information that showed the development of the leading-edge separation bubble and its subsequent bursting at higher angles of attack. The initiation of the stall process from the leading-edge separation bubble as opposed to trailing-edge flow reversal pointed to the need for transitional flow analysis. Both in the boundary layer and Reynolds-averaged, Navier-Stokes (N-S) analysis methods, transition models were incorporated to determine the location and extent of the transition zone that best modeled the measured separation bubble behavior. Computed results for steady flow gave remarkable agreement with the measurements.

Descriptors :   *VORTEX SHEDDING, *STALLING, *BUBBLES, *FLOW SEPARATION, THESES, TURBULENT FLOW, COMPUTATIONAL FLUID DYNAMICS, ANGLE OF ATTACK, COMPRESSIBLE FLOW, FLOW FIELDS, MACH NUMBER, NAVIER STOKES EQUATIONS, LAMINAR FLOW, PRESSURE DISTRIBUTION, REYNOLDS NUMBER, BOUNDARY LAYER FLOW, LASER VELOCIMETERS, STEADY FLOW.

Subject Categories : Aerodynamics
      Fluid Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE