Accession Number : ADA182231

Title :   Separation and Reattachment Near the Leading Edge of a Thin Oscillating Airfoil.

Descriptive Note : Final rept. 15 Mar 85-14 Oct 86,

Corporate Author : MCDONNELL DOUGLAS CORP LONG BEACH CA

Personal Author(s) : Cebeci,Tuncer ; Khattab,A A ; Schimke,S M

PDF Url : ADA182231

Report Date : Dec 1986

Pagination or Media Count : 44

Abstract : The evolution of unsteady boundary layers in the vincinity of the leading edge of a thin oscillating airfoil has been examined with a novel numerical method which is able to deal with the movement of the stagnation point and with regions of reverse and separated flow. Solutions to the unsteady boundary-layer equations, with a prescribed pressure distributions which causes flow reversal and separation, demonstrate the importance of numerical steps in distance and time and that a requirement similar to the stability criterion of Courant, Friedrichs and Lewy must be satisfied to avoid numerical errors. At the lower reduced frequencies of the investigations, solutions could not be obtained with this procedure and it was necessary to introduce interaction between the viscous and inviscid flows. The solutions obtained with the interactive method were increasingly different from those without interaction as the reduced frequency was decreased towards zero and, for some combinations Reynolds number and frequency, exhibited behavior consistent with the instability of separation bubbles. Keywords: Fluid dynamics; Aerodynamics.

Descriptors :   *BOUNDARY LAYER FLOW, *FLOW SEPARATION, *UNSTEADY FLOW, AERODYNAMICS, FLOW, REVERSIBLE, BUBBLES, SEPARATION, STABILITY, LEADING EDGES, ERRORS, NUMERICAL ANALYSIS, PRESSURE DISTRIBUTION, REYNOLDS NUMBER, FLUID DYNAMICS, INTERACTIONS, LOW FREQUENCY, REDUCTION, NUMERICAL METHODS AND PROCEDURES, ATTACHMENT, STAGNATION POINT, BOUNDARY LAYER, AIRFOILS, OSCILLATION, THINNESS, INVISCID FLOW, VISCOUS FLOW

Subject Categories : Fluid Mechanics
      Numerical Mathematics

Distribution Statement : APPROVED FOR PUBLIC RELEASE