The initial stages of two-dimensional unsteady leading-edge boundary-layer separation of laminar subsonic flow over a pitching NACA-0012 airfoil have been studied numerically at Reynold number (based on airfoil chord length) Rec = 10000, Mach number Munendlich = 0,2 and nondimensional pitch rate Omega+0=0,2. Computations have been performed using two separate algorithms for the compressible laminar Navier-Stokes equations. The first method, denoted the structured grid algorithm, utilizes a structured, boundary-fitted C grid and employs the implicit approximate-factorization algorithm of Beam and Warming. The second method, denoted the unstructured grid algorithm, utilizes an unstructured grid of triangles and employs the flux-difference splitting method of Roe and a discrete representation of Gauss'theorem for the inviscid and viscous terms, respectively. Both algorithms are second-order accurate in space and time and have been extensively validated through comparison with analytical and previous numerical results for a variety of problems. The results show the emergence of a primary clockwise-rotating recirculating region near the leading edge which can be traced to a pair of critical points (a centre and a saddle) that appears within the flowfield, followed by a secondary counter-clockwise-rotating recirculating region and a tertiary clockwise-rotating recirculating region. The primary and secondary recirculating regions interact with each other to give rise to the unsteady separation (Breakaway) of the boundary layer.
Two-dimensional unsteady leading-edge separation on a pitching airfoil
Zweidimensionale instationäre Strömungstrennung an der Vorderkante eines sich verstellenden Rotorblatts
AIAA Journal ; 32 , 4 ; 673-681
1994
9 Seiten, 17 Bilder, 2 Tabellen, 50 Quellen
Article (Journal)
English
Hubschrauber , Rotor (Drehflügel) , Anstellwinkel (Tragflügel) , Strömungstrennung , laminare Strömung , NACA-Profil , Algorithmus , Reynolds-Zahl , Navier-Stokes-Gleichung , Grenzschichtströmung , Gitternetz , Rezirkulation , Luftwiderstand , Differenzialgleichung , Strömungsvorgang , Stromlinie , Genauigkeit
Two-Dimensional Unsteady Leading-Edge Separation on a Pitching Airfoil
Online Contents | 1994
|Unsteady separation from the leading edge of an airfoil
AIAA | 1994
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