The fluid dynamic phenomena following the impulsive start of a NACA 0015 airfoil were studied by using a time accurate solution of the incompressible, laminar Navier-Stokes equations. Angle of attack was set at 10 deg to simulate steady-state poststall conditions at a Reynolds number of 12000. The calculation revealed that large initial lift values can be obtained, immediately following the impulsive start, when a trapped vortex develops above the airfoil. Before the buildup of this trapped vortex and immediately after the airfoil was set into motion, the fluid is attached to the airfoil's surface and flows around the trailing edge, demonstrating the delay in the buildup of the classical Kutta condition. The transient of this effect is quite short and is followed by an attached flow event that leads to the trapped vortex that has a longer duration. The just described initial phenomenon eventually transits into a fully developed separated flow pattern identifiable by an alternating, periodic vortex shedding.
Impulsive start of a symmetric airfoil at high angle of attack
Der Impuls-Start eines Tragflügels bei großem Anstellwinkel
AIAA Journal ; 34 , 2 ; 225-230
1996
6 Seiten, 14 Bilder, 26 Quellen
Article (Journal)
English
Tragflügelumströmung , NACA-Profil , inkompressible Strömung , laminare Strömung , Anstellwinkel (Tragflügel) , mathematisches Modell , Navier-Stokes-Gleichung , Lösung (Ergebnis) , Abreißen der Strömung , Reynolds-Zahl , Auftrieb , Wirbelströmung , diskontinuierlicher Vorgang , instationäre Strömung , reibungsbehaftete Strömung , Software , Maschennetz , Luftwiderstand , Druckverteilung , sichtbare Strömung , Wirbelbildung
Impulsive Start of a Symmetric Airfoil at High Angle of Attack
Online Contents | 1996
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