Multiple time-scale effects for a pitching 65-deg delta wing

Abstract

Normal force and pitching moment data are presented for a 65° delta wing undergoing pitch motions. Critical states are identified in the static data by apparent discontinuities in the force and moment values or their slopes. These critical states form boundaries, across which the time constants of the aerodynamic responses change. For angles of attack with either vortex breakdown or fully stalled flow present over the planform, significant unsteady aerodynamic effects occur due to lags in the flow-field response. For motions that cross the stall angle-of-attack, a persistent transient effect is shown to occur as the flow field changes to the new equilibrium flow-state. NOMENCLATURE Cm = pitching moment coefficient (nondimensional w.r.t. mean aerodynamic chord, dynamic pressure and planform area) CN = normal force coefficient (nondimensional w.r.t. dynamic pressure and planform area) cr = root chord q = pitch rate (nondimensional w.r.t. freestream speed and root chord) t = time (nondimensional w.r.t. freestream speed and root chord) Tc = time constant (nondimensional w.r.t. freestream speed and root chord) a = aerodynamic angle of attack (corrected to account for pitch rate) a(t0) = angle of attack at motion onset a(tf) = angle of attack at motion cessation 'Aerospace Engineer, Member AIAA. This paper is declared a work of the U. S. Government and is not subject to copyright protection in the United States. Subscript max = maximum