Unsteady aerodynamic loading produced by a sinusoidally oscillating delta wing

Abstract

The unsteady aerodynamic loading produced by an oscillating delta wing was examined for a range of reduced frequencies and mean angles of attack. A three degree of freedom force balance recorded normal and tangential force data. These data were then reduced to provide unsteady lift and drag force coefficient values. The resultant aerodynamic loads were highly transient in nature and lift enhancement up to twice that of steady-state values was achieved for limiting test cases. The delta wing also experienced lift reduction during portions of the pitching cycle. Reduced dynamic drag was seen for instantaneous wing angles of attack below static stall. Hysteresis loops demonstrated the unsteadiness of the resultant flowfields and were seen for all test cases. Force balance measurements supported hypotheses on both unsteady separation mechanisms and dynamics for a delta wing. Unsteady lift integrations over time highlighted relations between reduced frequency and mean angle of attack for total bounded vorticity throughout the pitching cycle.