An investigation of unsteady vortex flow over a maneuvering delta wing

An investigation of vortex breakdown using flow visualization was conducted with a 70{dollar}spcirc{dollar} delta wing under conditions of steady and unsteady pitch, roll and combinations of pitch and roll. All unsteady analyses were conducted at four values of reduced frequencies. Testing was carried out in the water tunnel located at the Royal Military College of Canada.; Steady state roll experiments with the delta wing pitched at 30{dollar}spcirc{dollar} showed that the behaviour of vortex breakdown as a function of roll angle could be considered linear over the front half of the delta wing; however, the behaviour beyond a certain critical roll angle was nonlinear. The steady state coupling effect for simultaneous variations in pitch and roll appeared to be a superposition of the individual effects of pure pitch and pure roll.; The observations showed that the unsteady behaviour of the vortex core angle as a function of angle of attack was independent of reduced pitch frequency. For all unsteady motions, a hysteresis effect existed that increased with reduced frequency. The coupling effect of pitch and roll for the right wing was a reduction in hysteresis; however, the coupling effect for the left wing was an increase in hysteresis.; For all motions investigated, an increase in reduced frequency also resulted in an increase in the amount of phase lag. For pure pitching and rolling motion, there was a notable increase in phase lag when the delta wing transitioned from the downstroke to the upstroke as compared to the transition from the upstroke to the downstroke. The coupling effects of unsteady pitch and roll was an apparent superposition of the phase lag.; Empirical prediction equations for steady state conditions were examined under modification for leading edge geometry. Limited success was obtained in predicting the location of the vortex breakdown for conditions of pure pitch and pure roll; however, neither equation accurately predicted the effects of the coupled variations of pitch and roll.