PNEUMATIC CONCEPT FOR TIP-STALL CONTROL OF CRANKED-ARROW WINGS

A novel blowing concept aimed at controlling the tip stall of cranked- arrow wings was experimentally investigated. The concept employs a tan gential jet sheet blown spanwise on the tip-panel upper surface, from a chordwise slot located at the leading-edge break. The blown sheet in teracts three dimensionally with the external now, forming a controlla ble vortex that powerfully influences the tip-panel upper-surface flow field leading to local lift improvement and stall delay. As a conseque nce, simultaneous blowing on both the tips alleviates pitch-up, wherea s one-side blowing provides roll control; a concurrent overall lift in crease occurs in both cases due to vortex augmentation. Low-speed wind -tunnel flow visualizations, pressure measurements, and six-component balance data were acquired on a generic cranked-arrow configuration to verify the concept and obtain preliminary indications of its aerodyna mic control potential.