DIRECT LIFT CONTROL USING DISTRIBUTED AERODYNAMIC BLEED

摘要

A novel approach to aerodynamic control for maneuvering and landing of carrier-based, fixed wing aircraft in the ship's wind field by augmenting the aircraft's conventional electromechanical control surfaces for direct lift control is investigated in wind tunnel experiments. The aerodynamic loads on the lifting surfaces are controlled using distributed air bleed that is driven through the surfaces by the pressure differences in flight (e.g., between and across the pressure and suction surfaces of the wing), and is regulated by low-power, surface-integrated louver valves for improved temporal response and reduced actuation requirements in comparison to conventional control. The present experiments utilize distributed bleed on a representative 3-D wing model (Re = 7.6·10~5). Bleed flow is driven through independent spanwise arrays of slots in the vicinity of the root, mid-span and wingtip (each 4% open area). It is shown that, depending on operating conditions, the bleed leads to a lift reduction or increase of up to 28% and 11%, respectively, with minimal change in pitching moment. Stereo PIV measurements in the model's near wake show the effects of bleed on the distribution of streamwise vorticity and the tip vortex and yield the variation of spanwise loading which corroborates the global load measurements.