Evaluation of Pulsed & Steady Blowing Flow Control in a Slotted Leading Edge Configuration.
Patterson, Colin Joseph.
- As aviation fuel prices continue to rise, airlines and aircraft manufacturers alike have a vested interest in reducing the fuel consumption of their aircraft. One of the promising technologies being developed to accomplish this is Active Flow Control (AFC). AFC systems are able to deliver the significant increases in maximum lift needed for the takeoff and landing portions of the mission and thereby, ... read moregiving AFC the potential to reduce the size and number of flap elements required in a high-lift wing configuration. This study focuses on an AFC system that injects high-momentum flow into the boundary layer from a slot in the leading edge. Testing was conducted in a 14inx14in wind tunnel test section. Lift and drag forces were measured directly using a 6-axis force transducer embedded within the airfoil itself. The airfoil used was a custom profile developed by Northrop Grumman and incorporates a leading edge slot at 3.5% cord. Both steady state blowing and pulsed blowing AFC were tested as part of this study. In each case the magnitude of the momentum injected was varied between 3% and 10% in the steady cases and 0.02% and .1% in the pulsed. In the case of steady blowing, the study was able to show improvements in the maximum coefficient of lift of as much as 28% with an uncertainty of Â±0.018. The steady blowing jets were also able to postpone stall from an angle of attack of 11Â° to 14Â° for all C? values greater than 3%. Pulsed blowing jets, on the other hand, were unable to generate the expected increase in maximum lift.read less