Application of active flow control technology in an unmanned aerial vehicle

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2009-05-15

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A low speed wind tunnel experimental investigation was conducted to determine the effectiveness of the leading edge pulsed blowing and the trailing edge jet blowing/ Gurney flap on the improvement of aerodynamic performance of an unmanned aerial vehicle at low Reynolds numbers. The wind tunnel tests for the leading edge pulsed jet blowing were conducted at 10%, 30% and 50% location of the chord length from the leading edge at a free stream velocity of 20 m/s. The jet momentum coefficient and the non-dimensional pulser frequency had been varied independently to investigate the effectiveness of the leading edge pulsed blowing. The trailing edge jet blowing tests were conducted at free stream velocity of 20 m/s at different jet momentum coefficients. The leading edge pulsed blowing showed a strong dependency of the actuator effectiveness on the jet momentum and the pulser frequency. The leading edge pulsed blowing had delayed the flow separation over the airfoil from an angle of attack of 17? to 22? with a docile stall for jet emanating at 10% location of the chord length for a jet momentum coefficient of 0.0275. The pulsed blowing at 50% chord location generated higher lift compared to the 10% location of the pulser with an abrupt stall at 19?. There was no evidence of the lift augmentation in the pre-stall angle of attack regime. The experimental results showed that the trailing edge jet flap was capable of generating significant roll moment at realistic jet momentum coefficients. The fluidic actuators were then integrated into the wings of a scale Extra 330 model airplane. The wind tunnel results for the leading edge pulsed blowing on the scale model indicated a delay in the stall of the airplane from an angle of attack of 12? to 21? with a 13% increase in the lift at take-off and landing speed of 17 m/s. The trailing edge jet actuators were also able to augment lift and demonstrate the roll control authority at low angle attacks at a cruising speed of 30 m/s.

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