A numerical study was conducted to investigate the relative benefits of using an oscillatory jet, a pulsed blowing jet and a pulsed suction jet for reducing the vertical drag of a flapped NACA-64A223 airfoil. Emphasis was placed on demonstrating the impact of these three active flow control (AFC) strategies on the resulting flowfields at a free stream Mach number of 0.138 and a range of peak jet Mach numbers. Based on the results of this study, the following conclusions are made: 1. Results from the present simulations have indicated that the URANS equations are capable of capturing the 'global' features of the flow and providing the necessary fidelity to quantify the benefits associated with each of the three AFC strategies considered in this study. 2. Among the three AFC strategies considered for reducing the vertical drag of the flapped NACA- 64A223 airfoil, the use of the pulsed suction jet was shown to result in the largest percent reduction. 3. Effective reduction of airfoil vertical drag was invariably achieved using the oscillatory and the pulsed suction jets - with the percent reduction being directly proportional to the peak Mach number of the jet. 4. For a peak jet Mach number of 0.25, 'almost' complete reattachment of the separated flow on the upper surface of the flap was feasible when using the oscillatory and the pulsed suction jets. 5. As compared to the oscillatory and the pulsed suction jets, the use of the pulsed blowing jet for airfoil vertical drag reduction proved to be the least effective - resulting in a moderate 16.7 % reduction as compared to 30.9 %, 37.7 %. 6. Results from the present study suggest that the use of a pulsed blowing jet and a pulsed suction jet, in concert, may yield drag reduction benefits that exceed those predicted in the present investigation.
Strategies for tiltrotor airframe download reduction using active flow control
Strategien für eine reduzierte Abwindwirkung von Kipprotoren auf den Rumpf mittels aktiver Strömungsregelung
AHS International Forum, 60 ; 519-535
2004
17 Seiten, 17 Bilder, 18 Quellen
Conference paper
English
Aerodynamik , Luftfahrzeug , Rotor (Drehflügel) , numerische Strömungssimulation , Tragflügelumströmung , Luftstrahl , Navier-Stokes-Gleichung , partielle Differenzialgleichung , instationäre Strömung , reibungsbehaftete Strömung , 3D-Strömung , Nachlaufströmung , Nutzlast , Windkanalprüfung , experimentelle Untersuchung , Mach-Zahl , Strömungswiderstand
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