© Marques Engineering Ltd
Abstract: Marqués P. (2014). Aerodynamics of the UCAV 1303 delta-wing configuration and flow structure modification using plasma actuators. International Journal of Unmanned Systems Engineering. 2(1): 15-28. This paper reviews the theoretical basis of plasma actuation, aerodynamic applications of plasma actuators, the aerodynamics of the UCAV 1303 aircraft configuration, and studies on the modification of the flow structure over the UCAV 1303 configuration using plasma actuation. Plasma actuators provide aerodynamic flow control by imparting thrust in the air based upon the Biefeld–Brown electrical effect. The electrical discharge between two electrodes separated by an insulating dielectric barrier is known as dielectric barrier discharge (DBD). Plasma actuators are more effective at low Reynolds numbers (Re) where the ratio of the jet velocity to flow velocity is highest. The actuators can be mounted on an aircraft lifting surface to control flight attitude, thus eliminating the cumbersome parts of mechanical and hydraulic transmission systems. Plasma actuators are particularly useful in flight conditions in which conventional control surfaces are ineffective. The complex flow physics of the 1303 UCAV blended wing-body configuration are investigated in this study. The 1303 UCAV configuration is a variant of the delta wing and exhibits aerodynamic properties commonly associated with traditional delta wings. The primary aerodynamic flow is dominated by the formation of two vortex patterns on the upper surface of the wing in the vicinity of the highly swept leading edges at high angles of attack (α). At a critical α, the leading edge vortex lift ends abruptly as the vortices experience a sudden increase in dynamic pressure and loss of axial velocity, undergoing vortex break down. The 1301 UCAV geometry is described as a near-lambda wing with concave trailing edge crank at the mid-section and concave trailing edge crank outboard. In contrast, the 1303 UCAV configuration combines increased aspect ratio and taper with planform edge alignment. A local minimum in chord associated with the inboard trailing edge crank results in a local maximum in section lift coefficient. With flow separation at the inboard crank, fully separated flow over the outboard wing panel is expected. Thus, the centroid of lift changes location, moving inboard and upstream leading to excessive pitch up behaviour in the lambda wing. DBD plasma actuators for hingeless flow control have been employed in a 47° UCAV 1303. The actuators and flow control were implemented at the wing leading edge to achieve longitudinal aircraft control without the use of hinged control surfaces. Wind-tunnel tests conducted at chord Re of 4.12 x 10^5 revealed considerable changes in the lift and drag of the plasma-controlled wing and significant improvements in control authority, which extended the operational flight envelope of the UCAV 1303 in flight conditions in which conventional flaps and ailerons are ineffective. © Marques Engineering Ltd.
Keywords: Dielectric barrier discharge, Flight control, Flow structure, Plasma actuators,
UCAV 1303, Vortex breakdown, Vortex lift.
IJUSEng - 2014, Vol. 2, No. 1, 15-28
Aerodynamics of the UCAV 1303 Delta-wing Configuration
and Flow Structure Modification Using Plasma Actuators
Unmanned Vehicle University, United Kingdom