The ability of UAVs to operate in complex and hostile environments makes them useful in military and civil operations concerning surveillance and reconnaissance. However, limitations in size of UAVs and communication delays prohibit their operation close to the ground and in cluttered environments, which increase risks associated with turbulence and wind gusts that cause trajectory deviations and potential loss of the vehicle. In the last decade, scientists and engineers have turned towards bio-inspiration to solve these issues by developing innovative flow control methods that offer better stability, controllability, and maneuverability. This paper presents an aerodynamic load solver for bio-inspired wings that consist of an array of feather-like flaps installed across the upper and lower surfaces in both the chord- and span-wise directions, mimicking the feathers of an avian wing. Each flap has the ability to rotate into both the wing body and the inbound airflow, generating complex flap configurations unobtainable by traditional wings that offer improved aerodynamic stability against gusting flows and turbulence. The solver discussed is an unsteady three-dimensional iterative doublet panel method with vortex particle wakes. This panel method models the wake-body interactions between multiple flaps effectively without the need to define specific wake geometries, thereby eliminating the need to manually model the wake for each configuration. To incorporate viscous flow characteristics, an iterative boundary layer theory is employed, modeling laminar, transitional and turbulent regions over the wing’s surfaces, in addition to flow separation and reattachment locations. This technique enables the boundary layer to influence the wake strength and geometry both within the wing and aft of the trailing edge. The results obtained from this solver are validated using experimental data from a low-speed suction wind tunnel operating at Reynolds Number 300,000. This method enables fast and accurate assessment of aerodynamic loads for initial design of complex wing configurations compared to other methods available.
The increased use of Unmanned Aerial Vehicles (UAVs) has created a continuous demand for improved flight
capabilities and range of use. During the last decade, engineers have turned to bio-inspiration for new and
innovative flow control methods for gust alleviation, maneuverability, and stability improvement using morphing
aircraft wings. The bio-inspired wing design considered in this study mimics the flow manipulation techniques
performed by birds to extend the operating envelope of UAVs through the installation of an array of feather-like
panels across the airfoil’s upper and lower surfaces while replacing the trailing edge flap. Each flap has the ability
to deflect into both the airfoil and the inbound airflow using hinge points with a single degree-of-freedom, situated
at 20%, 40%, 60% and 80% of the chord. The installation of the surface flaps offers configurations that enable
advantageous maneuvers while alleviating gust disturbances. Due to the number of possible permutations available
for the flap configurations, an iterative constant-strength doublet/source panel method has been developed with an
integrated boundary layer model to calculate the pressure distribution and viscous drag over the wing’s surface. As a
result, the lift, drag and moment coefficients for each airfoil configuration can be calculated. The flight coefficients
of this numerical method are validated using experimental data from a low speed suction wind tunnel operating at a
Reynolds Number 300,000. This method enables the aerodynamic assessment of a morphing wing profile to be
performed accurately and efficiently in comparison to Computational Fluid Dynamics methods and experiments as
discussed herein.
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