Modeling and Analysis of Active Turbulators on Low Reynolds Number Unmanned Aerial Vehicles

Abstract

ABSTRACT SETH RYAN SHORT. Modeling and Analysis of Active Turbulators on Low Reynolds Number Unmanned Aerial Vehicles. (Under the direction of Dr. Ashok Gopalarathnam.)

The current research explores an approach for obtaining performance gains on small unmanned aerial vehicles (UAVs) operating in a low Reynolds number flight regime. Performance gains are sought through the use of an adaptive “tripping†or turbulator system for reduction of the drag resulting from laminar separation bubbles. Because laminar bubbles change in strength and chordwise location with changes in aircraft operating conditions, an adaptive bubble-control system is necessary to eliminate or reduce the adverse effects of the bubble over a large speed range. In the current effort, the active system is modeled using the concept of an active ideal turbulator. This active ideal turbulator model, developed in the current effort, is implemented using the XFOIL code. The results from this model are compared with experiments for fixed and active turbulators and it is shown that the model is sufficiently good for use in assessing the impact of the technology.

The effect of the drag reduction on the aircraft performance is studied in this effort using three notional unmanned aerial vehicles of different sizes. For this pur- pose, models for determining the aircraft drag and power-system characteristics have been developed. The improvements in aircraft endurance, range and rate of climb are studied. The results show that the active system can be used to achieve significant performance improvements when the bubble drag on the baseline air- foil is large. Results are also presented for the weight and power-consumption penalties of the active system at which the drag-reduction benefits are negated.