Aerodynamic performance characteristics of winglet configurations for the low and medium Reynolds number operations

Three-dimensional numerical simulation-assisted parametric evaluation of winglet design for the small unmanned aerial vehicles (UAV) has been performed at low range and medium range of Reynolds number (Re) using commercial CFD package, Ansys-Fluent. By systematic variation of winglet parameters: sweep back and cant angle, the selection of optimum value of these parameters had to be selected for achieving better values of CL/CD and CL1.5/CD to minimize the drag and maximize the range and endurance. Out of these geometrical winglet parameters, by varying one winglet parameter while keeping other parameter as a constant, different sets of winglet configuration have been developed and the detailed representation of semi-wing with winglet geometry has been generated using Computed-Aided Design (CAD) tool. The computational domain has been solved for the Re of 0.9794 × 106 and 0.9794 × 105 using “3D Reynolds Averaged Navier–Stokes equations†along the turbulence model, k-𠜖 for all wing configurations with and without winglet planned for this study. From Lift and Drag values for each angle of attack (AOA), CL and CD have been estimated for identifying optimum value of CL/CD and CL1.5/CD to have maximum range and endurance with minimum drag during the cruise operation of small UAVs in low and medium Re range operation. Out of all wing with winglet configurations considered here, the winglet with cant of 70° and 90° results in ending up with better aerodynamic performances for providing better range and endurance. At the same time, the change in sweep angle of the winglet does not show any variation, in turn there is a decrease in aerodynamic performance.