Experimental study of the effects of DCA airfoil geometric parameters on the aerodynamic performance at low reynolds numbers flows

This study experimentally investigates the aerodynamic performance of Double Circular Arc (DCA) airfoils at low Reynolds, focusing on the effects of camber angle, relative thickness, and leading/trailing edge radii. Seven configurations were tested in a low-speed wind tunnel under various Reynolds numbers and angles of attack. Lift and drag coefficients were measured, complemented by pressure coefficient distributions and frequency-domain analysis of surface pressure fluctuations using Fast Fourier Transform (FFT). Results show that increasing camber angle enhances lift and delays stall, although drag increases at higher angles of attack. Distribution of pressure coefficient (C p ) indicate stronger suction peaks for larger camber, while FFT analysis reveals a dominant frequency between 58–64 Hz, with maximum amplitude for the highest camber case. Peak amplitude also rises with angle of attack, suggesting intensified unsteady flow. Thinner airfoils generate higher lift at low angles, whereas thicker sections improve stall characteristics and boundary layer stability. C p results for thicker profiles show reduced suction, consistent with lower FFT peak amplitudes. Variations in leading and trailing edge radii have minor aerodynamic effects, though sharper edges promote more abrupt stall and slightly higher fluctuation amplitudes. The dominant frequency, significantly below the estimated 100 Hz vortex shedding frequency, suggests coupled aerodynamic mechanisms rather than initial vortex shedding. Although DCA airfoils are traditionally known for their use in transonic flow applications, the findings presented here highlight their promising potential for broader use particularly in the development of wind turbine technology and low speed air vehicles.