Novel design of a circulation control airfoil with cylinder rotation

Abstract

The objective of this research is to investigate the efficacy of Magnus effect on a circulation control airfoil (CCA). To achieve this, the Reynolds-averaged Navier–Stokes method is employed to numerically simulate the flow around a three-dimensional CCA configuration. The numerical verification demonstrates that the k–ω shear stress transport turbulence model provides better characterization of flow circulation and separation in the trailing edge area of the airfoil while ensuring the independence of the grid. The rotation speed is set at 15%, 30%, and 45% of the free-stream velocity, respectively, encompassing both clockwise and counterclockwise directions. The analysis focused on the characteristics of lift-drag forces, velocity circulation, and flow separation. The findings reveal that as the rotational speed increases in a clockwise direction, there is a progressive enhancement in aerodynamic performance of the airfoil. Both the flow separation point and stagnation point exhibit a backward shift in their respective positions. However, counterclockwise rotation produces an opposing effect. The amplitudes of fluctuating aerodynamic force coefficients are suppressed completely whether in clockwise or in counterclockwise rotation, resulting in a stable flow pattern consisting of a pair of vortices near the trailing-edge area. While the qualitative application of Bernoulli's principle explains the correlation between velocity circulation and surface pressure, there is a 12% margin of error in the quantitative analysis. Furthermore, evaluating the efficiency of circulation control while taking into account the input energy reveals that rotating the cylinder at 45% of free-stream velocity leads to a 23.6% increase in the lift-to-drag ratio.