The aerodynamic study of the single and tandem asymmetrically heaving NACA0012 airfoils

The aerodynamic performance of a 2D NACA0012 airfoil exhibiting asymmetric heaving motion has been numerically studied by keeping the upstroke Strouhal number (St) at 0.3 and varying the downstroke St between 0.3 to 1.2. The Reynolds number (Re) and heaving amplitude (h₀) are fixed as 5000 and 0.75C; C is the airfoil chord length. It is observed that the maximum lift and thrust performance of the airfoil is achieved for the upstroke and downstroke St combination of 0.3 and 0.7. Later, the aerodynamic performance of the tandem 2D NACA0012 airfoils of identical dimension as previously is investigated by varying the initial pitch angle and phase difference between the front and rear airfoils while keeping their upstroke and downstroke St as 0.3 and 0.7. Here the rear airfoil is located at the downstream wake stable equilibrium position of the front airfoil and is heaved at a phase difference of -90º to +90º from the front airfoil. In addition, the rear airfoil pitch angle is varied between 0-20º but is kept constant over the complete heaving cycle. At a 10º phase difference and 10º pitch angle, a maximum lift and thrust of the tandem heaving airfoils are observed in the considered parametric space. The detail of the flow physics associated will the discussed in the presentation.