NACA 4415 is the most common and studied airfoil in aerodynamic studies. Incorporating flaps with NACA 4415 airfoil is an effective way to improve aerodynamic performance and efficiency. This study presents a comparative numerical analysis among a standard model of NACA 4415 airfoil, modified NACA 4415 incorporating gurney flap, and NACA 4415 airfoil incorporating bionic flap based on the coefficient of lift and coefficient of drag at various angles of attack (AOA) (i.e. -15°, -10°, -5°,0°,5°,10°,15°) and flap height of 2% of the chord length. The airfoil performance was evaluated under a constant upstream velocity of 20 m/s using Computational Fluid Dynamics (CFD) simulations. The performance was measured based on lift coefficient over drag coefficient ratio and it is validated using velocity and pressure contour over the surface of the airfoil. The highest lift coefficient over drag coefficient ratio was found in the NACA 4415 airfoil incorporating a gurney flap, then the standard NACA 4415 airfoil and the least value of the ratio comes with the NACA 4415 airfoil incorporating a bionic flap. For instance, the Gurney flap made a big difference, boosting the lift-to-drag ratio by 49.9% at 0° AOA compared to the standard airfoil. Conversely, the bionic flap reduced this ratio by 19.86%. However, in every case, NACA 4415 airfoil with Gurney flap outperforms than other two airfoils in this study. Moreover, the velocity and pressure contour also support the result found from lift and drag coefficient.