Numerical investigation of unsteady aerodynamics on a grooved NACA 4415 airfoil

Surface grooves have demonstrated the capability to mitigate laminar separation bubbles and enhance airfoil aerodynamic performance. However, wind turbine operation introduces dynamic effects that significantly impact airfoil behavior, leading to substantial deviations from static conditions. Numerical simulations were carried out to discuss the effectiveness of surface groove structures in controlling separation bubbles under dynamic conditions and their potential to enhance unsteady aerodynamics. The influence of groove parameters (depth, width, position) on the NACA 4415 airfoil’s boundary layer attributes and unsteady aerodynamic properties are analyzed across various pitching amplitudes and reduced frequencies. It is found that the position of groove structures under dynamic conditions is crucial, that groove structures located ahead of separation bubbles on the airfoil surface can effectively eliminate the separation bubbles, and their control effectiveness is superior to that under static conditions. Well-designed groove structures can reduce the airfoil’s maximum lift, drag, and moment coefficients under dynamic conditions. They also reduce the aerodynamic hysteresis effect and improve the aerodynamic damping characteristics. This comprehensive analysis sheds light on the critical interplay between dynamic wind conditions, airfoil behavior, and the potential of groove structures to optimize wind turbine performance.