Effects of SJA boundary conditions on predicting the aerodynamic behavior of NACA 0015 airfoil in separated condition

Synthetic jet actuators (SJAs) are popular active-flow control devices. Hence, they have been widely investigated through computational fluid dynamics (CFD) simulations and experiments. Although such simulations are faster, cheaper, and more popular than experiments, the simulation results of similar geometries often differ from one another. A reason for the differences between CFD results is the simplification of CFD models. To determine the influence level of SJA simplifications on the aerodynamics of an airfoil under a separated condition, this study compares the most complicated assumption for SJA simulation with the simplest one. A NACA 0015 airfoil is simulated at an angle of attack of 16.6° and a Reynolds number of 896000. Two different methods are applied to simulate SJA, namely, morphing mesh (MM) technique for piston movement and oscillatory inlet velocity (OIV) at the jet-exit location. Results reveal that the mean lift value of the MM case is only 3% less than that of the OIV case. However, the drag forces of MM case are approximately 15% higher than those of the OIV case. In addition, the vortex structures in the OIV case are smaller than those in the MM case. Finally, the cycle-averaged streamlines of the two models are similar near the trailing edge, but they differ in the vicinity of the SJA exit location.