  Large eddy simulation of a NACA0015 circulation control airfoil using
synthetic jets is conducted. A chord Reynolds number of 110000, the excitation
frequency of 175 Hz, the momentum coefficients of 0.0044 to 0.0688, and the
angles of attack of 0{\deg}, 6{\deg}, and 12{\deg} are employed in this study.
The numerical results presented in this paper show good agreement with the
experimental results. Fluctuations in the lift and drag coefficients on the
non-actuated airfoil are found to be governed by the vortex shedding frequency.
Provided that the momentum coefficient is sufficiently high, the lift and drag
coefficients tend to fluctuate at the synthetic jet frequency. The mean lift
coefficient linearly increases with the momentum coefficient at a low momentum
coefficient range and its incremental rate begins to decline at a high momentum
coefficient range. Increasing the angle of attack of the airfoil is observed to
slightly reduce the slope of the lift increment.
