  The objective of this computational study is to quantify the influence of
wall-normal and angular momentum injections in suppressing laminar flow
separation over a canonical airfoil. Open-loop control of fully separated,
incompressible flow over a NACA 0012 airfoil at $\alpha = 9^\circ$ and $Re =
23,000$ is examined with large-eddy simulations. This study independently
introduces wall-normal momentum and angular momentum into the separated flow
using swirling jets through model boundary conditions. The response of the flow
field and the surface vorticity fluxes to various combinations of actuation
inputs are examined in detail. It is observed that the addition of angular
momentum input to wall-normal momentum injection enhances the suppression of
flow separation. Lift enhancement and suppression of separation with the
wall-normal and angular momentum inputs are characterized by modifying the
standard definition of the coefficient of momentum. The effect of angular
momentum is incorporated into the modified coefficient of momentum by
introducing a characteristic swirling jet velocity based on the non-dimensional
swirl number. With this single modified coefficient of momentum, we are able to
categorize each controlled flow into separated, transitional, and attached
flows.
