Computer Modeling of Time History of Velocity Field and Net Momentum Output of a Synthetic Jet Actuator

Abstract

Synthetic jet actuators have been used for control of flow separation in high performance airfoils for increasing lift and low drag. The synthetic jets have zero net mass flux but impart net momentum to the flow. In this study, LES simulations was used to study the time history of outlet velocity profile and net momentum imparted to the flow by a synthetic jet actuator (SJA). The SJA studied is not symmetric and operates with the aid of a piezoelectric (PZT) ceramic circular plate actuator. A three-dimensional mesh for the computational domain of the SJA and surrounding volume was developed and was used to evaluate the details of the airflow conditions inside the SJA as well as at the outlet. The vibration of the PZT ceramic actuator was used as a boundary condition in the computational model to drive the SJA. Particular attention was given to the time evolution of the SJA outlet velocity profile. The time history of the outlet velocity profile of the synthetic jet was curve-fitted to an empirical equation. The resulting outlet velocity could be used as an inlet velocity for active close loop control of airflow separation around an airfoil at high angle of attack.