(Dr. Ari Glezer, advisor)

"Flow Control On a NACA 4418 Airfoil Using Streamwise Synthetic Jet Actuators"

Abstract

The effectiveness of streamwise synthetic jets for flow control on a NACA 4418 airfoil is experimentally investigated.  The jet actuators are embedded in the airfoil and issue jets through streamwise aligned narrow slots in the surface of the airfoil.  A total of five spanwise arrays of jet orifices are incorporated into the airfoil to investigate the influence of parameters such as: jet strength, jet location and multiple jet forcing.  Pressure measurements around the profile are used to detect changes in the flow field around the airfoil and to calculated lift and pressure drag.

Initial tests performed for a wide range of angles of attack revealed prominent changes due to synthetic jet forcing at high angles of attack.  Separation was postponed and the lift increased by up to 75% relative to the unforced case.  Pressure drag was also reduced due to the reattachment of the flow on the back of the suction side.

The current work focused mainly on the influence of synthetic jet stimulation on the airfoil performance at small angles of attack.  Potential improvements in the lift and form drag were identified.  Depending on the location of the synthetic jets and the forcing conditions the pressure drag was reduced up to 19% compared to the conventional airfoil. The reduction primarily resulted from an increase in lift due to forcing, which can be converted into a slightly decreased angle of attack thus reducing form drag.