THE EFFECT OF ACOUSTICS ON FLOW PASSING A HIGH-AOA AIRFOIL

✍ Scribed by F.-B. Hsiao; J.-J. Jih; R.-N. Shyu

• Publisher: Elsevier Science
• Year: 1997
• Tongue: English
• Weight: 312 KB
• Volume: 199
• Category: Article
• ISSN: 0022-460X
• DOI: 10.1006/jsvi.1996.0618

✦ Synopsis

In this paper a study is presented of the separated flow properties and corresponding aerodynamic behaviors of a high-AOA, NACA 633-018 airfoil under internal acoustically pulsing excitation in a subsonic wind tunnel. The measurements by means of pitot-static pressure tube and hot-wire anemometer include the boundary layer velocity profiles, boundary layer velocity energy spectra and velocity defect profiles in the wake. Results indicate that the acoustic excitation technique is able to alter the flow properties and thus to improve the aerodynamic performance, especially when the airfoil is fully stalled at high AOA. After the flow is effectively excited, the developed boundary layer delays its separation from the surface. The most effective excitation frequency is found to be equal to the shear layer instability frequency when the airfoil is around at the post-stall angle; however, it becomes of the vortex shedding frequency of the wake when the airfoil's AOA is increased beyond the stall. Data also show that the higher the pulsing acoustic level is, the better the flow properties are improved.