Acoustics of a Dual-jet Circulation Control Elliptical Airfoil

The objective of this research was to complete a comprehensive experimental study of the noise generated by a dual-slotted Circulation Control (CC) airfoil. The sound generated by a CC model was measured utilizing a microphone array for relatively high Reynolds numbers ( ~ 800,000) and low free stream Mach number ( < 0.1). Varied jet velocity and free stream velocity values were tested in order to investigate the magnitude and scaling of the various sound sources. These sources include those generated by both the external flow around the airfoil and the jet flow originating from slots at the trailing edge. The interaction of these to flow fields can generate an additional turbulent source mechanism. Reasonable agreement with the analytical models developed by Howe (2002) is shown for spectral shape as well as the free stream and jet velocity dependence. Further investigation, however, is requires in order to better predict the spectral magnitudes.