Date of Award
Master of Science in Engineering
Mechanical and Aeronautical Engineering
Dr. Parviz Merati
Dr. Richard B. Hathaway
Dr. Judah Ari-Gur
Masters Thesis-Open Access
This research investigated the effects of internal acoustic excitation on the boundary layer and surface of an airfoil. A NACA 16- 018 symmetric airfoil was tested in the Western Michigan University wind tunnel. The shedding vortex frequency of the airfoil was determined using hot-film anemometry. Using stroboscopic and holographic interferometry, the natural frequencies of the airfoil surface were determined. The airfoil surface was tuned such that the frequency of the shedding vortex is a resonant frequency and two internally mounted acoustic drivers were used to excite the surface of the airfoil at the shedding vortex frequency. The effects on pressure drag of acoustic excitation at various amplitudes were recorded. A reduction in drag of approximately 5-7% was recorded with excitation at 100 Hz and 83 dB and the power per unit area saved from a reduction in drag was approximately 1600 to 2800 times greater than that required to excite the boundary layer flow. A reduction in pressure drag has the potential of improving the efficiency of current airfoils and leading to better airfoil designs.
Holforty, Wendy L., "Internal Acoustic Excitation of an Airfoil Surface for Drag Reduction" (1994). Master's Theses. 4906.