Velocity-Field Measurements of an Axisymmetric Separated Flow Subjected to Amplitude-Modulated Excitation

By: Nasa, National Aeronautics and Space Adm

Active flow control was applied at the point of separation of an axisymmetric, backward-facing-step flow. The control was implemented by employing a Helmholtz resonator that was externally driven by an amplitude-modulated, acoustic disturbance from a speaker located upstream of the wind tunnel. The velocity field of the separating/reattaching flow region downstream of the step was characterized using hotwire velocity measurements with and without flow control. Conventional statistics of the data reveal that the separating/reattaching flow is affected by the imposed forcing. Triple decomposition along with conditional averaging was used to distinguish periodic disturbances from random turbulence in the fluctuating velocity component. A significant outcome of the present study is that it demonstrates that amplitude-modulated forcing of the separated flow alters the flow in the same manner as the more conventional method of periodic excitation. Trosin, Barry James Langley Research Center NASA/CR-2007-214889

• Format: Paperback
• Language: English
• ISBN: 1794172203
• ISBN13: 9781794172203
• Release Date: January 1
• Publisher: Independently Published
• Length: 112 Pages
• Weight: 0.61 lbs.
• Dimensions: 0.2" x 8.5" x 11.0"