Control of sound radiation from a wavepacket over a curved surfaceActive control of acoustic pressure in the far field resulting from the growth and decay of a wavepacket convecting in a boundary layer over a concave-convex surface is investigated numerically using direct computations of the Navier-Stokes equations. The resulting sound radiation is computed using linearized Euler equations with the pressure from the Navier-Stokes solution as a time-dependent boundary condition. The acoustic far field exhibits directivity type of behavior that points upstream to the flow direction. A fixed control algorithm is used where the attenuation signal is synthesized by a filter which actively adapt it to the amplitude-time response of the outgoing acoustic wave.
Document ID
19890046376
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Maestrello, Lucio (NASA Langley Research Center Hampton, VA, United States)
El Hady, Nabil M. (Analytical Services and Materials, Inc. Hampton, VA, United States)