Theoretical and Experimental Investigation of Vibration Damping by Vorticity Production
Abstract
Analytical models are formulated and solved to determine the energy transfer between a vibrating perforated plate of finite thickness and a mean shear flow over one or both sides of the plate. Energy transferred to the flow appears as the kinetic energy of vorticity produced in the perforates and swept downstream by the flow. Regions of positive and negative damping are identified as functions of the vibration frequency, and a new, analytic determination is made of the operating stages of self-sustained oscillations of shear flow over apertures (including wall cavities) and validated by comparison with experiment. Numerical predictions are also given that extend the analysis to perforates of arbitrary shape. A water channel experiment has been performed to measure the damping by vorticity production of a vibrating, perforated elastic plate at zero mean angle of attack. An outline description is given of experiments currently in progress in which a porous flap is excited by a large scale vortex flow in a wind tunnel; measurements are being made of the vibration damping achieved by vorticity production stimulated by blowing through surface apertures.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 1998
- Accession Number
- ADA351025
Entities
People
- Michael S. Howe
Organizations
- Boston University