BOUNDARY LAYER PRESSURE FLUCTUATIONS AND STRUCTURAL RESPONSE
Abstract
Investigations of the pressure fluctuations under a turbulent boundary layer, and the resultant vibration of simple panels, were extended to consider the vibration of stringer-panel arrays and the intermittent pressure field in the boundary layer transition region. The response of multi-panel arrays to turbulent boundary layer excitation was measured for a flow speed of 320 ft./sec. Displacement spectra for the first band of modes, measured at the bay centres, were compared with results due to acoustic excitation at grazing incidence. The vibration in the lower order modes is greater for the acoustic excitation but the converse is true for the higher order modes. Displacement cross correlation measurements show the presence of standing waves for distances up to three bay lengths but the wave system breaks down over larger distances. A comparison of random techniques used in structural damping measurements shows the autocorrelation decay method to be the most reliable. Using specially constructed gating apparatus, pressure measurements in the laminar-turbulent transition region show that the turbulent spots are autonomous regions of turbulent boundary layer, with similar pressure spectra. In addition there are low frequency pressure fluctuations due to the disturbances produced by the pressure steps on the mean flow. The background noise levels in the wind tunnel were measured.
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 01, 1967
- Accession Number
- AD0824657
Entities
People
- Deane R. Blackman
- Duncan M. Clark
- George J. Mcnulty
- John F. Wilby
Organizations
- University of Southampton