Measurement of turbulent boundary layer unsteady wall pressures beneath elastomer layers of various thicknesses on a plate

Cory J. Smith, Dean E. Capone, Timothy A. Brungart, William K. Bonness

Research output: Contribution to journalArticlepeer-review


The attenuation of turbulence-induced wall pressure fluctuations through elastomer layers is studied experimentally and analytically. Wall pressure statistics are measured downstream from a backward facing step, with no elastomer present and beneath 2-, 3- and 4-mm-thick elastomers in a water tunnel facility. In the absence of an elastomer layer, the wall pressure spectra, cross-spectra and velocity statistics measured at the various locations downstream from the backward facing step are in excellent agreement with those reported in the archival literature. The streamwise coherence measured beneath the elastomer layers is higher than that measured in the absence of an elastomer layer, an effect which increases with increasing elastomer thickness. It is speculated that this increase in coherence level is due to the ability of the elastomer to support shear stresses, which effectively increases the area over which an eddy influences the normal stresses measured by the pressure sensors. The high-frequency filtering of the elastomers is also observed in the coherence at the smallest streamwise separation. The attenuation of the turbulent boundary layer wall pressure fluctuations through the elastomer layer using an analytical elastomer transfer function is in excellent agreement with the attenuation measured experimentally through all thicknesses of elastomer and at all the free stream velocities at which the experiments are performed.

Original languageEnglish (US)
Pages (from-to)182-198
Number of pages17
JournalNoise Control Engineering Journal
Issue number3
StatePublished - May 1 2021

All Science Journal Classification (ASJC) codes

  • Building and Construction
  • Automotive Engineering
  • Aerospace Engineering
  • Acoustics and Ultrasonics
  • Mechanical Engineering
  • Public Health, Environmental and Occupational Health
  • Industrial and Manufacturing Engineering


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