Wall Pressure Fluctuations during Transition on a Flat Plate.
Abstract
Detailed measurements of wall pressure fluctuations have been made in the intermittent region of a flat plate boundary layer. Digital sampling and processing were used. The properties of these pressure fluctuations were found to be similar to the previous measurements made in the fully turbulent region. The measurements were repeated with a single two dimensional surface roughness on the plate. The only changes in the results were a decrease in the transition Reynolds number from 2.0 to 1.2 million per foot and an increase in the decay rate of the longitudinal cross-spectral density magnitude by a factor of about 1.5. Emmons' analytical model of the burst rate in the transition region was found to be inaccurate. His model treats the sources of the turbulent spots as independent random events with prescribed probability density functions. Both a delta function and a constant were used as the source density functions and in each case the burst rate was about two times higher than the present measurements. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 01, 1979
- Accession Number
- ADA075379
Entities
People
- Charles Joseph Gedney
Organizations
- Massachusetts Institute of Technology