Experimental Investigation of Turbulent Prandtl Number and Reynolds Analogy in Transitional and Post-Transitional Boundary Layers
Abstract
The effects of elevated free-stream turbulence and streamwise acceleration on flow and thermal structures in transitional boundary layers have been investigated experimentally on a heated flat plate. The effects on the turbulent Prandtl number and Reynolds analogy were included in this study. The free-stream turbulence levels ranged from 0.5 to 7%, and the acceleration strengths, based on K, ranged from 0.39xl0 to the minus 6th power to 4.lxl0 to the minus 6th power. A three-wire probe was used to measure the detailed momentum and thermal boundary layer structures, including the streamwise and cross-stream velocity fluctuations, the temperature fluctuation, the Reynolds stresses, the Reynolds heat fluxes, the eddy viscosity, the turbulent thermal diffusivity and the turbulent Prandtl number. The results show that elevated free-stream turbulence values result in an earlier onset of transition and reduced length of transition, whereas streamwise acceleration delays the onset of transition and lengthens the transition region, even at elevated FSTI. Compared to streamwise acceleration, FSTI is the more dominant factor on flow and thermal structure in transitional boundary layers; however, streamwise acceleration significantly reduces the turbulent spot formation rate.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 1993
- Accession Number
- ADA270092
Entities
People
- Ting Wang
Organizations
- Clemson University