Accession Number : ADA312506

Title :   Wall-Jet Turbulent Boundary Layer Heat Flux, Velocity, and Temperature Spectra and Time Scales.

Descriptive Note : Final rept. 1 Nov 95-9 Jul 96,

Corporate Author : WRIGHT LAB WRIGHT-PATTERSON AFB OH

Personal Author(s) : Holmberg, David G. ; Pestian, David J.

PDF Url : ADA312506

Report Date : JUN 1996

Pagination or Media Count : 11

Abstract : The interactions of boundary layer flow temperature fluctuations (t') and velocity fluctuations (u', v') together with surface heat flux fluctuations (q') have been investigated experimentally in a flat plate turbulent boundary layer in order to better understand time-resolved interactions between flow unsteadiness and surface heat flux. A Heat Flux Microsensor (HFM) was placed on a heated flat plate beneath a turbulent wall jet, and a split-film boundary layer probe was traversed above it together with a cold-wire temperature probe. The recorded simultaneous time-resolved u'v't'q' data can be correlated across the boundary layer. Results indicate that wall heat transfer (both mean and fluctuating components) is controlled by the u' fluctuating velocity field. In the presence of high free stream turbulence (FST), the heat flux is largely controlled by free stream eddies of large size and energy reaching deep into the boundary layer, such that heat flux spectra can be determined from the free-stream velocity field. This is evidenced by uq coherent present across the boundary layer, as well as by similarity in heat flux and a u velocity spectra, and by the presence of large velocity scales down to the nearest wall measuring location just above the laminar sublayer.

Descriptors :   *TURBULENT BOUNDARY LAYER, *HEAT FLUX, *BOUNDARY LAYER FLOW, HEAT TRANSFER, TURBULENCE, EDDIES(FLUID MECHANICS), FLOW FIELDS, TEMPERATURE GRADIENTS, THERMAL ANALYSIS, UNSTEADY FLOW, BOUNDARY LAYER TRANSITION, FREE STREAM, SURFACE TEMPERATURE, LAMINAR FLOW, LAMINAR BOUNDARY LAYER, JET MIXING FLOW.

Subject Categories : Fluid Mechanics
      Thermodynamics

Distribution Statement : APPROVED FOR PUBLIC RELEASE