Accession Number : ADA308223
Title : An Experimental Investigation 0f Heat Transfer in Three-Dimensional and Separating Turbulent Boundary Layers.
Descriptive Note : Technical rept. Jun 91-Dec 95,
Corporate Author : VIRGINIA POLYTECHNIC INST AND STATE UNIV BLACKSBURG DEPT OF AEROSPACE AND OCE AN ENGINEERING
Personal Author(s) : Lewis, Douglas J. ; Simpson, Roger L.
PDF Url : ADA308223
Report Date : 07 MAY 1996
Pagination or Media Count : 495
Abstract : The turbulence structure of convective beat transfer was studied experimentally in complex three-dimensional and separating turbulent boundary layers. Three test cases whose fluid dynamics have been well documented were examined. In case 1, time- and spatially-resolved surface heat transfer was measured in the nose region of a wing-body junction formed by a wing and a flat plate. Both the wing and the endwall were heated and held at a constant uniform temperature 20 C above ambient temperature. Heat flux rates were increased up to a factor of 3 over the heat flux rates in the approach boundary layer. The rms of the heat flux fluctuations were as high as 25% of the mean heat flux in the vortex-dominated nose region. Away from the wing, upstream of the time-averaged vortex center, augmentation in the heat flux is due to increased turbulent mixing caused by large-scale unsteadiness of the vortex. Adjacent to the wing the augmentation in heat flux is due to a change in the mean velocity field. In case 2, simultaneous surface heat flux and temperature profiles were measured at 8 locations in the spatially-developing pressure-driven three-dimensional turbulent boundary layer upstream of a wing-body junction. Mean heat transfer was decreased 10% by three-dimensionality. The turbulent Prandtl number in the near-wall region of logarithmic temperature variation was approximately 0.9 at all measurement locations in the three-dimensional boundary layer. Profiles of the skewness factor of temperature fluctuations and conditionally-averaged temperature signals during a sweep/ejection event suggest that the strength of ejections of hot fluid from the near-wall region are decreased by three-dimensionality.
Descriptors : *TURBULENT BOUNDARY LAYER, *CONVECTION(HEAT TRANSFER), *HEAT FLUX, *THREE DIMENSIONAL FLOW, PRESSURE GRADIENTS, ALGORITHMS, SPATIAL DISTRIBUTION, TIME DEPENDENCE, HIGH TEMPERATURE, TIME SERIES ANALYSIS, TURBULENCE, TURBULENT FLOW, POWER SPECTRA, VORTICES, COMPUTATIONAL FLUID DYNAMICS, FLOW VISUALIZATION, CORRELATION, FLOW FIELDS, TEMPERATURE GRADIENTS, THERMAL ANALYSIS, TWO DIMENSIONAL FLOW, UNSTEADY FLOW, AEROTHERMODYNAMICS, SURFACE TEMPERATURE, FLOW SEPARATION, WING BODY CONFIGURATIONS, PRESSURE DISTRIBUTION, REYNOLDS NUMBER, THERMAL STRESSES, BOUNDARY LAYER FLOW, STAGNATION POINT, JET MIXING FLOW, PRANDTL NUMBER.
Subject Categories : Fluid Mechanics
Distribution Statement : APPROVED FOR PUBLIC RELEASE