An Experimental Study of Surface Roughness Effects on Turbulent Boundary Layer Flow and Heat Transfer PDF Download
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Author: Hugh W. Coleman Publisher: ISBN: Category : Languages : en Pages : 46
Book Description
During the first year of this program the calibration and qualification of the turbulent heat transfer test apparatus were completed for heat transfer measurements. The heat transfer data taken for zero pressure gradient, constant wall temperature, incompressible flow over a smooth wall agree with standard, accepted data sets for such conditions within the scatter of the standard data.
Author: Hugh W. Coleman Publisher: ISBN: Category : Languages : en Pages : 46
Book Description
During the first year of this program the calibration and qualification of the turbulent heat transfer test apparatus were completed for heat transfer measurements. The heat transfer data taken for zero pressure gradient, constant wall temperature, incompressible flow over a smooth wall agree with standard, accepted data sets for such conditions within the scatter of the standard data.
Author: Publisher: ISBN: Category : Languages : en Pages : 270
Book Description
The primary objective of this research program was to investigate the effects of surface roughness on turbulent boundary layer heat transfer by obtaining accurate, comprehensive, quality heat transfer data for zero pressure gradient incompressible air flow over constant temperature test surfaces with well-defined surface roughness geometries. Knowledge gained from the experimental investigation was used to improve and extend the roughness energy transport model used in the discrete element prediction method, thus enhancing and expanding the capability to predict the effects of surface roughness on turbulent flow and heat transfer. Fluid dynamics and heat transfer data for turbulent boundary layer flow over a smooth and five rough surfaces were taken in the Turbulent Heat Transfer Test Facility (THTTF) for x-Reynolds numbers ranging up to 10,000,000. The smooth wall data was used for qualification of the THTTF and provided base line data for comparison with the data from rough surfaces.
Author: Paul B. Gooderum Publisher: ISBN: Category : Heat Languages : en Pages : 63
Book Description
Interferometric measurements were made of the density profiles of an unsteady turbulent boundary layer on the flat wall of a shock tube. The investigation included both subsonic and supersonic flow (Mach numbers of 0.50 and 1.77) with no pressure gradient and with heat transfer to a cold wall. Velocity profiles and average skin-friction coefficients were calculated. Effects on the velocity profile of surface roughness and flow length are examined.
Author: C. K. Liu Publisher: ISBN: Category : Boundary layer Languages : en Pages : 171
Book Description
Experimental data are presented on flow structure, mean, and fluctuating velocities in turbulent boundary layers over a family of flat surfaces with transverse roughness elements made of square bars of variable spacing. All flows were incompressible and had zero streamwise pressure gradient. The flow structures are described for surfaces extending from hydraulically smooth to fully rough. A distinct flow pattern is observed in the wall region for each of four cases: smooth, skimming, wake-interference and isolated-roughness flow. Maximum roughness was observed with a ratio of gap to bar width of approximately 11. The most obvious effect of an increase in surface roughness is the distinct increase of turbulence production and the concomittant increase in the value of eddy viscosity. It is shown that this increase in eddy viscosity increases the total thickness of the layer in the same way that an increase in molecular viscosity would do in a laminar layer. The normalization of eddy viscosity for the outer portion of the layer as suggested by Clauser is found to apply to the rough surfaces studied. (Author).
Author: Milton J. Thompson Publisher: ISBN: Category : Languages : en Pages : 96
Book Description
The report provides a summary of theoretical and experimental research on turbulent boundary layers under supersonic free stream conditions. The program included investigations of boundary layer behavior at various Mach Numbers for smooth, adiabatic surfaces, various types of surface roughness, and the combined effects of roughness and heat transfer. The experimental program involved velocity profile measurements and the momentum deficit method of calculating skin friction, determinations of local shear stress values, and the utilization of plug-type calorimeters for determinations of heat transfer rates.
Author: Michael L. Finson Publisher: ISBN: Category : Languages : en Pages : 46
Book Description
A Reynolds stress model for turbulent boundary layers is used to study surface roughness effects on skin friction and heat transfer. The issues of primary interest are the influence of roughness character (element shape and spacing) and the nature of roughness effects at high Mach numbers. Computations based on the model compare satisfactorily with measurements from experiments involving variations in roughness character, in low speed and modestly supersonic conditions. The more limited data base at hypersonic Mach numbers is also examined with reasonable success, although no quantitative explanation is offered for the reduction of heat transfer with increasing roughness observed by Holden at Me = 9.4. The present calculations indicate that the mean velocity is approximately uniform over much of the height range below the tops of the elements, y less than or equal to k. With this constant 'roughness velocity, ' it is simple to estimate the form drag on the elements. This roughness velocity has been investigated by systematically exercising the present model over ranges of potential parameters. The roughness velocity is found to be primarily a function of the projected element frontal area per unit surface area, thus providing a new and simple method for predicting roughness character effects. The model further suggests that increased boundary layer temperatures should be generated by roughness at high edge Mach numbers, which would tend to reduce skin friction and heat transfer, perhaps below smooth wall levels. (Author).
Author: Hugh W. Coleman
Author: Hugh W. Coleman
Author: Sylvia Huebbe-Walker
Author: 
Author: Frank Levi Young
Author: Stanford University. Thermosciences Division. Thermosciences Division
Author: Paul B. Gooderum
Author: Michael S. Holden
Author: C. K. Liu
Author: Milton J. Thompson
Author: Michael L. Finson