Measurement and calculation of surface roughness effects on turbulent flow and heat transfer
Abstract
Fluid dynamics and heat transfer data for turbulent boundary layer flow of air over a smooth surface and three welldefined rough surfaces were taken in the Turbulent Heat Transfer Test Facility (THTTF) for xReynolds numbers ranging up to 10,000,000. The smooth wall data provided base line data for comparison with the data from rough surfaces. The three rough surfaces were composed of 1.27 mm diameter hemispheres spaced 2, 4, and 10 diameters apart, respectively, in staggered arrays on otherwise smooth flat plates. Skin friction coefficient distributions and boundary layer profiles of mean velocity and Reynolds stresses were obtained using hotwire anemometry. The THTTF heat transfer data taken in aerodynamically smooth, transitionally rough, and fully rough flow regimes over the three welldefined rough surfaces for freestream velocities of 6, 12, 28, 43, 58, and 67 m/s were compared with the data sets taken at Stanford University using a single welldefined rough surface. It was observed that the Stanton numbers for a given surface collapse together in xReynolds number coordinates as the freestream velocity increases, with the Stanton number level being larger for rougher surfaces. The THTTF heat transfer data and the Stanford data were used to modify the roughness energy transport model in the discrete element prediction method. This method was used in calculation of the fluid dynamics and heat transfer for the THTTF and Stanford surfaces. The predictions were in excellent agreement with all data sets within the data uncertainty.
 Publication:

Ph.D. Thesis
 Pub Date:
 1989
 Bibcode:
 1989PhDT........44H
 Keywords:

 Boundary Layer Flow;
 Energy Transfer;
 Surface Roughness Effects;
 Turbulent Boundary Layer;
 Turbulent Heat Transfer;
 Coefficient Of Friction;
 Free Flow;
 Prediction Analysis Techniques;
 Skin Friction;
 Stanton Number;
 Turbulent Flow;
 Velocity Distribution;
 Wall Flow;
 Fluid Mechanics and Heat Transfer