Measurements of fluid pressure, velocity, including turbulent fluctuations
and heat transfer were made over the straight and curved lower surface of a
wind tunnel with an upper surface which could be flexed to control the str
eamwise pressure gradients. Laser-Doppler techniques were employed for flow
visualisation and detailed investigation of the how structure. These were
roughened in a structured manner with machined excrescences of pyramidal an
d trapezoidal shape. Fluid dynamic data are presented for smooth and rough
surfaces and heat transfer results from roughnesses of three different heig
hts. Velocity gradients and curvature, less than often found in turbo-machi
nery, in the ranges examined, had relatively little effect compared to the
roughness. The present observations are compared with relevant data in the
literature. The elements of the present work showed enhancement of heat tra
nsfer at comparable conditions over 70% more than the more commonly reporte
d spherical forms. The observations are also compared with the predictions
of a computational fluid dynamic procedure developed in the authors' labora
tory (F.H.A. Tarada, Heat transfer to rough turbine blading. University of
Sussex, D.Phil thesis, 1987) with which there is fair to good agreement. Al
though the code overpredicts the effects of surface curvature and pressure
gradients, and the level of heat transfer at the higher velocities, discrep
ancies are usually within the experimental uncertainties. The comprehensive
range of fluid dynamic and heat transfer results are presented by Hubbe-Wa
lker (S.E. Hubbe-Walker, An experimental study of the effects of roughness
and curvature on heat transfer in turbulent boundary layers. University of
Sussex, D.Phil. thesis, 1996), is intended to provide a database for the de
velopment of more recent analytical and CFD procedures. (C) 1999 Published
by Elsevier Science Ltd. All rights reserved.