Characteristics of turbulent combined-convection boundary layer along a vertical heated plate

Fluid flow and heat transfer characteristics in a turbulent combined-convec tion boundary layer in air along a vertical heated plate have been investig ated with normal hot and cold wires. The measured heat transfer rates and t urbulent quantities show that the turbulent transition moves downstream wit h a slight increase in freestream velocity. Then, the heat transfer rate ra pidly decreases to about 40% of that obtained in the turbulent natural-conv ection boundary layer, and velocity and temperature fluctuations become sma ller in amplitude and change from random to harmonic at a specific frequenc y. Thus, the characteristics of the turbulent combined-convection boundary layer differ in several respects from those observed in both natural and fo rced convections. Based on the experimental results, the regimes of boundar y layer flows are classified as a function of local Reynolds and Grashof nu mbers. (C) 2000 Begell House Inc. Published by Elsevier Science Inc. All ri ghts reserved.