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Turbulence and Shear Flow Phenomena -1 First International Symposium

ISBN:
1-56700-135-1 (Print)

CHARACTERISTICS OF TURBULENT COMBINED-CONVECTION BOUNDARY LAYER ALONG A VERTICAL HEATED PLATE

Yasuo Hattori
Fluid Dynamics Sector, Civil Engineering Research Laboratory, Central Research Institute of Electric Power Industry, 1646 Abiko, Abiko-city, Chiba, Japan

Toshihiro Tsuji
Department of Mechanical Engineering, Nagoya Institute of Technology Gokiso-cho, Showa-ku, Nagoya 466-8555, Japan

Yasutaka Nagano
Nagoya Industrial Science Research Institute; Department of Mechanical Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555, Japan

Nobukazu Tanaka
Fluid Dynamics Sector, Central Research Institute of Electric Power Industry 1646 Abiko, Abiko-shi, Chiba 270-1194, Japan

Abstract

Fluid flow and heat transfer characteristics in a turbulent combined-convection boundary layer in air along a vertical heated plate have been investigated with a normal hot wire and a cold wire. The measured heat transfer rates and turbulent quantities show that the turbulent transition moves downstream with a slight increase in freestream velocity. Then, the heat transfer rate rapidly decreases to about 40 % of that obtained in the turbulent natural-convection boundary layer, and velocity and temperature fluctuations become smaller in amplitude and change from random to harmonic at a specific frequency. Thus, the characteristics of the turbulent combined-convection boundary layer differ in several respects from those observed in both natural and forced convection. Based on the experimental results, the regimes of boundary layer flows are classified as a function of local Reynolds and Grashof numbers.