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ISSN Online: 2377-424X

ISBN Print: 0-89116-909-1

International Heat Transfer Conference 9
August, 19-24, 1990 , Jerusalem, Israel

SIMULTANEOUS MEASUREMENTS OF TIME-RESOLVED SURFACE HEAT FLUX AND FREESTREAM TURBULENCE AT A STAGNATION POINT

Get access (open in a dialog) DOI: 10.1615/IHTC9.2340
pages 375-380

Resumo

Two rapid-response thin-film heat flux gages have been used to measure time-resolved unsteady heat transfer signals. The Heat Flux Microsensor is a passive gage which measures the temperature difference across a thin thermal resistance layer. The second sensor, an actively powered gage, measures heat transfer by dissipating measured power. These gages have frequency performance windows of 50 kHz and 250 Hz, respectively. Each gage is placed at a flow stagnation point with a velocity probe placed outside the boundary layer. Simultaneous monitoring of these signals allows the documentation of the effects of freestream turbulence on boundary layer heat transfer. The results indicate a direct correlation between the turbulent velocity fluctuations and heat flux variation. The effects of single frequency turbulent components in the freestream on instantaneous heat transfer are compared to similar results obtained for single-frequency flow pulsation. It is anticipated that this sort of detailed information will lead to increased understanding of the effects of turbulence on heat transfer.