Title

Investigation of the Effect of Backward-Facing and Forward-Facing Steps on Turbulent Mixed-Convection Flow over a Flat Plate

Document Type

Article

Publication Date

4-2009

Publication Source

Experimental Heat Transfer

Volume

22

Issue

2

Inclusive pages

117-127

DOI

10.1080/08916150902805927

Publisher

Taylor & Francis Inc.

Place of Publication

United States

ISBN/ISSN

08916152

Peer Reviewed

yes

Abstract

The effects of backward-facing and forward-facing steps on a turbulent buoyancy-dominated mixed-convection flow over a flat plate are examined experimentally. Air velocity and temperature distributions and their turbulent fluctuations are measured simultaneously by using a two-component laser-Doppler velocimeter and a cold wire anemometer, respectively. The experiment was carried out for a step (backward-facing/forward-facing) height of 22 mm, a temperature difference, ΔT, of 30°C between the heated walls and the free-stream air (corresponding to a local Grashof number Grxi = 6.45 × 1010), and a free-stream velocity of 0.48 m/s. It was found that the introduction of backward- and forward-facing steps increases the turbulence intensity of the velocity and temperature fluctuations downstream of the step. The present results also reveal that the maximum local Nusselt number occurs in the vicinity of the reattachment zone, and it is approximately twice for the case of the backward-facing step and three times for the case of the forward-facing step than that of the flat plate value at similar flow and thermal conditions.

Disciplines

Engineering

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