Experimental study of free-convective flow on a vertical plate with a constant heat flux in the presence of one or more steps

• Published in: International journal of heat and mass transfer 1995-01, Vol.38 (1), p.147-154
• Main Authors: Burak, V.S., Volkov, S.V., Martynenko, O.G., Khramtsov, P.P., Shikh, I.A.
• Format: Article
• Language: English
• Subjects: Convection and heat transfer; Errors; Exact sciences and technology; Flow visualization; Fluid dynamics; Fundamental areas of phenomenology (including applications); Heat flux; Interferometers; Lasers; Physics; Plate metal; Surfaces; Temperature; Turbulent flow; Turbulent flows, convection, and heat transfer; Vortex flow
• ISSN: 0017-9310; 1879-2189
• DOI: 10.1016/0017-9310(94)E0108-7

Free-convective heat transfer on a vertical plate with a constant heat flux in the presence of one or more regular steps on a plate was studied experimentally. Temperature fields were investigated by a Mach-Zehnder interferometer. The structure of free-convective flows on a plate was studied by the method of tracking visualization using a laser knife. A circulation free-convective flow, having the shape of two oppositely rotating vortices, was observed directly behind a step. During the experiment the Rayleigh number varied from zero to Ra = 2.8 × 103. The maximum Rayleigh number attained had a value Ra ∼ 2 × 104. The free-convective flow rate grew with Ra; however, qualitative changes in the structure of flow and of a temperature field were not observed in this case. The flow was visualized at different distances between the steps. As the width of the spacing between the steps increased, the vortices, arising in the separation zone, became more extended downstream. With the ratio of the step height to the spacing width equal to 1:3 and greater, a stagnation zone appeared near the first upstream step. A vortex flow between the steps enhanced heat transfer between the plate and environment.