Heat transfer control in a separated flow behind a backward-facing step using tabs of various shapes
V.I. Terekhov, A.Yu. Dyachenko, Ya.I. Smulsky
Kutateladze Institute of Thermophysics SB RAS, Novosibirsk, Russia
Keywords: backward-facing step, tabs, heat transfer, turbulence, secondary flow
Abstract
The results of an experimental study of the influence of tabs (teeth) of various shapes on the intensity of turbulent heat transfer in the separation zone in the near wake of a backward-facing step are presented. In this stagnation region, a significant decrease in heat transfer is observed, which negatively affects the thermal-hydraulic efficiency. Five tab shapes were studied in the experiments: square, triangular, cylindrical, semi-cylindrical, and semi-conical ones. The tabs were installed at the step edge immediately before flow separation. Measurements were conducted at Reynolds number ReН = 4000 and varying tab pitch. It was found that square tabs with a pitch of 2.5 calibers (step height) have the greatest effect on flow and heat transfer, but at the same time, they cause the greatest hydraulic resistance, therefore, their thermal-hydraulic efficiency is lowest. Semi-conical tabs installed with a pitch of five calibers showed the best results.
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