Aerodynamics and Heat Transfer in a Separated Flow in an Axisymmetric Diffuser with Sudden Expansion
V. I. Terekhov, T. V. Bogatko
Kutateladze Institute of Thermophysics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090 Russia
Keywords: отрывное течение, турбулентный теплообмен, диффузор, градиент давления, separated flow, turbulent heat transfer, diffuser, pressure gradient
Abstract
Results of a numerical study of the influence of a positive pressure gradient in an axisymmetric diffuser with sudden expansion of a circular tube on aerodynamics and turbulent heat transfer in regions of flow separation, reattachment, and relaxation are reported. The air flow prior to separation is assumed to be fully turbulent and to have a constant Reynolds number ReD1 = 2.75×104. The tube expansion degree is 1.78, and the apex half-angle of the diffuser is varied from 0 to 5 oC. It is found that an increase in the pressure gradient leads to a decrease in the heat transfer intensity in the separation region, and the maximum heat release point moves away from the flow separation point. The calculated results are compared with experimental data. It is shown that the behavior of the separated flow behind the step becomes significantly different as the streamwise pressure gradient changes.
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