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TURBULENCE STRUCTURE OVER ALIGNED AND INCLINED RIBS IN ADVERSE PRESSURE GRADIENT

Jonathan M. Tsikata
Department of Mechanical and Manufacturing Engineering University of Manitoba E2-327 EITC, 75A Chancellors Circle, Winnipeg, MB. R3T 5V6 Canada

Mark F. Tachie
Department of Mechanical and Manufacturing Engineering, University of Manitoba, Winnipeg MB, R3T 5V6 Canada

Аннотация

This paper reports an experimental study of fully developed channel and adverse pressure gradient (APG) turbulent flows over transverse square ribs inclined at 90° and 45° to the approach flow. A particle image velocimetry (PIV) system was used to conduct velocity measurements in the streamwise-wall-normal plane in order to study the structural features of the flow over these rib configurations as well as the effects of APG on the flow. The results demonstrate that APG enhanced turbulence level compared to the fully developed channel flow. On the other hand, the 45° ribs decreased drag compared to 90° ribs. The two-point velocity correlations revealed that the inclination as well as the size of the hairpin packets varies with rib inclination and pressure gradient.