Mechanisms of turbulence transport in a turbine blade coolant passage witha rib turbulator

This paper provides detailed measurements of the flow in a ribbed coolant p assage, and attempts to delineate the important mechanisms that contribute to the production of turbulent shear stress and the normal stresses. If is shown that the separated flow behind the rib is dictated by large-scale str uctures, and that the dynamics of the large-scale structures, associated wi th sweep, ejection, and inward and outward interactions, all play an import ant role in the production of the turbulent shear stress. Unlike the turbul ent boundary layer in a separated shear flow past the rib, the inward and o utward interaction terms are both important, accounting for a negative stre ss production that is nearly half of the positive stress produced by the ej ection and sweep mechanisms. It is further shown that the shear layer wake persists well past the re-attachment location of the shear layer, implying that the flow between ribbed passages nel er recovers to that of a turbulen t boundary layer. Therefore, even past re-attachment, the use of statistica l turbulence models that ignore coherent structure dynamics is inappropriat e.