Buoyancy effects at high rotation number on the flow field inside a triangular shaped rib roughened channel

The flow field inside a triangular cooling channel for the leading edge of a gas turbine blade has been investigated. The efforts were focused on the interaction between effects of rotation and those induced by turbulence promoters, i.e. perpendicular square ribs placed on both leading and trailing sides of the duct. PIV and Stereo-PIV measurements have been conducted for Re=10000, rotation number of 0, 0.2, and 0.6, and buoyancy parameter equal to 0, 0.08, and 0.7. Coriolis secondary flows are detected in the duct cross section, but contrary to the smooth case, they are characterized by a single main vortex and are less affected by an increase of the rotation parameter. Moreover, their main topology is only marginally affected by the buoyancy forces. Conversely, the features of the recirculation structure downstream the ribs turned out to be more sensible to a change of the sense of rotation and to buoyancy forces.