Heat transfer characterization inside a rotating rib roughened cooling channel with multiple heated walls

This work experimentally investigates the effects of walls heating conditions on the heat transfer coefficient distribution inside a rotating cooling channel. The model has a square cross-section with a hydraulic diameter of 50 mm and one ribbed side. The ribs are perpendicular to the main flow direction, the rib pitch-to-height ratio is 10, and the blockage ratio is 10%. Detailed heat transfer measurements were performed employing the liquid crystals thermography in steady-state approach under two thermal boundary conditions: only ribbed wall heated or equal heat fluxes set to ribbed wall and sidewalls. Inlet Reynolds number was 20000 and the tests were conducted in both static and rotating conditions up to a rotation number of 0.18, with the ribbed wall acting as trailing edge side. The results show that the wall heating conditions have a negligible effect on the heat transfer distribution for the stationary case, whereas, they lead to a modification of the heat transfer distribution under rotation with an overall enhancement when three walls are heated.