Rotating heat transfer in turbine rotor blade cooling channels with turbulence promoters

An experimental study was made to obtain heat transfer data for two-pass square and rectangular channels with smooth and ribbed surfaces for two channel orientations (90° and 135° to the direction of rotational plane). In the two-pass square channel, ribs were placed on the leading and trailing surfaces at 45° angled ribs. In the two-pass rectangular channel, ribs were placed on the leading and trailing surfaces at 45° V-shaped ribs. Five different arrangements were tested in each setup. In rotation, the Coriolis and buoyancy forces induce secondary flow that causes different heat transfer patterns from the leading and trailing surfaces. This secondary flow redistributes the core flow and turbulence in an asymmetric fashion inside the coolant channel. The heat transfer from the first pass trailing and the second pass leading surfaces were augmented by rotation. However, the first pass leading and the second pass trailing surfaces showed a decrease in the heat transfer coefficient in rotation. The channel orientation of the coolant channel has significant effect on the secondary flow and heat transfer pattern. Ribs induced secondary flow that interact with the rotation secondary flow and created new characteristic processes in heat transfer.