EXPERIMENTAL INVESTIGATION OF HEAT TRANSFER ON THE INTERNAL TIP WALL IN A ROTATING TWO-PASS RECTANGULAR CHANNEL

The current study experimentally studied heat transfer characteristics of the blade tip wall in a rotating internal cooling channel. The aspect ratio of this rectangular channel was 1:4, and the hydraulic diameter was 25.6 mm. Due to the impact of the 180 turn, complex three dimensional flow significantly affected heat transfer on the internal tip surface. The liquid crystal method is used to capture the heat transfer contour on the internal tip surface. In this study, the leading and trailing surfaces of the channel wall were either smooth or roughened with 45 angled ribs. The Reynolds number inside the pressurize two-pass cooling channel ranged from 10,000 to 30,000 at both stationary and rotating conditions. Furthermore, two channel orientations (90 and 135) were tested. The effect of Coriolis force on heat transfer is studied with the rotation number up to 0.53. The tip heat transfer from the smooth channel wall was more sensitive to rotation and the largest heat transfer enhancement as a result of rotation was 68%.