HEAT TRANSFER IN A RIB-ROUGHENED ROTATING TWIN-PASS TRAPEZOIDAL-SECTIONED PASSAGE WITH COOLING APPLICATION TO GAS TURBINE ROTOR BLADE

摘要

An experimental study of heat transfer in a radially rotating twin-pass trapezoidal-sectioned duct with two opposite walls roughened by 45° staggered ribs was performed. Two channel orientations of 0° and 45° from the direction of rotation were tested. At each Reynolds number of 5000, 7500, 10000, 12500 and 15000, local Nusselt numbers along the centrelines of two rib-roughened surfaces with five different heating levels were acquired at rotating numbers of 0, 0.1, 0.3, 0.5, 0.7 and 1. A selection of experimental results illustrates the isolated and interactive impacts of convective inertial, Coriolis and rotating buoyancy forces on local and spatially-averaged heat transfers. The isolated Coriolis force-effect improves heat transfer over two unstable surfaces of the rotating twin-pass channel. Rotating buoyancy effect undermines local heat transfer and its influence is weakened when the rotating number increases. Both Coriolis force and rotating buoyancy provide the higher degree of heat transfer impacts in the first passage with radially outward flow relative to the second passage with radially inward flow. The increase of channel orientation from 0° to 45° respectively improves and impedes the heat transfers along the centrelines of the first (radially outward flow) and the second (radially inward flow) passages in the range of 5-26% when rotating numbers vary from 0.1 to 1.