EFFECT OF DIAMETER OF CLOSED-END COOLANT PASSAGES ON NAT URAL-CONVECTION WATER COOLING OF GAS-TURBINE BLADES

摘要

An experimental investigation was conducted on a water-cooled gas turbine with blade coolant-passage diameters ranging from 0.100 to 0.500 inch, corresponding to length-to-diameter ratios from 25.5 to 5.1, in various quadrants of the turbine. The investigation was conducted to determine (l) whether coolant-passage length-to-diameter ratio has a sig-nificant effect on natural-convection heat-transfer correlation, and (2) whether turbine blade temperatures could be calculated with reasonable accuracy from a theoretical natural-convection heat-transfer correlation.nBecause of large temperature gradients within liquid-cooled turbine blades, it was found necessary to account for the conduction process in order to determine the temperature difference between the coolant passage surface and the place of blade temperature measurement. By use of an electrical analog to make the conduction correction, it was found possi-ble to calculate turbine blade leading-edge temperatures within about 15° F of the measured temperatures for a water-cooled blade operating at a temperature of approximately 500° F with coolant passages from 0.125 to 0.500 inch in diameter. A larger scatter in calculated temperatures resulted for the blade trailing edge with a passage diameter of 0.100 inch.