LOCAL HEAT TRANSFER AUGMENTATION IN CHANNELS WITH TWO OPPOSITE RIBBED SURFACES

The local heat transfer coefficient distribution of a square channel with two opposite ribbed walls was determined. The square channel was connected to a sudden contraction entrance in order to simulate the inlet condition of the turbine blade cooling passages. The test channel was heated by thin stainless steel foils with a thickness of 0. 000025 m and instrumented with 180 thermocouples. The brass ribs of a square cross-section were glued periodically in-line onto the top and bottom walls of the foil-heated channel in patterns to achieve the desired spacing and angle-of-attack. The local heat transfer coefficients on the smooth side and the ribbed side walls, at the channel entrance and the downstream regions, were measured for eight rib configurations (e/D equals 0. 047, P/e equals 10 and 20, alpha equals 90 degree , 60 degree , 45 degree , and 30 degree ) and three Reynolds numbers (Re equals 10,000, 30,000 and 60,000).

LOCAL HEAT TRANSFER AUGMENTATION IN CHANNELS WITH TWO OPPOSITE RIBBED SURFACES Conference Paper