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AN EXPERIMENTAL INVESTIGATION OF HEAT TRANSFER IN A SEPARATING TURBULENT BOUNDARY LAYERDouglas J. Lewis ResumoHeat transfer from a constanttemperature surface in the twodimensional, steady freestream, adversepressuregradient separating turbulent boundary layer of Simpson et al. (1981 a,b) was studied experimentally using a constantcurrent resistance thermometer and a fast response thinlayered surface heat flux gage. Upstream of the incipient detachment (ID) location (1% backflow), the Stanton number St obeys the attached flow correlation recommended by Moffat and Kays (1984). Downstream the St vs. enthalpy thickness Reynolds number that is valid for zero and mild adversepressure gradient flows breaks down. The timemean heat transfer decreases rapidly downstream of ID with a broad minimum near the location of timemean detachment (50% backflow), which is approximately 30% below attachedboundarylayer levels. Downstream of the location of timemean detachment, heat transfer increases rapidly. The surface heat transfer under the backflow region was correlated to large nearwall velocity fluctuations and is approximately described by the correlation of Maciejewski and Moffat (1992). The rms of surface heat flux fluctuations attain a maximum value near the location of timemean detachment. Skewness and flatness factors of surface heat flux fluctuations increase to large values downstream of detachment because of the intermittently large heat transfer due to largescale turbulent structures. 