The thermal performance of two blast-cooled aircraft generators, one alternator and one d-c generator, was investigated in tests cover?ing wide ranges of load, speed, cooling air flow rate, inlet tempera?ture, and exhaust air pressure. Both machines were instrumented with large numbers of thermocouples installed in stationary and rotating components.nThe experimental apparatus and the measuring techniques employed in the tests are described. For both machines, correlations of air flow rate as function of pressure drop, exhaust pressure, speed of rotation and mean air temperature in the machine are presented. The variations of component temperature rises with flow rate are describ?ed and analyzed in detail and the effects of load, power factor, speed, and exhaust pressure are discussed. The effect of rotation on the heat transfer characteristics, as evidenced with changes in exhaust pressure and/or speed, is investigated for individual components and for the whole machines. A proper method of correlation is determined which involves the definition of an effective flow rate, by addition of a pressure-dependent term to the actual flow rate, so that the heat transfer characteristics are not significantly altered with decreasing pressures of less than 4 in. Hg.
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