STUDY OF HEAT TRANSFER FROM A HEATED CYLINDER IN TWO-PHASE, WATER-AIR FLOW.

The purpose of the study was to obtain experimental data on the effect of the water-to-air mass flow ratio in a horizontal, two-phase, air-water flow on the overall film heat transfer coefficient on a vertical cylinder, and to determine the variation of the local film heat transfer coefficient on a vertical cylinder, in a horizontal, two-phase air-water flow. A suitable apparatus was constructed, it consisted of a heated cylinder, a wind tunnel, nozzles, and temperature, power and pressure monitoring equipment. The two-phase flow was formed by spraying water into the wind tunnel air flow. It was found that introduction of water droplets into the airstream sharply increased the overall film heat transfer coefficient and, after a water-to-air flow ratio of about 0.04, the heat transfer rate varied only slightly with increases in waterto-air ratio. At the peak condition noted in the study, overall film heat transfer coefficient was increased by a factor of 8.5 by the introduction of water into the airstream. Heat transfer from the cylinder occurs almost entirely on the front half of the cylinder with the maximum heat transfer rate at the stagnation point of 14.9 times that of dry air. Author