Effect of temperature factor on heat transfer in turbulent flow of high-temperature gas in an inlet region of a tube

The effect has been experimentally studied of the temperature factor on the heat exchange at turbulent flow of high-temperature gas in the inlet portion of a tube. The experiments have been conducted on a copper cooled tube, dia. 21.6 mm, with entry angles of 0, 45, 90 and 180 deg, carrying nitrogen (up to 6000 K) or air (up to 5000 K). The flow rates have been changed from 200 to 700 m/s, and the Reynolds number has been varied from 4x103 to 106. It has been established that at turbulent flow of heated nitrogen or air the heat exchange in the inlet portion of the tube with cold walls does not practically depend on the temperature factor, and the entry conditions may be taken into account by the value of the constant multiplier in the criterional equation