A metallic cylinder 12.7 mm in diameter and 94 mm long is heated internally by an electrical heater and is subjected to a cross flow of air in a low-speed wind tunnel. The upstream air velocity and temperature were maintained at 10 m/s and 26.2 degree C, respectively. The heater's surface temperature was maintained at 128.4 degree C. Determine the heat transfer rate by convection using the following correlations: a- Hilpert's correlation
b- Zukauskas correlation
c- Churchill's correlation.