A new archive of heat transfer coefficients from square and chamfered cylinders at angles of attack in crossflow

Preceding research on the usage of experimental and numerical simulations has been established for convection heat transfer coefficient between fluid and blunt objects regarding correlations between the Nusselt and Reynolds number. Despite previous modifications of flow situation and consideration of different shapes used in implementing these studies, Tong and colleagues carried out first study investigating correlations between Nusselt and Reynolds number taking into consideration different angle of attacks of a two-dimensional square and chamfered cylindrical objects with extension to larger Reynolds number. The work is published in peer-reviewed journal, International Journal of Thermal Sciences.

The numerical simulation used involves a two-dimensional cylindrical shape with various  chamfered dimensions. Inlet conditions involved a steady and uniform velocity while unsteady flow patterns which resulted in a transient solution were obtained. These equations which were non-linear and dependent derived the overall rate of heat transfer, Nusselt number and Reynolds number. Five angles of attack were used in this study which consists of 0, 11.25, 22.5, 33.75 and 45⁰ with Reynolds number in range of 30,000-2,300,000.

At a lower Reynolds number, close correlation was observed in Nusselt number values for square and octagonal chamfered cylinders. While at higher Reynolds number range, Nusselt numbers of octagonal chamfered cylinders were approximately 80% of that of square cylinders at a zero degree angle of attack. A very large value was also seen at a 45⁰ angle of attack as Nusselt number of square cylinder became two times as that of the octagonal cylinder when considering a higher range of Reynolds number.

The authors’ calculations were done using air, however, the methods developed can be extended to other fluids with different Prandtl numbers. This study is the first to look at variation of surface average Nusselt numbers at high Reynolds numbers for square/ chamfered cylinders at all possible angles of attack.