Fluid flow across tube arrays is highly complex, involving boundary layer separation, wake turbulence, and vortex shedding. The average convective heat transfer coefficient is calculated using the **Zukauskas correlation**:
\[Nu_D = C Re_{D,max}^m Pr^n \left( \frac{Pr}{Pr_s} \right)^{0.25}\]
Calculating Maximum Velocity (\(u_{max}\))
All Reynolds numbers in Zukauskas calculations are evaluated using maximum velocity \(u_{max}\) within the bundle. For aligned configurations, this occurs at the transverse gap \(S_T\):
\[u_{max} = u_\infty \frac{S_T}{S_T - D}\]
Where \(u_\infty\) is the inlet velocity, \(S_T\) is the transverse pitch, and \(D\) is the tube outer diameter.
References
- Zukauskas, A. (1972). Heat transfer from tubes in crossflow. Advances in Heat Transfer, Vol. 8, pp. 93-160. Academic Press.
