Numerical analysis of thermal-hydraulic characteristics on serrated fins with different attack angles and wavelength to fin length ratio

This paper defined the variable of the attack angles α, β and wavelength to fin length ratio ξ. Through numerical modeling five fins which have same geometrical parameters and different α, and comparing the numerical results with experimental data, we found the Colburn factor j and friction factor f fit with each other well. This numerical modeling was also used to analyze thirty samples which have different β and ξ. The results showed that the j factor first increased and later decreased while β increased from 0° to 50°, and when β ≈ tan−1(hf/L), fins have the highest j factor. However, the f factor was increasing slowly as β increased. Using the field synergy principle we can see the average field-synergy angle decreased while α increased, and the average field-synergy angle first decreased and then increased while β increased, when β ≈ tan−1(hf/L), fins have the smallest average field-synergy angle. Furthermore, with the same α and β, the j factor increased while ξ decreased, but the average field-synergy angle decreased gradually. It is demonstrated that different α, β and ξ can improve the thermal-hydraulic characteristics of serrated fins. And the proposed relation between β and hf/L (β = tan−1(hf/L)) has a deviation of 9%.