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 alpha,beta and wavelength to fin length ratio xi. Through numerical modeling five fins which have same geometrical parameters and different alpha, 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 beta and xi. The results showed that the j factor first increased and later decreased while beta increased from 0 degrees to 50 degrees, and when beta approximate to tan(-1)(h(f)/L), fins have the highest j factor. However, the f factor was increasing slowly as beta increased. Using the field synergy principle we can see the average field-synergy angle decreased while alpha increased, and the average field-synergy angle first decreased and then increased while beta increased, when beta approximate to tan(-1)(h(f)/L), fins have the smallest average field-synergy angle. Furthermore, with the same alpha and beta, the j factor increased while xi decreased, but the average field-synergy angle decreased gradually. It is demonstrated that different alpha, beta and xi can improve the thermal-hydraulic characteristics of serrated fins. And the proposed relation between beta and h(f)/L (beta = tan(-1)(h(f)/L)) has a deviation of 9%. (C) 2015 Elsevier Ltd. All rights reserved.