Equivalent Diameter for Predicting Vortex Shedding of Finned Cylinders in Cross-Flow
Abstract This article explores different equivalent diameter equations found in the literature for shedding frequency scaling and applying it to various types of finned cylinders in industrial heat exchangers. The focus is on three finned cylinder types: straight, twist-serrated, and crimped spirally finned cylinders. Within each finned cylinder category, at least three different finned cylinders are investigated. The results indicate that utilizing the appropriate equivalent diameter for vortex shedding frequency scaling collapses the data within the Strouhal bounds of a bare cylinder away from resonance excitation. However, the onset of flow-excited acoustic resonance and peak acoustic pressure in all the finned cylinder cases occur at a reduced flow velocity earlier than their equivalent diameter bare cylinder. This suggests that although utilizing the appropriate equivalent diameter can predict the shedding frequency away from resonance, it cannot be used in velocity scaling to predict the onset of acoustic resonance in finned tube bundle.