Characteristics of Vortices in Louver Fins

Abstract

Research results pertinent to heat exchangers are available in existing literature and heat transfer text books. However, it was short of sufficient flow visualizations in louver fins because of the difficulty in its flow visualization. Flow visualization by means of the dye injection method and the laser Doppler velocimetry (LDV) was performed to disclose flow characteristics in louver fins. Fin pitches P_f and louver angles θ in louver fins were varied. Flow patterns in each louver fins are visualized using the fluorescein dye illuminated a laser light sheet. The LDV data were used to calculate Reynolds stress distributions and power spectrum distributions. It is disclosed that vortices in cases of θ=15° and 20° for P_f =100mm exhibit a distinctive periodic characteristics, and the Strouhal number is uniquely related to the Reynolds number.