気柱共鳴音発生時の千鳥配列管群内の渦放出現象計測(流体工学,流体機械)

概要

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The relation between the vortex shedding phenomena and the resonant noise caused by tube banks was experimentally investigated. We measured the spectrum, the coherence, the phase delay of velocity fluctuations, the gap velocity in the tube banks and the sound pressure level near the duct exit in the case of tube banks that has the same pitch ratio as that of a heat exchanger of a power station. When acoustic resonance occurred at the natural frequency of the duct 343 Hz, we found several peaks with different frequencies, the main peaks being at 343 Hz and 263 Hz of the velocity fluctuation of the flow inside of the tube banks. The coherence of the velocity fluctuations due to vortex shedding in the transverse direction is large in the case with resonance. The Strouhal number 0.22 calculated by vortex shedding frequency 263 Hz and mean gap flow velocity agrees approximately with Strouhal number 0.23 determined by the Fitz-hugh's map. However, the other Strouhal number for 343 Hz is about 0.29, which controls the resonant frequency and is not predicted by Fitz-hugh's map.
一般社団法人日本機械学会の論文
2002-11-25