2420 ボイラ模型における気柱共鳴現象と管群からの渦放出に関する研究

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In the present paper the attention is focused on the vortex shedding from the tube banks with acoustic resonance which occurred in the two-dimensional model of boiler. There were three sets of in-line tube banks which installed rigidly in the model. We measured the sound pressure level, phase delay of acoustic pressures, velocity fluctuation and the gap velocity. As a result, we found many peak frequencies of SPL with different Strouhal numbers, mainly about S_t=0.15,0.26 and 0.52. The vortex shedding of S_t=0.15 were generated inside of the tube banks without acoustic resonance. When the acoustic resonance occurred, the vortex was shed at the resonant frequencies, mainly about 395 (S_t=0.15), 765 (S_t=0.26) and 1110Hz (S_t=0.52). The resonant noise at 395Hz (S_t=0.15) generated from the space between two sets of tube banks. Using the node number of acoustic pressure mode in longitudinal and transverse direction, the resonant frequency of 395Hz (S_t=0.15) was (1,2) mode, 765Hz (S_t=0.26) was (1,4) mode, and 1128Hz (S_t=0.52) was (0,8) mode.
2003-08-05