Pages 283-284
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.
