風洞内音場と管群気柱共鳴に関する研究

抄録

One of the major noise problems in the heat exchangers for the thermal power and chemical plants is the acoustic resonance induced by vortex shedding of the flowing fluid. This phenomenon occurs when the vortex shedding frequency coincides with the natural frequency of the acoustic field in the heat exchanger and it sometimes leads to destroy the structure of the plants. Many researches elucidated that the vortex frequency is determined by Strouhal number and the direction of the acoustic resonance mode is perpendicular to the flowing fluid. Based on these research results, the baffle plate is inserted into the tube array to increase the natural frequency of the acoustic field of the heat exchanger. Recently it has reported that the acoustic resonance in the flowing direction at twice frequency of Strouhal number occurs and sometimes the acoustic resonance having the half or triple frequency of Strouhal number are observed. In this study, it is discussed the relation of three dimensional acoustic mode of the wind tunnel involving the tube array and the acoustic resonance induced by vortex shedding and furthermore the generation of higher and sub harmonic acoustic resonance are discussed.