2025 Volume 53 Issue 10 Pages 615-623
Ducts are widely used in various industrial fields, such as exhaust ducts for engines and ducts for air conditioners. The noise radiated from the exit of ducts degrades the work environment, making its reduction a significant issue. In silencers, the expansion and insertion types are effective across a wide frequency band, but their overall effect is limited. In contrast, side branch and resonant silencers provide a large reduction effect but are only effective within a narrow frequency band. Therefore, many studies have focused on broadening the reduction properties. The author previously applied a resonator to a duct but did not achieve sufficient reduction due to its small size. We have two questions : (1) What is the relationship between size and reduction effect? (2) What is the most effective installation position of the resonator? In this paper, experi-ments and analyses are conducted and discussed to clarify these two questions.
