A Study on the Resonator of HVAC Silencers

Large axial fans mounted on ships to supply air to the engine combustion chamber and to prevent gas explosion in the engine room produce high levels of noise. In particular, the blade passing frequency (BPF) noise due to the rotation speed of the fan blade is dominant. However, this low-frequency noise is difficult to control using sound-absorbing materials that are generally used in a silencer. Therefore, a hybrid silencer with appropriate arrangement of resonators and sound-absorbing materials is used. However, for the optimal design of the silencer, side-branch resonators are applied horizontally rather than perpendicularly to the direction of the sound wave and are installed in various ways with sound-absorbing materials and a pressure loss-improving device. This study classified design factors that affect the resonant frequency when a side-branch resonator is applied to a HVAC silencer. The change in the resonant frequency was observed and a database was built by producing a resonator model and an experimental facility that can control each design factor.