Hybrid active control of fluid-borne sound and structure-borne sound in liquid-filled pipe system

In order to control outstanding low-frequency line spectral noise and vibration of liquid-filled piping system, a set of active noise cancellation and vibration reduction system is designed with harmonic adaptive control algorithm and validated through experiments. A pump water circulation pipeline experimental system is established and an active muffler is installed in the pipeline to control the fluid-borne sound, while an active vibration reduction system with 8×8- channels is used to control the structure-borne sound by reducing the vibration of the baffle structure attached to the pipe opening. Active control experiments involved in low-frequency line spectrum noise and vibration are carried out and the results show that within the frequency band of 50∼200 Hz, at most frequencies more than 10 dB noise reduction can be obtained outside the pipe opening by combining active noise and vibration control. The contribution of fluid-borne sound and structural radiation sound is analyzed by controlling fluid-borne sound and structure-borne sound separately for the specific experiment system. The experiments verify that the active noise cancellation and vibration reduction system has good noise reduction performance, and hybrid active control of fluid-borne sound and structure-borne is necessary in order to achieve significant noise reduction as the ratio is different at various frequencies.