Compliant-wall methods for fluid-borne noise reduction

Abstract

One means of addressing fluid-borne noise in hydraulic systems is to add a compliant-walled section to the flow path. The impedance mismatch at the section boundary reflects a substantial amount of acoustic energy back to the source, and additional damping may be present due to the compliant material. While hoses can be used to add this compliance, the hose wall vibration produces undesirable breakout noise from the system. Additionally, the requirement that the hoses contain system pressure determines the minimum practical hose stiffness. An alternative approach is to use a silencer composed of a rigid outer housing, an internal compliant liner, and a central flow path through the liner. Such a configuration would avoid the pressure bearing and breakout noise complications while still adding compliance to the system. These two approaches are compared in this study, with simulated transmission loss presented for various lengths and material properties of the compliant sections.