Effects of Source and Load Impedance on the Insertion Loss of Expansion Chamber Hydraulic Noise Suppressors

Currently, the acoustical performance of hydraulic noise attenuators is usually measured in terms of insertion loss (IL) and transmission loss (TL). Compared with the TL, experimental measurements of IL appear to be easier, however, the acquisition of source and load impedance for theoretical IL seems to be time-consuming and costly. Considering that the analogy between electrical system variables and fluidic ones is complete, well-established electrical circuit representations could be used for hydraulic systems using expansion chamber configurations as the hydraulic suppressors. Utilizing the Thevenin theorem and Norton theorem in the electrical network theory, two types of pressure oscillation source representations are equivalent insofar as the suppressors are concerned and then the expression for IL could be simplified. Finally, through the experimental measurements of the IL, the most suitable electrical representation would be selected. By implementing this method, the measurements of source impedance and load impedance tend to be avoided, which appears to be an attractive approach.