Eng. Dept., Mobil Res. and Develop. Corp., P.O. Box 1026, Princeton, NJ 08543
A transfer impedance method has been developed to analyze the acoustic response of a complex piping system to low-frequency pulsation sources such as a reciprocating compressor. The acoustic transfer impedance of a piping system is defined as the complex amplitude of acoustic pressure in the piping system generated by a constant-frequency source at a given location that has a unity complex amplitude of acoustic volume velocity. In this method, the transfer impedance in each pipe component is expressed in terms of transmission and reflection coefficients that are determined through boundary conditions. Recurrence relations are derived to relate the transmission and reflection coefficients of one pipe component to those of an adjacent pipe component. This method is particularly useful in analyzing piping acoustic resonance and pulsation mode shape in which the location of maximum acoustic pressure can be easily identified. If the pulsation source is known, the pulsation levels in the piping system can be calculated. Compared with most of existing methods, this method provides a better understanding on how acoustic energy propagates in the piping system in addition to giving a quicker and simpler solution. Further development of this method may lead to design optimization of pulsation control devices.