Investigating the hydraulic resonance behaviour in pressurised in-series piping systems

Abstract

This study outlines a methodology to inspect the resonant characteristics of in-series-pipes hydraulic systems. The numerical model is based on the impedance approach, assuming the sinusoidal fluctuations of flow-rate and pressure parameters, in conjunction with the Transfert Matrix concept, being implemented for automatic calculations within a complex piping systems framework. To verify the validity of the used numerical technique, the computed results were compared with a conventional numerical solution quoted in the literature. Applications address the free and forced vibration cases occurring into an in-series-pipes system. The free vibration case, is caused by an oscillating valve downstream with a constant level tank upstream; while the forced vibration case is caused by the closure of a turbine downstream. The obtained results show the reliability of the proposed numerical procedure to determine the natural frequencies of a complex in-series hydraulic system. However, this study unveils that the “equivalent pipe” concept is not accurate for analyzing the resonating behavior of a complex in-series pipe system.