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

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 transfer 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 analysing the resonating behaviour of a complex in-series pipe system.