Self-sustained aero-acoustic pulsations in gas transport systems: Experimental study of the influence of closed side branches

Strouhal numbers of flow-excited acoustic resonance of closed side branches

Self-excited resonances of two side-branches in close proximity

Flow induced pulsations in resonant pipe networks with closed branches are considered in this review paper. These pulsations, observed in many technical applications, have been identified as self-sustained aeroacoustic oscillations driven by the instability of the flow along the closed branches. The fundamental aspects of the flow induced pulsations are discussed, with particular attention to the description of the sound sources. A single mode model for the prediction of the self-sustained oscillations is presented, the "energy balance". This model consists of the evaluation of the amplitude of each acoustic mode of the system by means of a balance between the acoustic source power and the acoustic power losses. The main components of this prediction method are discussed; these are the evaluation of the acoustic behavior of a pipe network and the modeling of the sound sources and the acoustic losses. Several field and scale model examples of pipe systems displaying self-sustained oscillations are presented, in order to discuss the parameters influencing the aeroacoustic behavior of pipe networks. Finally some counter-measures for the prevention of self-sustained oscillations are reviewed and perspectives for future work are considered.

Aeroacoustics of Pipe Systems with Closed Branches

Pressure pulsations and mechanical vibrations in pipe systems may cause excessive noise and may even lead to damage of piping or machinery. The excitation mechanism can be hydraulic or mechanical. In fluid-filled pipe systems pulsations and vibrations will be strongly coupled. In this study, calculation and measurement methods have been developed for the analysis of vibrations and pulsations in fluid-filled pipe systems, taking fluid-structure interaction into account.

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Analysis of pulsations and vibrations in fluid-filled pipe systems

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Jan Cornelis Bruggeman

Papers

Flow induced pulsations in pipe systems