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Influence of Air Content on Transient Flow Behaviors in Viscoelastic Pipes

Author(s): Yan Zhu, Huan-Feng Duan, Fei Li, Chen-Guang Wu, Yi-Xing Yuan, Zhen-Feng Shi

Linked Author(s): HF Duan

Keywords: Air-water mixing flow, transient pipe flow, unsteady friction, viscoelasticity, air content.

Abstract: Air is easily introduced into water supply pipelines due to many factors of the system condition and operation equipment, such as air release from water under low pressure condition and air injection from devices (e. g. , air valve, pump). As a result, air-water mixing flows are commonly formed in pressurized water supply pipes and may cause different practical problems, such as reducing water conveyance capability, lowering pipe strength and damaging system facilities. This preliminary study aims to investigate the influence of air content on the transient behaviors of the induced air-water mixing flows in a form of homogeneous mixture fluid in viscoelastic pipes. Laboratory experiments and numerical simulations are adopted for the investigation. The numerical model based on the method of characteristics (MOC) and the discrete vaporous cavity model (DVCM) is calibrated and validated by the experimental data gained in this study, and then adopted for systematic analysis of the influence and relative importance of different factors, including unsteady friction, viscoelasticity and air content, on transient flows in viscoelastic pipes. The time-domain amplitude damping and frequency-domain frequency shifting of transient responses are examined for the effects of different influence factors in this study. The obtained results and implications are discussed for the modelling and analysis of transient flows in viscoelastic pipes


Year: 2017

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