Energy dissipation in a rapid filling vertical pipe with trapped air

Zhou, Ling; Lu, Yanqing; Karney, Bryan W.; Wu, Guoying; Elong, Alain; Huang, Kun

doi:10.1080/00221686.2022.2132309

Cited by 12 publications

(3 citation statements)

References 42 publications

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“…Most of the research associated with the development of mathematical models focuses on the study of transient flows generated in filling processes with trapped air [9][10][11][12][13]; however, in the last decade, mathematical models have been proposed to represent the hydraulic behaviour generated during the pipe emptying process. Research has been carried out on the analysis of emptying in pipes with pressurised air, carrying out several experimental measurements, which has led to the physical understanding of hydraulic operation.…”

Section: Introductionmentioning

confidence: 99%

Different Experimental and Numerical Models to Analyse Emptying Processes in Pressurised Pipes with Trapped Air

et al. 2023

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In hydraulic engineering, some researchers have developed different mathematical and numerical tools for a better understanding of the physical interaction between water flow in pipes with trapped air during emptying processes, where they have made contributions on the use of simple and complex models in different application cases. In this article, a comparative study of different experimental and numerical models existing in the literature for the analysis of trapped air in pressurised pipelines subjected to different scenarios of emptying processes is presented, where different authors have develope, experimental, one-dimensional mathematical and complex computational fluid dynamics (CFD) models (two-dimensional and three-dimensional) to understand the level of applicability of these models in different hydraulic scenarios, from the physical and computational point of view. In general, experimental, mathematical and CFD models had maximum Reynolds numbers ranging from 2670 to 20,467, and it was possible to identify that the mathematical models offered relevant numerical information in a short simulation time on the order of seconds. However, there are restrictions to visualise some complex hydraulic and thermodynamic phenomena that CFD models are able to illustrate in detail with a numerical resolution similar to the mathematical models, and these require simulation times of hours or days. From this research, it was concluded that the knowledge of the information offered by the different models can be useful to hydraulic engineers to identify physical and numerical elements present in the air–water interaction and computational conditions necessary for the development of models that help decision-making in the field of hydraulics of pressurised pipelines.

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Section: Introductionmentioning

confidence: 99%

Different Experimental and Numerical Models to Analyse Emptying Processes in Pressurised Pipes with Trapped Air

et al. 2023

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“…In recent decades, there has been a surge in interest regarding the analysis of transient flow phenomena involving entrapped air. This surge is driven by the recognition that air pockets can induce more extreme absolute pressure patterns compared to transient flow scenarios in the absence of air, as discussed in various works [1,5,6]. This peculiarity arises from the inherent greater elasticity of air compared to that of both water and the pipes themselves.…”

Section: Introductionmentioning

confidence: 99%

Enhancing Friction Models for Starting Up Water Installations Containing Trapped Air

Fuertes-Miquel,

Arrieta-Pastrana,

Coronado-Hernández

2023

Applied Sciences

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Starting up water installations is typically a task that falls within the purview of water utility companies. These operations involve the presence of two separate fluids (water and air) that can be analyzed in terms of consideration two distinct behaviors (hydraulic and thermodynamic). During a filling process, trapped air pockets exhibit a trend of declining volume, generating pressure surges that are typically not addressed under current worldwide regulations. This research introduces an innovative mathematical approach based on physical equations to investigate filling operations in water installations involving trapped air, incorporating an unsteady friction model (using the Brunone friction coefficient), in combination with the rigid water column model. The validation of the proposed model is carried out in an experimental facility measuring 7.36 m in length. The proposed model is then applied to a case study involving a 460 m long pipeline with an internal pipe diameter of 150 mm, featuring an undulating profile composed of three branches, to demonstrate how the gravity term should be calculated in real-world water installations. The results showed that the proposed model, considering an unsteady friction model, is suitable for simulating the start up of water pipelines for the experimental facility analysis and the case study. The Swamee–Jain formula yielded the best results compared to other formulations for computing the friction factor.

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“…For instance, although the Bergant et al (2012) study [20] conducted an experimental-numerical investigation using typical air valve and pipe sizes, the pipeline lengths employed were quite short. Regarding pipeline filling, studies often concentrate on either horizontal [21] or vertical pipes [22], which are prevalent in few large-scale systems [6]. Furthermore, the common use of orifices for air exchanges in these studies, rather than the more commonly employed air valves, introduces an added challenge when translating the findings into practical applications [3].…”

Section: Introductionmentioning

confidence: 99%

Exploring the Sensitivity of the Transient Response following Power Failure to Air Valve and Pipeline Characteristics

Tasca,

Besharat,

Ramos

et al. 2023

Water

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Air valves are protective devices often used in pressurised water pipelines, ideally admitting air to limit sub-atmospheric pressures and controlling the release of entrapped air. This work summarises a comprehensive sensitivity analysis of the transient behaviour in a rising water pipeline with an air valve following a pump trip. The paper examines the water hammer stages associated with a pump trip, namely, the initial depressurisation, followed by air admission, then air expulsion, and finally the creation of a secondary pressure wave. For each air valve location and specific set of design conditions, the relationship between the transient magnitude and air valve outflow capacity is found to be non-linear, but to roughly follow the shape of a logistic curve having a lower left plateau for attenuated (type 1) behaviour and transitioning through type 2 behaviour to a higher right plateau for water-hammer-dominated (type 3) behaviour. Through an extensive set of simulations covering a wide range of conditions, the study identifies the size of the critical outflow orifices associated with both type 1 and type 3 responses and assesses the influence of the location of the air valve on the transient magnitude and on the timing of air pocket collapse. Furthermore, the paper highlights that a non-slam air valve is capable of effectively mitigating transient magnitudes provided that its design parameters are judiciously chosen and account for both the system’s attributes and the characteristics of the transient event.

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Energy dissipation in a rapid filling vertical pipe with trapped air

Cited by 12 publications

References 42 publications

Different Experimental and Numerical Models to Analyse Emptying Processes in Pressurised Pipes with Trapped Air

Different Experimental and Numerical Models to Analyse Emptying Processes in Pressurised Pipes with Trapped Air

Enhancing Friction Models for Starting Up Water Installations Containing Trapped Air

Exploring the Sensitivity of the Transient Response following Power Failure to Air Valve and Pipeline Characteristics

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