Numerical modelling for analysing drainage in irregular profile pipes using OpenFOAM

[EN] Different methods of two-dimensional and three-dimensional numerical resolution models have been used to predict the air¿water interaction in pipe systems in the early twenty-first century, where reliable and adequate results have been obtained when compared with experimental results. However, the study of the drainage process in pressurized systems with air admitted through openings has not been studied using this type of model due to the complexity that this represents. In this research, a two-dimensional numerical model is developed in the open-source software OpenFOAM; this model represents the drainage of an irregular pipe with air admitted by an air valve, defined by a structured mesh. A validation of the numerical model related to the air admitted by the variation of the air valve diameter is also performed.Paternina-Verona, DA.; Coronado-Hernández, OE.; Fuertes-Miquel, VS. (2022). Numerical modelling for analysing drainage in irregular profile pipes using OpenFOAM. Urban Water Journal. 19(6):569-578. https://doi.org/10.1080/1573062X.2022.205092956957819

Numerical modelling for analysing drainage in irregular profile pipes using OpenFOAM

Different methods of two-dimensional and three-dimensional numerical resolution models have been used to predict the air–water interaction in pipe systems in the early twenty-first century, where reliable and adequate results have been obtained when compared with experimental results. However, the study of the drainage process in pressurized systems with air admitted through openings has not been studied using this type of model due to the complexity that this represents. In this research, a two-dimensional numerical model is developed in the open-source software OpenFOAM; this model represents the drainage of an irregular pipe with air admitted by an air valve, defined by a structured mesh. A validation of the numerical model related to the air admitted by the variation of the air valve diameter is also performed. © 2022 Informa UK Limited, trading as Taylor & Francis Group

Modelos matemáticos para el análisis de los procesos de llenado y vaciado en los sistemas hidráulicos a presión

Durante los procesos de llenado y vaciado en los sistemas hidráulicos a presión pueden generarse importantes sobrepresiones o depresiones, independientemente de la presencia o no de ventosas. Por ello, el conocimiento físico del problema planteado y la posibilidad de evaluar los picos de presión que potencialmente pueden generarse presenta un indudable interés práctico. Para lograr estos objetivos, es fundamental disponer de herramientas adecuadas y modelos matemáticos fiables y contrastados que permitan la simulación de los transitorios hidráulicos con aire atrapado de la forma más realista posible. En este trabajo se analizan diversos modelos matemáticos para el análisis de los procesos de llenado y vaciado en los sistemas hidráulicos a presión: (i) modelos matemáticos 1D; (ii) modelos simplificados: modelos cuasi-estáticos; (iii) modelos complejos: modelos 2D/3D con técnicas CFD

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

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

Rapid Filling Analysis with an Entrapped Air Pocket in Water Pipelines Using a 3D CFD Model

A filling operation generates continuous changes over the shape of an air–water interface, which can be captured using a 3D CFD model. This research analyses the influence of different hydro-pneumatic tank pressures and air pocket sizes as initial conditions for studying rapid filling operations in a 7.6 m long PVC pipeline with an irregular profile, using the OpenFOAM software. The analysed scenarios were validated using experimental measurements, where the 3D CFD model was suitable for simulating them. In addition, a mesh sensitivity analysis was performed. Air pocket pressure patterns, water velocity oscillations, and the different shapes of the air–water interface were analysed

Three-dimensional simulation of transient flows during the emptying of pipes with entrapped air

Two-and three-dimensional analyses of transient flows considering the air-water interaction have been a challenge for researchers due to the complexity in the numerical resolution of the multiphase during emptying in pressurized water pipelines. The air-water dynamic interaction of emptying processes can be analyzed using thermodynamic and hydraulic laws. There is a lack in the current literature regarding the analysis of those phenomena using 3D models. In this research, several simulations were performed to study the complex details of two-phase flows. A 3D model was proposed to represent the emptying process in a single pipeline, considering a PVoF model and two-equation turbulence model. The model was numerically validated through 12 experimental tests and mesh sensitivity analysis. The pressure pulses of the air pockets were evaluated and compared with the experimental results and existing mathematical models, showing how the 3D models are useful for capturing more detailed information, such as pressure and velocity patterns of discrete air pockets, distribution of air and water velocity contours, and the exploration of temperature changes for an air pocket expansion

Three-dimensional analysis of air-admission orifices in pipelines during hydraulic drainage events

[EN] Air valves operate as protection devices in pipelines during drainage processes in order to mitigate vacuum pressures and control the transient flows. Currently, different authors have proposed one-dimensional models to predict the behaviour of orifices during filling and draining events, which offer good numerical results. However, the three-dimensional dynamic behaviour of air-admission orifices during drainage processes has not been studied in depth in the literature. In this research, the effects of air inflow on an orifice installed in a single pipe during drainage events are analysed using a three-dimensional computational fluid dynamics model by testing orifices with diameters of 1.5 and 3.0 mm. This model was validated with different experimental measurements associated to the vacuum pressure, obtaining good fits. The three-dimensional model predicts additional information associated to the aerodynamic effects that occur during the air-admission processes, which is studied. Subsonic flows are observed in different orifices with Mach numbers between 0.18 and 0.30. In addition, it is shown that the larger-diameter orifice ensures a more effective airflow control compared to the smaller-diameter orifice.This research was funded by grant No. INV03CI2214 of the Universidad Tecnologica de Bolivar.Paternina-Verona, DA.; Coronado-Hernández, OE.; Espinoza-Román, HG.; Besharat, M.; Fuertes-Miquel, VS.; Ramos, HM. (2022). Three-dimensional analysis of air-admission orifices in pipelines during hydraulic drainage events. Sustainability. 14(21):1-14. https://doi.org/10.3390/su142114600114142

Improving Pump Characteristics through Double Curvature Impellers: Experimental Measurements and 3D CFD Analysis

The outlet angle and shape of impeller blades are important parameters in centrifugal pump design. There is a lack of detailed studies related to double curvature impellers in centrifugal pumps in the current literature; therefore, an experimental and numerical analysis of double curvature impellers was performed. Six impellers were made and then assessed in a centrifugal pump test bed and simulated via 3D CFD simulation. The original impeller was also tested and simulated. One of the manufactured impellers had the same design as the original, and the other five impellers had a double curvature. Laboratory tests and simulations were conducted with three rotation speeds: 1400, 1700, and 1900 RPM. Head and performance curve equations were obtained for the pump–engine unit based on the flow of each impeller for the three rotation speeds. The results showed that a double curvature impeller improved pump head by approximately 1 m for the range of the study and performance by about 2% when compared to basic impeller. On the other hand, it was observed that turbulence models such as k-e and SST k-w reproduced similar physical and numerical results

Effects of orifice sizes for uncontrolled filling processes in water pipelines

The sizing of air valves during the air expulsion phase in rapid filling processes is crucial for design purposes. Mathematical models have been developed to simulate the behaviour of air valves during filling processes for air expulsion, utilising 1D and 2D schemes. These transient events involve the presence of two fluids with different properties and behaviours (water and air). The effect of air valves under scenarios of controlled filling processes has been studied by various authors; however, the analysis of uncontrolled filling processes using air valves has not yet been considered. In this scenario, water columns reach high velocities, causing part of them to close air valves, which generates an additional peak in air pocket pressure patterns. In this research, a two-dimensional computational fluid dynamics model is developed in OpenFOAM software to simulate the studied situations

Effects of Orifice Sizes for Uncontrolled Filling Processes in Water Pipelines

[EN] The sizing of air valves during the air expulsion phase in rapid filling processes is crucial for design purposes. Mathematical models have been developed to simulate the behaviour of air valves during filling processes for air expulsion, utilising 1D and 2D schemes. These transient events involve the presence of two fluids with different properties and behaviours (water and air). The effect of air valves under scenarios of controlled filling processes has been studied by various authors; however, the analysis of uncontrolled filling processes using air valves has not yet been considered. In this scenario, water columns reach high velocities, causing part of them to close air valves, which generates an additional peak in air pocket pressure patterns. In this research, a two-dimensional computational fluid dynamics model is developed in OpenFOAM software to simulate the studied situations.Aguirre-Mendoza, AM.; Paternina-Verona, DA.; Oyuela, S.; Coronado-Hernández, OE.; Besharat, M.; Fuertes-Miquel, VS.; Iglesias Rey, PL.... (2022). Effects of Orifice Sizes for Uncontrolled Filling Processes in Water Pipelines. Water. 14(6):1-11. https://doi.org/10.3390/w1406088811114