Numerical Studies on Air-Core Vortex Formation During Draining of Liquids from Tanks

Basu, Prateep; Agarwal, D. D.; Tharakan, T. John; Salih, A.

doi:10.1615/interjfluidmechres.v40.i1.30

Cited by 26 publications

(19 citation statements)

References 9 publications

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“…Vortex formation has been a subject of research interest [15]- [17] as vortices can be both useful, such as for cyclone separators [18], [19], and harmful, such as to hydraulic machinery and structures in hydropower plants [20], [21]. However, the application of vortices for hydropower generation, GVHP, has not been considered in detail to date.…”

Section: Introductionmentioning

confidence: 99%

A Parametric Experimental Investigation of the Operating Conditions of Gravitational Vortex Hydropower (GVHP)

Power¹,

McNabola²,

Coughlan³

2015

JOCET

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Abstract-Globalenergy consumption is growing considerably, raising such issues as increased energy-related greenhouse gas emissions, reduced security of supply, and growing fuel costs. Renewable resources, such as hydropower, offer an alternative energy source to meet the growing demand. Small hydropower (SHP) has been a major focus of hydropower research in recent years, as many of the large scale hydroelectric opportunities around the world have already been exploited. In particular, low head SHP is gaining interest as traditional turbines, such as the Kaplan and Pelton turbines, are typically limited to heads greater than 3m. Gravitational vortex hydropower (GVHP) is one such low head hydropower solution. GVHP exploits the energy available in a vortex flow, enabling hydropower generation at heads as low as 0.7m. A vertical axis turbine is placed in the centre of a vortex flow and rotates with the flow, thus generating mechanical energy. This paper describes a parametric experimental investigation of the operating conditions of GVHP. Various flow rates, inlet conditions, blade sizes and blade numbers were tested and the turbine rotational speed, vortex height and applied resistance force were recorded for each setting. The power input, power output and efficiency were then calculated and compared for the various settings. It was found that the turbine efficiency increases with blade size and blade number for the blade configurations tested. Maximum power outputs were found for the largest flow rate tested and when there was a considerable resistance force applied to the turbine. Finally, of three inlet heights tested, a height of 25 cm above the tank base (35% of the overall tank height) was found to be optimum for turbine performance. These results have implications both for future research and for practice, with energy generating applications in low head rivers and in wastewater networks.Index Terms-Clean energy, experimental model, gravitational vortex hydropower (GVHP), low head, new energy device.

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Section: Introductionmentioning

confidence: 99%

A Parametric Experimental Investigation of the Operating Conditions of Gravitational Vortex Hydropower (GVHP)

Power¹,

McNabola²,

Coughlan³

2015

JOCET

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“…6 Surface tension is approximated by the continuum surface force (CSF) model. 7 The discrete equations are solved by using the first order upwind discretization scheme and the PISO pressure-velocity coupling scheme. 8 The flow characteristics of mercury droplet in micro-channel are simulated, and the acceleration threshold and response time are obtained.…”

Section: Nnumerical Numerical Results and Analysismentioning

confidence: 99%

Vibration interference analysis and verification of micro-fluidic inertial switch

Liu

Yang

et al. 2014

AIP Advances

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The micro-fluidic inertial switch based on liquid metal utilizes the moving mercury droplet to close the switch under the action of acceleration, which is characterized by no moving parts, small contact resistance, long service life and large current. In addition to the requirement of response time, accuracy and reliability, the micro-fluidic inertial switch needs to overcome the impact of the ambient vibration. The influence of the ambient vibration on the performance of switch is investigated by loading pulse or sinusoidal interference signals in the X, Y and Z direction. The numerical results suggest that the performance of micro-fluidic inertial switch is greatly affected by impact interference signal in X sensitive direction as compared with low frequency harmonic signal. If the impact signal with high amplitude lasts only for a short time, the wrong operation might also occur. The interference signals in insensitive direction have a relatively small impact on the performance of switch, and the impact of interference signal can be reduced by reasonable structural design. Finally, anodic bonding, deep reactive ion etching (DRIE) and sputtering technique are adopted to fabricate the micro-fluidic inertial switch. The acceleration threshold of the prototype is tested. The experiment results agree with the numerical results, which indicate that the simulation method is valid.

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“…At this moment, the dip raises into a vortex with an air-core and the free surface creates a long and slender string shape lengthens to the bottom of the tank, and it is named as air-core vortex [3]. As the level reaches a certain critical height Hc, the dip forms into the air-core on the surface which consequently enters the outlet [2]. This phenomenon repetitively continued until the draining finished (except when the reverse jet is occurred).…”

Section: Comparison Of Drainage Timementioning

confidence: 99%

“…Air-core vortex is one of the rotational motions of the liquid at which air entraining the vortex through its core [1] and it can be detected along the draining process inside the tank. As the level reaches a certain critical height, Hc, the dip forms into the air-core on the surface which subsequently enters the outlet [2]. The air-core vortex phenomenon continuously been generated at which the dip grows into a vortex with an air-core and it creates a long and slender string shape lengthens to the bottom of the tank [3].…”

Section: Introductionmentioning

confidence: 99%

“…The air-core vortex phenomenon continuously been generated at which the dip grows into a vortex with an air-core and it creates a long and slender string shape lengthens to the bottom of the tank [3]. This air-core vortex formation is deepened by the intensification of rotational flow along the draining process [2]. The rate of liquid draining is decreased and the flow at the outlet nozzle is highly rotational when the core of the vortex extents to the bottom of the tank [1].…”

Section: Introductionmentioning

confidence: 99%

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Benchmark on the Dynamics of Liquid Draining Inside a Tank

Sakri

Ali²,

Zaki³

2019

E3S Web Conf.

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Immense information and details observation of flow physics inside a draining tank can be achieved by adopting reliable numerical simulations. Yet the accuracy of numerical results has been always debatable and it is mainly affected by the grid convergence error and computational modeling approaches. Hence, this study is divided into two stages. In the first stage, this paper determines a systematic method of refining a computational grid for a liquid draining inside a tank using OpenFOAM software. The sensitivity of the computed flow field on different mesh resolutions is also examined. In order to study the effect of grid dependency, three different grid refinements are investigated: fine, medium and coarse grids. By using a form of Richardson extrapolation and Grid Convergence Index (GCI), the level of grid independence is attained. In this paper, a monotonic convergence criteria is reached when the fine grid has the GCI value below 10% for each parameter. In the second stage, different computational modeling approaches (DNS, RANS k-ε, RANS k-ω and LES turbulence models) are investigated using the finer grid from the first stage. The results for the draining time and flow visualization of the generation of an air-core are in a good agreement with the available published data. The Direct Numerical Simulation (DNS) seems most reasonably satisfactory for VOF studies relating air-core compared to other different turbulence modeling approaches.

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Numerical Studies on Air-Core Vortex Formation During Draining of Liquids from Tanks

Cited by 26 publications

References 9 publications

A Parametric Experimental Investigation of the Operating Conditions of Gravitational Vortex Hydropower (GVHP)

A Parametric Experimental Investigation of the Operating Conditions of Gravitational Vortex Hydropower (GVHP)

Vibration interference analysis and verification of micro-fluidic inertial switch

Benchmark on the Dynamics of Liquid Draining Inside a Tank

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