Improvement of Gas Entrainment Prediction Method —Introduction of Surface Tension Effect—

Ito, Kei; Sakai, Takaaki; Eguchi, Yuzuru; Monji, Hideaki; Ohshima, Hiroyuki; Uchibori, Akihiro; Xu, Yongze

doi:10.3327/jnst.47.771

Cited by 5 publications

(7 citation statements)

References 13 publications

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“…The equation was derived in the study of Ito et al (2010) based on the Burgers (1948) vortex model. It should be noted that due to typographical errors the correct equation is given in Sakai et al (2008).…”

Section: Methods Of Gas-core Length Determinationmentioning

confidence: 99%

Predicting Free-Surface Vortices with Single-Phase Simulations

Škerlavaj¹,

Škerget

Ravnik

et al. 2014

Engineering Applications of Computational Fluid Mechanics

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In this article, single-phase, computational-fluid-dynamics simulations of free-surface vortices are presented. The purpose of the simulations is to determine the appropriate turbulence model for free-surface vortices, which could later be applied to simulations of flow in various engineering systems. The water flow in the laboratory model of a free-surface vortex was numerically simulated by unsteady single-phase computations. The vortex circumferential velocity, the downward velocity inside the vortex core and the predicted length of the free-surface vortex gas core were compared with available measurements. For the two-equation turbulence models, the results indicated the importance of the curvature correction (CC). The effect of the time-step size and the choice of the advection scheme were analyzed. For the tested case, it was determined that the unsteadiness of the flow was insufficient for the correct behavior of the scale-adaptive simulation (SAS) turbulence model. With the CC option, the shear-stress-transport (SST-CC) turbulence model and the SAS-CC turbulence model can both be used for such predictions; however, the SAS-CC model was found to be more reliable. Single-phase simulations successfully predicted the gas-core length for vortices with a short gas core. However, for long cores, the length was underpredicted.

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Section: Methods Of Gas-core Length Determinationmentioning

confidence: 99%

Predicting Free-Surface Vortices with Single-Phase Simulations

Škerlavaj¹,

Škerget

Ravnik

et al. 2014

Engineering Applications of Computational Fluid Mechanics

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“…By introducing C in equation (1) and using the relation between the suction parameter a and the vortex core radius r 0 an analytical correlation for the critical submergence h crit can be derived (equation (3)). 4 1 crit g τ…”

Section: Advanced Combined Methodsmentioning

confidence: 99%

“…The constant suction parameter (also called downward velocity gradient) represents the intensity of the pump suction for the actual intake. On the basis of the Burgers and Rott model Ito et al [4] used a differential equation to describe the surface deformation. Integration of this equation yields a simple formula for the maximal surface deformation of the vortex, i.e.…”

Section: Analytical Model From Burgers and Rottmentioning

confidence: 99%

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Investigation of the critical submergence at pump intakes based on multiphase CFD calculations

Pandazis¹,

Blömeling²

2014

Advances in Fluid Mechanics X

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Surface vortices occur at pump intakes, when the water-level sinks below a critical value. They can affect the intake flow in a disadvantageous manner. Pump disturbances may be initiated and the mass flow may be decreased or completely interrupted. The determination of the critical value to avoid surface vortices is an important part of safety analyses of postulated abnormal operations and accidents in Light Water Reactors. The vortex formation phenomena are investigated within the research project "Generic numerical determination of the critical submergence at pump intakes to avoid gas entrainment" sponsored by the German Federal Ministry of Economics and Technology. In this project a coupled numerical-analytical method has been developed to calculate the critical submergence. The method is based on the results of two-phase numerical CFD simulations and on the analytical vortex model of Burgers and Rott. It allows an efficient investigation of various influence parameters, which affect the critical submergence. The results of the method are compared with the experimental results from Jain et al. and Moriya and show a very good agreement. The present paper describes the performed CFD simulations as well as some validation results.

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“…of a theoretically occurring gas‐core vortex . Since the measurement of the undisturbed velocity profile requires the use of (laser)optical measurement techniques, the applicability of the model is normally restricted to laboratory and pilot plant setups or the conduction of numerical simulations.…”

Section: Theoretical Backgroundmentioning

confidence: 99%

Large‐Scale Experiments on the Formation of Surface Vortices with and without Vortex Suppression

Szeliga

Elgott

Bezecny

et al. 2019

Chemie Ingenieur Technik

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Experiments were carried out in a 50‐m3 cylindrical tank to determine the influence of strong momentum on the formation of large‐scale gas‐core vortices. Gas‐core lengths were measured for varying volume flow rates and submergence depths. The critical Froude numbers were also determined and the efficiency of different vortex suppressors on the gas‐core formation was investigated. The horizontal velocity field inside the vortex core region was additionally recorded using particle image velocimetry. The experimental results were used to verify numerical simulations and compared to vortex models and correlations from literature.

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Improvement of Gas Entrainment Prediction Method —Introduction of Surface Tension Effect—

Cited by 5 publications

References 13 publications

Predicting Free-Surface Vortices with Single-Phase Simulations

Predicting Free-Surface Vortices with Single-Phase Simulations

Investigation of the critical submergence at pump intakes based on multiphase CFD calculations

Large‐Scale Experiments on the Formation of Surface Vortices with and without Vortex Suppression

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