Research activities on nuclear reactor physics and thermal-hydraulics in Japan after Fukushima-Daiichi accident

Miwa, Shuichiro; Yamamoto, Yasunori; Chiba, Go

doi:10.1080/00223131.2017.1417177

Cited by 21 publications

(3 citation statements)

References 196 publications

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“…FIV is a fluid-structure interaction problem, and state-of-the-art of fluid mechanics (including multiphase flow) and structural dynamics should be thoroughly investigated for practical solutions. According to the recent technical roadmap of FIV phenomena published by Japan Society of Mechanical Engineers, problems due to FIV area are becoming significant in the areas of energy industries such as piping systems in nuclear and coal power plants, flow instability in hydroelectric power plant, wind resistivity of solar panels, combustion vibration in biomass plant, noise arose by abnormal ignition in combustion systems, and many more (JSME, 2018;Miwa et al, 2018). Additionally, fluid-structure interaction problems are commonly seen in gas, liquified natural gas (LNG), and petrochemical plants.…”

Section: Introductionmentioning

confidence: 99%

State-of-the-art in plant component flow-induced vibration (FIV)

Miwa

Hibiki

2019

Exp. Comput. Multiph. Flow

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Flow-induced vibration (FIV) continues to be a critical phenomenon for plant safety. Notably, the understanding of FIV generated by multiphase flow is still immature, and various accidents and troubles have been reported for the plant components including a steam generator, natural gas lines, piping systems, and so on. It is because FIV is complicated to be predicted during the plant's design stage, and usually is first noticed in the operation stage. Hence, a practical solution for new types of FIV has been through post-processing by conducting the laboratory-scale experiment to simulate the prototype. Computational fluid dynamics (CFD) has become a powerful tool to assess FIV, but the approach is still under development for multiphase flow case. It is partly due to the lack of experimental data, incomplete interfacial transfer terms included in the two-fluid model, as well as the difficulty to couple two-phase flow dynamics and structural dynamics in the simulation stage. Additionally, inadequate FIV database for the simulation benchmark also needs to be resolved for the advancement of CFD and finite-element-method (FEM) models. The present review summarizes fundamentals of FIV caused by gas-liquid two-phase flow, and recent FIV research activities ranging from experiment to simulation.

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Section: Introductionmentioning

confidence: 99%

State-of-the-art in plant component flow-induced vibration (FIV)

Miwa

Hibiki

2019

Exp. Comput. Multiph. Flow

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“…Fuel consumption optimization of ships is compromised due to the formation of a wake on the water surface associated to air being entrained across the boundary layer [1,2]. Pressurized water reactors (PWRs) face partially filled cold legs associated to emergency core cooling as a result of gas entrainment when the coolant strikes the water's surface [3,4]. Plunging jets have been proved efficient methods to aerate industrial effluents [5][6][7][8].…”

Section: Introductionmentioning

confidence: 99%

“…Ma et al [19] applied a Eulerian/Eulerian two-fluid computational multiphase fluid dynamics (CMFD) model along with a supplement sub-grid air entrainment model to predict the distribution of void fraction in vertical plunging water jets. Miwa et al [4] made use of analytical and dimensionless numbers such as the Weber number and Laplace length scale to propose a predictive model for the computation of air entrainment ratio (entrained air rate/impinging jet rate), which deviated from the experimental values by about 15.9%. Yin et al [20] used the volume of fluid and coupled level set method to investigate the numerical response of a vertical plunging jet.…”

Section: Introductionmentioning

confidence: 99%

Volume of Fluid Computations of Gas Entrainment and Void Fraction for Plunging Liquid Jets to Aerate Wastewater

Bahadar

2020

ChemEngineering

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Among various mechanisms for enhancing the interfacial area between gases and liquids, a vertical liquid jet striking a still liquid is considered an effective method. This method has vast industrial and environmental applications, where a significant application of this method is to aerate industrial effluents and wastewater treatment. Despite the huge interest and experimental and numerical efforts made by the academic and scientific community in this topic, there is still a need of further study to realize improved theoretical and computational schemes to narrow the gap between the measured and the computed entrained air. The present study is a numerical attempt to highlight the air being entrained by water jet when it intrudes into a still water surface in a tank by the application of a Volume of Fluid (VOF) scheme. The VOF scheme, along with a piecewise linear interface construction (PLIC) algorithm, is useful to follow the interface of the air and water bubbly plume and thus can provide an estimate of the volume fraction for the gas and the liquid. Dimensionless scaling derived from the Fronde number and Reynolds number along with geometric similarities due to the liquid jet’s length and nozzle diameter have been incorporated to validate the experimental data on air entrainment, penetration and void fraction. The VOF simulations for void fraction and air-water mixing and air jet’s penetration into the water were found more comparable to the measured values than those obtained using empirical and Euler-Euler methods. Although, small overestimates of air entrainment rate compared to the experiments have been found, however, VOF was found effective in reducing the gap between measurements and simulations.

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Experimental Study of Air Entrainment Rates due to Inclined Liquid Jets

et al. 2019

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The air entrainment rate due to inclined liquid jet plunging into a pool was investigated experimentally. Three types of fluids with varying physical properties in terms of viscosity and surface tension were utilized. For the impinging jet test section, nozzles with different inner diameters were selected. The inclination angles and liquid jet velocities at the nozzle outlet were varied and the entrained air rate was measured by the soap meniscus method. Taking the falling velocity of the liquid jet as a characteristic velocity, it was found that the air entrainment rate under the present experimental condition largely depended on the Weber number. From the obtained database, a new empirical model dependent on the Weber number and Laplace length scale is proposed which is capable of predicting the air entrainment flow rate at a mean absolute relative deviation of 21.7 %.

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Research activities on nuclear reactor physics and thermal-hydraulics in Japan after Fukushima-Daiichi accident

Cited by 21 publications

References 196 publications

State-of-the-art in plant component flow-induced vibration (FIV)

State-of-the-art in plant component flow-induced vibration (FIV)

Volume of Fluid Computations of Gas Entrainment and Void Fraction for Plunging Liquid Jets to Aerate Wastewater

Experimental Study of Air Entrainment Rates due to Inclined Liquid Jets

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