Flow Structure of Subcooled Boiling Water Flow in a Subchannel of 3×3 Rod Bundles

Yun, Byong-Jo; Park, Goon-Cherl; Juliá, J. Enrique; Hibiki, Takashi

doi:10.3327/jnst.45.402

Cited by 10 publications

(5 citation statements)

References 23 publications

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“…The effective heat removal depends on the complex hydrodynamics of the two‐phase flow around the nuclear rods bundle. The hydrodynamics observed in the nuclear reactor core is complicated owing to the presence of nuclear rods (which is a challenging geometry), and also due to the complex phenomena of bubble nucleation, growth, detachment, and simultaneous motion of bubbles and the liquid phase …”

Section: Introductionmentioning

confidence: 99%

“…These limitations have been self‐imposed by the authors, primarily to take care of optical distortions brought in by the geometry of heater rods; however, that poses an important shortcoming when it comes to scaling up the technology of BWRs. However, only a few of these works have reported liquid phase velocity . Majority of the experimental data reported in the literature are based on invasive measurement techniques, which provide only point measurements, with the further limitation being that the measurements themselves threaten to irreversibly affect the flow itself.…”

Section: Introductionmentioning

confidence: 99%

“…Local void fraction, interfacial velocities, and interfacial area concentration were measured using the double‐sensor conductivity probe. Yun et al did subcooled boiling experiments on a 3 × 3 rod bundle assembly and measured vapor phase parameters using a conductivity probe (double‐sensor) and local liquid velocity using a Pitot tube at several flow conditions. Yun et al utilized a Pitot tube for measuring local liquid velocity and used optical fiber probe for vapor phase measurements.…”

Section: Introductionmentioning

confidence: 99%

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Velocity measurements in convective boiling flow using radioactive particle tracking technique

2019

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The design, performance, and safety analysis of nuclear reactors, in particular boiling water reactors, requires information about the vapor-liquid flow dynamics. Such data are necessary for stand-alone analysis of the thermal hydraulics, as well as to serve as a database for validation of computational fluid dynamics models. Challenges in collecting such data are magnified in the context of flow boiling, which is known to be a complex, multi-scale problem. The present work focuses on investigating the two-phase flow dynamics of convective boiling flows on a test section equipped with different heater rods arrangements. Noninvasive radioactive particle tracking (RPT) has been used for measuring liquid velocity field, mean flow patterns, and turbulent kinetic energy of the liquid phase. A novel tracer particle reconstruction algorithm based on support vector regression has been applied in this study. This is the first application of RPT for measuring liquid velocity fields in convective boiling flows.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Velocity measurements in convective boiling flow using radioactive particle tracking technique

2019

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“…The void fraction data were collected for the evaluation and improvement of the drift-flux model correlations and pressure drop data were obtained for the assessment and development of two-phase friction multiplier model and two-phase spacer-grid-loss coefficient model in the rod bundle flow channel. Some studies (Yun et al, 2008;Yang et al, 2013;Hosokawa et al, 2014;Ren et al, 2018) have focused on the local measurements of radial void fraction, IAC, and two-phase velocity profiles in the rod bundle flow channel. The obtained radial profile data of the flow parameters were mainly used for the development for two-phase interfacial transfer model, which is required to close the two-fluid model (Ishii, 1975;Ishii and Hibiki, 2010), and the validation of numerical simulations in the rod bundle.…”

mentioning

confidence: 99%

“…However, the available radial profile database for the local flow parameters are not enough to thoroughly know the whole picture of the flow characteristics and correctly make the constitutive models required for accurate predictions using the two-fluid model in the rod bundle flow channel. The available databases from local measurements, moreover, only consist of the 3×3 rod bundle data of Yun et al (2008), the 4×4 rod bundle data of Hosokawa et al (2014), the 5×5 rod bundle data of Ren et al (2018), and the 8×8 rod bundle data of Yang et al (2013).…”

mentioning

confidence: 99%

Local measurements of upward air-water two-phase flows in a vertical 6×6 rod bundle

Shen

Miwa

Xiao

et al. 2019

Exp. Comput. Multiph. Flow

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A 3 m high vertical rod bundle flow channel consisting of 6×6 rods with the rod diameter of 10 mm and the pitch of 16.7 mm and a channel box with the cross section of 100 mm × 100 mm was used to study the local two-phase flow characteristics under influences of the 36 rods and the channel box. The air and water were selected as the two-phase working fluids in the present experiments. A double-sensor probe installed at the axial position of z/DH = 149 and six evenly-installed differential pressure (DP) gauges measured the upward-moving two-phase flow in the rod bundle flow channel under the atmospheric condition. Since the local parameters of void fraction, interfacial area concentration (IAC), bubble diameter, and gas velocity are essential to know the internal structures of the two-phase flow, their data at 16 points within an octant symmetric triangular area of the flow channel cross section were collected by the double-sensor probe under various flow conditions in the experiments. The local measurements of double-sensor probe were found to agree well with the void fractions from the DP gauges and the superficial gas velocity from a gas flowmeter. Both the measured void fractions and IACs displayed a transition from radial wall-peaking profile to radial core-peaking profile in the low superficial liquid velocity flow conditions and pure radial wall-peaking profiles in the high superficial liquid velocity flow conditions. The measured Sauter mean diameters showed their radial wall-peaking profiles with the peaking degree decreasing with the increasing superficial gas velocity in both the low and high superficial liquid velocity flow conditions. The measured gas velocities in the main flow direction showed a transition from a radial nearly-flat profile or a radial mid-peaking profile to radial core-peaking profiles in the low and high superficial liquid velocity flow conditions. The area-averaged void fractions and IACs integrated from their measured local values were respectively compared with the predictions of existing drift-flux and IAC correlations. The comparison results showed that the drift-flux correlation of Ozaki et al. (2013) and the IAC correlation of Shen and Deng (2016) give the reasonable prediction and can be recommended for the predictions of the void fraction and the IAC respectively in the bubbly flows in the rod bundle flow channel. Keywords 6×6 rod bundle flow channel gas-liquid two-phase flow void fraction interfacial area concentration double-sensor probe

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Dynamic film thickness between bubbles and wall in a narrow channel

et al. 2011

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The present paper describes a novel technique to characterize the behavior of the liquid film between gas bubbles and the wall in a narrow channel. The method is based on the electrical conductance. Two liquid film sensors are installed on both opposite walls in a narrow rectangular channel. The liquid film thickness underneath the gas bubbles is recorded by the first sensor, while the void fraction information is obtained by measuring the conductance between the pair of opposite sensors. Both measurements are taken on a large two-dimensional domain and with a high speed. This makes it possible to obtain the two-dimensional distribution of the dynamic liquid film between the bubbles and the wall. In this study, this method was applied to an air-water flow ranging from bubbly to churn regimes in the narrow channel with a gap width of 1.5 mm.

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Flow Structure of Subcooled Boiling Water Flow in a Subchannel of 3×3 Rod Bundles

Cited by 10 publications

References 23 publications

Velocity measurements in convective boiling flow using radioactive particle tracking technique

Velocity measurements in convective boiling flow using radioactive particle tracking technique

Local measurements of upward air-water two-phase flows in a vertical 6×6 rod bundle

Dynamic film thickness between bubbles and wall in a narrow channel

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