scholarly journals Flow Characteristics in a 3×3 Rod Bundle under Flooding Conditions

2020 ◽  
Author(s):  
Michio MURASE ◽  
Naoki SANO ◽  
Toshiya TAKAKI ◽  
Raito GODA ◽  
Kosuke HAYASHI ◽  
...  
Keyword(s):  
Flow Characteristics ◽  
Rod Bundle

scholarly journals Numerical Investigation on the Flow Characteristics in a 17 × 17 Full-Scale Fuel Assembly

Energies ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 397 ◽  
Author(s):  
Zihao Tian ◽  
Lixin Yang ◽  
Shuang Han ◽  
Xiaofei Yuan ◽  
Hongyan Lu ◽  
...  
Keyword(s):  
Fuel Assembly ◽  
Flow Characteristics ◽  
Full Scale ◽  
Pressurized Water Reactor ◽  
Lateral Velocity ◽  
Pressurized Water ◽  
Spacer Grids ◽  
Rod Bundle ◽  
Real Size ◽  
Cfd Method

In a previous study, several computational fluid dynamics (CFD) simulations of fuel assembly thermal-hydraulic problems were presented that contained fewer fuel rods, such as 3 × 3 and 5 × 5, due to limited computer capacity. However, a typical AFA-3G fuel assembly consists of 17 × 17 rods. The pressure drop levels and flow details in the whole fuel assembly, and even in the pressurized water reactor (PWR), are not available. Hence, an appropriate CFD method for a full-scale 17 × 17 fuel assembly was the focus of this study. The spacer grids with mixing vanes, springs, and dimples were considered. The polyhedral and extruded mesh was generated using Star-CCM+ software and the total mesh number was about 200 million. The axial and lateral velocity distribution in the sub-channels was investigated. The pressure distribution downstream of different spacer grids were also obtained. As a result, an appropriate method for full-scale rod bundle simulations was obtained. The CFD analysis of thermal-hydraulic problems in a reactor coolant system can be widely conducted by using real-size fuel assembly models.

Flow Distribution and Slug Flow Characteristics for Hydraulically Equilibrium Air-Water Two-Phase Flows in a Vertical 2×3 Rod Channel

2003 ◽  
Author(s):  
Keiko Kano ◽  
Michio Sadatomi ◽  
Akimaro Kawahara ◽  
Tsukasa Kuno
Keyword(s):  
Flow Characteristics ◽  
Prediction Method ◽  
Flow Distribution ◽  
Bubble Velocity ◽  
Accurate Estimation ◽  
Two Phase ◽  
Taylor Bubble ◽  
Rod Bundle ◽  
Superficial Gas Velocity ◽  
Churn Flow

To complete subchannel analysis for predicting thermal-hydraulic behavior of coolant in a BWR rod bundle channel, accurate estimation of fluid transfer between subchannels is necessary. In order to validate a prediction method, flow distributions data of gas and liquid phases are essential. But, such data reported so far are limited to those in a two-subchannel system alone. Then we have measured flow distributions of both phases and Taylor bubble velocity in a multi-subchannel system as called 2×3 rod bundle channel. It has been found that flow distributions of gas and liquid in bubble and annular flows under a hydraulically equilibrium flow condition are close to those of single-phase flow, but in slug-churn flow the distributions are different. In slug-churn flow, both superficial gas velocity and Taylor bubble velocity are higher in larger subchannel. These experimental data are presented and discussed in this paper.

Flow Characteristics of Upward Two-Phase Flows in a Rod Bundle Geometry

2021 ◽  
Author(s):  
Xu Han ◽  
Xiuzhong Shen ◽  
Toshihiro Yamamoto ◽  
Ken Nakajima ◽  
Takashi Hibiki
Keyword(s):  
Flow Characteristics ◽  
Two Phase Flows ◽  
Two Phase ◽  
Rod Bundle

Experimental Investigation of the Subchannel Axial Pressure Drop and Hydraulic Characteristics of a 61-Pin Wire Wrapped Rod Bundle

2021 ◽  
Author(s):  
Craig Menezes ◽  
Rodolfo Vaghetto ◽  
Yassin A. Hassan
Keyword(s):  
Pressure Drop ◽  
Friction Factor ◽  
Flow Characteristics ◽  
Reynolds Numbers ◽  
Experimental Measurements ◽  
Local Pressure ◽  
Computational Tools ◽  
Hydraulic Behavior ◽  
Rod Bundle ◽  
Geometrical Features

Abstract Wire-wrapped hexagonal fuel bundles have been extensively investigated due to their enhanced heat transfer and flow characteristics. Experimental measurements are important to study the thermal-hydraulic behavior of such assemblies and to validate and improve the predicting capabilities of specialized correlations and computational tools. Presently, very limited experimental data is available on the local subchannel pressure drop. Experimental measurements of subchannel pressure drop were conducted in a 61-pin wire-wrapped rod bundle replica, for Reynolds numbers between 190 and 22,000. Specialized instrumented rods were utilized to measure the local pressure drop and estimate the subchannels' friction factor. Three interior subchannels, one edge subchannel and one corner subchannel were selected to study the effects of location and flow regimes on the friction factor and hydraulic behavior. The transition boundaries from laminar to transitions regimes, and from transition to turbulent regimes were estimated for the subchannels analyzed. The results were found in agreement with the predictions of the Upgraded Cheng and Todreas Detailed Correlation (UCTD). The results of the experimental campaign provided a better understanding of hydraulic behavior of the subchannels of wire-wrapped bundles, in relation to its geometrical features

Subchannel Analysis on Two-Phase Flow Characteristics Through Narrow Gaps in a Tight-Lattice Rod Bundle

2004 ◽  
Author(s):  
Hidesada Tamai ◽  
Akira Ohnuki ◽  
Hajime Akimoto
Keyword(s):  
Liquid Phase ◽  
Turbulent Mixing ◽  
Two Phase Flow ◽  
Flow Characteristics ◽  
Cross Flow ◽  
Phase Flow ◽  
Two Phase ◽  
Rod Bundle ◽  
Tight Lattice ◽  
Narrow Gaps

Evaluation of a critical heat flux is one of the most important issues for design of an advanced water-cooled reactor core. Since it becomes difficult to perform full-scale experiments due to a larger scale of the advanced reactor cores, an analytical approach has been widely noticed in the core design. To predict the critical heat flux in high accuracy, it is required to correctly understand a horizontal distribution of a two-phase flow in the rod bundles. In this study, the two-phase flow characteristics through narrow gaps in the tight-lattice 37-rod bundle experiment at JAERI were investigated using the subchannel analysis code, NASCA. At the center of the bundle, liquid flowed toward the periphery due to the diversion cross-flow at the elevation where boiling started and the turbulent mixing and the void drift were not influential as they can be neglected. On the periphery of the bundle, the flow mixings due to the diversion cross flow, turbulent mixing and void drift were almost the same order. Gas flowed in the same way with the liquid phase due to the diversion cross-flow, and the turbulent mixing and the void drift moved the gas in the opposite way of the liquid phase migration. An amount of the diversion cross-flow for the liquid phase increased in proportion to the square of the mass velocity. The characteristics of cross flow were almost the same in the different local power peaking and in the different gap widths in the present model.

scholarly journals A Large-Scale Direct Simulation on Fluid Flow Characteristics in a Tight-Lattice Rod Bundle

2003 ◽  
Vol 2003 (0) ◽  
pp. 208
Author(s):  
Kazuyuki Takase ◽  
Yasuo Ose ◽  
Hiroyuki Yoshida ◽  
Takuma Kano ◽  
Hajimei Akimoto
Keyword(s):  
Fluid Flow ◽  
Large Scale ◽  
Flow Characteristics ◽  
Direct Simulation ◽  
Rod Bundle ◽  
Fluid Flow Characteristics ◽  
Tight Lattice

CFD STUDY ON FLOW CHARACTERISTICS OF FUEL ROD BUNDLE WITH SPACER GRID

2019 ◽  
Vol 2019.27 (0) ◽  
pp. 1247
Author(s):  
Liu Yimeng ◽  
Li Shaodan ◽  
Chen Gang ◽  
Zhang Xiaohui ◽  
Liu Jiange
Keyword(s):  
Flow Characteristics ◽  
Spacer Grid ◽  
Fuel Rod ◽  
Rod Bundle

Experimental Study of Jet Flow Impingement Within a Rod Bundle Using PIV Technique

2008 ◽  
Author(s):  
Noushin Amini ◽  
Yassin A. Hassan
Keyword(s):  
Particle Image ◽  
Rectangular Channel ◽  
Flow Characteristics ◽  
Reynolds Numbers ◽  
Reynolds Stresses ◽  
Particle Image Velocimetry Technique ◽  
Time Resolved ◽  
Rod Bundle ◽  
Piv Technique ◽  
Image Velocimetry

In this investigation Particle Image Velocimetry technique was implemented to a matched refractive index facility which was placed in a rectangular channel of L:1016 mm×W:76.2 mm×H:76.2 mm. Water was pumped into either one or both of the inlet jets which were entering the channel’s top wall with several different Reynolds numbers. The instantaneous and time-resolved velocity fields were successfully obtained from which several flow characteristics such as vorticity, turbulence instabilities and Reynolds stresses can be calculated.

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