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14th International Conference on Fracture, ICF 2017

作者： Bai, Xiaoming Guo, Licheng Shi, Kaikai Zheng, Liangang Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610213 China Department of Astronautic Science and Mechanics Harbin Institute of Technology Harbin150001 China

A mesoscale numerical model for the damage and fracture behavior of particle reinforced composites is proposed in present work. In this model, the digital image technique is used to reconstruct the real microstructure of composite material. The damping boundary condition is applied to absorb the artificial reflected stress wave during the simulation. Thus, the damage and fracture behavior of particle reinforced material under complex impact loads can be investigated. © 2017 ICF 2017 - 14th International Conference on Fracture. All rights reserved.

关键词： Particle reinforced composites

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Numerical investigations of free surface vortices at hydraulic bottom intakes 17

Numerical investigations of free surface vortices at hydraul...

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17th International Topical Meeting on Nuclear reactor Thermal Hydraulics, NURETH 2017

作者： Shi-wen, Liu Jie, Zhou Wei, Huang Xiang, Cheng Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China 328# Section 1 Changshun Road ShuangliuChengdu610041 China

To study the development mechanisms and flow structure characteristics of the free surface vortices and get a better understanding of the vortices phenomena. Two-phase, three dimensions, transient CFD simulations of free surface vortices at hydraulic bottom intakes have been conducted by using a volume-of-fluid (VOF) method and the scale-adaptive simulation turbulence model with curvature correction (SAS-CC). The flow field distribution and structure in different stages of transient free surface vortices were presented and analyzed. It was found that the movement and development of the vortex was determined by the interactions of main flow transportation, the axial stretching and radial dissipation of vortex. In addition, the flow characteristics on different flow conditions also have been studied, the results showed that a relatively large flow rate and small export size lead to stronger vortex, and increasing the fluid viscosity would to some extent reduce the vortex. © 2016 Association for Computing Machinery Inc. All Rights Reserved.

关键词： Vortex flow

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Research on heat removal capability of secondary passive residual heat removal system for small modular reactor 17

Research on heat removal capability of secondary passive res...

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17th International Topical Meeting on Nuclear reactor Thermal Hydraulics, NURETH 2017

作者： Zhang, Dan Ran, Xu Zhou, Ke Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Xiehe Community ShuangLiu County Changshun Road No.328 Chengdu China

The transient performance of the Secondary Passive Residual Heat Removal system (SPRHR) for a small modular PWR was studied, the study focused on the thermal hydraulic characteristics at different initial water inventory in natural circulation loop of SPRHR. The result shows that, for SPRHR of SMR, after the short term of reactor scram, the small water inventory could maintain the two phase heat transfer state in the secondary side of Once-Through Steam Generator and the first side of emergency condenser, which will strengthen the heat transfer in SPRHR. However, for long time’s operation such as 72h, the water make up to the SPRHR should be considered as defense in depth for potential water leakage from system in accident situation. © 2016 Association for Computing Machinery Inc. All Rights Reserved.

关键词： Hydraulics

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A High Efficiency and Precision Interpolation Method for searching Fluid Field Information around Droplets in Sparse Two-phase Flow 17

A High Efficiency and Precision Interpolation Method for sea...

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17th International Topical Meeting on Nuclear reactor Thermal Hydraulics, NURETH 2017

作者： Zhao, Fulong A. Bo, Hanliang B. Zhou, Ya C. Liu, Ying D. Institute of Nuclear and New Energy Technology Tsinghua University Beijing100084 China Science and Technology on Reactor System Design Technology Laboratory Nuclear PowerInstitute of China Chengdu610041 China

In the nuclear power station, the steam-water separator is a crucial appliance, a sequence of droplet lifecycle phenomena take place, including the droplet formation, droplet motion in the steam space, the mutual collisions between droplets, droplet extinction and the phase transformation. Together with the entraining steam, the droplets experiencing above complex processes consist a typical sparse two-phase flow, which can be well investigated by the Euler-Lagrange approach in terms of numerical simulations. With the Euler-Lagrange method, the microscopic behavior of the droplets and the steam-water separating mechanism are promising to be captured. When applying the Euler-Lagrange approach to simulate the droplets motion in the fluid field, one should first obtain the fluid parameters surrounding the droplets by the interpolation method, which may significantly influence the efficiency and precision of subsequent simulation results. In the present work, we examined the performance of four different interpolation schemes in the simulation of the droplet-steam flow inside the steam-water separator, including the k-d tree and the brute force search algorithm, the nearest point and 4-point interpolation method, and the boundary layer meshes refinement and total mesh refinement method. The computational efficiency and precision of the four methods were studied in comparison. The nearest point interpolation scheme takes less computing time, whereas with lower accuracy. Therefore, the sufficiently fine meshes are necessary to improve the calculation accuracy, which in turn lead to the reduced computational efficiency. The accuracy of the four-points interpolation scheme is remarkably higher than that of the nearest point interpolation scheme at the cost of much more (more than 2 folds) CPU time. To make a trade-off between the efficiency and precision, a high efficiency and precision interpolation method is put forward by combining the nearest point interpolation scheme

关键词： Mesh generation

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Radiolytic gas bubbles' model and its application to AHR's transient neutronics analysis

Radiolytic gas bubbles' model and its application to AHR's t...

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2017 Transactions of the American Nuclear Society, ANS 2017

作者： Liangzi, Wang Dong, Yao Yingrui, Yu Shuai, Wang Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China First-section of Chang Shun Avenue No. 328 ChengDu SiChuan610213 China

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Investigation of temperature field inside a Rod bundle using two-color laser induced fluorescence 17

Investigation of temperature field inside a Rod bundle using...

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17th International Topical Meeting on Nuclear reactor Thermal Hydraulics, NURETH 2017

作者： Mi, Zhengpeng Li, Xing Huang, YunLong Tan, Sichao Du, Sijia Fundamental Science on Nuclear Safety and Simulation Technology Laboratory Harbin Engineering University Harbin150001 China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610041 China

Two-color laser induced fluorescence (LIF) technique is applied to investigate the temperature distribution in rod bundles with spacer grid in this paper. In order to evaluate the characteristic, dye spectrum was analyzed to study the spectral characteristic of dye, especially temperature-variation characteristic and thermosensitivity. A transparent experimental facility using matching index of refraction (MIR) approach was designed. Various influencing factors were analyzed in calibration experiment, and the point-to-point calibration curves of temperature-light intensity applied to rod bundle were present. Accordingly, using the calibration curves, temperature field was reconstructed downstream of the spacer grid. The results showed that sensitivity of dye according to different temperature and accuracy of experiment can be improved by selecting suitable dye combination and different wavelength range. Dye peculiarity with temperature was verified in this paper. Calibration curves of temperature-light intensity were obtained by point-to-point calibration. The temperature field in rod bundles can be reconstructed, based on calibration relations. Furthermore, the temperature distributions downstream of the spacer grid are obtained. It is concluded that two-color laser-induced fluorescence technique is applicable to non-intrusive and full-field measurement in rod bundles, and it can be used as good provider for data base to validate CFD codes and evaluate the spacer grid performance. © 2016 Association for Computing Machinery Inc. All Rights Reserved.

关键词： Temperature distribution

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The application of Lagrangian particle Tracking method in the study of steam generator sludge collector

The application of Lagrangian particle Tracking method in th...

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2017 International Congress on Advances in Nuclear Power Plants: A New Paradigm in Nuclear Power Safety, ICAPP 2017

作者： Wu, Ge Cheng, Xiang Huang, Wei Nuclear Power Institute of China Science and Technology on Reactor System Design Technology Laboratory NO.328 First Sec. of Changshun Ave. Shuangliu District Chengdu China

ISBN: (纸本)9784890471676

During the operation of the Pressurized Water reactor recirculation steam generator, sludge particles from the feed water system and secondary system, mainly corrosion products, converge in the secondary side of steam generator. Since the saturated steam exiting the steam generator carries almost no sludge, the corrosion products' concentration increases with time. Although a part of the sludge can be removed by the blowdown system, the rest will either suspend in the water or deposit as a result of gravity, boiling or turbulence. Some sludge particles deposited on the surfaces of heat transfer tubes, tube sheet, and tube supporting plates or in the gaps around will cause a variety of problems, such as accelerating component device corrosion. The sludge collector is a passive device located in the upper internals of a PWR U-tube natural recirculation steam generator. It is able to trap and collect the sludge particles suspending in the secondary side fluid, which helps in reducing the amount of sludge available to settle on the tube bundle area. In this paper, the flow conditions and the sludge particle tracks around the sludge collector in a typical U-tube recirculation steam generator are studied by using a Computational Fluid Dynamics method. For the simulation method, a k-e model is selected as the turbulent model, and the two-way coupling Lagrangian Particle Tracking scheme is employed to account for the momentum transfer effects between the continuous phase of fluid and the discrete phase of particles. The forces acting on the sludge particles in this paper include the drag force, buoyancy force, and other additional forces such as added mass force and pressure gradient force. And the number of the representative particles captured by the sludge collector is also studied, while the mass flow rate entering the sludge collector is always paid more attention. The simulation results have successfully captured the flow patterns and the tracks of the representative

关键词： Steam generators

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CFD simulation and validation of turbulent mixing in a rod bundle with vaned spacer grids based on LDV test

CFD simulation and validation of turbulent mixing in a rod b...

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2017 International Congress on Advances in Nuclear Power Plants: A New Paradigm in Nuclear Power Safety, ICAPP 2017

作者： Chen, Xi Li, Songwei Li, Zhongchun Du, Sijia Zhang, Yu Peng, Huanhuan Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China No. 328 Section 1 Changshun Avenue Shuangliu sub-district Chengdu Sichuan610213 China

ISBN: (纸本)9784890471676

Spacer grids with mixing vanes are generally used in fuel assemblies of Pressurized Water reactor (PWR), because that mixing vanes could enhance the lateral turbulent mixing in subchannels. Thus, heat exchangements are more efficient, and the value of departure from nucleate boiling (DNB) is greatly increased. Actually turbulent mixing is composed of two kinds of flows: swirling flow inside the subchannel and cross flow between subchannels. Swirling flow could induce mixing between hot water near the rod and cold water in the center of the subchannel, and may accelerate deviation of the bubbles from the rod surface. Besides, crossing flow help to mixing water between hot subchannels and cold subchannels, which impact relatively large flow area. As a result, how to accurately capture and how to predict the complicated mixing phenomenon are of great concernments. Recently many experimental studies has been conducted to provide detailed turbulent mixing in rod bundle, among which Laser Doppler Velocimetry method is widely used. With great development of Computational Fluid Dynamics, CFD has been validated as an analysis method for nuclear engineering, especially for single phase calculation. This paper presents the CFD simulation and validation of the turbulent mixing induced by spacer grid with mixing vanes in rod bundles. Experiment data used for validation came from 5 X5 rod bundle test with LDV technology, which is organized by science and technology on reactor system design technology Laboratory. A 5 X5 rod bundle with two spacer grids were used. Each rod has dimension of 9.5 mm in outer diameter and distance between rods is 12.6 mm. Two axial bulk velocities were conducted at 3.0 m/s for high Reynolds number and 1.0 m/s for low Reynolds number. Working pressure was 1.0 bar, and temperature was about 25 V. Two different distances from the downstream of the mixing spacer grid and one from upstream were acquired. Mean axial velocities and turbulent intensities (Wrms

关键词： Mixing

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Structural design and strength analysis of multi-ring packed flywheel with heavy metal alloy segments

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IOP Conference Series: Materials science and Engineering 2019年第1期657卷

作者： L Jiang W Zhang C W Wu L P Zhang Y X Zhang Z Y Liu National Key Laboratory of Science and Technology on Reactor System Design Technology Nuclear Power Institute of China Chengdu 610041 China State Key Laboratory of Structural Analysis for Industrial Equipment Dalian University of Technology Dalian 116024 China

Flywheel, as a kinetic energy storage and conversion device, has promising applications due to its high efficiency, no pollution and long lifetime. In particular, with a three-layer structure packed with heavy metal alloy middle layer, a flywheel can achieve both a large rotational inertia and a high energy density. To guarantee structural strength safety of this type of multi-ring packed flywheel operating at high temperature, structural and thermal stress analysis for a flywheel with a tungsten alloy layer sandwiched between two stainless steel layers is carried out using finite element method (FEM). Based on plane stress assumption, flywheel stress characteristic along radius under assembly force, centrifugal force and thermal loading is demonstrated. The results show that, the rise of temperature causes inconsistent thermal expansion between neighbouring layers and results in a large thermal stress. Particularly, a high circumferential tensile stress occurs in the middle layer. It is also found that, the segments of the middle tungsten alloy layer can efficiently relieve the inconsistent thermal expansion and lower the thermal stress. Moreover, the number of segments significantly influences the efficiency of thermal stress releasing and the reserved gap between adjacent segments significantly improves the contact pressure between inner hub and tungsten alloy layer. This work may provide reference for structural design of the multi-ring packed flywheels under thermal loading.

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Study of bottom reflooding in a narrow rectangular Channel 17

Study of bottom reflooding in a narrow rectangular Channel

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17th International Topical Meeting on Nuclear reactor Thermal Hydraulics, NURETH 2017

作者： Xu, Wei Yao, Jun Liu, Xiaojing Cheng, Xu Zeng, Wei School of Nuclear Science and Engineering Shanghai Jiao Tong University 800 Dongchuan Road Minhang District Shanghai China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Cheng Du610041 China

For the purpose of figuring out the thermal-hydraulic behaviors during bottom reflooding in the narrow rectangular channel of plate-type fuel reactor, experimental apparatus was established to simulate the bottom reflooding process, with different inlet velocities, initial surface temperatures. The narrow channel was formed between a heating plate made of stainless steel and a heat-proof glass. Thermo-couples (TCs) were fixed to measure the solid temperature in the vertical and horizontal directions, and a high-speed camera was used to record flow regime near the quench front. Based on experimental results, conclusion is drawn that rewetting velocity increases with the increasing inlet velocity and decreasing initial solid temperature. The rewetting temperature, which is strongly affected by the initial wall temperature, is almost independent of the inlet velocity. A new conception of ‘temperature variation velocity’ is put forward, and rewetting front and rewetting temperature can be obtained by this means. Moreover, an analytical model of rewetting velocity in narrow rectangular channel is discussed and proposed, and this proposed correlation can predict rewetting velocity in narrow rectangular channel more precisely. © 2016 Association for Computing Machinery Inc. All Rights Reserved.

关键词： Velocity

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