Subjects: Nuclear Science and Technology >> Nuclear Science and Technology submitted time 2024-04-27
Abstract： [background] This study focuses on the phenomenon of bubbling in plate-type fuel assemblies within nuclear reactors. The study uses Fluent software for numerical simulation research and compares the differences between fission gas bubbles and solid bubbles, which have been previously studied. [Purpose] The purpose of the study is to investigate the effects of bubbling on temperature distribution, heat flux, and heat transfer capability in plate-type fuel assemblies. [Methods]The study employs Fluent software for numerical simulation to analyze the effects of both fission gas bubbles and solid bubbles on the thermal-hydraulic characteristics of plate-type fuel assemblies. [Results] The findings reveal that gas bubbles cause a local increase in temperature, with the heat flux around the bubbles tripling, though the overall heat flux of the fuel plate remains largely unchanged. The formation of bubbles locally enhances heat transfer capability by approximately 10%, with a 4% increase in heat flux on the bubble side. Under conditions of high flow rates, the presence of bubbles leads to a significant pressure difference across the fuel plate, causing deformation of the fuel plate and potentially leading to the blockage of the flow channel. [Conclusions] These discoveries provide significant references for the design and safety assessment of nuclear fuel plates, highlighting the importance of considering the effects of gas bubbling on thermal-hydraulic characteristics in the design and operation of nuclear reactors.
Subjects: Nuclear Science and Technology >> Nuclear Science and Technology submitted time 2024-03-21
Abstract： [background] This study focuses on the phenomenon of bubbling in plate-type fuel assemblies within nuclear reactors. The study uses Fluent software for numerical simulation research and compares the differences between fission gas bubbles and solid bubbles, which have been previously studied. [Purpose] The purpose of the study is to investigate the effects of bubbling on temperature distribution, heat flux, and heat transfer capability in plate-type fuel assemblies. [Methods]The study employs Fluent software for numerical simulation to analyze the effects of both fission gas bubbles and solid bubbles on the thermal-hydraulic characteristics of plate-type fuel assemblies. [Results] The findings reveal that gas bubbles cause a local increase in temperature, with the heat flux around the bubbles tripling, though the overall heat flux of the fuel plate remains largely unchanged. The formation of bubbles locally enhances heat transfer capability by approximately 10%, with a 4% increase in heat flux on the bubble side. Under conditions of high flow rates, the presence of bubbles leads to a significant pressure difference across the fuel plate, causing deformation of the fuel plate and potentially leading to the blockage of the flow channel. [Conclusions] These discoveries provide significant references for the design and safety assessment of nuclear fuel plates, highlighting the importance of considering the effects of gas bubbling on thermal-hydraulic characteristics in the design and operation of nuclear reactors.
Subjects: Materials Science >> Materials Science (General) submitted time 2023-03-31 Cooperative journals: 《腐蚀科学与防护技术》
Abstract： none
Subjects: Mechanics >> Applied Mechanics submitted time 2023-03-20 Cooperative journals: 《应用力学学报》
Abstract： The changes of peak flexion and extension moments , peak power, joint work , joint impulsemoments , and cumulative joint impulse moments per unit distance of knee and ankle joints at different nun-ning speeds were compared to explore the effects of different running speeds on the single touchdown loadand cumulative load characteristics of lower limb joints. 'Twelve young male college students were recruitedas subjects , and the kinetic parameters of their knee and ankle joints were collected simultaneously using VICON infrared high-speed motion capture system and Bertec Fit 3D ergometer at four speeds of 8 km/ h,10 km/h,12 km/h and 14 km/ h. The peak flexion and extension moments , peak power , joint work , impulsemoments and joint cumulative impulse moments per unit distance of knee and ankle joints were analyzed.'The results show that the plantarflexion peak moment of the ankle during the support period , the peak pow-er during the landing cushion period and the off-ground pedal extension period and the joint work by theankle joint all increase significantly ( P<0.05) with the increase of speed. But , the peak extension mo-ment , peak power and joint work of knee during the support period do not change significantly (P>0.05)with the increase of speed. The cumulative impulse moments of the knee and ankle joints during the 1 kmrun decreased significantly (P<0.05) with the increase of speed , and the single step impulse moments ofthe knee and ankle joints do not change significantly (P>0.05 ). The increase of running speed do notaffect the single touchdown impulse moments of the ankle and knee in male college students , but it canreduce the cumulative impulse moments per unit distance of the knee and ankle joints. The plantarflexionpeak moment , peak power , and joint work in the ankle joint in male college students increase significantlywith the increase of running speed.Therefore , within a certain speed range , the increase in nunning speeddoes not increase the risk of knee , while the effect of running speed on the ankle needs further study.
Subjects: Materials Science >> Materials Science (General) submitted time 2016-11-08 Cooperative journals: 《腐蚀科学与防护技术》
Abstract：缓蚀剂作为一种有效的抑制金属与恶劣环境作用产生腐蚀的手段已在工业中广泛应用。合成有机化合物尤其是带有N、S及O原子的缓蚀剂展现出优异的缓蚀效率。但大多数有机化合物不仅价格昂贵、生产成本较高，而且对人类健康或环境保护有一定的负面影响，因此使用低成本，安全低毒的缓蚀剂对于金属缓蚀非常重要。天然高分子作为金属缓蚀剂对环境无害，易得且可再生，已成为国内外缓蚀剂研究热点。本文概述了天然高分子基缓蚀剂对于金属在腐蚀性介质中的缓蚀作用的应用研究进展。
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