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A double-layer reflective metasurface with increased polarization independent channels through rotating array 认领 引用
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作者 Bo YIN Xiaoliang LI Shubin WANG 《Optoelectronics Letters》 EI 2026年第6期337-343,共7页
The implementation of multifunctional metasurfaces through loading diodes has extremely high costs,while increasing the number of channels in the element through polarization multiplexing technology is limited.This pa... The implementation of multifunctional metasurfaces through loading diodes has extremely high costs,while increasing the number of channels in the element through polarization multiplexing technology is limited.This paper proposes a dual-band five-channel(DBFC)1-bit surface,which expands the polarization independent(PD)channels through rotating array.The polarization-independent metasurface element consists of three layers of metal,with the top layer comprising three rectangular patches oriented in the x-direction,the middle layer featuring a Jerusalem cross structure with accompanying resonators,and the bottom layer being a metal ground plane.The middle layer element can easily independently provide the required 1-bit reflection phases for two orthogonal polarizations in every frequency.The rectangular patches in the x-direction on the top layer do not contribute to the phase of y-polarization.By rotating the upper layer dielectric array 90°,the rectangular patches change to the y-direction.Under y-polarized illumination,the current distribution in the middle layer is shielded,providing a fifth set of polarization independent phases.The proposed 1-bit DBFC metasurface array has advantages in terms of structure and cost,while enhancing the utilization rate of the metasurface array.It has high application potential in microwave imaging,wireless power transmission,and other projects. 展开更多
关键词 Polarization independent channels Rotating array multifunctional metasurfaces loading diodes three rectangular patches Double layer reflective metasurface rotating arraythe polarization multiplexing technology
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Experimental and Numerical Study on Flow and Heat Transfer Characteristics in Rectangular Channels with Leaf-Shaped Pin Fins 认领 引用 被引量：1
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作者 Chao Zhang Runze Yan +2 位作者 Honghui Li Qingheng Tang Qinghai Zhao 《Frontiers in Heat and Mass Transfer》 EI CAS 2025年第2期421-440,共20页
The growing need for enhanced heat dissipation is compelling the development of more effective heat exchangers.Innovation inspired by nature bionics,four types of leaf-shaped pin fins were proposed and four combinatio... The growing need for enhanced heat dissipation is compelling the development of more effective heat exchangers.Innovation inspired by nature bionics,four types of leaf-shaped pin fins were proposed and four combinations of them were considered.The leaf-shaped design of the cooling pin fin enhances uniformity and synergy,effectively creating an optimized flow path that boosts cooling performance.Eight three-dimensional conjugate heat transfer models in staggered arrangement were developed using ANSYS-Fluent software.Aluminum6061material was used as the heat sinkmaterial and single-phase liquid water flowed through the rectangular channel where the Reynolds(Re)number varies from 40 to 100.Using the same boundary conditions as the software simulations,two leaf-shaped channels were printed to validate numerical models.Velocity field and temperature differences of the eight proposed leaf-shaped pin fins configurations were discussed by comparison with cylindrical pin fins.Based on the findings of this study,at a Reynolds number of 80,the Leaf B Staggered Array(LBSA)records a maximum temperature that is 0.72 K lower than that of the cylindrical pin fins arrangement.Additionally,the LBSA exhibits a reduction in the friction factor by approximately 33.3%relative to the circular pin fins array under the same Re.This implies that the design of LBSA has been optimized to provide better heat dissipation performance while maintaining lower energy consumption.Furthermore,the LBSA demonstrates the most favorable thermal-hydraulic performance index(TPI),which is 1.18 times higher than that of the circular pin fins arrangement at Re=80.The temperature reduction and friction factor reduction of the lobed channel is more pronounced than that of the conventional cooling channel,highlighting its potential to increase heat transfer efficiency and reduce energy consumption in practical applications. 展开更多
关键词 Heat transfer enhancement leaf-shaped pin fins rectangular channel single-phase heat transfer staggered arrangement
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Experimental and Numerical Study on Heat Transfer Enhancement of a Rectangular Channel with Discontinuous Crossed Ribs and Grooves 认领 引用 被引量：10
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作者 唐新宜 朱冬生 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2012年第2期220-230,共11页
Experimental and numerical investigations have been conducted to study turbulent flow of water and heat transfer characteristics in a rectangular channel with discontinuous crossed ribs and grooves.The tests investiga... Experimental and numerical investigations have been conducted to study turbulent flow of water and heat transfer characteristics in a rectangular channel with discontinuous crossed ribs and grooves.The tests investigated the overall heat transfer performance and friction factor in ribbed and ribbed-grooved channels with rib angle of 30°.The experimental results show that the overall thermo-hydraulic performance for ribbed-grooved channel is increased by 10%-13.6% when compared to ribbed channel.The investigation on the effects of different rib angles and rib pitches on heat transfer characteristics and friction factor in ribbed-grooved channel was carried out using Fluent with SST(shear-stress transport) k-ω turbulence model.The numerical results indicate that the case for rib angle of 45° shows the best overall thermo-hydraulic performance,about 18%-36% higher than the case for rib angle of 0°.In addition,the flow patterns and local heat transfer characteristics for ribbed and ribbed-grooved channels based on the numerical simulation were also analyzed to reveal the mechanism of heat transfer enhancement. 展开更多
关键词 heat transfer enhancement rib groove rectangular channel turbulent flow
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Analysis of Bubble Behavior in a Horizontal Rectangular Channel under Subcooled Flow Boiling Conditions 认领 引用 被引量：4
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作者 Ke Sun Xiaoyu Hu +4 位作者 Da Li Guodong Zhang Kui Zhao Haiyang Zhao Shuzhan Bai 《Fluid Dynamics & Materials Processing》 EI 2021年第1期81-95,共15页
Experiments on subcooled flow boiling have been conducted using water in a rectangular flow channel.Similar to the coolant channel in internal combustion engines(IC engines),the flow channel in this experiment was asy... Experiments on subcooled flow boiling have been conducted using water in a rectangular flow channel.Similar to the coolant channel in internal combustion engines(IC engines),the flow channel in this experiment was asymmetrically heated.Bubble images were captured using a high speed camera from the side view of the channel.The experimental conditions in terms of bulk temperature,bulk velocity,pressure and heat flux ranged from 65°C–75°C,0.25 m/s–0.75 m/s,1–1.7 bar and 490 kW/m2–700 kW/m2,respectively.On the basis of these tests,a statistical analysis of the bubble size has been conducted considering a population of 1400 samples.It has been found that the mean Sauter bubble diameter increases with the decrease of subcooling,bulk velocity,pressure and increased heat flux.A modified correlation has been finally proposed to predict the mean Sauter bubble diameter under subcooled flow boiling conditions upstream of the onset of significant void,which shows good accuracy with the experimental results. 展开更多
关键词 Subcooled flow boiling horizontal rectangular channel mean Sauter bubble diameter
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Uniform Flow of Molten Metals in Rectangular Open Channels 认领 引用 被引量：3
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作者 Miguel A. Barron Joan Reyes Dulce Y. Medina 《World Journal of Engineering and Technology》 2022年第3期518-526,共9页
The flow of liquids in open channels has been studied since ancient Rome. However, the vast majority of published reports on flow in open channels are focused on the transport of drinking water and sewage disposal. Th... The flow of liquids in open channels has been studied since ancient Rome. However, the vast majority of published reports on flow in open channels are focused on the transport of drinking water and sewage disposal. The literature on the transport of molten metals in open channels is quite scarce. In this work, the uniform flow of pig iron and molten aluminum in rectangular open channels is studied. Specific energy curves are constructed and critical heights are analytically determined. The transition from subcritical to supercritical flow is analyzed as a function of the angle of inclination of the channel and the roughness of its walls. Manning’s equation is applied to the pig iron flow using data reported in the literature for molten aluminum. The need to correct the roughness coefficient for pig iron is observed in order to obtain results consistent with those previously reported. 展开更多
关键词 Critical Height Froude Number Molten Metal Flow Open Channel Rectangular Channel Uniform Flow
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Heat Transfer and Friction Characteristics in Rectangular Channel using Different Coolants 认领 引用
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作者 Fifi N.M. Elwekeel Qun Zheng Antar M.M. Abdala 《Journal of Marine Science and Application》 2013年第4期484-492,共9页
Several industrial applications such as electronic devices,heat exchangers,gas turbine blades,etc.need cooling processes.The internal cooling technique is proper for some applications.In the present work,computational... Several industrial applications such as electronic devices,heat exchangers,gas turbine blades,etc.need cooling processes.The internal cooling technique is proper for some applications.In the present work,computational simulations were made using ANSYS CFX to predict the improvements of internal heat transfer in the rectangular ribbed channel using different coolants.Several coolants such as air,steam,air/mist and steam/mist were investigated.The shear stress transport model(SST)is selected by comparing the standard k-ωand Omega Reynolds Stress(ωRS)turbulence models with experimental results.The results indicate that the heat transfer coefficients are enhanced in the ribbed channel while injecting small amounts of mist.The heat transfer coefficients of air/mist,steam and steam/mist increase by 12.5%,49.5%and 107%over that of air,respectively.Furthermore,in comparison to air,the air/mist heat transfer coefficient enhances by about 1.05 to 1.14 times when the mist mass fraction increases from 2%to 8%,respectively.The steam/mist heat transfer coefficient increases by about 1.12 to 1.27 times higher than that of steam over the considered range of mist mass fraction. 展开更多
关键词 heat transfer rib roughness mist rectangular channel shear stress transport
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Numerical Simulation of Asymmetric Merging Flow in a Rectangular Channel 认领 引用
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作者 Abuzar Abid Siddiqui 《World Journal of Mechanics》 2016年第4期118-130,共13页
The steady, asymmetric and two-dimensional flow of viscous, incompressible and Newtonian fluid through a rectangular channel with splitter plate parallel to walls is investigated numerically. Earlier, the position of ... The steady, asymmetric and two-dimensional flow of viscous, incompressible and Newtonian fluid through a rectangular channel with splitter plate parallel to walls is investigated numerically. Earlier, the position of the splitter plate was taken as a centreline of channel but here it is considered its different positions which cause the asymmetric behaviour of the flow field. The geometric parameter that controls the position of splitter is defined as splitter position parameter a. The plane Poiseuille flow is considered far from upstream and downstream of the splitter. This flow-problem is solved numerically by a numerical scheme comprising a fourth order method, followed by a special finite-method. This numerical scheme transforms the governing equations to system of finite-difference equations, which are solved by point S.O.R. iterative method. In addition, the results obtained are further refined and upgraded by Richardson Extrapolation method. The calculations are carried out for the ranges -1 α R 5. The results are compared with existing literature regarding the symmetric case (when a = 0) for velocity, vorticity and skin friction distributions. The comparison is very favourable. Moreover, the notable thing is that the decay of vorticity to its downstream value takes place over an increasingly longer scale of x as R increases for symmetric case but it is not so for asymmetric one. 展开更多
关键词 Parallel Walls Rectangular Channel with Parallel Splitter Special Finite-Difference Method S. O. R. and Richardson Extrapolation Methods
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脉动通道内矩形翼涡流发生器不同间距对颗粒污垢的影响 认领 引用
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作者 韩志敏 刘威 +3 位作者 李江 陈则齐 常宏亮 徐志明 《工程热物理学报》 EI CAS CSCD 北大核心 2026年第6期2136-2142,共7页
换换热器长期运行后容易在通道内产生污垢,使换热性能下降。为解决通道内的污垢问题,本文采用数值模拟方法,系统研究了单一光滑通道、单一脉动流通道以及脉动流和矩形翼涡流发生器共同作用下,复杂通道内的颗粒污垢沉积特性,并探讨了矩... 换换热器长期运行后容易在通道内产生污垢,使换热性能下降。为解决通道内的污垢问题,本文采用数值模拟方法,系统研究了单一光滑通道、单一脉动流通道以及脉动流和矩形翼涡流发生器共同作用下,复杂通道内的颗粒污垢沉积特性,并探讨了矩形翼涡流发生器不同相对间距的影响。结果表明,相较于光滑通道,矩形翼脉动通道的抑垢效果更佳,其抑垢效果能达到44.23%;在矩形翼脉动通道内,随着矩形翼涡流发生器间距增大污垢热阻先减小后增大,当相对间距D/L为0.36时抑垢效果最好,其抑垢效果能达到48.83%。 展开更多
关键词 脉动通道 矩形翼涡流发生器 间距 颗粒污垢 数值模拟
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局部变形窄矩形流道内环状流液膜特性实验研究 认领 引用
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作者 蒋隆涛 任全耀 +6 位作者 陈铠东 蒲曾坪 肖毅 李垣明 王阳阳 刘海东 张航旗 《核动力工程》 EI CAS CSCD 北大核心 2026年第2期17-25,共9页
为探究局部变形对窄矩形流道环状流液膜稳定性的影响,基于自主开发的液膜厚度传感器,构建了含球形/枕形变形的实验流道,系统开展了不同气液流速液膜波动特性研究,评价了局部变形对液膜特性的影响。结果表明:枕形变形因尖锐边缘导致流动... 为探究局部变形对窄矩形流道环状流液膜稳定性的影响,基于自主开发的液膜厚度传感器,构建了含球形/枕形变形的实验流道,系统开展了不同气液流速液膜波动特性研究,评价了局部变形对液膜特性的影响。结果表明:枕形变形因尖锐边缘导致流动分离点前移,下游涡流区扩展至变形高度的5倍,液膜剥离速率较球形变形提升100%,主频显著向低频迁移;液膜厚度随气液流速比(Jg/Jl)呈非线性衰减,当Jg/Jl大于50时,液膜稳定性丧失,厚度骤降至10μm左右;并揭示了剪切应力集中与能量耗散率对液膜破裂的协同作用,表明几何突变通过重构流场压力梯度与湍动能分布加剧液膜失稳;进一步表明局部变形高度对液膜稳定性有显著影响,变形高度增加会显著强化湍动能耗散及剪切应力集中效应,加剧液膜失稳;揭示了流道几何畸变与气液竞争机制的耦合作用规律。 展开更多
关键词 环状流液膜 窄矩形流道 局部变形 扰动波
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超临界CO2在正弦肋窄矩形通道内流动传热数值研究 认领 引用
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作者 毛赏 刘得赎 +4 位作者 郭庆 吴学红 王燕令 刘勇 周涛 《原子能科学技术》 EI CAS CSCD 北大核心 2026年第8期1586-1595,共10页
为探究正弦肋结构对超临界CO2(supercritical CO2,SCO2)流动传热特性的影响,本文采用SST k-ω湍流模型对正弦肋窄矩形通道内的流动与传热过程进行数值研究。分析了正弦肋结构参数(振幅A为2~4 mm、周期p为20~60 mm)和运行参数(... 为探究正弦肋结构对超临界CO2(supercritical CO2,SCO2)流动传热特性的影响,本文采用SST k-ω湍流模型对正弦肋窄矩形通道内的流动与传热过程进行数值研究。分析了正弦肋结构参数(振幅A为2~4 mm、周期p为20~60 mm)和运行参数(质量流量G为300~500 kg/(m2·s)、入口温度Tin为300~320 K、热流密度q为20~40 kW/m2和运行压力P为8~10 MPa)对SCO2传热性能的影响。结果表明,平均传热系数have随G的增加而增加,随Tin升高呈先增后降的趋势,而随q与P的增加而降低。正弦肋通道通过强化壁面附近的湍流强度,改善了传热性能。对比不同结构配置下的平均壁面温度Tw,ave与have发现,较大的振幅(A=4 mm)和中等周期(p=40 mm)具有最优的强化传热性能。然而,从最大壁面温度(Tw,max)和综合性能评价标准(PEC)的角度评估,较小的振幅(A=2 mm)和周期(p=20 mm)具有最低的最大壁面温度(Tw,max=342.29 K)和最优的综合性能(PEC=1.20)。本文研究结果为其在高效紧凑式换热器中的应用提供了重要的理论依据与设计参考。 展开更多
关键词 正弦肋 窄矩形通道 超临界CO2 传热性能 数值模拟
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矩形窄缝通道偏离泡核沸腾后的传热试验研究 认领 引用
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作者 唐路尧 许巍 +1 位作者 宋美琪 刘晓晶 《核技术》 EI CAS CSCD 北大核心 2026年第5期163-172,共10页
为提升研究堆在特定低压事故瞬态下的安全性,针对板式燃料元件矩形窄缝通道内的偏离泡核沸腾后(Post Departure from Nucleate Boiling,post-DNB)传热特性展开研究。采用间接热块方案设计试验段,在低压条件下,对质量流速80.9-206.1 kg&#... 为提升研究堆在特定低压事故瞬态下的安全性,针对板式燃料元件矩形窄缝通道内的偏离泡核沸腾后(Post Departure from Nucleate Boiling,post-DNB)传热特性展开研究。采用间接热块方案设计试验段,在低压条件下,对质量流速80.9-206.1 kg·(m2·s)-1、入口过冷度27.2-53.2 K工况下的稳定膜态沸腾传热进行试验。分析post-DNB稳定膜态沸腾下传热特性,对压力、质量流速和入口过冷度等关键热工参数开展敏感性分析。结果表明:在参数变化范围内,换热系数随平衡含气率先减小后增大,换热系数随质量流速与系统压力而增大,入口过冷度的影响呈现质量流速依赖性(小质量流速下削弱传热,大质量流速下增强传热)。该研究为矩形窄缝通道post-DNB传热模型的建立提供了试验基础。 展开更多
关键词 矩形窄缝通道 偏离泡核沸腾后工况 稳定膜态沸腾 间接热块
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燃料组件内并联窄缝通道流量分配近似解 认领 引用
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作者 周磊 郑健涛 +1 位作者 徐建军 闫晓 《核科学与工程》 CAS CSCD 北大核心 2026年第2期243-249,共7页
套管型、平板型燃料组件已经在国内外新型研究堆中得到应用,由于这类燃料结构紧凑,故可有效提高堆芯功率密度和中子注量率。这些燃料组件的冷却剂流道是彼此分隔的平行窄缝通道,通道之间的流量分配是决定燃料元件两侧功率分配和芯块最... 套管型、平板型燃料组件已经在国内外新型研究堆中得到应用,由于这类燃料结构紧凑,故可有效提高堆芯功率密度和中子注量率。这些燃料组件的冷却剂流道是彼此分隔的平行窄缝通道,通道之间的流量分配是决定燃料元件两侧功率分配和芯块最高温度的关键。本文基于流体质量守恒方程和动量守恒方程,经过合理简化和数学推导给出了特定条件下并联窄缝通道流量分配结果的近似解。结合两种燃料冷却剂通道几何特点,进一步给出了便于工程计算的简化形式。本文可为相关反应堆燃料组件优化设计提供参考,也可为燃料组件水力学实验结果分析和计算程序验证提供理论指导。 展开更多
关键词 矩形通道 环形通道 流量分配 燃料组件 理论研究
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矩形窄缝流道的临界热流密度预测:一种基于卡尔曼滤波器的机器学习模型 认领 引用
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作者 邓榆峰 张璜 +5 位作者 刘瑞洋 吕蒙 银华强 李健 解衡 石磊 《核技术》 EI CAS CSCD 北大核心 2026年第7期44-50,共7页
高通量研究堆作为一种中子通量不低于1×1014 cm-2·s-1的非动力堆,在科学研究、材料性能测试以及医疗、工业等领域放射性同位素生产方面具有重要应用。高通量堆多采用板状燃料元件,其堆芯功率密度高、冷却剂流动工况... 高通量研究堆作为一种中子通量不低于1×1014 cm-2·s-1的非动力堆,在科学研究、材料性能测试以及医疗、工业等领域放射性同位素生产方面具有重要应用。高通量堆多采用板状燃料元件,其堆芯功率密度高、冷却剂流动工况更加复杂,使得临界热流密度(Critical Heat Flux,CHF)的准确预测成为堆芯安全设计及运行的关键环节之一。传统CHF预测方法在应对复杂几何结构、非均匀热负荷等实际场景时,存在预测偏差较大、适用范围有限等问题。因此,为了提升板状燃料元件矩形窄缝流道CHF预测精度,本文提出一种将卡尔曼滤波与反向传播(Back Propagation,BP)神经网络相结合的机器学习模型。该模型以CHF查询表(Look-Up Table,LUT)数据库为基础,通过扩展卡尔曼滤波(Extended Kalman Filter,EKF)对CHF-LUT数据进行动态修正与融合,采用BP神经网络进行训练,以实现对矩形窄缝流道CHF值的高精度预测。为验证模型有效性,本文将预测结果与直接使用CHF-LUT预测以及Sudo公式预测结果进行对比分析。结果表明,EKF-ML模型显著提升了基于CHF-LUT的矩形窄缝流道CHF预测精度,相对误差均值达到0.78%,预测相对均方根误差(relative Root Mean Square Error,rRMSE)在给定工况下降至12.48%。该研究为窄缝流道的CHF值预测提供一种新的思路和方法。 展开更多
关键词 矩形窄缝流道 临界热流密度 机器学习 扩展卡尔曼滤波 CHF查询表
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矩形直通道内气泡形成及液塞–泄漏与CO2传质 认领 引用
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作者 柳叶 贾力 +1 位作者 党超 孙晓哲 《工程热物理学报》 EI CAS CSCD 北大核心 2026年第2期498-503,共6页
碳捕集技术是减少温室气体排放的有效手段。本文利用高速摄像系统研究了小尺度矩形直通道内一乙醇胺吸收混合气体内CO2的过程,探索了泰勒气泡的流动特性和液相泄漏流的量化分析,旨在揭示小尺度矩形直通道内CO2吸收过程的传质特性... 碳捕集技术是减少温室气体排放的有效手段。本文利用高速摄像系统研究了小尺度矩形直通道内一乙醇胺吸收混合气体内CO2的过程,探索了泰勒气泡的流动特性和液相泄漏流的量化分析,旨在揭示小尺度矩形直通道内CO2吸收过程的传质特性。提出了体积修正因子的概念,量化分析了液相流量增大时泄漏流的泄漏程度,考察了不同一乙醇胺溶液浓度(3%,5%,10%)和液相流量(15∼70 mL·min-1)对泄漏流的影响。结果表明:适当的泄漏流对CO2的吸收传质起到促进作用;气泡行进速度的提升有助于加大气泡周围的浓度梯度,从而促进气液相间传质。 展开更多
关键词 小尺度矩形直通道 传质特性 气液两相流 体积修正因子 泄漏流
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窄矩形通道内液态铅铋换热特性研究 认领 引用
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作者 成正澳 赵鹏程 沈梦思 《核技术》 EI CAS CSCD 北大核心 2026年第1期107-121,共15页
窄矩形通道由于其紧凑的结构,具备良好的换热能力,可广泛运用于反应堆工程领域,液态铅铋合金(Lead-Bismuth Eutectic,LBE)为第四代液态金属反应堆候选冷却剂。相对于常规流体如水或空气,液态铅铋合金有着更小的普朗特数(Pr),其换热特性... 窄矩形通道由于其紧凑的结构,具备良好的换热能力,可广泛运用于反应堆工程领域,液态铅铋合金(Lead-Bismuth Eutectic,LBE)为第四代液态金属反应堆候选冷却剂。相对于常规流体如水或空气,液态铅铋合金有着更小的普朗特数(Pr),其换热特性与常规流体有很大的不同,因此不能直接采用雷诺类比方法进行数值模拟。本文采用计算流体动力学(Computational Fluid Dynamics,CFD)软件Fluent对窄矩形通道内湍流流动开展数值模拟,并选用湍流普朗特数(Prt)模型对数值模型进行修正,将数值模拟的努塞尔数(Nu)结果与液态金属湍流换热关联式进行了对比,分析了不同湍流模型和湍流普朗特数模型的适用性。根据窄矩形通道内液态金属换热特性和湍流边界层结构分析,本文推荐湍流模型使用Standard k-ω或者Realizable k-ε模型,湍流普朗特数模型使用Cheng&Tak模型,推荐模型组合计算的Nu数与经验关系式误差小于±10%;随着Prt的增大,温度边界层内对数区无量纲温度减小,温度边界层厚度减小。研究结果对准确模拟窄矩形通道内液态铅铋合金的湍流换热具有重要参考价值。 展开更多
关键词 窄矩形通道 液态金属 数值模拟 换热特性 边界层结构特性
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转子相变液冷系统中矩形管道换热特性研究 认领 引用
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作者 李瑞玮 赵晟 +1 位作者 阮琳 李志 《电工电能新技术》 CSCD 北大核心 2026年第5期53-62,共10页
为适应大容量水电机组向高转速发展的需求,立式电机转子高效冷却技术亟待研究。蒸发冷却技术凭借传热效率高、温度均匀性好的特点,将会成为转子冷却极具竞争优势的解决方案之一,但目前转子磁极线圈相变液冷系统设计缺乏有效指导。本文... 为适应大容量水电机组向高转速发展的需求,立式电机转子高效冷却技术亟待研究。蒸发冷却技术凭借传热效率高、温度均匀性好的特点,将会成为转子冷却极具竞争优势的解决方案之一,但目前转子磁极线圈相变液冷系统设计缺乏有效指导。本文聚焦平行于竖直转轴旋转的矩形截面冷却通道,开展了系统性理论分析及实验研究,探究了离心加速度(30 g~70 g)和热负荷(200~500 W)对转子相变液冷系统矩形管道换热特性的影响规律。理论推导平行转轴旋转的管内受热流体的动量方程和能量方程发现,旋转管道内流动及换热过程受有效格拉晓夫数Greff、罗斯比数Ro、雷诺数Re、普朗特数Pr等无量纲数共同作用。实验结果表明,管道的换热特性受离心加速度和热负荷的协同影响,属于典型的混合对流换热场景(0.1<Greff/Re2<10)。基于理论推导和实验结果,提出了适用于旋转矩形截面管道混合对流换热系数预测关联式,实现预测误差范围±6%以内。 展开更多
关键词 转子相变液冷 矩形截面通道 管道内冷 换热特性 离心加速度
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氦氙混合气体在矩形窄缝通道内流动传热特性数值研究 认领 引用
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作者 李长忠 李卓凡 +2 位作者 仇子铖 王成龙 秋穗正 《原子能科学技术》 EI CAS CSCD 北大核心 2026年第7期1407-1420,共14页
氦氙混合气体在特定比例下传热性能优异、快中子吸收截面低、压缩性能良好,适合作为气冷快堆冷却剂和闭式布雷顿系统循环工质。窄缝通道在堆芯内广泛存在,其内部氦氙混合气体的流动传热特性直接影响反应堆的热工水力行为和系统安全特性... 氦氙混合气体在特定比例下传热性能优异、快中子吸收截面低、压缩性能良好,适合作为气冷快堆冷却剂和闭式布雷顿系统循环工质。窄缝通道在堆芯内广泛存在,其内部氦氙混合气体的流动传热特性直接影响反应堆的热工水力行为和系统安全特性。本文基于计算流体力学方法,研究分析了氦氙混合气体在矩形窄缝通道内的流动传热行为。以热工水力性能比为评价指标,探究了热工参数和通道参数,如加热方式、宽高比和粗糙度等,对其流动传热特性的影响。结果表明:窄缝通道单面加热时可承受更高的热流密度;Dittus-Boelter关联式显著高估努塞尔数;氙组分占比和宽高比增加会导致综合传热能力下降,压力则无显著影响;增加粗糙度可以强化换热,但影响程度相对有限。 展开更多
关键词 氦氙混合气体 矩形窄缝通道 流动传热 湍流普朗特数 热工水力性能比
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Analytical Models for Velocity Distributions in Compound Channels with Emerged and Submerged Vegetated Floodplains 认领 引用
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作者 ZHANG Mingwu JIANG Chunbo +3 位作者 HUANG Heqing Gerald Charles NANSON CHEN Zhengbing YAO Wenyi 《Chinese Geographical Science》 SCIE CSCD 2017年第4期577-588,共12页
The lateral distributions of depth-averaged velocity in open compound channels with emerged and submerged vegetated floodplains were analyzed based on the analytical solution of the depth-integrated Reynolds-Averaged ... The lateral distributions of depth-averaged velocity in open compound channels with emerged and submerged vegetated floodplains were analyzed based on the analytical solution of the depth-integrated Reynolds-Averaged Navier-Stokes equation with a term to account for the effects of vegetation.The three cases considered for open channels were two-stage rectangular channel with emerged vegetated floodplain,rectangular channel with submerged vegetated corner,and two-stage rectangular channel with submerged vegetated floodplain,respectively.To predict the depth-averaged velocity with submerged vegetated floodplains,we proposed a new method based on a two-layer approach where flow above and through the vegetation layer was described separately.Moreover,further experiments in the two-stage rectangular channel with submerged vegetated floodplain were carried out to verify the results.The analytical solutions of the cases indicated that the corresponding analytical depth-averaged velocity distributions agree well with the simulated and experimental prediction.The analytical solutions of the cases with theoretical foundation and without programming calculation were reasonable and applicable,which were more convenient than numerical simulations.The analytical solutions provided a way for future researches to solve the problems of submerged vegetation and discontinuous phenomenon of depth-averaged velocity at the stage point for compound channels.Understanding the hydraulics of flow in compound channels with vegetated floodplains is very important for supporting the management of fluvial processes. 展开更多
关键词 compound channel velocity distribution vegetated floodplain two-stage rectangular channel analytical solution
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Power allocation and mode selection methods for cooperative communication in the rectangular tunnel 认领 引用 被引量：2
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作者 Zhai Wenyan Sun Yanjing +1 位作者 Xu Zhao Li Song 《International Journal of Mining Science and Technology》 EI CAS CSCD 2015年第2期253-260,共8页
For the multipath fading on electromagnetic waves of wireless communication in the confined areas,the rectangular tunnel cooperative communication system was established based on the multimode channel model and the ch... For the multipath fading on electromagnetic waves of wireless communication in the confined areas,the rectangular tunnel cooperative communication system was established based on the multimode channel model and the channel capacity formula derivation was obtained.On the optimal criterion of the channel capacity,the power allocation methods of both amplifying and forwarding(AF)and decoding and forwarding(DF)cooperative communication systems were proposed in the limitation of the total power to maximize the channel capacity.The mode selection methods of single input single output(SISO)and single input multiple output(SIMO)models in the rectangular tunnel,through which the higher channel capacity can be obtained,were put forward as well.The theoretical analysis and simulation comparison show that,channel capacity of the wireless communication system in the rectangular tunnel can be effectively enhanced through the cooperative technology;channel capacity of the rectangular tunnel under complicated conditions is maximized through the proposed power allocation methods,and the optimal cooperative mode of the channel capacity can be chosen according to the cooperative mode selection methods given in the paper. 展开更多
关键词 Rectangular tunnel Multimode channel model Channel capacity Cooperative communication Power allocation Mode selection
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Interference Robust Channel Hopping Strategies for Wireless Sensor Networks 认领 引用 被引量：2
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作者 LIU Ye JIANG Fulong +3 位作者 LIU Hao WU Jianhui HU Chen ZHANG Meng 《China Communications》 SCIE CSCD 2016年第3期96-104,共9页
Due to the shared nature of the wireless medium, the performance of wireless sensor network is often limited by both internal interference and external interference. The internal interference is that simultaneous traf... Due to the shared nature of the wireless medium, the performance of wireless sensor network is often limited by both internal interference and external interference. The internal interference is that simultaneous traffic activity by neighboring nodes in the same network, while the external interference is from wireless transmissions by other types of devices, such as Wi-Fi and Bluetooth nodes. In this paper, we present two channel hopping algorithms for multichannel, single-radio wireless sensor networks. The first algorithm achieves collision-free transmission environment while do not introduce extra control overhead. The second algorithm, in addition to reducing internal interference effects, reduces the external interference effects from Wi-Fi devices. Simulation results show that both of them significantly improve performance in wireless sensor network. 展开更多
关键词 WSN channel assignment latin rectangular array interference
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