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Flow characteristics of single-phase flow in narrow annular channels

ZENG Heyi, SU Guanghui, JIA Dounan

《能源前沿（英文）》 2008年 第2卷 第4期   页码 466-470 doi: 10.1007/s11708-008-0101-7

摘要： The characteristics of single-phase flow in narrow annular channels were analyzed and theoretical model was proposed. Based on the present model, the theoretical calculation was performed to predict the flow characteristics for the developed flow in narrow annuli with the gap sizes of 1.0, 1.5 and 2.0 mm, respectively. The results were in good agreement with the experimental data. In addition, the gap size of narrow annuli has great impact upon the flow characteristics. The decrease of gap size reduces friction factor. The higher the Reynolds number, the more remarkable the effect of gap size upon friction coefficient during single-phase flowing through narrow annular channels. The effect of gap size upon friction coefficient is dependent on the Reynolds number, and will decrease with the decrease of the Reynolds number.

关键词： narrow annuli     remarkable     mm     developed     friction    

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Comparative study of oscillating flow characteristics of cryocooler regenerator at low temperatures

Yonglin JU , Qingqing SHEN ,

《能源前沿（英文）》 2009年 第3卷 第1期   页码 80-84 doi: 10.1007/s11708-009-0008-y

摘要： A brief review is presented on previous experimental results and correlations on the friction factor of cryocooler regenerators operating at oscillating flow and pulsating pressure conditions, for different mesh sizes of packed woven screens, focusing on the effects of different operating frequencies ranging from 20 to 80 Hz, at room and cryogenic temperatures. A comparison of the friction factor data with those of other studies is presented to clarify the reason for the difference. Finally, a new oscillating flow correlation of regenerators, in terms of several non-dimensional parameters, is discussed and compared.

关键词： friction factor     regenerator     oscillating flow     high frequency    

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Effects of alfalfa coverage on runoff, erosion and hydraulic characteristics of overland flow on loess

Shufang WU, Pute WU, Hao FENG, G. P. Merkley

《环境科学与工程前沿（英文）》 2011年 第5卷 第1期   页码 76-83 doi: 10.1007/s11783-011-0282-x

摘要： An evaluation of the interactions between vegetation, overland and soil erosion can provide valuable insight for the conservation of soil and water. An experiment was conducted to study water infiltration, runoff generation process, rate of sediment erosion, and hydrodynamic characteristics of overland flow from a sloping hillside with different draw-off discharges from alfalfa and control plots with 20° slope. The effect of alfalfa on runoff and sediment transport reduction was quantitatively analyzed. Alfalfa was discussed for its ability to reduce the overland flow scouring force or change the runoff movement. Compared to the bare-soil plots, alfalfa plots generated a 1.77 times increase in infiltration rate. Furthermore, the down-slope water infiltration rate for the bare soil plots was higher than in the up-slope, while the opposite was found in the alfalfa plots. In addition, alfalfa had a significant effect on runoff and sediment yield. In comparison to the control, the runoff coefficient and sediment transportation rate decreased by 28.3% and 78.4% in the grass slope, respectively. The runoff generated from the alfalfa and bare-soil plots had similar trends with an initial increase and subsequent leveling to a steady-state rate. The transport of sediment reduced with time as a consequence of the depletion of loose surface materials. The maximum sediment concentration was recorded within the first few minutes of each event. The alfalfa plots had subcritical flow while the bare-soil plots had supercritical flow, which indicate that the capability of the alfalfa slope for resisting soil erosion and sediment movement was greater than for bare soil plots. Moreover, the flow resistance coefficient and roughness coefficient for the alfalfa plots were both higher than for the bare-soil plots, which indicate that overland flow in alfalfa plots had retarded and was blocked, and the flow energy along the runoff path had gradually dissipated. Finally, the ability to erode and transport sediment had decreased.

关键词： alfalfa     soil erosion     runoff and sedimentation     soil water infiltration     overland flow     hydrodynamic characteristics    

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Influence of mass air flow ratio on gas-particle flow characteristics of a swirl burner in a 29 MW pulverized

Rong YAN, Zhichao CHEN, Shuo GUAN, Zhengqi LI

《能源前沿（英文）》 2021年 第15卷 第1期   页码 68-77 doi: 10.1007/s11708-020-0697-9

摘要： In a gas/particle two-phase test facility, a three-component particle-dynamics anemometer was used to measure the characteristics of gas/particle two-phase flows in a 29 megawatt (MW) pulverized coal industrial boiler equipped with a new type of swirling pulverized coal burner. The distributions of three-dimensional gas/particle velocity, particle volume flux, and particle size distribution were measured under different working conditions. The mean axial velocity and the particle volume flux in the central region of the burner outlet were found to be negative. This indicated that a central recirculation zone was formed in the center of the burner. In the central recirculation zone, the absolute value of the mean axial velocity and the particle volume flux increased when the external secondary air volume increased. The size of the central reflux zone remained stable when the air volume ratio changed. Along the direction of the jet, the peak value formed by the tertiary air gradually moved toward the center of the burner. This tertiary air was mixed with the peak value formed by the air in the adiabatic combustion chamber after the cross-section of / = 0.7. Large particles were concentrated near the wall area, and the particle size in the recirculation zone was small.

关键词： industrial pulverized coal boiler     swirl burner     air/particle flow     particle dynamic analyzer (PDA)    

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Analysis of flow and heat transfer characteristics of porous heat-storage wall in greenhouse

OUYANG Li, LIU Wei

《能源前沿（英文）》 2008年 第2卷 第4期   页码 406-409 doi: 10.1007/s11708-008-0094-2

摘要： The flow and heat transfer characteristics of porous heat-storage wall in greenhouse are studied by using the one-dimensional steady energy two-equation model for saturated porous medium. The results show that the heat exchange between the air and the solid matrix of the porous heat-storage wall depends upon the inlet air velocity, the porosity and the permeability of porous medium, and the thermal conductivity of the solid matrix. Because the incidence of solar radiation on the porous heat-storage wall is not uniform, the new composite porous solar wall with different porosity is proposed to reduce the disadvantageous effect.

关键词： incidence     thermal conductivity     heat-storage     exchange     composite    

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低高宽比矩形微通道中流动沸腾的压降特性

张炳雷,徐进良,肖泽军

《中国工程科学》 2007年 第9卷 第12期   页码 86-93

摘要： 以甲醇为工质，在不同进口温度、质量流率、热流密度和倾角下，对低高宽比矩形微通道中流动沸腾压降特性进行了研究，并分别采用均相模型和分相模型对通道压降进行了计算。通过对比实验结果与计算结果发现，均相模型中两相平均粘度的计算应当采用Dukler公式，用其他计算式时误差较大；利用LockhartMartinelli关系式进行的分相模型计算发现，现有C值计算公式，如Chisholm,Lee and Lee，Mishima及Qu and Mudawar等，都不能用于预测该实验中低高宽比微通道的两相压降。实验发现当通

关键词： 压降特性；均相模型；分相模型；微通道；流动沸腾    

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Characteristics of force acting on adjustable axial flow pump blade

WEI Peiru, CHEN Hongxun, LU Wei

《能源前沿（英文）》 2008年 第2卷 第4期   页码 508-513 doi: 10.1007/s11708-008-0054-x

摘要： The internal three-dimensional turbulent flow of adjustable axial-flow pump arrangement was simulated, and the force acting on the blade surface was calculated under different operating conditions. Based on the calculated results, finite element method (FEM) was adopted to analyze stress and strain distributions of the adjustment blade in different operations. Hydraulic moment, centrifugal moment and friction moment which must be conquered by adjusting the blades were also calculated.

关键词： three-dimensional     adjustable axial-flow     calculated     FEM     centrifugal    

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Numerical simulation and analysis of periodically oscillating pressure characteristics of inviscid flow

Yan GU, Yonglin JU

《能源前沿（英文）》 2012年 第6卷 第1期   页码 21-28 doi: 10.1007/s11708-012-0173-2

摘要： Floating liquefied natural gas (LNG) plants are gaining increasing attention in offshore energy exploitation. The effects of the periodically oscillatory motion on the fluid flow in all processes on the offshore plant are very complicated and require detailed thermodynamic and hydrodynamic analyses. In this paper, numerical simulations are conducted by computational fluid dynamics (CFD) code combined with user defined function (UDF) in order to understand the periodically oscillating pressure characteristics of inviscid flow in the rolling pipe. The computational model of the circular pipe flow is established with the excitated rolling motion, at the excitated frequencies of 1–4 rad/s, and the excitated amplitudes of 3°–15°, respectively. The influences of flow velocities and excitated conditions on pressure characteristics, including mean pressure, frequency and amplitude are systematically investigated. It is found that the pressure fluctuation of the inviscid flow remains almost constant at different flow velocities. The amplitude of the pressure fluctuation increases with the increasing of the excitated amplitude, and decreases with the increasing of the excitated frequency. It is also found that the period of the pressure fluctuation varies with the excitated frequency. Furthermore, theoretical analyses of the flow in the rolling circular pipe are conducted and the results are found in qualitative agreement with the numerical simulations.

关键词： pressure fluctuation     rolling     floating production storage and offloading unit for liquefied natural gas (LNG-FPSO) offshore    

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Characteristics of flow and heat transfer of shell-and-tube heat exchangers with overlapped helical baffles

Tingting DU, Wenjing DU

《工程管理前沿（英文）》 2019年 第6卷 第1期   页码 70-77 doi: 10.1007/s42524-019-0005-8

摘要：

The characteristics of flow and heat transfer of shell-and-tube heat exchangers with overlapped helical baffles (STHXsHB) were illustrated through a theoretical analysis and numerical simulation. The ideal helical flow model was constructed to demonstrate parts of the flow characteristics of the STHXsHB, providing theoretical evidence of short-circuit and back flows in a triangular zone. The numerical simulation was adopted to describe the characteristics of helical, leakage, and bypass streams. In a fully developed section, the distribution of velocity and wall heat transfer coefficient has a similar trend, which presents the effect of leakage and bypass streams. The short-circuit flow accelerates the axial velocity of the flow through the triangular zone. Moreover, the back flow enhances the local heat transfer and causes the ascent of flow resistance. This study shows the detailed features of helical flow in STHXsHB, which can inspire a reasonable optimization on the shell-side structure.

关键词： heat exchanger     overlapped helical baffle     triangular zone     helical flow    

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Numerical simulation and experimental research on heat transfer and flow resistance characteristics of

Shaozhi ZHANG, Xiao NIU, Yang LI, Guangming CHEN, Xiangguo XU

《能源前沿（英文）》 2020年 第14卷 第2期   页码 267-282 doi: 10.1007/s11708-020-0662-7

摘要： The asymmetric plate heat exchanger (APHE) has the possibility of achieving balanced pressure drops on both hot and cold sides for situations with unbalanced flow, which may in turn enhance the heat transfer. In this paper, the single-phase water flow and heat transfer of an APHE consisted of two types of plates are numerically (400≤ ≤12000) and experimentally (400≤ ≤3400) investigated. The numerical model is verified by the experimental results. Simulations are conducted to study the effects of , an asymmetric index proposed to describe the geometry of APHEs. The correlations of the Nusselt number and friction factor in the APHEs are determined by taking and working fluids into account. It is found that an optimal exists where the pressure drops are balanced and the heat transfer area reaches the minimum. The comparison between heat transfer and flow characteristics of the APHEs and the conventional plate heat exchanger (CPHE) is made under various flow rate ratios of the hot side and the cold side and different allowable pressure drops. The situations under which APHE may perform better are identified based on a comprehensive index .

关键词： plate heat exchanger     asymmetric     simulation     correlation     heat transfer enhancement    

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A novel flow-resistor network model for characterizing enhanced geothermal system heat reservoir

Jian GUO, Wenjiong CAO, Yiwei WANG, Fangming JIANG

《能源前沿（英文）》 2019年 第13卷 第1期   页码 99-106 doi: 10.1007/s11708-018-0555-1

摘要： The fracture characteristics of a heat reservoir are of critical importance to enhanced geothermal systems, which can be investigated by theoretical modeling. This paper presents the development of a novel flow-resistor network model to describe the hydraulic processes in heat reservoirs. The fractures in the reservoir are simplified by using flow resistors and the typically complicated fracture network of the heat reservoir is converted into a flow-resistor network with a reasonably simple pattern. For heat reservoirs with various fracture configurations, the corresponding flow-resistor networks are identical in terms of framework though the networks may have different section numbers and the flow resistors may have different values. In this paper, numerous cases of different section numbers and resistor values are calculated and the results indicate that the total number of flow resistances between the injection and production wells is primarily determined by the number of fractures in the reservoir. It is also observed that a linear dependence of the total flow resistance on the number of fractures and the relation is obtained by the best fit of the calculation results. Besides, it performs a case study dealing with the Soultz enhanced geothermal system (EGS). In addition, the fracture numbers underneath specific well systems are derived. The results provide insight on the tortuosity of the flow path between different wells.

关键词： enhanced geothermal systems     flow-resistor network model     fracture characteristics     heat reservoir    

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Effects of rotor and stator geometry on dissolution process and power consumption in jet-flow high shear

Lin Yang, Wenpeng Li, Junheng Guo, Wei Li, Baoguo Wang, Minqing Zhang, Jinli Zhang

《化学科学与工程前沿（英文）》 2021年 第15卷 第2期   页码 384-398 doi: 10.1007/s11705-020-1928-7

摘要： The jet-flow high shear mixer (JF-HSM) is a new type of intensified equipment with special configurations of the rotor and the stator. The mass transfer property and power consumption were studied in the solid-liquid system for a series of JF-HSMs involving different configuration parameters, such as rotor diameter, rotor blade inclination, rotor blade bending direction, stator diameter, and stator bottom opening diameter. The flow characteristics were examined by computational fluid dynamic simulations. Results indicate that the turbulent power consumption of the JF-HSM is affected by the change in rotor blade inclination and stator bottom opening. With the increase in the shear head size and the change in the rotor into a backward-curved blade, the solid-liquid mass transfer rate can be remarkably increased under the same input power. Dimensionless correlations for the mass transfer coefficient and power consumption were obtained to guide the scale-up design and selection of such a new type of equipment to intensify the overall mixing efficiency.

关键词： jet-flow high shear mixer     solid particle dissolution     power consumption characteristics     CFD Simulation    

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Research on the dynamic mechanical characteristics and turning tool life under the conditions of excessively

Genghuang HE, Xianli LIU, Fugang YAN

《机械工程前沿（英文）》 2012年 第7卷 第3期   页码 329-334 doi: 10.1007/s11465-012-0303-x

摘要：

The dynamic mechanical characteristics of excessively heavy-duty cutting were analyzed based on the cutting experiments with 2.25Cr-1Mo-0.25V steel used in hydrogenated cylindrical shells. By investigating the influence of dynamic mechanical characteristics on the tools’ failure in limited heavy-duty cutting processes, the model of dynamic shearing force in the cutting area was established. However, the experimental results showed that the dynamic shear flow stress in the cutting area greatly influenced the tools’ fatigue. The heavy-duty cutting tool was damaged in the form of a shearing fracture. Through a comprehensive analysis of the theory, the critical condition of the tools’ fracture under extreme loading was established.

关键词： extreme loading cutting     shear flow stress     dynamic cutting force     fatigue fracture    

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Convective mass transfer from a horizontal rotating cylinder in a slot air jet flow

Hongting MA , Dandan MA , Na YANG ,

《能源前沿（英文）》 2009年 第3卷 第3期   页码 289-296 doi: 10.1007/s11708-009-0019-8

摘要： The effects of air jet impinging on the mass transfer characteristics from a rotating spinning cylinder surface were experimentally investigated. The effects of rotational Reynolds number

关键词： air jet impinging     rotating cylinder     critical point     mass transfer characteristics    

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提高光流估计性能的渐进性高斯多维预滤波方法的研究

付昀,徐维朴

《中国工程科学》 2004年 第6卷 第12期   页码 56-61

摘要：

基于光流计算方法统一框架理论，研究了一种利用高斯多维滤波器的渐进性和时空性提高光流估计性能的有效方法。在保持现有光流计算方法的前提下，通过调节时间维和空间维的方差参数，改变时空预滤波和光滑效果，突出时间混叠和光流主信息，从而提高重构视频序列的信噪比。试验中以标准的Flower Garden和Football序列的前50帧作为参考图像序列，以LK算法为参考光流算法。结果显示，滤波窗口为5×5时的最佳时间方差参数为0.4，最佳空间方差参数为［1.6，2.0］；加入高斯多维预滤波前后利用光流场重构图像的平均峰值信噪比PSNR提高2.572dB，提高幅度为13.6%。

关键词： 光流计算     高斯多维滤波     峰值信噪比     运动估计    

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标题 作者 时间 类型 操作

Flow characteristics of single-phase flow in narrow annular channels

ZENG Heyi, SU Guanghui, JIA Dounan

期刊论文

Comparative study of oscillating flow characteristics of cryocooler regenerator at low temperatures

Yonglin JU , Qingqing SHEN ,

期刊论文

Effects of alfalfa coverage on runoff, erosion and hydraulic characteristics of overland flow on loess

Shufang WU, Pute WU, Hao FENG, G. P. Merkley

期刊论文

Influence of mass air flow ratio on gas-particle flow characteristics of a swirl burner in a 29 MW pulverized

Rong YAN, Zhichao CHEN, Shuo GUAN, Zhengqi LI

期刊论文

Analysis of flow and heat transfer characteristics of porous heat-storage wall in greenhouse

OUYANG Li, LIU Wei

期刊论文

低高宽比矩形微通道中流动沸腾的压降特性

张炳雷,徐进良,肖泽军

期刊论文

Characteristics of force acting on adjustable axial flow pump blade

WEI Peiru, CHEN Hongxun, LU Wei

期刊论文

Numerical simulation and analysis of periodically oscillating pressure characteristics of inviscid flow

Yan GU, Yonglin JU

期刊论文

Characteristics of flow and heat transfer of shell-and-tube heat exchangers with overlapped helical baffles

Tingting DU, Wenjing DU

期刊论文

Numerical simulation and experimental research on heat transfer and flow resistance characteristics of

Shaozhi ZHANG, Xiao NIU, Yang LI, Guangming CHEN, Xiangguo XU

期刊论文

A novel flow-resistor network model for characterizing enhanced geothermal system heat reservoir

Jian GUO, Wenjiong CAO, Yiwei WANG, Fangming JIANG

期刊论文

Effects of rotor and stator geometry on dissolution process and power consumption in jet-flow high shear

Lin Yang, Wenpeng Li, Junheng Guo, Wei Li, Baoguo Wang, Minqing Zhang, Jinli Zhang

期刊论文

Research on the dynamic mechanical characteristics and turning tool life under the conditions of excessively

Genghuang HE, Xianli LIU, Fugang YAN

期刊论文

Convective mass transfer from a horizontal rotating cylinder in a slot air jet flow

Hongting MA , Dandan MA , Na YANG ,

期刊论文

提高光流估计性能的渐进性高斯多维预滤波方法的研究

付昀,徐维朴

期刊论文