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Investigation of bubble diameter and flow regime between water and dilute aqueous ethanol solutions in

Baharak SAJJADI, Mostafa Keshavarz MORAVEJI, Reza DAVARNEJAD

《化学科学与工程前沿（英文）》 2011年 第5卷 第2期   页码 194-202 doi: 10.1007/s11705-010-1019-2

摘要： In this study, the effect of ethanol addition into pure water and its concentration on bubble diameter, gas hold-up and flow regimes were investigated in an airlift reactor. Air and water with ethanol (concentration ranging from 0%–1%, v/v) were as dispersed and continuous phases, respectively. Superficial gas velocity was considered as an effective parameter. Bubble size distribution was measured by photography and picture analysis at various concentrations of ethanol and various velocities of gas. Alcohol concentration enhancement caused bubble diameter to decrease. Furthermore, the bubbles diameter in pure water was nearly 4 times higher than that of ethanol with concentration of 1% (v/v) and also was 3.4 times higher than that of ethanol with concentration of 0.25% (v/v) at the highest aeration gas velocity inlet. For ethanol solutions in lower superficial gas velocity, a homogenous flow regime was observed. This trend continued to inlet gas velocity of about 0.4 cm/s. The transition flow regime occurred after this datum although in pure water, a homogenous flow regime was observed up to a superficial gas velocity of 0.7 cm/s. The gas hold-up in dilute ethanol solutions were more than (around 2 times) that of pure water and increased with increasing concentration of ethanol in those solutions.

关键词： airlift rector     bubble diameter     gas hold-up     flow regime     ethanol    

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Experimental study for the stratified to slug flow regime transition mechanism of gas-oil two-phase flow

LIU Yiping, YANG Weilin, WANG Jing

《能源前沿（英文）》 2008年 第2卷 第2期   页码 152-157 doi: 10.1007/s11708-008-0012-7

摘要： Theoretical relations that predict the transition from a stratified pattern to a slug pattern, including a one-dimensional wave model that contains less empiricism than the commonly used Taitel-Dukler model, and the ideal model for stratified flow for the gas-liquid flow in horizontal pipes are presented. Superficial velocities of each phase, as the onset of slugging occurs, were predicted, and theoretical analysis was conducted on the stratified to slug flow regime transition. The friction, existing between the fluid and pipe wall, and on the interface of two phases, was especially taken into account. A theoretical model was applied to an experiment about air-oil two-phase flow in a 50 mm horizontal pipe. The effect of pipe diameter on the transition was also studied. The results show that this approach gives a reasonable prediction over the whole range of flow rates, and better agreement has been achieved between predicted and measured critical parameters.

关键词： two-phase     Superficial     reasonable prediction     one-dimensional     gas-liquid    

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Study of two-phase flow regime identification in horizontal tube bundles under vertical upward cross-flow

HUANG Xinghua, WANG Li, JIA Feng

《能源前沿（英文）》 2008年 第2卷 第3期   页码 333-338 doi: 10.1007/s11708-008-0043-0

摘要： A wavelet-transform based approach for flow regime identification in horizontal tube bundles under vertical upward cross-flow condition was presented. Tests on two-phase flow pattern of R134a were conducted under low mass velocity and flow boiling conditions over ranges of mass flux 4–25 kg/ms, vapor quality 0.02–0.90. Time series of differential pressure fluctuations were measured and analyzed with discrete wavelet transform. Different time-scale characteristics in bubbly flow, churn flow and annular flow were analyzed. The wavelet energy distributions over scales were found to be appropriate for flow regime identification. Based on the wavelet energy distribution over characteristic scales, a criterion of flow regime identification was proposed. The comparison with experiment results show that it is feasible to use the discrete wavelet transform as the tool of flow regime identification in horizontal tube bundles under vertical upward cross-flow condition.

关键词： two-phase     discrete     appropriate     wavelet-transform     criterion    

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Burnett simulations of gas flow and heat transfer in microchannels

Fubing BAO, Jianzhong LIN

《机械工程前沿（英文）》 2009年 第4卷 第3期   页码 252-263 doi: 10.1007/s11465-009-0037-6

摘要： In micro- and nanoscale gas flows, the flow falls into the transition flow regime. There are not enough molecule collisions and the gas deviates from the equilibrium. The Navier-Stokes equations fail to describe the gas flow in this regime. The direct simulation Monte Carlo method converges slowly and requires lots of computational time. As a result, the high-order Burnett equations are used to study the gas flow and heat transfer characteristics in micro- and nanoscale gas flows in this paper. The Burnett equations are first reviewed, and the augmented Burnett equations with high-order slip boundary conditions are then used to model the gas flow and heat transfer in Couette and Poiseuille flows in the transition regime.

关键词： micro- and nanoscale gas flow     slip-transition flow regime     Burnett equations     numerical simulation    

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Experimental investigation of multiphase flow behavior in drilling annuli using high speed visualization

Alap Ali ZAHID, Syed Raza ur REHMAN, Anwarul HASAN, S. RUSHD, Mohammad Azizur RAHMAN

《能源前沿（英文）》 2020年 第14卷 第3期   页码 635-643 doi: 10.1007/s11708-018-0582-y

摘要： Imaging with high definition video camera is an important technique to visualize the drilling conditions and to study the physics of complex multiphase flow associated with the hole cleaning process. The main advantage of visualizing multiphase flow in a drilling annulus is that the viewer can easily distinguish fluid phases, flow patterns and thicknesses of cutting beds. In this paper the hole cleaning process which involves the transportation of cuttings through a horizontal annulus was studied. The two-phase (solid-liquid) and the three-phase (solid-liquid-gas) flow conditions involved in this kind of annular transportation were experimentally simulated and images were taken using a high definition camera. Analyzing the captured images, a number of important parameters like velocities of different phases, heights of solid beds and sizes of gas bubbles were determined. Two different techniques based on an image analysis software and MATLAB coding were used for the determinations. The results were compared to validate the image analyzing methodology. The visualization technique developed in this paper has a direct application in investigating the critical conditions required for efficient hole cleaning as well as in optimizing the mud program during both planning and operational phases of drilling. Particularly, it would be useful in predicting the cuttings transport performance, estimating solid bed height, gas bubble size, and mean velocities of bubbles/particles.

关键词： visualization     horizontal annulus     hole cleaning     multiphase flow     image analysis     flow regime    

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一种通用的基于斯托克斯流的复杂流束轮廓工程方法 Article

杨振宇, 南浪, 岑浩璋

《工程（英文）》 2021年 第7卷 第5期   页码 655-662 doi: 10.1016/j.eng.2021.02.008

摘要：

为了在微流控管道中实现诸如混合强化、反应控制和材料合成等应用，经常需要编辑其中的流束轮廓。传统的流束轮廓编辑方法通过激发惯性二次流，使管道中流体重新分布，然而在惯性流可以忽略的微流控环境中，难以借助这类方法形成流束轮廓。传统方法使用的对称式管道内结构也限制了可以创造的流束轮廓的多样性。此外，这类方法生成的每个流束轮廓均对应一个严格定义的特定流动环境，因而在有变化的流动环境中，难以再现这些轮廓。为了解决上述问题，我们提出一种基于非惯性二次流的工程方法来编辑流束轮廓：在微管道内部署一系列级联的具有不同几何形状的阶梯来操控处于斯托克斯流范围内的流体；通过调整这些微阶梯的形状可以定制输出任意的流束轮廓；设计数值式流束轮廓预测程序，可快速预测以任意次序排列的预定义的微阶梯所输出的流束轮廓。该方法可用于生成包括非对称流束轮廓在内的各种稳定的流束轮廓，并且广泛适用于多种微流控流动环境，促进对复杂微流场的预测和设计。

关键词： 微流控     流束轮廓     斯托克斯流     流体动力学聚焦     流动塑形    

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Calculation of collision frequency function for aerosol particles in free molecule regime in presence

Xiaowei LUO, Yannick BENICHOU, Suyuan YU

《能源前沿（英文）》 2013年 第7卷 第4期   页码 506-510 doi: 10.1007/s11708-013-0275-5

摘要： The collision frequency function for aerosol particles has already been calculated for the free molecule regime and for the continuum range. The present work, taking into account the influence of internal force fields such as magnetic force, electric force and molecular forces, created by particles themselves, recalculated the collision frequency in the case of particles much smaller than the mean free path of the gas (free molecule regime). Attractive forces increase naturally the collision frequency, while repulsive forces decrease it. The calculation was performed for all types of central forces deriving from a potential, including Coulomb forces and Van der Waals forces.

关键词： aerosol particles     collision frequency function     coagulation    

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Kinetic roughening transition and missing regime transition of melt crystallized polybutene-1 tetragonal

Motoi YAMASHITA

《化学科学与工程前沿（英文）》 2009年 第3卷 第2期   页码 125-134 doi: 10.1007/s11705-009-0001-3

摘要： The morphology and lateral growth rate of polybutene-1 ( -PB1) have been investigated for crystallization from the melt over a wide range of crystallization temperatures from 50 to 110°C. The morphology of -PB1 crystals is a rounded shape at crystallization temperatures lower than 85°C, while lamellar single crystals possess faceted morphology at higher crystallization temperatures. The kinetic roughening transition occurs around 85°C. The nucleation and growth mechanism for crystallization does not work below 85°C, since the growth face is rough. However, the growth rate shows the supercooling dependence derived from the nucleation and growth mechanism. The nucleation theory seems still to work even for rough surface growth. Possible mechanisms for the crystal growth of this polymer are discussed.

关键词： isotactic polybutene-1     tetragonal phase (form Ⅱ)     melt crystallization     growth rate     kinetic roughening     morphology    

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Numerical study on natural convection in a square enclosure containing a rectangular heated cylinder

Jianhua LU, Zhaoli GUO, Zhenhua CHAI, Baochang SHI,

《能源前沿（英文）》 2009年 第3卷 第4期   页码 373-380 doi: 10.1007/s11708-009-0078-x

摘要： In this paper, the natural convection in a square enclosure with a rectangular heated cylinder is investigated via the lattice Boltzmann method. A detailed study is conducted on the effect of the cylinder width and the Rayleigh number on the fluid flow and heat transfer. The flow structures and heat transfer patterns are classified into eight buoyant regimes, i.e., four steady regimes, two periodic regimes, one multiple periodic regime, and one chaos regime, two of which are reported for the first time.

关键词： natural convection     buoyant regime     heated cylinder     lattice Boltzmann    

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photogeneration and extraction dynamics of polymer solar cells probed by a transient photocurrent nearby the regime

Boa Jin, Hyunmin Park, Yang Liu, Leijing Liu, Jongdeok An, Wenjing Tian, Chan Im

《化学科学与工程前沿（英文）》 2021年 第15卷 第1期   页码 164-179 doi: 10.1007/s11705-020-1976-z

摘要： To understand the complex behaviors of photogenerated charge carriers within polymer-based bulk-heterojunction-type solar cells, the charge-carrier photogeneration and extraction dynamics are simultaneously estimated using a transient photocurrent technique under various external-bias voltages, and a wide range of excitation intensities are analyzed. For this purpose, conventional devices with 80 nm thick active layers consisting of a blend of representative P3HT and PTB7 electron-donating polymers and proper electron-accepting fullerene derivatives were used. After the correction for the saturation behavior at a high excitation-intensity range nearby the regime of the space charge-limited current, the incident-photon-density-dependent maximum photocurrent densities at the initial peaks are discussed as the proportional measures of the charge-carrier-photogeneration facility. By comparing the total number of the extracted charge carriers to the total number of the incident photons and the number of the initially photogenerated charge carriers, the external quantum efficiencies as well as the extraction quantum efficiencies of the charge-carrier collection during a laser-pulse-induced transient photocurrent process were obtained. Subsequently, the charge-carrier concentration-dependent mobility values were obtained, and they are discussed in consideration of the additional influences of the charge-carrier losses from the device during the charge-carrier extraction that also affects the photocurrent-trace shape.

关键词： charge-carrier photogeneration     transient photocurrent     polymer solar cells     charge-carrier extraction     space charge-limited current    

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Is atmospheric oxidation capacity better in indicating tropospheric O formation?

《环境科学与工程前沿（英文）》 2022年 第16卷 第5期 doi: 10.1007/s11783-022-1544-5

摘要：

● This study summarizes and evaluates different approaches that indicate O3 formation.

关键词： O3     AOC     O3 formation regime    

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Numerical study of internal flow field and flow passage improvement of an inlet particle separator

Florian PAOLI, Tong WANG

《能源前沿（英文）》 2011年 第5卷 第4期   页码 386-397 doi: 10.1007/s11708-011-0156-8

摘要： By performing gas flow field numerical simulations for several inlet Reynolds numbers (from 2 × 10 to 9 × 10 ) and byflow ratios (from 10% to 20%), the present study has proposed to improve the flow passage of an inlet particle separator. An adjacent objective of the study is to lower pressure losses of the inlet particle separator (IPS). No particle has been included in the gas flow for a -epsilon turbulence model. The velocity distribution in different sections and the pressure coefficient along the duct have been analyzed, which indicates that there exist important low-velocity regions and vortices in the separation area. Therefore, the profile of streamlines along the original passage has been considered. This profile illustrated a vacuum region in the same area. All investigations suggest that the separation area is the most critical one for fulfilling the objective on pressure losses limitation. Then the flow passage improvement method has focused on the separation area. An improved shape has been designed in order to suit smoothly to the streamlines in this region. Similar numerical studies as those for the original shape have been conducted on this improved shape, confirming some considerable enhancements compared with the original shape. The significant vortices which appear in the original shape reduce in amount and size. Besides, pressure losses are greatly decreased in both outlets (up to 30% for high Reynolds number) and the flow is uniform at the main outlet. Subsequent engineering surveys could rely on expressions obtained for in both outlets which extend the pressure losses for a wide range of inlet Reynolds numbers. As a result, the numerical calculations demonstrate that the flow passage improvement method applied in this study has succeeded in designing a shape which enhances the flow behavior.

关键词： streamlines     pressure losses     flow passage improvement     inlet particle separator (IPS)    

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EFFECTS OF SUBSTITUTION OF MINERAL NITROGEN WITH ORGANIC AMENDMENTS ON NITROGEN LOSS FROM SLOPING CROPLAND OF PURPLE SOIL

《农业科学与工程前沿（英文）》 2022年 第9卷 第3期   页码 396-406 doi: 10.15302/J-FASE-2022456

摘要：

● Interflow acts as the dominant pathway for N loss loadings.

关键词： improved fertilization regime     interflow     nitrogen forms     nitrogen leaching     purple soil     sloping cropland    

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物质流分析的跟踪观察法

陆钟武

《中国工程科学》 2006年 第8卷 第1期   页码 18-25

摘要：

流动，是物质（如铜、铝等）流动和流体流动二者所具有的基本特征，基于这个论点，简要地回顾了流体力学中研究流体流动的两种方法，即拉格朗日法和欧拉法；相应地提出了物质流分析的两种方法，即跟踪观察法和定点观察法。由于前者在文献中未见报道，因此对它进行了重点说明。强调了物质流的跟踪观察法既适用于稳态物质流（产品产量不变），也适用于非稳态物质流（产品产量增长或下降）。以钢铁产品生命周期的铁流图为例，说明了物质流的跟踪模型。在引入了物质流的非稳度后，提出了物质流各项指标的计算式，以及它们之间的相互关系。以瑞典铅酸电池系统为对象，计算了其中铅流的各项指标，并进行了必要的分析。

关键词： 物质流的研究方法     物质流的跟踪观察法     物质流的基本公式     物质流的非稳度    

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UPFC setting to avoid active power flow loop considering wind power uncertainty

Shenghu LI, Ting WANG

《能源前沿（英文）》 2023年 第17卷 第1期   页码 165-175 doi: 10.1007/s11708-020-0686-z

摘要： The active power loop flow (APLF) may be caused by impropriate network configuration, impropriate parameter settings, and/or stochastic bus powers. The power flow controllers, e.g., the unified power flow controller (UPFC), may be the reason and the solution to the loop flows. In this paper, the critical existence condition of the APLF is newly integrated into the simultaneous power flow model for the system and UPFC. Compared with the existing method of alternatively solving the simultaneous power flow and sensitivity-based approaching to the critical existing condition, the integrated power flow needs less iterations and calculation time. Besides, with wind power fluctuation, the interval power flow (IPF) is introduced into the integrated power flow, and solved with the affine Krawcyzk iteration to make sure that the range of active power setting of the UPFC not yielding the APLF. Compared with Monte Carlo simulation, the IPF has the similar accuracy but less time.

关键词： active power loop flow (APLF)     unified power flow controller (UPFC)     wind power uncertainty     interval power flow (IPF)    

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标题 作者 时间 类型 操作

Investigation of bubble diameter and flow regime between water and dilute aqueous ethanol solutions in

Baharak SAJJADI, Mostafa Keshavarz MORAVEJI, Reza DAVARNEJAD

期刊论文

Experimental study for the stratified to slug flow regime transition mechanism of gas-oil two-phase flow

LIU Yiping, YANG Weilin, WANG Jing

期刊论文

Study of two-phase flow regime identification in horizontal tube bundles under vertical upward cross-flow

HUANG Xinghua, WANG Li, JIA Feng

期刊论文

Burnett simulations of gas flow and heat transfer in microchannels

Fubing BAO, Jianzhong LIN

期刊论文

Experimental investigation of multiphase flow behavior in drilling annuli using high speed visualization

Alap Ali ZAHID, Syed Raza ur REHMAN, Anwarul HASAN, S. RUSHD, Mohammad Azizur RAHMAN

期刊论文

一种通用的基于斯托克斯流的复杂流束轮廓工程方法

杨振宇, 南浪, 岑浩璋

期刊论文

Calculation of collision frequency function for aerosol particles in free molecule regime in presence

Xiaowei LUO, Yannick BENICHOU, Suyuan YU

期刊论文

Kinetic roughening transition and missing regime transition of melt crystallized polybutene-1 tetragonal

Motoi YAMASHITA

期刊论文

Numerical study on natural convection in a square enclosure containing a rectangular heated cylinder

Jianhua LU, Zhaoli GUO, Zhenhua CHAI, Baochang SHI,

期刊论文

photogeneration and extraction dynamics of polymer solar cells probed by a transient photocurrent nearby the regime

Boa Jin, Hyunmin Park, Yang Liu, Leijing Liu, Jongdeok An, Wenjing Tian, Chan Im

期刊论文

Is atmospheric oxidation capacity better in indicating tropospheric O formation?

期刊论文

Numerical study of internal flow field and flow passage improvement of an inlet particle separator

Florian PAOLI, Tong WANG

期刊论文

EFFECTS OF SUBSTITUTION OF MINERAL NITROGEN WITH ORGANIC AMENDMENTS ON NITROGEN LOSS FROM SLOPING CROPLAND OF PURPLE SOIL

期刊论文

物质流分析的跟踪观察法

陆钟武

期刊论文

UPFC setting to avoid active power flow loop considering wind power uncertainty

Shenghu LI, Ting WANG

期刊论文