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MHD effect on the critical temperature differences of oscillatory thermocapillary convection in two-layerfluid system

Hulin HUANG, Xiaoming ZHOU,

《能源前沿（英文）》 2010年 第4卷 第2期   页码 155-160 doi: 10.1007/s11708-009-0063-4

摘要： The effect of different directional magnetic fields on critical temperature differences of oscillatory thermocapillary convection in a rectangular cavity with differentially heated side walls filled with two viscous, immiscible, incompressible fluids is simulated in the absence of gravity. In this two-layer fluid system, the upper layer fluid is the electrically non-conducting encapsulant boron oxide (BO), while the lower one is the electrically conducting molten indium phosphide (InP). The interface between the two fluids is assumed to be flat and non-deformable. The computational results show that all the magnetic fields along the , and directions can delay the transition from steady convection to oscillatory convection, and critical temperature differences increase with an increasing Hartmann number. Furthermore, the effect of a magnetic field along the direction is strongest, followed by that along the direction, and that along the direction is the weakest for the same intensity of the magnetic field.

关键词： magnetohydrodynamic     magnetic fields     thermocapillary convection     critical temperature difference     oscillatory convection     two-layer fluid system    

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Optimal Method of Capacitated Lot-Sizing Planning in Manufacturing Systems

CHANG Jian-feng, ZHONG Yue-xian, HAN Zan-dong

《机械工程前沿（英文）》 2006年 第1卷 第1期   页码 67-70 doi: 10.1007/s11465-005-0020-9

摘要：

This paper analyzes the capacitated lot-sizing problem considering an individual machine s production capacity using a two-layer hierarchical method to minimize the sum of the dynamic inventory cost and the overtime penalty cost. The genetic algorithm, the parameter linear programming method, and a heuristic method were used in the developed method. The method uses the genetic operator to define the lot-sizing matrix (the first layer), linear programming to determine eachmachine' s schedule (the second layer) according to the lot-sizing matrix, and the heuristic method to verify the feasibility of the solutions by adjusting them to meet the constraint requirements. The scheduling of machines in a press shop demonstrates the effectiveness of the algorithm. The result shows that the algorithm is convergent.

关键词： heuristic     two-layer hierarchical     algorithm     constraint     developed    

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An autonomous system for thermal convection of viscoelastic fluids in a porous layer using a thermal

Qi WEI, Xiaohui ZHANG

《能源前沿（英文）》 2010年 第4卷 第4期   页码 507-516 doi: 10.1007/s11708-010-0017-x

摘要： Thermal convection of viscoelastic fluids saturating a horizontal porous layer heated from below is analyzed using a thermal nonequilibrium model to take account of the interphase heat transfer between the fluid and the solid. The viscoelastic character of the flow is considered by a modified Darcy’s law. An autonomous system with five differential equations is deduced by applying the truncated Galerkin expansion to the momentum and heat transfer equations. The effects of interphase heat transfer on the thermal convection of viscoelastic fluids in a porous medium are analyzed and discussed. The results show that the weak interphase heat transfer tends to stabilize the steady convection.

关键词： thermal convection     porous media     viscoelastic fluid     thermal nonequilibrium model    

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Extended two-fluid model applied to analysis of bubbly flow in multiphase rotodynamic pump impeller

Zhiyi YU, Guoyu WANG, Shuliang CAO

《机械工程前沿（英文）》 2009年 第4卷 第1期   页码 53-59 doi: 10.1007/s11465-009-0006-0

摘要： This paper presents an extended two-fluid model based on the Navier-Stokes equations and the standard turbulence model, to simulate the three-dimensional air-water bubbly flow in turbo machinery. In the governing equations, the drag force and added mass force are added and the additional source terms arising from fluctuations of gas volume fraction are considered. The discrete equations are solved using a developed two-phase semi-implicit method for pressure-linked equations, consistent (SIMPLEC) algorithm in body-fitted coordinates with a staggered grid system. Simulation is then carried out for the pure liquid flow and air-water two-phase flow with the inlet gas volume fraction being 15% in a multiphase rotodynamic pump impeller and the pump head performance is predicted. Comparison with experimental results shows the reliability and commonality of the numerical model.

关键词： two-fluid model     multiphase rotodynamic pump     SIMPLEC algorithm     numerical simulation    

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双层高通量计算——包括翘曲情况下的有效质量计算 Article

Andrew Supka, Nicholas A. Mecholsky, Marco Buongiorno Nardelli, Stefano Curtarolo, Marco Fornari

《工程（英文）》 2022年 第10卷 第3期   页码 74-80 doi: 10.1016/j.eng.2021.03.031

摘要：

本文使用了双层高通量计算。在涉及改变晶体结构和（或）化学成分的第一层中，本文分析了选定的IIIV半导体、填充和未填充的方钴矿，以及岩盐和层状硫属化物。第二层在整个布里渊区（BZ）中搜索费米能级1.5 eV (1 eV = 1.602176×10−19 J)范围内的临界点，并通过计算有效质量来表征这些点。本文介绍了几种从第一原理计算有效质量的方法并对它们进行了比较。本文使用的方法还包括计算翘曲临界点的态密度有效质量，由于临界点存在潜在非解析性，传统方法无法给出一致的结果。本文证明了考虑能带结构的全部复杂性以及计算有效质量的互补方法价值的必要性。本文还通过计算证明翘曲仅发生在有退化性的情况下。

关键词： 高通量     电子结构     能带翘曲     有效质量    

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Simulating multiphase flow in a two-stage pusher centrifuge using computational fluid dynamics

Chong PANG, Wei TAN, Endian SHA, Yuanqing TAO, Liyan LIU

《化学科学与工程前沿（英文）》 2012年 第6卷 第3期   页码 329-338 doi: 10.1007/s11705-012-1205-5

摘要： The design of two-stage pusher centrifuges have developed rapidly, but a good understanding of the theory behind their practice is a long-standing problem. To better understand centrifugal filter processes, the computational fluid dynamics (CFD) software program FLUENT has been used to model the three-dimensional geometry and to simulate multiphase flows based on Euler-Euler, moving mesh, dynamic mesh and porous media models. The simulation tangential velocities were a little smaller than those for rigid-body motion. In the stable flow region, the radial velocities were in good agreement with the theoretical data. Additionally, solid concentration distribution were obtained and also showed good agreement with the experimental data. These results show that this simulation method could be an effective tool to optimize the design of the two-stage pusher centrifuge.

关键词： two-stage pusher centrifuge     multiphase flow     CFD     dynamic mesh     porous media    

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Numerical studies of dynamic behavior of liquid film on single-layer wire mesh with different wettabilities

《化学科学与工程前沿（英文）》   页码 1672-1680 doi: 10.1007/s11705-022-2205-8

摘要： Droplet impacting on the stainless steel wire mesh is very common in chemical devices, like a rotating packed bed. Surface wettability of wire mesh significantly affects the liquid flow pattern and liquid dispersion performance. However, the effect of surface wettability on the impaction phenomena at microscale such as liquid film is still unknown. In this work, the dynamic behavior of liquid film on the surface of wire mesh was analyzed by computational fluid dynamics simulation. The dynamic behavior of liquid film on the surface of wire mesh can be divided into the following three steps: (1) spreading step; (2) shrinkage process; (3) stabilizing or disappearing step. Effects of surface wettability, as well as operating conditions, on wetting area and liquid film thickness were studied. Compared to the hydrophilic wire mesh, the final wetting area of hydrophobic wire mesh is zero in most cases. The average liquid film thickness on the surface of hydrophilic wire mesh is 30.02–77.29 μm, and that of hydrophobic wire mesh is 41.76–237.37 μm. This work provided a basic understanding of liquid film flow at microscale on the surface with various surface wettabilities, which can be guiding the packing optimization and design.

关键词： stainless steel wire mesh     computational fluid dynamics     surface wettability     liquid film     impacting    

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Two-dimensional modeling of sintering of a powder layer on top of nonporous substrate

Tiebing CHEN, Yuwen ZHANG,

《机械工程前沿（英文）》 2010年 第5卷 第2期   页码 143-148 doi: 10.1007/s11465-010-0006-0

摘要： Selective laser sintering (SLS) of a two-component metal powder layer on the top of multiple sintered layers by a moving Gaussian laser beam is modeled. The loose metal powder layer is composed of a powder mixture with significantly different melting points. The physical model that accounts the shrinkage induced by melting is described by using a temperature-transforming model. The effects of the porosity and the thickness of the atop loose powder layer with different numbers of the existing sintered metal powder layers below on the sintering process are numerically investigated. The present work will provide a better understanding to simulate much more complicated three-dimensional SLS process.

关键词： laser     sintering     melting     solidification     heat transfer    

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Numerical study and control method of interaction of nucleation and boundary layer separation in condensing

Liansuo AN , Zhi WANG , Zhonghe HAN ,

《能源前沿（英文）》 2009年 第3卷 第3期   页码 254-261 doi: 10.1007/s11708-009-0047-4

摘要： The spontaneous nucleation flow in turbine cascade was numerically studied. The model was implemented within a full Navier–Stokes viscous flow solution procedure and the process of condensation was calculated by the quadrature method of moments that shows good accuracy with very broad size distributions. Results were presented for viscous and inviscous flow, showing the influence of boundary layer separation and wake vortices on spontaneous nucleation. The results show that the degree of flow separation in wet steam flow is greater than that in superheated steam flow due to condensation shock and that the loss cannot be neglected. Furthermore, the impact of boundary layer separation and wake vortices on velocity profiles and its implications for profile loss were considered. The calculations showed that layer separation and wake vortices influence nucleation rate, leading to different droplet distributions. A method for controlling homogeneous nucleation and for reducing degree of flow separation in high-speed transonic wet steam flow was presented. The liquid phase parameter distribution is sensitive to the suction side profile of turbine cascade, which impacts the nucleation rate distribution leading to different droplet distributions and affects the degree of flow separation. The numerical study provides a practical design method for turbine blade to reduce wetness losses.

关键词： wet steam     two-phase flow     spontaneous condensation     numerical simulation     flow separation     profile loss    

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Review of fluid and control technology of hydraulic wind turbines

Maolin CAI, Yixuan WANG, Zongxia JIAO, Yan SHI

《机械工程前沿（英文）》 2017年 第12卷 第3期   页码 312-320 doi: 10.1007/s11465-017-0433-2

摘要：

This study examines the development of the fluid and control technology of hydraulic wind turbines. The current state of hydraulic wind turbines as a new technology is described, and its basic fluid model and typical control method are expounded by comparing various study results. Finally, the advantages of hydraulic wind turbines are enumerated. Hydraulic wind turbines are expected to become the main development direction of wind turbines.

关键词： wind turbine     hydraulic system     fluid model     control technology    

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Experimental study on high-efficiency polishing for potassium dihydrogen phosphate (KDP) crystal by using two-phaseair–water fluid

Ziyuan LIU, Hang GAO, Dongming GUO

《机械工程前沿（英文）》 2020年 第15卷 第2期   页码 294-302 doi: 10.1007/s11465-019-0576-4

摘要： A high-efficiency polishing approach using two-phase air–water fluid (TAWF) is proposed to avoid surface contamination and solve the inefficiency of previous water-dissolution polishing techniques for potassium dihydrogen phosphate (KDP) crystal. In the proposed method, controllable deliquescence is implemented without any chemical impurity. The product of deliquescence is then removed by a polishing pad to achieve surface planarization. The mechanism underlying TAWF polishing is analyzed, a special device is built to polish the KDP crystal, and the effect of relative humidity (RH) on polishing performance is studied. The relationship between key parameters of polishing and surface planarization is also investigated. Results show that the polishing performance is improved with increasing RH. However, precisely controlling the RH is extremely difficult during TAWF polishing. Controllable deliquescence can easily be disrupted once the RH fluctuates, which therefore needs to be restricted to a low level to avoid its influence on deliquescence rate. The material removal of TAWF polishing is mainly attributed to the synergistic effect of deliquescence and the polishing pad. Excessive polishing pressure and revolution rate remarkably reduce the life of the polishing pad and the surface quality of the KDP crystal. TAWF polishing using IC-1000 and TEC-168S increase the machining efficiency by 150%, and a smooth surface with a root mean square surface roughness of 5.5 nm is obtained.

关键词： potassium dihydrogen phosphate (KDP) crystal     controllable deliquescence     two-phase air–water fluid     high-efficiency polishing     material removal    

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CFD simulation of the hydrodynamics in an internal air-lift reactor with two different configurations

Mona EBRAHIMIFAKHAR, Elmira MOHSENZADEH, Sadegh MORADI, Mostafa MORAVEJI, Mahmoud SALIMI

《化学科学与工程前沿（英文）》 2011年 第5卷 第4期   页码 455-462 doi: 10.1007/s11705-011-1116-x

摘要： Computational fluid dynamics (CFD) was used to investigate the hydrodynamic parameters of two internal airlift bioreactors with different configurations. Both had a riser diameter of 0.1 m. The model was used to predict the effect of the reactor geometry on the reactor hydrodynamics. Water was utilized as the continuous phase and air in the form of bubbles was applied as the dispersed phase. A two-phase flow model provided by the bubbly flow application mode was employed in this project. In the liquid phase, the turbulence can be described using the - model. Simulated gas holdup and liquid circulation velocity results were compared with experimental data. The predictions of the simulation are in good agreement with the experimental data.

关键词： airlift reactor     gas holdup     liquid circulation velocity     bubbly flow     computational fluid dynamics (CFD)    

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Performance of a bi-layer solar steam generation system working at a high-temperature of top surface

Jinxin ZHONG, Congliang HUANG

《能源前沿（英文）》 2023年 第17卷 第1期   页码 141-148 doi: 10.1007/s11708-021-0725-4

摘要： Many efforts have been focused on enhancing the vapor generation in bi-layer solar steam generation systems for obtaining as much pure water as possible. However, the methods to enhance the vapor temperature is seldom studied although the high-temperature vapor has a wide use in medical sterilization and electricity generation. In this work, to probe the high-temperature vapor system, an improved macroscopic heat and mass transfer model was proposed. Then, using the finite element method to solve the model, the influences of some main factors on the evaporation efficiency and vapor temperature were discussed, including effects of the vapor transport conditions and the heat dissipation conditions. The results show that the high-temperature vapor could not be obtained by enhancing the heat-insulating property of the bi-layer systems but by applying the optimal porosity and proper absorbers. This paper is expected to provide some information for designing a bi-layered system to produce high-temperature vapor.

关键词： solar steam generation     solar energy     numerical method     porous material    

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Advanced nitrogen removal using pilot-scale SBR with intelligent control system built on three layer

YANG Qing, WANG Shuying, YANG Anming, GUO Jianhua, BO Fengyang

《环境科学与工程前沿（英文）》 2007年 第1卷 第1期   页码 33-38 doi: 10.1007/s11783-007-0006-4

摘要： Since eutrophication has become increasingly severe in China, nitrogen and phosphorous have been the concern of wastewater treatment, especially nitrogen removal. The stabilization of the intelligent control system and nitrogen removal efficiency were investigated in a pilot-scale aerobic-anoxic sequencing batch reactor (SBR) with a treatment capacity of 60 m/d. Characteristic points on the profiles of dissolved oxygen (DO), pH, and oxidation reduction potential (ORP) could exactly reflect the process of nitrification and denitrification. Using the intelligent control system not only could save energy, but also could achieve advanced nitrogen removal. Applying the control strategy water quality of the effluent could stably meet the national first discharge standard during experiment of 10 months. Even at low temperature ( = 13vH), chemical oxygen demand (COD) and total nitrogen (TN) in the effluent were under 50 and 5 mg/L, respectively.

关键词： eutrophication     pilot-scale aerobic-anoxic     stabilization     oxidation reduction     nitrification    

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Precision control system of two-DOF stage with linear ultrasonic motor

ZHANG Hanlei, SHI Yunlai, ZHAO Chunsheng

《机械工程前沿（英文）》 2008年 第3卷 第4期   页码 421-425 doi: 10.1007/s11465-008-0063-9

摘要： Using an appropriate control method, linear ultrasonic motors can be used in applications requiring high position accuracy. In this paper, a closed loop PI control system is designed to achieve high position accuracy during the control of a two-DOF stage driven by linear ultrasonic motors. Two ultrasonic motors are mounted on the stage to generate motion in two orthogonal directions. The PI control algorithm is used to increase the stability and accuracy of position control. The -axis mover covers 30 mm forward and backward in less than 0.3 s settling time and the -axis mover in less than 0.4 s. Experimental results denote that the control strategy proposed in this paper appears to have high efficiency, quick response, and high accuracy.

关键词： settling     position accuracy     PI control     control algorithm     orthogonal    

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标题 作者 时间 类型 操作

MHD effect on the critical temperature differences of oscillatory thermocapillary convection in two-layerfluid system

Hulin HUANG, Xiaoming ZHOU,

期刊论文

Optimal Method of Capacitated Lot-Sizing Planning in Manufacturing Systems

CHANG Jian-feng, ZHONG Yue-xian, HAN Zan-dong

期刊论文

An autonomous system for thermal convection of viscoelastic fluids in a porous layer using a thermal

Qi WEI, Xiaohui ZHANG

期刊论文

Extended two-fluid model applied to analysis of bubbly flow in multiphase rotodynamic pump impeller

Zhiyi YU, Guoyu WANG, Shuliang CAO

期刊论文

双层高通量计算——包括翘曲情况下的有效质量计算

Andrew Supka, Nicholas A. Mecholsky, Marco Buongiorno Nardelli, Stefano Curtarolo, Marco Fornari

期刊论文

Simulating multiphase flow in a two-stage pusher centrifuge using computational fluid dynamics

Chong PANG, Wei TAN, Endian SHA, Yuanqing TAO, Liyan LIU

期刊论文

Numerical studies of dynamic behavior of liquid film on single-layer wire mesh with different wettabilities

期刊论文

Two-dimensional modeling of sintering of a powder layer on top of nonporous substrate

Tiebing CHEN, Yuwen ZHANG,

期刊论文

Numerical study and control method of interaction of nucleation and boundary layer separation in condensing

Liansuo AN , Zhi WANG , Zhonghe HAN ,

期刊论文

Review of fluid and control technology of hydraulic wind turbines

Maolin CAI, Yixuan WANG, Zongxia JIAO, Yan SHI

期刊论文

Experimental study on high-efficiency polishing for potassium dihydrogen phosphate (KDP) crystal by using two-phaseair–water fluid

Ziyuan LIU, Hang GAO, Dongming GUO

期刊论文

CFD simulation of the hydrodynamics in an internal air-lift reactor with two different configurations

Mona EBRAHIMIFAKHAR, Elmira MOHSENZADEH, Sadegh MORADI, Mostafa MORAVEJI, Mahmoud SALIMI

期刊论文

Performance of a bi-layer solar steam generation system working at a high-temperature of top surface

Jinxin ZHONG, Congliang HUANG

期刊论文

Advanced nitrogen removal using pilot-scale SBR with intelligent control system built on three layer

YANG Qing, WANG Shuying, YANG Anming, GUO Jianhua, BO Fengyang

期刊论文

Precision control system of two-DOF stage with linear ultrasonic motor

ZHANG Hanlei, SHI Yunlai, ZHAO Chunsheng

期刊论文