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Development of a fan-stirred constant volume combustion chamber and turbulence measurement with PIV

《能源前沿（英文）》 2022年第16卷第6期页码 973-987 doi: 10.1007/s11708-021-0762-z

摘要： A fan-stirred combustion chamber is deve-loped for spherically expanding flames, with P and T up to 10 bar and 473 K, respectively. Turbulence characteristics are estimated using particle image velocimetry (PIV) at different initial pressures (P = 0.5–5 bar), fan frequencies (ω = 0–2000 r/min), and impeller diameters (D = 100 and 114 mm). The flame propagation of methanol/air is investigated at different turbulence intensities (u′=0–1.77 m/s) and equivalence ratios (φ = 0.7–1.5). The results show that u′ is independent of P and proportional to ω, which can be up to 3.5 m/s at 2000 r/min. L_T is independent of P and performs a power regression with ω approximately. The turbulent field is homogeneous and isotropic in the central region of the chamber while the inertial subrange of spatial energy spectrum is more collapsed to –5/3 law at a high Re_T. Compared to laminar expanding flames, the morpho-logy of turbulent expanding flames is wrinkled and the wrinkles will be finer with the growth of turbulence intensity, consistent with the decline of the Taylor scale and the Kolmogorov scale. The determined S_L in the present study is in good agreement with that of previous literature. The S_L and S_T of methanol/air have a non-monotonic trend with φ while peak S_T is shifted to the richer side compared to S_L. This indicates that the newly built turbulent combustion chamber is reliable for further experimental study.

关键词： fan-stirred combustion chamber turbulence characteristics particle image velocimetry (PIV) methanol turbulent expanding flames

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通过一个等价雷诺数揭示层流到湍流的转捩区域 Article

陈晓东

《工程（英文）》 2019年第5卷第3期页码 576-579 doi: 10.1016/j.eng.2018.09.013

摘要：

Flow transition from laminar to turbulent mode (and vice versa)—that is, the initiation of turbulence—is one of the most important research subjects in the history of engineering. Even for pipe flow, predicting the onset of turbulence requires sophisticated instrumentation and/or direct numerical simulation, based on observing the instantaneous flow structure formation and evolution. In this work, a local Reynolds number equivalence γ (ratio of local inertia effect to viscous effect) is seen to conform to the Universal Law of the Wall, where γ = 1 represents a quantitative balance between the abovementioned two effects. This coincides with the wall layer thickness (y⁺ = 1, where y⁺ is the dimensionless distance from the wall surface defined in the Universal Law of the Wall). It is found that the characteristic of how the local derivative of γ against the local velocity changes with increasing velocity determines the onset of turbulence. For pipe flow, γ ≈ 25, and for plate flow, γ ≈ 151.5. These findings suggest that a certain combination of γ and velocity (nonlinearity) can qualify the source of turbulence (i.e., generate turbulent energy). Similarly, a re-evaluation of the previous findings reveals that only the geometrically narrow domain can act locally as the source of turbulence, with the rest of the flow field largely being left for transporting and dissipating. This understanding will have an impact on the future large-scale modeling of turbulence.

关键词：局部等价雷诺数转捩壁面律管流平板流动建模

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Stormwater treatment: examples of computational fluid dynamics modeling

Gaoxiang YING, John SANSALONE, Srikanth PATHAPATI, Giuseppina GAROFALO, Marco MAGLIONICO, Andrea BOLOGNESI, Alessandro ARTINA

《环境科学与工程前沿（英文）》 2012年第6卷第5期页码 638-648 doi: 10.1007/s11783-012-0442-7

摘要： Control of rainfall-runoff particulate matter (PM) and PM-bound chemical loads is challenging; in part due to the wide gradation of PM complex geometries of many unit operations and variable flow rates. Such challenges and the expense associated with resolving such challenges have led to the relatively common examination of a spectrum of unit operations and processes. This study applies the principles of computational fluid dynamics (CFD) to predict the particle and pollutant clarification behavior of these systems subject to dilute multiphase flows, typical of rainfall-runoff, within computationally reasonable limits, to a scientifically acceptable degree of accuracy. The Navier-Stokes (NS) system of nonlinear partial differential equations for multi-phase hydrodynamics and separation of entrained particles are solved numerically over the unit operation control volume with the boundary and initial conditions defined and then solved numerically until the desired convergence criteria are met. Flow rates examined are scaled based on sizing of common unit operations such as hydrodynamic separators (HS), wet basins, or filters, and are examined from 1 to 100 percent of the system maximum hydraulic operating flow rate. A standard turbulence model is used to resolve flow, and a discrete phase model (DPM) is utilized to examine the particle clarification response. CFD results closely follow physical model results across the entire range of flow rates. Post-processing the CFD predictions provides an in-depth insight into the mechanistic behavior of unit operations by means of three dimensional (3-D) hydraulic profiles and particle trajectories. Results demonstrate the role of scour in the rapid degradation of unit operations that are not maintained. Comparisons are provided between measured and CFD modeled results and a mass balance error is identified. CFD is arguably the most powerful tool available for our profession since continuous simulation modeling.

关键词： stormwater unit operations and processes (UOPs) hydrodynamic separation filtration adsorption computational fluid dynamics (CFD) turbulence modeling discrete phase model particle separation detention/retention basins clarification

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湍流效应对桁架式桥梁断面气动弹性性能影响的研究

Hoang Trong Lam, Hiroshi Katsuchi, Hitoshi Yamada

《工程（英文）》 2017年第3卷第6期页码 845-853 doi: 10.1016/j.eng.2017.10.001

摘要：

本文介绍了在不同湍流条件下通过随机系统识别（SSI）方法提取颤振导数（FD）的过程。研究旨在通过对节段模型风洞试验来研究湍流对悬索式大跨度桥梁的影响。针对不同的湍流特性，对桁架式桥梁断面进行了几项风洞试验，包括降低湍流强度和湍流尺度。研究包括湍流对模型动态响应的影响。利用系统识别技术提取FD，对风洞试验中的瞬态响应和抖振响应进行了分析，同时讨论了该方法存在的困难。利用时域SSI 同时从一自由度（1DOF）和二自由度（2DOF）系统提取所有的FD。最后，讨论了不同情况下的结果并得出结论。

关键词：颤振导数系统识别湍流效应抖振响应

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Numerical simulation of sudden-expansion two-phase flows with two-scale second-order moment particle turbulence

ZENG Zhuoxiong, HAN Shoulei, ZHOU Lixing

《能源前沿（英文）》 2007年第1卷第2期页码 202-206 doi: 10.1007/s11708-007-0026-6

摘要： A two-scale second-order moment particle turbulence model is developed, based on the concept of particle large-scale fluctuation due to turbulence and particle small-scale fluctuation due to collision. The model is employed to simulate gas-particle flows in a sudden-expansion chamber. Simulation results are compared with the experimental results and with those obtained by the single-scale second-order moment two-phase turbulence model. It is shown that the two-scale model is with higher calculating accuracy than the single-scale model.

关键词： gas-particle single-scale second-order large-scale fluctuation second-order sudden-expansion

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Evaluation of the wind energy potential of two south west sites in Nigeria

Olaleye M. AMOO

《能源前沿（英文）》 2012年第6卷第3期页码 237-246 doi: 10.1007/s11708-012-0201-2

摘要： Wind resource assessment is a crucial first step in gauging the potential of a site to produce energy from wind turbines. In this paper, the wind energy potential of Abeokuta (07°03'N, 03°19'E) and Ijebu-Ode (06°47'N, 03°58'E), two south west sites in Nigeria were examined. Twenty years (1990–2010) of monthly mean wind data from a 10 m height were subjected to two-parameter Weibull analysis and other statistical analyses. The results show that the average annual mean wind speed variation for Abeokuta ranges from 2.2 to 5.0 m/s. For Ijebu-Ode, it ranges from 2.0 to 5.0 m/s. The wind power density variation based on the Weibull analysis ranges from 4.26 to 24.51 W/m for Abeokuta and from 8.54 to 76.46 W/m for Ijebu-Ode. Ijebu-Ode was found to be the better of the two sites in terms of annual variation of mean wind speed.

关键词： wind potential wind speed wind power density wind gust turbulence intensity Nigeria

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零方程湍流模型在列车车厢内气流数值模拟中的应用

杨培志,顾小松

《中国工程科学》 2006年第8卷第1期页码 26-29

摘要：

采用k-ε湍流模型对列车车厢内气流进行数值模拟需要消耗大量的计算时间，为此，提出了采用零方程湍流模型对列车车厢内的气流组织进行数值模拟；分别采用零方程湍流模型与k-ε湍流模型对列车车厢内的空气流动及传热进行了数值计算，经分析比较可知，该两种湍流模型的数值计算结果吻合程度较好，采用零方程湍流模型可大大缩短计算时间，利用其简单、快捷的特点，可以为列车空调系统的工程设计提供简便的数值模拟方法。

关键词：空调零方程湍流模型数值模拟列车

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Simulating the air flow in the conveying pipe of the foreign fiber detection device

Ting CHEN, Lili WU, Ke WANG,

《化学科学与工程前沿（英文）》 2010年第4卷第3期页码 275-279 doi: 10.1007/s11705-009-0274-6

摘要： Cotton bales are frequently intermingled with foreign fibers which will interfere in the process of spinning, weaving and dyeing and will worsen the product quality. Nowadays, cotton fibers are sorted manually in most of the cotton textile mills with very low efficiency. There is a great demand for foreign fiber detection devices in Chinese cotton textile mills. The air flow in the conveying pipe of the device has an important effect on the image acquisition, image analysis and removal of foreign fibers. As a primary effort, the air flow in the conveying pipe of the foreign fiber detection device was simulated numerically. The effects of the inlet air velocity on the air turbulence intensity and air velocity along the detecting section were studied.

关键词： product quality Chinese process turbulence intensity primary

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空调硬卧车内气流组织的数值模拟研究

张登春

《中国工程科学》 2004年第6卷第9期页码 66-72

摘要：

空调车内气流组织研究是车厢内热环境控制的基础，合理的车内气流组织可有效地改善乘客的冷热舒适性。采用k-ε湍流模型对25K型空调硬卧车内气流组织进行了数值模拟，研究了不同送风方式和送风参数下车内空气流场和温度场分布规律，并与实验结果进行了对照，两者基本一致。研究结果对于改善硬卧车内人体冷热舒适性提供了理论依据，对车内气流组织优化设计有指导意义。

关键词：硬卧车湍流模型气流组织数值模拟

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旅客列车硬座车厢内气流模拟与浓度场分析

张登春,翁培奋

《中国工程科学》 2007年第9卷第11期页码 80-86

摘要：

采用稳态不可压缩雷诺时均N-S方程、k-ε湍流模型，对旅客列车空调硬座车厢内气流场和浓度场进行了数值计算。采用立方体代表旅客，以人体呼出的CO₂作为代表性污染物，研究了非空载下车厢内气流和浓度分布。计算结果表明：现有的送风方式除车厢两端外，车厢内沿长度方向气流分布比较均匀；人体散热和太阳辐射对车厢内流场温度场影响较大，非空载时车厢内流场分布与空载时有较大差别，太阳照射和人体产生的热气流使车厢内存在较大的温度梯度；车厢内过道区浓度较低，但座位区由于人员集中，人体呼吸区污染物积聚，浓度偏高，且车厢中部断面污染

关键词：车厢湍流模型流场浓度场计算流体动力学

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Continuous modeling of soil morphology —thermomechanical behavior of embankment dams

Bettina ALBERS, Krzysztof WILMANSKI

《结构与土木工程前沿（英文）》 2011年第5卷第1期页码 11-23 doi: 10.1007/s11709-010-0081-7

摘要： Macroscopic modeling of soils is based on a number of properties that refer to the mesoscopic morphology. The most fundamental parameters of this art are: 1) coupling parameters between partial stresses of components and deformations of components, 2) porosities, 3) saturation, and 4) permeability and diffusivity, tortuosity. The main aim of this paper is to present in juxtaposition continuous one-, two-, and three-component models of geomaterials appearing in construction of embankment dams. In particular, the above mentioned features, especially saturation with water and seepage problems, modeling of fluidization yielding piping, and generalizations of the Darcy law and changes of porosity, are presented.

关键词： thermomechanical modeling soil morphology saturation porosity

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Flow and thermal modeling of liquid metal in expanded microchannel heat sink

《能源前沿（英文）》页码 796-810 doi: 10.1007/s11708-023-0877-5

摘要： Liquid metal-based microchannel heat sinks (MCHSs) suffer from the low heat capacity of coolant, resulting in an excessive temperature rise of coolant and heat sink when dealing with high-power heat dissipation. In this paper, it was found that expanded space at the top of fins could distribute the heat inside microchannels, reducing the temperature rise of coolant and heat sink. The orthogonal experiments revealed that expanding the top space of channels yielded similar temperature reductions to changing the channel width. The flow and thermal modeling of expanded microchannel heat sink (E-MCHS) were analyzed by both using the 3-dimensional (3D) numerical simulation and the 1-dimensional (1D) thermal resistance model. The fin efficiency of E-MCHS was derived to improve the accuracy of the 1D thermal resistance model. The heat conduction of liquid metal in Z direction and the heat convection between the top surface of fins and the liquid metal could reduce the total thermal resistance (R_t). The above process was effective for microchannels with low channel aspect ratio, low mean velocity (U_m) or long heat sink length. The maximum thermal resistance reduction in the example of this paper reached 36.0%. The expanded space endowed the heat sink with lower pressure, which might further reduce the pumping power (P). This rule was feasible both when fins were truncated (h₂ < 0, h₂ is the height of expanded channel for E-MCHS) and when over plate was raised (h₂ > 0).

关键词： liquid metal cooling heat sink expanded microchannel flow and thermal modeling

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一种集成的统一建模语言框架

Mohammad ALSHAYEB,Nasser KHASHAN,Sajjad MAHMOOD

《信息与电子工程前沿（英文）》 2016年第17卷第2期页码 143-159 doi: 10.1631/FITEE.1500094

摘要：

The unified modeling language (UML) is one of the most commonly used modeling languages in the software industry.It simplifies the complex process of design by providing a set of graphical notations, which helps express the objectoriented analysis and design of software projects. Although UML is applicable to different types of systems, domains, methods,and processes, it cannot express certain problem domain needs. Therefore, many extensions to UML have been proposed. In this paper, we propose a framework for integrating the UML extensions and then use the framework to propose an integrated unified modeling language-graphical (iUML-g) form. iUML-g integrates the existing UML extensions into one integrated form. This includes an integrated diagram for UML class, sequence, and use case diagrams. The proposed approach is evaluated using a case study. The proposed iUML-g is capable of modeling systems that use different domains.

关键词： Unified modeling language (UML) Integration Modeling System analysis and design

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Computer modeling of crystal growth of silicon for solar cells

Lijun LIU, Xin LIU, Zaoyang LI, Koichi KAKIMOTO

《能源前沿（英文）》 2011年第5卷第3期页码 305-312 doi: 10.1007/s11708-011-0155-9

摘要： A computer simulator with a global model of heat transfer during crystal growth of Si for solar cells is developed. The convective, conductive, and radiative heat transfers in the furnace are solved together in a coupled manner using the finite volume method. A three-dimensional (3D) global heat transfer model with 3D features is especially made suitable for any crystal growth, while the requirement for computer resources is kept permissible for engineering applications. A structured/unstructured combined mesh scheme is proposed to improve the efficiency and accuracy of the simulation. A dynamic model for the melt-crystal (mc) interface is developed to predict the phase interface behavior in a crystal growth process. Dynamic models for impurities and precipitates are also incorporated into the simulator. Applications of the computer simulator to Czochralski (CZ) growth processes and directional solidification processes of Si crystals for solar cells are introduced. Some typical results, including the turbulent melt flow in a large-scale crucible of a CZ-Si process, the dynamic behaviors of the mc interface, and the transport and distributions of impurities and precipitates, such as oxygen, carbon, and SiC particles, are presented and discussed. The findings show the importance of computer modeling as an effective tool in the analysis and improvement of crystal growth processes and furnace designs for solar Si material.

关键词： computer modeling silicon crystal growth solar cells

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Lamb wave propagation modeling for structure health monitoring

Xiaoyue ZHANG, Shenfang YUAN, Tong HAO

《机械工程前沿（英文）》 2009年第4卷第3期页码 326-331 doi: 10.1007/s11465-009-0045-6

摘要： This study aims to model the propagation of Lamb waves used in structure health monitoring. A number of different numerical computational techniques have been developed for wave propagation studies. The local interaction simulation approach, used for modeling sharp interfaces and discontinuities in complex media (LISA/SIM theory), has been effectively applied to numerical simulations of elastic wave interaction. This modeling is based on the local interaction simulation approach theory and is finally accomplished through the finite elements software Ansys11. In this paper, the Lamb waves propagating characteristics and the LISA/SIM theory are introduced. The finite difference equations describing wave propagation used in the LISA/SIM theory are obtained. Then, an anisotropic metallic plate model is modeled and a simulating Lamb waves signal is loaded on. Finally, the Lamb waves propagation modeling is implemented.

关键词： Lamb wave modeling LISA/SIM theory finite difference equation finite element