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Optimization of Gravity-Driven Hydraulic Flocculators to Treat Peat Extraction Runoff Water

JOURNAL OF IRRIGATION AND DRAINAGE ENGINEERING 2016年第2期142卷 4015045-1-4015045-11页

作者： Mohammadighavam, Shahram Heiderscheidt, Elisangela Marttila, Hannu Klove, Bjorn Univ Oulu Water Resources & Environm Engn Res Grp POB 4300 Oulu 90014 Finland

Peatland drainage and peat extraction result in runoff water rich in humus, sediments, and nutrients that requires simple purification methods to prevent pollution of surface waters. Chemical treatment of drainage water has been suggested as best management practice. However, good chemical purification results require flocculators to achieve efficient particle aggregation. This study evaluated gravity-driven hydraulic flocculators using full-scale three-dimensional (3D) computational fluid dynamic (CFD) turbulence models to simulate hydraulics, combined with data obtained in jar tests to estimate optimal mixing conditions for coagulation [velocity gradient (G-values)]. The CFD model was first run for several barrier configurations. The optimal structure was then tested for different ratios of distance between barriers [or opening slot width (B)] and flocculator width (W). The relationship between distribution of G-values and the target value of 40-60 s(-1) was determined for different designs. The best B/W ratio was found to be 1/4. For this ratio, the flow depth was the only variable parameter that needed to be optimized by the CFD model to achieve target G-values. (C) 2015 American Society of Civil Engineers.

关键词： computational fluid dynamics technique Drainage Flocculation Optimization models Wastewater management Water treatment plant Water quality

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Residual Stress Distributions Based on Solder Joint Shape with Free Boundaries 7

Residual Stress Distributions Based on Solder Joint Shape wi...

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International Conference on fluid Power and Mechatronics FPM

作者： Zhang, Guoliang Zhong, Wei Peng, Jiagen China Acad Engn Phys Inst Elect Engn Mianyang Sichuan Peoples R China

ISBN: (纸本)9781479987702

Whether low or high temperature brazing seal structure, the solder joint shapes are important concern for the residual stress distributions. Many investigations of the residual stress distributions with the ideal solder joint shape in the brazing seal so far have been carried out theoretically and experimentally, whereas ones of the residual stress distributions with actual solder joint shape in these seal systems are rarely performed. In order to more accurately understand characteristics of the residual stress distributions within the brazing seal, computational fluid dynamics technique is used to predict the actual solder joint shape firstly. Furthermore, the residual stress distributions resulted from the actual solder solidification behavior in the taper configuration of the brazing seal are investigated by experimental observation and finite element method (FEM) simulation in this paper. Results gained show that the residual stress distributions occurred on the actual solder joint are more consistent with the experimental results than them generated on the ideal solder joint. The overall residual stresses are found to increase drastically near the welding interfaces.

关键词： residual stress distributions solder joint shape FEM simulation computational fluid dynamics technique

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Aerodynamic Interference Issues in Aircraft Directional Control

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JOURNAL OF AEROSPACE ENGINEERING 2015年第1期28卷 4014048.1-4014048.7页

作者： Nicolosi, Fabrizio Della Vecchia, Pierluigi Ciliberti, Danilo Univ Napoli Federico II Dept Ind Engn I-80125 Naples Italy

This work investigates the aerodynamic interference among airplane components caused by rudder deflection for a typical turboprop aircraft geometry through the computational fluid dynamics technique. At no sideslip, an airplane is in symmetric flight conditions. The rudder deflection creates a local sideslip angle close to the vertical tailplane, and this effect is increased by fuselage and horizontal tail. Typical semiempirical methods, such as United States Air Force Stability and Control Data Compendium (USAF DATCOM), do not take into account for these effects, proposing the same corrective parameters both for pure sideslip and rudder deflection conditions. Numerical analyses executed on several aircraft configurations with different wing and horizontal tailplane positions show that the interference factors are smaller than those predicted by the USAF DATCOM procedure, providing guidelines for a more accurate aircraft directional control analysis and hence rudder preliminary design. (C) 2014 American Society of Civil Engineers.

关键词： Aerodynamics Aircraft computational fluid dynamics technique Directional control Tailplane

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Residual Stress Distributions Based on Solder Joint Shape with Free Boundaries

Residual Stress Distributions Based on Solder Joint Shape wi...

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International Conference of fluid Power and Mechatronics

作者： Guoliang Zhang Wei Zhong Jiagen Peng Inst. of Electron. Eng. China Acad. of Eng. Phys. Mianyang China

ISBN: (纸本)9781479987719

关键词： Residual stress distributions Solder joint shape FEM simulation computational fluid dynamics technique

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Residual Stress Distributions Based on Solder Joint Shape with Free Boundaries

Residual Stress Distributions Based on Solder Joint Shape wi...

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2015 International Conference on fluid Power and Mechatronics

作者： Guoliang Zhang Wei Zhong Jiagen Peng Institute of Electronic Engineering China Academy of Engineering Physics

Whether low or high temperature brazing seal structure, the solder joint shapes are important concern for the residual stress distributions. Many investigations of the residual stress distributions with the ideal solder joint shape in the brazing seal so far have been carried out theoretically and experimentally, whereas ones of the residual stress distributions with actual solder joint shape in these seal systems are rarely performed. In order to more accurately understand characteristics of the residual stress distributions within the brazing seal, computational fluid dynamics technique is used to predict the actual solder joint shape firstly. Furthermore, the residual stress distributions resulted from the actual solder solidification behavior in the taper configuration of the brazing seal are investigated by experimental observation and finite element method（FEM） simulation in this paper. Results gained show that the residual stress distributions occurred on the actual solder joint are more consistent with the experimental results than them generated on the ideal solder joint. The overall residual stresses are found to increase drastically near the welding interfaces.

关键词： residual stress distributions solder joint shape FEM simulation computational fluid dynamics technique

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Automated Diagnostics and Visualization of Potential Energy Performance Problems in Existing Buildings Using Energy Performance Augmented Reality Models

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JOURNAL OF COMPUTING IN CIVIL ENGINEERING 2014年第1期28卷 17-29页

作者： Golparvar-Fard, Mani Ham, Youngjib Univ Illinois Dept Civil & Environm Engn Urbana IL 61802 USA Univ Illinois Dept Comp Sci Urbana IL USA

Quick and reliable identification of energy performance problems in buildings is a critical step in improving their efficiency. The current practice of building diagnostics typically involves nonintrusive data collection using thermal cameras. This requires large amounts of unordered and nongeo-tagged two-dimensional (2D) imagery to be manually analyzed at a later stage, which makes the analysis time-consuming and labor-intensive. Because of the absence of a benchmark for energy performance, identification of performance problems also heavily relies on the auditor's knowledge, and consequently may lead to subjective and error-prone inspections. As a step towards rapid and objective identification of performance problems, this paper presents a new method for automated analysis and visualization of deviations between buildings' actual and simulated energy performances. The proposed method is based on the recently developed energy performance augmented reality (EPAR) environments. In the EPAR modeling method, actual and expected three-dimensional (3D) spatio-thermal models are generated and superimposed in a common 3D virtual environment. The method leverages unordered collections of thermal and digital imagery for actual energy performance modeling, in addition to computational fluid dynamics (CFD) analysis for expected energy performance simulation. Based on the EPAR models which store actual and simulated thermal values at the level of 3D points, two new algorithms are developed to facilitate identification of potential performance problems: (1)3D thermal mesh modeling using k-d trees and nearest-neighbor searching to automate calculation of temperature deviations, and (2)automated visualization of performance deviations using a metaphor based on traffic light colors. The proposed modeling method is validated on several interior locations of instructional and residential buildings. Empirical observations show that automated analysis using EPAR models enables perform

关键词： Thermal factors Imaging techniques Reconstruction computational fluid dynamics technique Energy consumption Diagnosis Thermogaphy Image-based three-dimensional (3D) reconstruction computational fluid dynamics (CFD) Building diagnostics

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Comparison between CFD and Surface Overflow Rate Models to Predict Particulate Matter Separation in Unit Operations for Combined Sewer Overflows

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JOURNAL OF ENVIRONMENTAL ENGINEERING 2014年第12期140卷 04014041-04014041页

作者： Carbone, M. Garofalo, G. Piro, P. Univ Calabria Dept Civil Engn I-87036 Arcavacata Di Rende Italy

Modeling particulate matter (PM) separation has been a significant topic since unit operations (UOs) has been introduced for clarification of combined sewer overflows (CSOs). In contrast with surface overflow rate (SOR) model, long debated for the limits of its applicability, computational fluid dynamics (CFD) has been an emerging tool for accurately predicting hydrodynamics and PM transport in UOs. In this study an Eulerian-Lagrangian CFD model and a SOR model coupled with particle size distribution (PSD) are used to predict PM separation from three Type I settling UOs with same surface area (SA) but different inlet locations. UOs are loaded with hydraulic conditions and PM gradation measured from samples collected in the combined sewer system of the city of Cosenza, Italy. Specifically, the samples characterize the influent flow entering into a detention tank located downstream of the combined sewer system. The detention tank is used for treating the combined sewer by gravitational settling. The two models predict the overall PM separation efficiency and the separated PM percentage as a function of flow rate and particle size for three different UO configurations. The difference between results from the two models increases as a function of flow rate (differences ranging from about 5 up to 23%) for all three UO configurations. This is probably because of the fact the SOR does not account for the mixing phenomena because of turbulence generated by high hydraulic loadings. Under those conditions, CFD model, properly validated with field measurements, may represent a more accurate predictive tool for design of stormwater settling tanks (STs) than a SOR model.

关键词： Combined Sewers Overflow computational fluid dynamics technique Sedimentation tanks Particle size distribution Urban areas Drainage Flow rates Comparative studies Combined sewer overflow (CSO) computational fluid dynamics (CFD) Settling tank (ST) Particle size distribution (PSD) Urban drainage

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Flow Due to Multiple Jets Downstream of a Barrage: Experiments, 3D computational fluid dynamics, and Depth-Averaged Modeling

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JOURNAL OF HYDRAULIC ENGINEERING 2013年第7期139卷 754-762页

作者： Jeffcoate, Penelope Stansby, Peter Apsley, David Univ Manchester Sch Mech Aerosp & Civil Engn Manchester M13 9PL Lancs England

The flow through and downstream of a row of seven open draft tubes in a barrage has been investigated through laboratory experiments in a wide flume, a three-dimensional (3D) computational fluid dynamics simulation, and a two-dimensional depth-averaged computation. Agreement between the experiments and the 3D modeling is shown to be good, including the prediction of an asymmetric Coand effect. One aim is to determine the distance downstream at which depth-averaged modeling provides a reasonable prediction;this is shown to be approximately 20 tube diameters downstream of the barrage. Upstream of this, the depth-averaged modeling inaccurately predicts water level, bed shear, and the 3D flow field. The 3D model shows that bed shear stress can be markedly magnified near the barrage, particularly where the jets become attached. (C) 2013 American Society of Civil Engineers.

关键词： Tidal power Jets (fluid) Ducts Renewable energy Open channel flow computational fluid dynamics technique Three-dimensional models Tidal power Jets (fluid) Ducts Renewable energy Open channel flow computational fluid dynamics technique

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Passive and Active Methods for Enhancing Water Quality of Service Reservoir

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JOURNAL OF HYDRAULIC ENGINEERING-ASCE 2013年第7期139卷 745-753页

作者： Zhang, Jun-Mei Khoo, Boo Cheong Teo, Chit Pin Haja, Nazarudeen Tham, Tuck Kuan Zhong, Liang Lee, Heow Pueh Natl Heart Ctr Singapore Cardiac Mech Engn & Physiol Unit Singapore 168752 Singapore Natl Univ Singapore Dept Mech Engn Singapore 117576 Singapore Publ Util Board Water Supply Network Dept Singapore 228231 Singapore

Knowledge of flow pattern and water age distributions in service reservoirs is of the utmost importance for ensuring water quality supplied to the customers. In this article, a balancing reservoir was first investigated as a benchmark case. Using the computational fluid dynamics (CFD) method coupled with dynamic meshes, the flow pattern and water age distributions in the reservoir were simulated under actual service conditions. The calculated flow pattern indicated the migration and evolution of flow recirculation regions in the reservoir, which would lead to nonuniform lateral and vertical distributions of the water age, and therefore residual chlorine concentration. A passive flow control method, by adjusting the original circular nozzles to elliptical nozzles, was explored to enhance the water quality. It was found that using elliptical nozzles could assist fluid mixing in the reservoir. The water in the modified reservoir with elliptical nozzles had 5% lower age values than those of the original. Next, bubble plumes were used as an active method to enhance the water quality in the balancing reservoir. It was found that bubble plumes could enhance the fluid mixing significantly in both the vertical and lateral directions. Consequently, the modified reservoir with bubble plumes had 10% lower age values than those of the original reservoir. Therefore, the use of bubble plumes is suggested to be a viable approach for enhancing the water quality in a balancing reservoir, which is deemed to be novel in this field. (C) 2013 American Society of Civil Engineers.

关键词： Numerical analysis Water quality Bubbles Reservoirs computational fluid dynamics technique Numerical analysis Water Mixing Bubble Elliptical nozzle Mean age

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Generic Free-Flow Rating for Cutthroat Flumes

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JOURNAL OF HYDRAULIC ENGINEERING 2013年第7期139卷 727-735页

作者： Temeepattanapongsa, S. Merkley, G. P. Barfuss, S. L. Smith, B. L. Utah State Univ Dept Civil & Environm Engn Logan UT 84322 USA Utah State Univ Utah Water Res Lab Logan UT 84322 USA Utah State Univ Dept Mech & Aerosp Eng Logan UT 84322 USA

computational fluid dynamics (CFD) software was used to generate water depth and discharge data for 51 Cutthroat flume sizes, including all 24 standard sizes published by the flume's developer and 27 intermediate sizes. The hydraulic model was validated by using data from several sources, including physical model testing for 15 standard sizes and three intermediate sizes. Grid-size independence was also confirmed for a range of computational cell sizes and the calibration results for 15 standard flume sizes were compared with previously published calibration parameters. Through the validated CFD simulations, a full set of calibration and validation data was generated for each of 51 flume sizes, filling the gaps in the experimental data and permitting a full analysis of the performance of the flume. The study resulted in a generic calibration for free-flow conditions for any Cutthroat flume in the dimensional range of the 24 standard sizes and specified dimensional ratios according to the original design criteria. The error in the predicted discharge for all flume sizes is less than 3% of the full-scale discharge. (C) 2013 American Society of Civil Engineers.

关键词： Flow measurement Flumes Canals Calibration computational fluid dynamics technique Flow measurement Flumes Cutthroat flume Canals Calibration

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