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Fiber Bundle Topology Optimization for Surface Flows

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Chinese Journal of Mechanical Engineering 2024年第3期37卷 236-264页

作者： Yongbo Deng Weihong Zhang Jihong Zhu Yingjie Xu Jan G Korvink State Key Laboratory of Applied Optics Changchun Institute of OpticsFine Mechanics and PhysicsChinese Academy of SciencesChangchun 130033China State IJR Center of Aerospace Design and Additive Manufacturing Northwestern Polytechnical UniversityXi’an 710072China Institute of Microstructure Technology(IMT) Karlsruhe Institute of Technology(KIT)Hermann-von-Helmholtzplatz 176344 Eggenstein-LeopoldshafenGermany

This paper presents a topology optimization approach for the surface flows on variable design *** this approach,the matching between the pattern of a surface flow and the 2-manifold used to define the pattern can be optimized,where the 2-manifold is implicitly defined on another fixed 2-manifold named as the base *** fiber bundle topology optimization approach is developed based on the description of the topological structure of the surface flow by using the differential geometry concept of the fiber *** material distribution method is used to achieve the evolution of the pattern of the surface *** evolution of the implicit 2-manifold is realized via a homeomorphous *** design variable of the pattern of the surface flow and that of the implicit 2-manifold are regularized by two sequentially implemented surface-PDE *** two surface-PDE filters are coupled,because they are defined on the implicit 2-manifold and base manifold,*** surface Navier-Stokes equations,defined on the implicit 2-manifold,are used to describe the surface *** fiber bundle topology optimization problem is analyzed using the continuous adjoint method implemented on the first-order Sobolev *** numerical examples have been provided to demonstrate this approach,where the combination of the viscous dissipation and pressure drop is used as the design objective.

关键词： Fiber bundle Topology optimization 2-manifold Surface flow Material distribution method Porous medium model

环氧树脂涂层中添加含铝复合粉增强碳钢基材的防腐性

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Journal of Central South university 2024年第3期31卷 723-736页

作者： Meysam TOOZANDEHJANI Pooria MOOZARM NIA Ebrahim ABOUZARI LOTF Farhad OSTOVAN Mahnaz SHAMSHIRSAZ New Technologies Research Center Amirkabir University of TechnologyTehran Polytechnic424 Hafez Ave.P.B.15875-4413TehranIran Section for Surface Physics and Catalysis Department of PhysicsTechnicFysikvejBygning 311Kongens LyngbyDK-2800Denmark Institute of Nanotechnology and Institute of Quantum Materials and Technology Karlsruhe Institute of TechnologyP.O.Box 364076021 KarlsruheGermany Department of Materials Science and Engineering Bandar Abbas BranchIslamic Azad UniversityBandar AbbasIran

采用电化学阻抗谱(EIS)和电位极化(Tafel)试验,研究了在环氧树脂涂层中添加含铝粉末以增强碳钢基材的防腐性,含铝粉末包括纯铝、Al/CNT、Al/Al_(2)O_(3)、Al/CNT/Al_(2)O_(3)。用球磨法合成含2 wt.%碳纳米管、2 wt.%氧化铝纳米颗粒的复... 详细信息

采用电化学阻抗谱(EIS)和电位极化(Tafel)试验,研究了在环氧树脂涂层中添加含铝粉末以增强碳钢基材的防腐性,含铝粉末包括纯铝、Al/CNT、Al/Al_(2)O_(3)、Al/CNT/Al_(2)O_(3)。用球磨法合成含2 wt.%碳纳米管、2 wt.%氧化铝纳米颗粒的复合粉末,然后以1 wt.%的浓度加入到环氧树脂涂层中。结果表明,由于环氧树脂复合涂层的防护性能增强,从而提高了其耐腐蚀性。研究还发现,Al/CNT/Al_(2)O_(3)复合添加剂的保护性能比其他添加剂更显著,因为其颗粒尺寸的减小和具有某些形状的颗粒,进一步减少了腐蚀环境通过涂层渗透的路径,避免了金属基底/涂层界面可能发生的反应。EP-Al/CNT/Al_(2)O_(3)保持了一次时间常数特性,并在整个暴露时间内表现出最高的阻抗和最强的稳定性。这些添加剂的存在增强了涂层,从而改善了涂层的屏障性能。

关键词：铝复合材料环氧树脂复合材料涂层腐蚀电化学阻抗图谱(EIS) Tafel极化

Non-crossing Quantile Regression Neural Network as a Calibration Tool for Ensemble Weather Forecasts

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Advances in Atmospheric Sciences 2024年第7期41卷 1417-1437页

作者： Mengmeng SONG Dazhi YANG Sebastian LERCH Xiang'ao XIA Gokhan Mert YAGLI Jamie M.BRIGHT Yanbo SHEN Bai LIU Xingli LIU Martin Janos MAYER School of Electrical Engineering and Automation Harbin Institute of TechnologyHarbin150001China Heidelberg Institute for Theoretical Studies Schloss-Wolfsbrunnenweg 3569118HeidelbergGermany Chair of Statistical Methods and Econometrics Karlsruhe Institute of Technology(KIT)Bluecherstr.1776185KarlsruheGermany Key Laboratory of Middle Atmosphere and Global Environment Observation Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing100029China Solar Energy Research Institute of Singapore(SERIS) National University of Singapore(NUS)Singapore117574Singapore UK Power Networks LondonSE61NPUK China Meteorological Administration Beijing100081China Heilongjiang Meteorological Bureau Harbin150001China Department of Energy Engineering Faculty of Mechanical EngineeringBudapest University of Technology and EconomicsMűegyetem rkp.3H-1111BudapestHungary

Despite the maturity of ensemble numerical weather prediction(NWP),the resulting forecasts are still,more often than not,*** such,forecast calibration tools have become *** those tools,quantile regression(QR)is highly competitive in terms of both flexibility and predictive ***,a long-standing problem of QR is quantile crossing,which greatly limits the interpretability of QR-calibrated *** this point,this study proposes a non-crossing quantile regression neural network(NCQRNN),for calibrating ensemble NWP forecasts into a set of reliable quantile forecasts without *** overarching design principle of NCQRNN is to add on top of the conventional QRNN structure another hidden layer,which imposes a non-decreasing mapping between the combined output from nodes of the last hidden layer to the nodes of the output layer,through a triangular weight matrix with positive *** empirical part of the work considers a solar irradiance case study,in which four years of ensemble irradiance forecasts at seven locations,issued by the European Centre for Medium-Range Weather Forecasts,are calibrated via NCQRNN,as well as via an eclectic mix of benchmarking models,ranging from the naïve climatology to the state-of-the-art deep-learning and other non-crossing *** and stringent forecast verification suggests that the forecasts post-processed via NCQRNN attain the maximum sharpness subject to calibration,amongst all ***,the proposed conception to resolve quantile crossing is remarkably simple yet general,and thus has broad applicability as it can be integrated with many shallow-and deep-learning-based neural networks.

关键词： ensemble weather forecasting forecast calibration non-crossing quantile regression neural network CORP reliability diagram post-processing

Numerical Noise Prediction in Fluid Machinery

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Journal of Thermal Science 2005年第3期14卷 230-235,248页

作者： Iris PANTLE Franco MAGAGNATO Martin GABI Department of Fluid Machinery University of Karlsruhe D-76128 Karlsruhe Department of Fluid Machinery University of Karlsruhe D-76128 Karlsruhe Department of Fluid Machinery University of Karlsruhe D-76128 Karlsruhe

Numerical methods successively became important in the design and optimization of fluid machinery. However, as noise emission is considered, one can hardly find standardized prediction methods combining flow and acoustical optimization. Several numerical field methods for sound calculations have been developed. Due to the complexity of the considered flow, approaches must be chosen to avoid exhaustive computing. In this contribution the noise of a simple propeller is investigated. The configurations of the calculations comply with an existing experimental setup chosen for evaluation. The used in-house CFD solver SPARC contains an acoustic module based on Ffowcs Williams-Hawkings Acoustic Analogy. From the flow results of the time dependent Large Eddy Simulation the time dependent acoustic sources are extracted and given to the acoustic module where relevant sound pressure levels are calculated. The difficulties, which arise while proceeding from open to closed rotors and from gas to liquid are discussed.

关键词： numerical noise prediction fluid machinery computational aero-acoustics large eddy simulation

Continuous flow pyrolysis of virgin and waste polyolefins:a comparative study,process optimization and product characterization

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Frontiers of Chemical Science and Engineering 2024年第6期18卷 133-149页

作者： Ecrin Ekici Güray Yildiz Magdalena Joka Yildiz Monika Kalinowska ErolŞeker Jiawei Wang karlsruhe Institute of Technology Institute of Catalysis Research and TechnologyEggenstein-Leopoldshafen 76344Germany Izmir Institute of Technology Faculty of EngineeringDepartment of Energy Systems EngineeringIzmir 35430Türkiye Department of Materials Engineering and Production Faculty of Mechanical EngineeringBialystok University of TechnologyBialystok 15-351Poland Department of Agricultural and Food Engineering and Environmental Development Institute of Civil Engineering and EnergeticsFaculty of Civil Engineering and Environmental SciencesBialystok University of Technology15-351 BialystokPoland Department of Chemistry Biology and BiotechnologyInstitute of Civil Engineering and EnergeticsFaculty of Civil Engineering and Environmental SciencesBialystok University of TechnologyBialystok 15-351Poland Izmir Institute of Technology Faculty of EngineeringDepartment of Chemical EngineeringIzmir 35430Türkiye Energy and Bioproducts Research Institute(EBRI) Aston UniversityBirmingham B47ETUnited Kingdom

Under optimal process conditions,pyrolysis of polyolefins can yield ca.90 wt%of liquid product,i.e.,combination of light oil fraction and heavier *** this work,the experimental findings reported in a selected group of publications concerning the non-catalytic pyrolysis of polyolefins were collected,reviewed,and compared with the ones obtained in a continuously operated bench-scale pyrolysis *** process parameters were used for the pyrolysis of waste and virgin counterparts of high-density polyethylene,low-density polyethylene,polypropylene and a defined mixture of those(i.e.,25:25:50 wt%,respectively).To mitigate temperature drops and enhance heat transfer,an increased feed intake is employed to create a hot melt plastic *** 1.5 g·min^(-1) feed intake,1.1 L·min^(-1) nitrogen flow rate,and a moderate pyrolysis temperature of 450℃,the formation of light hydrocarbons was favored,while wax formation was limited for polypropylene-rich *** of virgin plastics yielded more liquid(maximum 73.3 wt%)than that of waste plastics(maximum 66 wt%).Blending polyethylenes with polypropylene favored the production of liquids and increased the formation of gasoline-range *** products were mainly composed of C3 hydrocarbons,and no hydrogen production was detected due to moderate pyrolysis temperature.

关键词： waste plastics polyolefins chemical recycling pyrolysis alternative fuels waste-to-energy

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低温耐磨的CoCrNi多主元合金（英文）

Science Bulletin 2024年第2期 227-236页

作者：任越周青华东鹏黄卓斌李钰龙贾茜 Peter Gumbsch Christian Greiner 王海丰刘维民 State Key Laboratory of Solidification Processing Center of Advanced Lubrication and Seal Materials Northwestern Polytechnical University Institute for Applied Materials Karlsruhe Institute of Technology IAM-ZM Micro Tribology Center μTC Karlsruhe Institute of Technology Fraunhofer IWM State Key Laboratory of Solid Lubrication Lanzhou Institute of Chemical Physics Chinese Academy of Sciences

Traditional high strength engineering alloys suffer from serious surface brittleness and inferior wear performance when servicing under sliding contact at cryogenic temperature. Here, we report that the recently emerging CoCrNi multi-principal element alloy defies this trend and presents dramatically enhanced wear resistance when temperature decreases from 273 to 153 K, surpassing those of cryogenic austenitic steels. The temperature-dependent structure characteristics and deformation mechanisms influencing the cryogenic wear resistance of CoCrNi are clarified through microscopic observation and atomistic simulation. It is found that sliding-induced subsurface structures show distinct scenarios at different deformation temperatures. At cryogenic condition, significant grain refinement and a deep plastic zone give rise to an extended microstructural gradient below the surface, which can accommodate massive sliding deformation, in direct contrast to the strain localization and delamination at 273 ***, the temperature-dependent cryogenic deformation mechanisms(stacking fault networks and phase transformation) also provide additional strengthening and toughening of the subsurface material. These features make the CoCrNi alloy particularly wear resistant at cryogenic conditions and an excellent candidate for safety–critical applications.

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Prediction of the Resonance Characteristics of Combustion Chambers on the Basis of Large-Eddy Simulation

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Journal of Thermal Science 2005年第2期14卷 156-161页

作者： Franco MAGAGNATO Balázs PRITZ Horst BCHNER Martin GABI Department of Fluid Machinery university of karlsruhe GermanyDepartment of Fluid Machinery University of KarlsruheGermanyEngler-Bunte-Institute/Division for Combustion Technology University of KarlsruheGermanyDepartment of Fluid Machinery University of KarlsruheGermany

In the last few years intensive experimental investigations were performed at the university of karlsruhe to develop an analytical model for the Helmholtz resonator-type combustion system. In the present work the resonance characteristics of a Helmholtz resonator-type combustion chamber were investigated using large-eddy simulations (LES), to understand better the flow effects in the chamber and to localize the dissipation. In this paper the results of the LES are presented, which show good agreement with the experiments. The comparison of the LES study with the experiments sheds light on the significant role of the wall roughness in the exhaust gas pipe.

关键词： compressible large-eddy simulation combustion instabilities oscillating flow damping ratio.

Calculation of the VKI turbine blade with LES and DES

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Journal of Thermal Science 2007年第4期16卷 321-327页

作者： F.Magagnato B.Pritz M.Gabi FSM University of KarlsruheGermany

The prediction of the laminar to turbulent transition is essential in the calculation of turbine blades, compressor blades or airfoils of airplanes since a non negligible part of the flow field is laminar or transitional. In this paper we compare the prediction capability of the Detached Eddy Simulation （DES） with the Large Eddy Simulation （LES） using the high-pass filtered （HPF） Smagorinsky model （Stolz et al.[1]） when applied to the calculation of transitional flows on turbine blades. Detailed measurements from Canepa et al.[2] of the well known VKI-turbine blade served to compare our results with the experiments. The calculations have been made on a fraction of the blade （10%） using non-reflective boundary conditions of Freund at the inlet and outlet plane extended to internal flows by Magagnato et al.[3] in combination with the Synthetic Eddy Method （SEM） proposed by Jarrin et al.[4]. The SEM has also been extended by Pritz et al.[5] for compressible flows. It has been repeatedly shown that hybrid approaches can satisfactorily predict flows of engineering relevance. In this work we wanted to investigate if they can also be used successfully in this difficult test case.

关键词： Turbine blade LES DES transition

Effect of Continuous Phase Viscosity on Membrane Emulsification

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Chinese Journal of Chemical Engineering 2000年第2期8卷 108-112页

作者：王志王世昌 Volker Schroeder Helmar Schubert Institute of Food Process Engineering Karlsruhe UniversityD-76128 KarlsruheGermany

Oil-in-water(o/w) emulsions were produced with a membrane emulsification system. The effect of the continuous phase viscosity on the emulsification was studied. The theoretical analyses show that the continuous phase viscosity influences not only the flow field of the continuous phase but also the interfacial tension. The droplet size distribution and disperse phase flux for different continuous phase viscosity were investigated experimentally at constant wall shear stress and constant volume flow rate of the continuous phase respectively.

关键词： membrane emulsification viscosity continuous phase