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Odour-sensitive passenger comfort in small aircraft cabins

AERONAUTICAL JOURNAL 2024年第1321期128卷 429-440页

作者： Nasoulis, C. P. Mantziou, S. Gkoutzamanis, V. G. Kalfas, A. I. Aristotle Univ Thessaloniki Dept Mech Engn Lab Fluid Mech & Turbomachinery Thessaloniki Greece

This work presents a numerical investigation targeting to simulate the slice of a small aircraft cabin as an experimental facility with a controlled environment, to assess passenger comfort when exposed to high volatile organic compound (VOC) concentrations. The mixing and transport of chemical species are evaluated using computational fluid dynamics for 800 s of in-cabin actual flow time and measurements are taken every 10 s from selected computational nodes close to the passengers' noses. The results are used to create a dataset that trains four different machine learning classifiers, namely, the Random Forest, Support Vector Machine, Logistic Regression and Naive Bayes, and their performance is compared. Moreover, an additional simulation of the cabin with a filtering system utilising high-efficiency particulate air and activated carbon filters is conducted, to evaluate the impact of the molecular weight of the compounds on their residence time, and compare it to the simulation without the filters. Results indicate that the model is insensitive to the inlet air mass flow variation and that the mass of the VOCs measured in the monitored computational nodes remains relatively unaffected, meaning that the impact of the air-conditioning system setting is minor. Additionally, a Boruta feature selection algorithm is used to determine the importance of each measurement of the simulation and to form a dataset that will train the four machine learning classifiers. Furthermore, the comparison of the two simulations, the one with and the one without the filters, indicates that the residence time (RT) of the compounds is independent of their molecular weight, as they all show equivalent percentile reductions, with the naphthalene and styrene showing a 28.5% and 28.3% reduction respectively, compared to the simulation without the filters. Finally, in-cabin flow irregularities are present, disrupting the flow symmetry and suggesting that not all passengers share the same trave

关键词： Aircraft cabin environment Volatile organic compounds (VOCs) concentration computational fluid dynamics simulation Passenger comfort

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Multicrystalline Informatics Applied to Multicrystalline Silicon for Unraveling the Microscopic Root Cause of Dislocation Generation

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ADVANCED MATERIALS 2024年第8期36卷 2308599-2308599页

作者： Yamakoshi, Kenta Ohno, Yutaka Kutsukake, Kentaro Kojima, Takuto Yokoi, Tatsuya Yoshida, Hideto Tanaka, Hiroyuki Liu, Xin Kudo, Hiroaki Usami, Noritaka Nagoya Univ Grad Sch Engn Nagoya 4648603 Japan Tohoku Univ Inst Mat Res Sendai 9808577 Japan RIKEN Ctr Adv Intelligence Project Tokyo 1030027 Japan Nagoya Univ Grad Sch Informat Nagoya 4648601 Japan Osaka Univ SANKEN Osaka 5670047 Japan

A comprehensive analysis of optical and photoluminescence images obtained from practical multicrystalline silicon wafers is conducted, utilizing various machine learning models for dislocation cluster region extraction, grain segmentation, and crystal orientation prediction. As a result, a realistic 3D model that includes the generation point of dislocation clusters is built. Finite element stress analysis on the 3D model coupled with crystal growth simulation reveals inhomogeneous and complex stress distribution and that dislocation clusters are frequently formed along the slip plane with the highest shear stress among twelve equivalents, concentrated along bending grain boundaries (GBs). Multiscale analysis of the extracted GBs near the generation point of dislocation clusters combined with ab initio calculations has shown that the dislocation generation due to the concentration of shear stress is caused by the nanofacet formation associated with GB bending. This mechanism cannot be captured by the Haasen-Alexander-Sumino model. Thus, this research method reveals the existence of a dislocation generation mechanism unique to the multicrystalline structure. Multicrystalline informatics linking experimental, theoretical, computational, and data science on multicrystalline materials at multiple scales is expected to contribute to the advancement of materials science by unraveling complex phenomena in various multicrystalline materials. Multicrystalline informatics, integrating experiment, theory, computation, and data science in multi-scale cyber and physical spaces, advances material science in multicrystalline materials. The formation of nanofacet structures associated with grain boundary bending is revealed as one of the universal origins of dislocation generation in multicrystalline ***

关键词： ab initio calculation computational fluid dynamics simulation dislocation clusters finite element stress analysis grain boundaries machine learning multiscale structural characterizations

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Research and optimization of slit issues in the kW-scale redox flow batteries stack

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JOURNAL OF ENERGY STORAGE 2025年 106卷

作者： Niu, Yingchun Yuan, Shengwei Liu, Ziyu Heydari, Ali Liu, Yinping Qiu, Wei Xu, Chunming Xu, Quan China Univ Petr State Key Lab Heavy Oil Proc Beijing 102249 Peoples R China

The assembly of the frame and bipolar plates in redox flow batteries (RFBs) often results in assembly gaps, forming 'slit.' Due to differing coefficients of thermal expansion between the plate frame and bipolar plates, thermal expansion and contraction occur under the influence of assembly environment temperatures and operational temperatures of RFBs, exacerbating the 'slit' issue. The presence of 'slits' can reduce the utilization rate of the electrolyte and decrease mass transfer efficiency during the battery cycling process. However, the flow channel design for kilowatt (kW)-scale stacks often overlooks the impact of these slits. Therefore, this paper examines the influence of 'slit' structures on the flow characteristics of electrolytes within carbon cloth using kWscale stacks with interdigitated flow channel structures as an example, and optimizes the interdigitated flow field with slits. The study analyzes the flow characteristics of electrolytes on carbon cloth in flow field structures with no slits, slits at both ends and slits on three sides. It further investigates the effects of slit width and the length of interdigitated flow channels on the flow patterns of electrolytes on carbon cloth when slits are present. Through numerical simulation, velocity and pressure distribution maps at the center of the carbon cloth, as well as velocity distributions at various positions, are obtained. The results show that slits affect the position and extent of the low-speed zone on the carbon cloth. As slit width increases, the resistance of the slit decreases, gradually increasing the flow velocity of the electrolyte towards the carbon cloth. However, when the slit width exceeds 0.5 mm, the impact of the slit on flow over the carbon cloth remains largely unchanged. With a fixed slit width of 0.5 mm, increasing the length of the interdigitated flow channels reduces the flow velocity and pressure within the carbon cloth but significantly improves the uniformity of the carb

关键词： kW-scale redox flow batteries Interdigitated flow channels Slit computational fluid dynamics simulation

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Establishment of CFD-ANN-NSGA-II model for stirred reactor design

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CHEMICAL ENGINEERING SCIENCE 2025年 311卷

作者： Jiang, Zhou Chen, Jiajun Xie, Suwen Li, Xingyan Liu, Huazong Wang, Luyao Hong, Chen Li, Ganlu Li, Hui Chen, Kequan Nanjing Tech Univ Coll Biotechnol & Pharmaceut Engn State Key Lab Mat Oriented Chem Engn Nanjing 211816 Peoples R China Jiangxi Vocat Coll Appl Technol Ganzhou 342800 Peoples R China

Herein, the multiobjective optimization method based on the CFD-ANN-NSGA-II model is proposed to efficiently optimize the structural parameters of the stirred reactor, thereby improving its gas-liquid mass transfer efficiency and reducing its energy consumption. Coupling CFD simulations with the ANN-NSGA-II model enabled accurate performance predictions. The R2 values of the parameters epsilon, kLa, t, and P/V were 0.940, 0.989, 0.956, and 0.970, respectively, and their mean square error values were 0.0010, 0.0224, 0.0218, and 0.0521, respectively. The optimal reactor structural parameters were H/D = 2.16, d/D = 0.38, w/d = 0.50, and C1/D = 0.30. The epsilon and kLa values of the structure increased with optimization to 13.5 % and 0.171 s-1, respectively, while the t and P/V values decreased. The study describes an efficient and reliable theoretical method for the multiobjective optimization of chemical equipment, verifying the potential of adopting artificial intelligence in complex fluid system optimization, with important value for engineering applications.

关键词： Stirred reactor computational fluid dynamics simulation Artificial neural network Genetic algorithm Volumetric mass transfer coefficient

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Thermal assessments for design and active ventilation system of indoor dry storage facility of Chinshan Nuclear Power Plant

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NUCLEAR ENGINEERING AND DESIGN 2025年 431卷

作者： Wang, Wen-Yu You, Bo-Shuan Natl Kaohsiung Univ Sci & Technol Dept Energy & Refrigerating Air Conditioning Engn Kaohsiung 824 Taiwan Natl Univ Tainan Dept Greenergy Tainan 701 Taiwan

Dry storage of spent nuclear fuel (SNF) and the cooling of fuel assemblies are essential for the nuclear industry. SNF will be stored in concrete dry casks and an indoor dry storage facility at the Chinshan Nuclear Power Plant. In this study, Ansys Fluent is used to simulate the symmetric boundaries of thermal cases and the ventilation characteristics of eight vertical dry storage casks for SNF as cylinders in the studied dry storage facility. Incompressible ideal gas is adopted in the simulation, and the low Reynolds k-epsilon turbulence model is used. The following parameters are analyzed in this study: (i) different heat loads, (ii) different arrangements, (iii) accident conditions, and (iv) installation of an active ventilation system at the outlet position of the dry storage systems (DSSs) in the facility. The results show that the DSS heat load, half-blockages, and arrangements significantly influence the temperature distribution in the facility. Installing an active ventilation system at the outlet position affects the staff and significantly decreases the temperature distribution in the facility. It is recommended that the rotational fan speed be set at 600 to 750 rpm for future designs. The results provide future design guidelines for indoor dry storage facilities.

关键词： Active ventilation system Building design computational fluid dynamics simulation Chinshan Nuclear Power Plant Indoor dry storage

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Elucidating the Electrochemical Corrosion of a Water Pump Impeller in an Industrial Cooling System with Zero Liquid Discharge

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WATER 2025年第2期17卷 173-173页

作者： Jarrahi, Mina Mousavi Khajavian, Ehsan Nezhad, Amir Hossein Noorbakhsh Zahrani, Ehsan Mohammadi Alfantazi, Akram Ferdowsi Univ Mashhad Fac Engn Dept Mat Sci & Engn Mashhad 91775 1111 Iran Khalifa Univ Sci & Technol Dept Chem Engn POB 2533 Abu Dhabi U Arab Emirates

The electrochemical corrosion of a single-suction centrifugal water pump impeller made of gray cast iron operating at 85 degrees C was investigated in two industrial water media, i.e., groundwater extracted from a borehole and treated wastewater. Open circuit potential (OCP) measurement plus potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) techniques elucidated the electrochemical corrosion performance and inductively coupled plasma-optical emission spectroscopy (ICP-OES) characterized the water samples. The retired and brand-new impellers were studied using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and visual and metallographic examinations. Impeller trailing edges were vulnerable to corrosion damage due to increased total fluid pressure, velocity, and temperature. The groundwater was more contaminated with Ca, Mg, Na, Si, and S elements and possessed higher conductivity, pH, and suspended solids than the treated wastewater. The impeller was more susceptible to graphitic corrosion in the groundwater due to emerging microgalvanic cells. A kinetic control electrochemical mechanism was elucidated as the corrosion rate-controlling step in the wastewater. A mixed kinetic and diffusion control mechanism was predominant in the groundwater because a short Warburg impedance element emerged. This study showcased the significance of integrated industrial water management and treatment strategies to protect pumps' integrity and uptime in critical industrial units implementing a zero-liquid discharge program.

关键词： electrochemical corrosion gray cast iron computational fluid dynamics simulation EIS Warburg diffusion impedance centrifugal water pump zero liquid discharge cooling system

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Parametric analysis of venturi-type microbubble generator and the bubble fragmentation dynamics

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DESALINATION AND WATER TREATMENT 2025年 322卷

作者： Zhou, Yi Cui, Jingyu Chen, Zhen Liu, Jiancong He, Lipeng Fan, Wei Huo, Mingxin Northeast Normal Univ Sch Environm 2555 Jingyue St Changchun 130117 Peoples R China Lversheng Chongqing Environm Technol Co Ltd Chongqing Peoples R China Changchun Univ Technol Sch Mechatron Engn Changchun 130012 Peoples R China

Venturi-type tubes facilitate efficient microbubble generation, enhancing gas-liquid mixing, mass transfer, and reactions in wastewater treatment. However, the demand for high transfer efficiency with low energy consumption necessitates advancements in the parametric analysis of generators. This study presents a novel microbubble generator that integrates a suction chamber with a Venturi system. Through a comprehensive analysis of suction performance, gas-phase transport modes, and bubble collapse kinetics, we analyzed structural parameters using computational fluid dynamics simulations. The effective design features a centrally positioned nozzle, an air inlet at 2 mm depth, and a 12.5 degrees divergence angle. simulations indicated that a single bubble at the throat of the generator undergoes significant kinetic energy reduction and pressure energy increase in the expansion section, leading to pronounced tearing and deformation from inhomogeneous turbulence, resulting in smaller bubbles reduced to approximately 1/20 of their initial volume. Based on these analysis results, a laboratory-scale bubble generator was constructed, with flow tests demonstrating bubble sizes under 300 mu m. Notably, the dissolved oxygen concentration in water treated by the generator was 12.6% above the saturated level, showcasing superior oxygen enrichment compared to traditional aeration methods. This study provides valuable insights for advancing micro- and nano-bubble generation technologies.

关键词： Venturi-type bubble generator Bubble fragmentation Microbubble computational fluid dynamics simulation

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The impact of the wind attack angle on a typical bridge deck's flutter behavior by the distributed aerodynamic characteristics method

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JOURNAL OF VIBRATION AND CONTROL 2024年第3-4期30卷 727-739页

作者： Li, Ke Yang, Qingshan Wang, Xianmeng Li, Shaopeng Hui, Yi Fang, Genshen Qian, Guowei Chongqing Univ Key Lab New Technol Construct Cities Mt Area Minist Educ Chongqing Peoples R China Chongqing Univ Sch Civil Engn Chongqing Peoples R China Chongqing Key Lab Wind Engn & Wind Energy Utilizat Chongqing Peoples R China Tongji Univ State Key Lab Disaster Reduct Civil Engn Shanghai Peoples R China Univ Tokyo Sch Engn Dept Civil Engn Bunkyo Ku Tokyo Japan Chongqing Univ Sch Civil Engn 83 Shabei St Chongqing 400045 Peoples R China

To investigate the influence of the wind attack on a bridge deck's flutter performance, the concept of "pressure flutter derivatives" was introduced as a part of the "distributed aerodynamic characteristics" method, which can be used to visualize the dominant fluctuations of the pressure field. The distributions of the aerodynamic damping and stiffness under different wind attack angles were visualized, instead of using an overall force perspective. The analysis was carried out through two-dimensional computational fluid dynamics simulations based on a typical box deck section. Necessary data were obtained through the forced vibrations of the deck. The dominant pressure fluctuations were demonstrated, around which the wind attack angles' impact on the Scanlan flutter derivatives was discussed. For the deck section used in this study, the wind attack angle was found to most affect the windward parts of the deck. When wind attack angle ranged from -1.5 degrees to 3 degrees, two regions contributed the most: one located behind the windward faring vertex and the other located behind the first vertex of the upper slab. When the wind attack angle decreased to -3 degrees, a new dominant region appeared behind the first vertex of the lower slab, which caused a sudden reduction of the flutter critical speed.

关键词： Bridge aerodynamics wind attack angle aerodynamic damping distributed aerodynamic characteristics method computational fluid dynamics simulation

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Mitigating near-surface polarizations in membrane distillation via membrane surface decoration

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DESALINATION 2024年 579卷

作者： Zhang, Yaoling Guo, Fei Dalian Univ Technol Sch Energy & Power Engn 2 Linggong Rd Dalian 116024 Peoples R China

Temperature and concentration polarizations near the membrane surface zone can significantly affect the performance of membrane distillation, resulting in reduced transmembrane flux and overall efficiency. The fundamental approach to mitigating near-surface polarizations involves enhancing turbulence flow near the membrane surface to minimize the formation of polarization layers. This study focuses on modifying the membrane surface via surface decoration to reduce the polarization layers. The effects of membrane surface decoration on the performance of membrane distillation were systematically investigated through an air gap membrane distillation module under various operating conditions. The hydrodynamic characteristics of the flow near the membrane surface were studied using computational fluid dynamics simulations. The characteristics of both bottom-up and top-down disturbing configurations were analyzed. In addition, we investigated the influence of various flow disturbing methods on the mass transfer coefficient in membrane distillation processes. The membrane distillation test results show that at feed temperatures of 50 degrees C and 70 degrees C, there are respective increases in transmembrane flux of 30 % and 12 %. The results provide insights into optimizing the flow state near the membrane surface for enhanced membrane distillation performance.

关键词： Membrane distillation Near -surface polarization Membrane surface decoration Bottom -up disturbance computational fluid dynamics simulation

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Surrogate-based aerodynamic shape optimization of high-speed train heads: A review of four key technologies

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PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART F-JOURNAL OF RAIL AND RAPID TRANSIT 2024年第8期238卷 907-920页

作者： Wang, Hongbo Wang, Shuangbu Zhuang, Dayuan Zhu, Zaiping You, Pengcheng Tang, Zhao Ding, Guofu Southwest Jiaotong Univ Sch Mech Engn Chengdu Peoples R China Southwest Jiaotong Univ Inst Smart City & Intelligent Transportat 999 Xian Rd Chengdu 611756 Peoples R China Southwest Jiaotong Univ State Key Lab Rail Transit Vehicle Syst Chengdu Peoples R China Bournemouth Univ Natl Ctr Comp Animat Poole England

With the increase in running speed, the aerodynamic characteristics of high-speed trains have a significant impact on running stability, energy consumption and passenger comfort. Since the shape of the high-speed train head can directly influence the surrounding airflow, optimizing the head shape is the primary way to improve the aerodynamic performance of the train. This paper reviews current research studies on the surrogate-based aerodynamic shape optimization of high-speed train heads, aiming to provide a comprehensive reference for designers to enhance design efficiency and optimization performance. The entire optimization process is divided into four essential steps, and the key optimization technologies in each step are discussed, including parametric modeling, computational fluid dynamics (CFD) simulation, surrogate model and optimization algorithm. By introducing the practical applications of these technologies, we summarize their advantages and disadvantages and suggest four potential research directions for the future.

关键词： High-speed train shape optimization parametric modeling computational fluid dynamics simulation surrogate model optimization algorithm

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