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Development and verification of a reduced dimethoxymethane/n-heptane/toluene kinetic mechanism and modelling for CI engines

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APPLIED THERMAL ENGINEERING 2022年 214卷

作者： Shi, Xiuyong Qian, Weiwei Wang, Haoyu Pan, Mingzhang Wang, Qiwei Ni, Jimin Tongji Univ Sch Automot Studies Shanghai 201804 Peoples R China Guangxi Univ Coll Mech Engn Nanning 530004 Peoples R China

Dimethoxymethane (CH3OCH2OCH3, DMM) has been regarded as a potential alternative fuel for CI engines due to its advantage of high oxygen contents and renewability. However, little investigation has been conducted for computational fluid dynamics (CFD) simulation because of the lack of appropriate reduced mechanisms of DMM. In this study, a reduced DMM/n-heptane/toluene kinetic mechanism is developed, which contains 173 species and 698 reactions based on the decoupling methodology. In addition, the new reduced mechanism has been validated via comparison to experiments of ignition delay times, laminar flame speeds, and species concentrations. It is found that the prediction of reduced kinetic mechanism proposed by this study can well capture the combustion characteristics of dimethoxymethane, n-heptane, and toluene. Meanwhile, it is worth noting that the maximum flame speeds of DMM appears at a slightly richer mixture (higher equivalence ratio) in comparison with n-heptane. The DMM maximum laminar flame speeds of 45 cm/s, 55 cm/s, and 64 cm/s are observed at temperatures of 298 K, 328 K, and 358 K, respectively. Eventually, the proposed model has been coupled with CFD software to simulate the combustion process of CI engines, the results indicate that both the simulated pressure and heat release rate have a good agreement with the experiments. Moreover, the addition of DMM leads to an increase in NO product, while a reduction in soot distribution.

关键词： Dimethoxymethane Reduced kinetic modeling Ignition delay times Laminar flame speed computational fluid dynamics simulation

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The face behind the Covid-19 mask - A comprehensive review

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ENVIRONMENTAL TECHNOLOGY & INNOVATION 2022年 28卷 102837页

作者： Ganesapillai, Mahesh Mondal, Bidisha Sarkar, Ishita Sinha, Aritro Ray, Saikat Sinha Kwon, Young-Nam Nakamura, Kazuho Govardhan, K. Vellore Inst Technol Sch Chem Engn Mass Transfer Grp Vellore Tamil Nadu India Ulsan Natl Inst Sci & Technol Dept Urban & Environm Engn Ulsan South Korea Yokohama Natl Univ Fac Engn Div Mat Sci & Chem Engn Yokohama Kanagawa 2408501 Japan Vellore Inst Technol Sch Elect Engn Dept Micro & Nanoelect Vellore Tamil Nadu India Vellore Inst Technol Sch Chem Engn Vellore 632014 Tamil Nadu India

The threat of epidemic outbreaks like SARS-CoV-2 is growing owing to the exponen-tial growth of the global population and the continual increase in human mobility. Personal protection against viral infections was enforced using ambient air filters, face masks, and other respiratory protective equipment. Available facemasks feature considerable variation in efficacy, materials usage and characteristic properties. Despite their widespread use and importance, face masks pose major potential threats due to the uncontrolled manufacture and disposal techniques. Improper solid waste management enables viral propagation and increases the volume of associated biomedical waste at an alarming rate. Polymers used in single-use face masks include a spectrum of chemical constituents: plasticisers and flame retardants leading to health-related issues over time. Despite ample research in this field, the efficacy of personal protective equipment and its impact post-disposal is yet to be explored satisfactorily. The following review assimilates information on the different forms of personal protective equipment currently in use. Proper waste management techniques pertaining to such special wastes have also been discussed. The study features a holistic overview of innovations made in face masks and their corresponding impact on human health and environment. Strategies with SDG3 and SDG12, outlining safe and proper disposal of solid waste, have also been discussed. Furthermore, employing the CFD paradigm, a 3D model of a face mask was created based on fluid flow during breathing techniques. Lastly, the review concludes with possible future advancements and promising research avenues in personal protective equipment.(c) 2022 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (http://***/licenses/by/4.0/).

关键词： Biodegradability computational fluid dynamics simulation Health impacts Psychological aspects Solid waste management Engineered nanomaterials

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CFD simulations of the Truncated IHF Semi-Elliptical Nozzle Flow: Convective Calibration Plate

CFD Simulations of the Truncated IHF Semi-Elliptical Nozzle ...

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AIAA Aviation Forum and Exposition

作者： Gokcen, Tahir AMA Inc NASA Ames Res Ctr MS 230-2 Moffett Field CA 94035 USA

ISBN: (数字)9781624106101

ISBN: (纸本)9781624106101

This paper reports computational simulations of a high-enthalpy panel test facility at NASA Ames Research Center. The recently developed facility configuration uses a truncated version of an existing semi-elliptical nozzle in the 60-MW Interaction Heating Facility, and it provides testing capability for panel test articles as large as 43.2 cm x 43.2 cm (17 in x 17 in). A water-cooled calibration plate, which is attached to the semi-elliptical nozzle bottom surface and instrumented with twenty Gardon-gage heat flux calorimeters and twelve pressure gages, is used to characterize the convective heating environment over the panel test articles. The present analysis comprises computational fluid dynamics simulations of the nonequilibrium flowfield in the facility nozzle and test box, and the flowfields over panel test articles. Both laminar and turbulent simulations are performed, and the computational results are compared with the calibration plate measurements. Comparisons of computed and measured heat fluxes indicate that the boundary layer in the semi-elliptical nozzle is transitional at certain conditions (relatively higher arc-heater pressures or mass flow rates).

关键词： computational fluid dynamics simulation Transitional Flow Heat Flux Enthalpy Boundary Layer Transition Total Mass Flow Rate Gardon Gages NASA Ames Research Center Turbulence Models Mach Number

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Modeling and experiments of cavitation on a pocket-textured surface

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PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART J-JOURNAL OF ENGINEERING TRIBOLOGY 2020年第1期234卷 94-103页

作者： Mao, Yang Yin, Zhongwei Shanghai Jiao Tong Univ Sch Mech Engn Shanghai Peoples R China

A two-dimensional computational fluid dynamics model was developed and an experiment was performed to investigate the role of pocket texture on fully lubricated motion with the cavitation effect. This paper discusses the cavitated simulation models and experiments to describe texture cavitation to solve the lubricating properties of the textured friction pair. The effects of velocity and texture scale on the support force and friction coefficient are discussed. It was found that the results of the two-dimensional computational fluid dynamics model with cavitation are nearly consistent with the experimental results;the hydrodynamic pressure decreased and the sliding speed dropped, and the effect of pressure became highly pronounced with ideal texture size. In addition, the simulation solution can show the internal flow field, and extend the solutions to large-scale textures and multiple textures. Meanwhile, appropriate texture parameters can optimize the friction coefficient and support force. The texture depth ratio plays a more important role on the value of the support force, and the width ratio has a greater influence on the friction coefficient.

关键词： computational fluid dynamics simulation texture cavitation friction coefficient support force

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Numerical and experimental investigation on longitudinal drift motion of a novel regular tetrahedron closure device in casting process

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AIN SHAMS ENGINEERING JOURNAL 2022年第6期13卷

作者： Jiao, Jingwei Liu, Junyi Shao, Fei Xie, Xingkun Chen, Xujun Army Engn Univ PLA Coll Field Engn Teaching & Res Sect Rd Bridge & River Crossing 88 Houbiaoying Rd Nanjing 210007 Peoples R China

A novel prefabricated rapid closure device is proposed to plug dike breaches through a simplified dam structured by different types of closure devices. The experiments show that, however, the closure device will be affected by the flow of water and moves longitudinally in the process of falling. This would adversely affect the arrangement of the devices and construction of stable dams. Hence, a threedimensional (3D) calculation model is established based on computational fluid dynamics (CFD) methodology to investigate the displacements, forces and velocities of this kind of closure device in water. Having established the consistency of numerical simulations and the model test data, the device underwater movements are investigated for various water depths, current velocities and device weights. Numerical predictions and model test observations suggest that the longitudinal translation travelled by the closure device nonlinearly goes up with the increment of water depth and current velocity as well as the reduction of device mass. For the closure devices with same penetration depth underwater, its horizontal displacement in shallower water is greater than that in deeper water. For the conditions of water depth greater than 2.5 m, the flow velocity greater than 2 m/s and the device mass less than 2.13 t, the longitudinal drift of plugging device cannot be underrated. CO 2022 THE AUTHORS. Published by Elsevier BV on behalf of Faculty of Engineering, Ain Shams University This is an open access article under the CC BY-NC-ND license (http://***/licenses/by-ncnd/4.0/).

关键词： Emergency closure Dike breach Closure device Longitudinal drift computational fluid dynamics simulation

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Prediction of the 3D Distribution of NOx in a Furnace via CFD Data Based on ELM

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FRONTIERS IN ENERGY RESEARCH 2022年 10卷

作者： Lv, Manli Zhao, Jianping Cao, Shengxian Shen, Tao Changchun Univ Sci & Technol Coll Comp Sci & Technol Changchun Peoples R China Northeast Elect Power Univ Sch Automat Engn Jilin Peoples R China Harbin Boiler Co Ltd Harbin Peoples R China

A novel method for the prediction of three-dimensional (3D) spatial distribution of NOx in a furnace is proposed and evaluated. computational fluid dynamics (CFD) simulations are conducted to generate the data sets of 3D NOx spatial distribution. The data sets are partitioned based on NOx generation mechanisms to improve the model accuracy. Combining the Pearson coefficient and mutual information (PMI), the model input variables are optimized by feature selection. The prediction model of 3D NOx spatial distribution in the furnace is established based on extreme learning machine (ELM). The experiments are conducted considering a 350 MW coal-fired boiler with a change in the burner tilt angles under a rated load. The experimental results show that the data-driven method based on PMI-ELM can realize the rapid prediction of the 3D spatial distribution of NOx in the furnace with 12.84% mean absolute percentage error.

关键词： three dimensional(3D) distribution of NOx computational fluid dynamics simulation coal-fired boiler Pearson coefficient and mutual information extreme learning machine

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Mechanisms of the ascites volume differences between patients receiving a left or right hemi-liver graft liver transplantation: From biofluidic analysis

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COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2022年 226卷 107196-107196页

作者： Qu, Wei Li, Xiaofan Huang, Hao Xie, Chiyu Song, Hongqing Capital Med Univ Beijing Friendship Hosp Dept Gen Surg Liver Transplantat Sect Beijing 100050 Peoples R China Univ Sci & Technol Beijing Beijing 100083 Peoples R China Tsinghua Univ Beijing 100084 Peoples R China 30 Xueyuan Rd Beijing 100083 Peoples R China

Background and objective: Post-transplant refractory ascites (RA) is common in patients receiving living donor liver transplantation (LDLT) using a left hemi-liver graft than in those using a right hemi-liver graft. However, there is currently no clear mechanism explaining the effect of grafts on ascites drainage. The purpose of this study is to analyze the values of blood flow parameters in the portal vein under different grafts using computational fluid dynamics (CFD) to interpret the relationship between portal pressure values with ascites drainage. Methods: In this work, ascites drainage was counted in 30 patients who underwent left-sided liver transplantation and 26 patients who underwent right-sided liver transplantation. The portal vein flow models of the transplanted liver under different flow rates were established based on computed tomography (CT) images and finite element theory. Ascites drainage and blood flow parameters were qualitatively compared. Results: The results show that the ascites drained from patients who received LDLT with a left hemiliver is three times as that with a right hemi-liver. The simulation results show that the coefficient of the pressure-velocity curve of the left-liver is 1.7 times of the right-liver under the same hydrodynamic conditions, which qualitatively agrees with the clinical data. Moreover, the streamline of the transplanted left liver shows more vortexes compared with the right liver, which is a major reason for the left liver's higher pressure value. Conclusion: This clinical phenomenon is reproduced and comprehensively explained by the hemodynamic parameters of the portal vein. This work establishes the relationship between portal pressure values and floating water drainage, and offers a new way for physicians to predict postoperative risks intuitively. (c) 2022 Elsevier B.V. All rights reserved.

关键词： Biofluid mechanics computational fluid dynamics simulation Left or right liver transplantation Hemodynamics

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Numerical simulation of nonlinear phenomena in a standing-wave thermoacoustic engine with gas-liquid coupling oscillation

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APPLIED THERMAL ENGINEERING 2022年 207卷

作者： Luo, Jiaqi Zhou, Qiang Jin, Tao Zhejiang Univ Inst Refrigerat & Cryogen Key Lab Refrigerat & Cryogen Technol Zhejiang Pro Hangzhou 310027 Peoples R China

A computational fluid dynamics (CFD) model based on the compressible, nonlinear Navier-Stokes equations is developed to simulate the nonlinear phenomena in a gas-liquid standing-wave thermoacoustic engine, which employs gas as the working fluid and liquid as the phase-matching element. The CFD model is well validated when comparing the simulated onset and steady-state performances with those measured from a real experimental system. Based on the CFD model, the nonlinear phenomena of the engine are analyzed from three aspects. Firstly, the nonlinear dynamic phenomena of self-excited thermoacoustic oscillation from onset to saturation are investigated, focusing on onset temperature difference and steady-state pressure amplitude. Then, the nonlinear acoustic phenomena of the engine operating at steady state are analyzed. The steady-state fluctuating pressure is decomposed into a superimposition of the acoustic modes with different frequencies, which reveals the existence of high-order harmonics. Finally, the nonlinear hydrodynamic phenomena including multi-dimensional flow effect and mass streaming are observed by examining the steady-state flow fields in the engine. The proposed CFD model provides an effective approach to comprehending the mechanism of nonlinear phenomena in gas liquid coupling thermoacoustic engines.

关键词： Thermoacoustic engine Gas-liquid coupling oscillation computational fluid dynamics simulation Nonlinear phenomenon

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Scoreboard: Management and Creation of In Situ and In Transit Data Extractions via computational Steering

Scoreboard: Management and Creation of In Situ and In Transi...

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AIAA Science and Technology Forum and Exposition (AIAA SciTech Forum)

作者： Whitlock, Brad J. Laganella, Christopher Duque, Earl P. N. Intelligent Light 301 Route 17N7th Floor Rutherford NJ 07070 USA Intelligent Light Res & Developement 301 Route 17N7th Floor Rutherford NJ 07070 USA

ISBN: (数字)9781624106095

ISBN: (纸本)9781624106095

Scoreboard brings together in transit, extract management and creation, and interactive computational steering into a single system. Scoreboard is flexible and supports both in situ and in transit where the method is selected at run time. Scoreboard can be built with minimal dependencies and produce data extracts specified by an input file. The set of data extracts can be interactively managed from a dynamically generated user interface that also supports simulation steering during in transit.

关键词： FORTRAN Data Structures Vortex Breakdown Unstructured Grid Helicopter Rotor Vorticity Angle of Attack computational fluid dynamics simulation Data Analytics Aircraft Wings

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Mathematical and numerical modeling of an airlift perfusion bioreactor for tissue engineering applications

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BIOCHEMICAL ENGINEERING JOURNAL 2022年 178卷

作者： Capuana, Elisa Pavia, Francesco Carfi Lombardo, Maria Elena Rigogliuso, Salvatrice Ghersi, Giulio La Carrubba, Vincenzo Brucato, Valerio Univ Palermo Dept Engn Viale Sci Ed 6 I-90128 Palermo Italy Consorzio Univ Caltanissetta Corso Vittorio Emuanuele 92 I-93100 Caltanissetta Italy Inst Natl Rech Sci Ctr Energie Mat & Telecommun 1650 Blvd Lionel Boulet Varennes PQ J3X 1S2 Canada Univ Palermo Abiel Srl Viale SciEd 16 I-90128 Palermo Italy Univ Palermo Dept Biol Chem & Pharmaceut Sci & Technol STEBICE Viale SciEd 16 I-90128 Palermo Italy

The Tissue Engineering (TE) strategy is widely focused on the development of perfusion bioreactors to promote the production of three-dimensional (3D) functional tissues. To optimize tissue production, it is worth investigating the engineering parameters of a bioreactor system for identifying a beneficial range of operation variables. Mathematical and numerical modeling of a perfusion bioreactor is capable to provide relevant insights into the fluid flow and nutrients transport while predicting experimental data and exploring the impact of changing operating parameters, such as fluid velocities. In this work, the hydrodynamic parameters and oxygen transport were investigated using mathematical equations and computational fluid dynamics (CFD) analysis modeling on a novel perfusion bioreactor working as an airlift external loop. Mathematical models and numerical simulation were associated with experimental results at different configurations to evaluate the effect of the reactor parameters on its hydrodynamics. All predictions of gas holdup and liquid circulation velocity from the modeling were in good agreement with the experimental data. A Poly-L-lactic acid (PLLA) scaffold was produced by Thermally Induced Phase Separation (TIPS) and used as 3D support for biological tests in static and dynamic conditions to assess cell viability and proliferation inside the bioreactor. The whole set of fluid-dynamic and biological results showed that our bioreactor environment offers the benefits of an in vitro potential system to produce functional engineered tissues.

关键词： Flow rate and mass transport mathematical model computational fluid dynamics simulation Dynamic cell culture Tissue engineering

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