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Characterization of H2-air detonations with high-speed (2.5 MHz) Rayleigh scattering and single-shot planar laser-induced fluorescence of nitric oxide

Characterization of H2-air detonations with high-speed (2.5 ...

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AIAA science and Technology Forum and Exposition, AIAA SciTech Forum 2025

作者： Chatelain, Karl P. Alicherif, Mhedine Guiberti, Thibault F. Lacoste, Deanna A. Mechanical Engineering Program Physical Science and Engineering Division PO box 4700 Thuwal23955-6900 Saudi Arabia

ISBN: (纸本)9781624107238

This study characterizes a CJ hydrogen-air detonation using high-speed Rayleigh scattering and single-shot planar laser-induced fluorescence of nitric oxide (NO-PLIF). Firstly, we demonstrate that a Nd:YAG laser cluster can be employed to conduct high-speed Rayleigh scattering visualizations of hydrogen-air detonations at 25 kPa, achieving effective visualization frequencies of 2.5MHz in this study. This multipulse Rayleigh scattering diagnostic is complementary to the existing techniques: (i) it enables the characterization of any detonation, from CJ detonations in large aspect ratio channel to marginal detonations in narrow channels;(ii) it is significantly less expensive than typical burst-mode lasers;(iii) it has adjustable visualization frequency, which can go beyond 10MHz with the same energy per pulse. This makes this diagnostic even more suitable for high-pressure detonations or for undiluted conditions, where structures are smaller and detonations faster, respectively;(iv) it is easily applicable to higher initial pressures since the Rayleigh signal scales with number density. Secondly, we combine this multipulse Rayleigh scattering with NO-PLIF to complement the average speed and speed decay measurements with local induction zone length (δi) measurements. This five-beam configuration provides measurement capabilities similar to our previous three beam configuration, outside of the local speed decay. Furthermore, an experimental and numerical assessment reveals that δi measurements cannot be achieved from Rayleigh scattering, as they are significantly underestimated—by approximately 25%—compared to those from NO-PLIF. Hence, NO-PLIF is recommended over Rayleigh scattering for accurate δi measurements in future studies. © 2025, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.

关键词： Rayleigh scattering

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Sintering-based lithography metal additive manufacturing of chiral mechanical metamaterials with a twist 1

Sintering-based lithography metal additive manufacturing of ...

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1st International Conference on Digital Sovereignty, ICDS 2024

作者： Melentiev, Ruslan Wagih, Ahmed Van Der Heijden, Bram Lubineau, Gilles Grande, Carlos A. Thuwal23955-6900 Saudi Arabia Thuwal23955-6900 Saudi Arabia Mechanical Engineering Program Physical Sciences and Engineering Division Saudi Arabia Thuwal23955-6900 Saudi Arabia Chemical Engineering Program. Physical Science and Engineering Division King Abdullah University of Science and Technology Saudi Arabia

Metamaterials are a cla b of materials with extraordinary capabilities derived from their engineered structure. In 2017, Frenzel et al. (science 358, 2017) conceptualized "three-dimensional mechanical metamaterials with a twist,"which convert linear deformation into rotational motion - a mechanical response that surpa bes the bounds of Cauchy continuum mechanics. However, the lack of suitable manufacturing technologies for producing metallic twist metamaterials has precluded their experimental validation and potential applications to date. Herein, 316L-stainle b-steel twist metamaterials are fabricated at various scales using an emerging sintering-based technology - lithography metal manufacturing (LMM) - and their mechanical responses are tested using stereo digital image correlation. Results provide the first empirical evidence of compre bion-induced rotation in steel twist metamaterials and highlight their sensitivity to manufacturing defects. Video, Application 1 Supplementary 1 Video, Application 2 Supplementary 2 Video, Application 3 Supplementary 3 © 2025 The Author(s).

关键词： Sintering

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Sensitivity study of resolution and convergence requirements for the extended overlap region in wall-bounded turbulence

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physical Review Fluids 2024年第8期9卷 L082601-L082601页

作者： Sergio Hoyas Ricardo Vinuesa Peter Schmid Hassan Nagib Instituto Universitario de Matemática Pura y Aplicada Universitat Politècnica de València FLOW Engineering Mechanics KTH Royal Institute of Technology Department of Mechanical Engineering Division of Physical Sciences and Engineering (PSE) King Abdullah University of Science and Technology (KAUST) Mechanical Materials and Aerospace Engineering Armour College of Engineering ILLINOIS TECH

Direct numerical simulations (DNSs) are among the most powerful tools for studying turbulent flows. Even though the achievable Reynolds numbers are lower than those obtained through experimental means, DNS offers a clear advantage: The entire velocity field is known, allowing for the evaluation of any desired quantity. This capability includes the computation of derivatives of all relevant terms. One such derivative provides the indicator function, which is the product of the wall distance and the wall-normal derivative of the mean streamwise velocity. This derivative may depend on mesh spacing and distribution, but it is extremely affected by the convergence of the simulation. The indicator function is crucial for understanding inner and outer interactions in wall-bounded flows and describing the overlap region between them. We find a clear dependence of this indicator function on the mesh distributions we examine, raising questions about classical mesh and convergence requirements for DNS and achievable accuracy. Within the framework of the logarithmic plus linear overlap region, coupled with a parametric study of channel flows and some pipe flows, sensitivities of extracted overlap parameters are examined. This study reveals a path to establishing their high-Reτ or nearly asymptotic values at modest Reynolds numbers, but larger than the ones used in this work, accessible by high-quality DNS with reasonable cost.

关键词： Boundary layers Complex fluids Three-dimensional turbulence Turbulence Turbulent boundary layers

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Assessment of the wall effects on the cellular structure by combined planar laser-induced fluorescence and Rayleigh scattering

Assessment of the wall effects on the cellular structure by ...

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AIAA science and Technology Forum and Exposition, AIAA SciTech Forum 2025

作者： Alicherif, Mhedine Chavez, Samir B. Rojas Chatelain, Karl P. Guiberti, Thibault F. Lacoste, Deanna A. PO box 4700 Thuwal23955-6900 Saudi Arabia Mechanical Engineering Program Physical Science and Engineering Division King Abdullah University of Science and Technology Thuwal23955-6900 Saudi Arabia

ISBN: (数字)9781624107238

ISBN: (纸本)9781624107238

This study investigates the structure of the detonation front in a stoichiometric H2-air mixture (2H2-O2-3.76N2), seeded with 2000,ppm of NO, at 25,kPa and 293,K, for two channel positions: centered and near thewalls (side). Acombination of NO-PLIF and Rayleigh scattering techniques was used to characterize key features of the detonation front, such as unburned gas pockets, transverse waves, cellular irregularities, and triple point trajectories. The irregular features were categorized into four distinct "events", and their occurrence probabilities were determined for each configuration based on samples of over one hundred detonation cells. The centered configuration showed fewer irregularities with lower probabilities for all events, indicating a regular structure. In contrast, the side configuration showed higher probabilities for all events, indicating a more irregular structure closer to the walls. With the same techniques a correlation between the formation of unburned gas pockets and a local thickening of the front was investigated. While the processes seems to be interconnected in the center of the channel this correlation is lost closer to the walls. The results suggest a strong dependence between the occurrence detonation irregularities and their position relative to the walls. © 2025, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.

关键词： Rayleigh scattering

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Back-end-of-line integration of 2D materials on silicon microchips

Back-end-of-line integration of 2D materials on silicon micr...

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2023 International Electron Devices Meeting, IEDM 2023

作者： Lanza, M. Pazos, S. Zhu, K. Yuan, Y. Shen, Y. Alharbi, O. Zheng, W. Zhang, X. Alshareef, H.N. Materials Science and Engineering Program Physical Science and Engineering Division Thuwal23955-6900 Saudi Arabia

ISBN: (纸本)9798350327670

Two-dimensional (2D) materials have excellent electronic and thermal properties that could help to improve the performance of electronic devices and circuits. However, scalable 2D materials synthesis and their integration in silicon microchips (with, for example, complementary metal-oxide-semiconductor, CMOS) transistors presents some challenges, mainly related to the presence of local defects that degrade device/circuit performance. In this invited article, we discuss the integration of 2D materials in silicon microchips. We analyze the type of materials and their properties, the main synthesis and manipulation methods, the type of circuits fabricated, the electronic performance achieved, as well as the future challenges and solutions. We focus on microchips with pre-patterned CMOS circuits on which the 2D material is deposited at the back-end-of-line (BEOL). © 2023 IEEE.

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Design,simulation,and testing of a tunable MEMS multi-threshold inertial switch

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Microsystems & Nanoengineering 2024年第2期10卷 37-46页

作者： Qiu Xu Rodrigo T.Rocha Yousef Algoos Eric Feron Mohammad I.Younis Faculty of Electronic Information Engineering Huaiyin Institute of TechnologyHuai’an223003PR China Computer Electrical and Mathematical Science and Engineering DivisionKing Abdullah University of Science and TechnologyThuwal23955-6900Saudi Arabia Piezoelectric Microsystem Technologies Silicon Austria LabsVillach9524Austria Physical Sciences and Engineering Division King Abdullah University of Science and TechnologyThuwal23955Saudi Arabia Mechanical Engineering Department State University of New YorkBinghamtonNY13902USA

This paper presents a tunable multi-threshold micro-electromechanical inertial switch with adjustable threshold *** demonstrated device combines the advantages of accelerometers in providing quantitative acceleration measurements and g-threshold switches in saving power when in the inactive state upon experiencing acceleration below the *** designed proof-of-concept device with two thresholds consists of a cantilever microbeam and two stationary electrodes placed at different positions in the sensing *** adjustable threshold capability and the effect of the shock duration on the threshold acceleration are analytically investigated using a nonlinear beam *** are shown for the relationships among the applied bias voltage,the duration of shock impact,and the tunable *** fabricated prototypes are tested using a shock-table *** analytical results agree with the experimental *** designed device concept is very promising for the classification of the shock and impact loads in transportation and healthcare applications.

关键词： tunable acceleration testing

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Extremely large water droplet impact onto a deep liquid pool

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physical Review E 2024年第4期109卷 045107-045107页

作者： Sandip Dighe Dilip Kumar Maity Jeffrey N. Fonnesbeck Som Dutta Tadd Truscott Mechanical Engineering Program Physical Science and Engineering Division King Abdullah University of Science and Technology Thuwal 23955 Kingdom of Saudi Arabia Department of Mechanical Engineering Utah State University Logan Utah 84322 USA

Most studies of droplet impact on liquid pools focus on droplet diameters up to the capillary length (0.27 cm). We break from convention and study extremely large water droplets (1 to 6 cm diameter) falling into a pool of water. We demonstrate that the depth and width of the cavity formed by large droplet impact is greatly influenced by the deformed shape of the droplet at impact (i.e., prolate, spherical, and oblate), and larger droplets amplify this behavior by flattening before impact. In particular, the maximum cavity depth is a function of the Froude number and axis ratio of the droplet just before impact. Further, the cavity depth is more dependent on the droplet height than width, and the maximum cavity diameter is independent of the droplet height. In general, we observe that more oblate droplets result in decreasing cavity depths for a fixed liquid volume. This is because an increase in horizontal droplet diameter results in a reduced impact energy flux and therefore reduced cavity depth.

关键词： Capillary interactions Drop breakup Drops & bubbles Thin fluid films Wakes & jets Water

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NONMETALIC COMPOSITES AGING IN OIL AND GAS APPLICATION 20

NONMETALIC COMPOSITES AGING IN OIL AND GAS APPLICATION

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20th European Conference on Composite Materials: Composites Meet Sustainability, ECCM 2022

作者： Badeghaish, Wael Wagih, Ahmed Seraj, Muhamed Lubineau, Gilles Physical Science and Engineering Division Mechanical Engineering Program Laboratory of Mechanics of Composites for Energy and Mobility Thuwal23955 Saudi Arabia

ISBN: (纸本)9782970161400

Polymeric composites have been used to replace metals in many onshore and offshore applications due to their corrosion resistance. Transporting petrochemical gases and acids via composite materials at high pressure and temperature represents a challenge because the lack of confidence in such aggressive environments. Therefore, understanding the change in the physical and mechanical properties in polymeric composites under aggressive oil conditions is essential for providing novel designs and materials for these applications. This work presents a short literature review on the challenges facing application of polymeric composites in the oil and gas downhole aggressive corrosion environment. Moreover, it presents preliminary inspection on the integrity of a thermoplastic polymer (PEEK) subjected to HCl (0.8 Ph) at high temperatures (50 and 100 °C) for 14 days. The preliminary results demonstrated the good chemical resistance of PEEK at high temperature. Moreover, there was no effect on the mechanical properties of the PEEK at these conditions. ©2022 Wael et al.

关键词： Corrosion resistance

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Comment on "Electrical Switch of Poisson's Ratio in IV-VI Monolayers via Pseudophase Transitions"

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JOURNAL OF physical CHEMISTRY LETTERS 2022年第16期13卷 3609-3610页

作者： Jangir, Arun Ho, Duc Tam Schwingenschlogl, Udo Applied Physics Program Physical Science and Engineering Division King Abdullah University of Science and Technology (KAUST) Thuwal 23955-6900 Saudi Arabia

Significant modulation of Poisson's ratio of IV-VI semiconductor monolayers in an electric field was claimed to be discovered by first-principles calculations in The Journal of physical Chemistry Letters, 2021,12,... 详细信息

关键词： Monolayers

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Inhibiting scar formation via wearable multilayer stacked electret patch:Self-creation of persistent and customizable DC electric field for fibrogenic activity restriction

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InfoMat 2024年第3期6卷 66-80页

作者： Sung-Won Kim Sumin Cho Donghan Lee Jiyu Hyun Sunmin Jang Inwoo Seo Hyun Su Park Hee Jae Hwang Hyung-Seop Han Dae Hyeok Yang Heung Jae Chun Suk Ho Bhang Dongwhi Choi School of Chemical Engineering Sungkyunkwan UniversitySuwonRepublic of Korea Department of Mechanical Engineering(Integrated Engineering Program) Kyung Hee UniversityYonginGyeonggiRepublic of Korea Biomaterials Research Center Biomedical Research DivisionKorea Institute of Science and Technology(KIST)SeoulRepublic of Korea Department of Medical Life Sciences College of MedicineInstitute of Cell and Tissue EngineeringThe Catholic University of KoreaSeoulRepublic of Korea

Electrical stimulation has recently received attention as noninvasive treatment in skin wound healing with its outstanding biological property for clinical ***,the complexity of equipment for applying appropriate electrical stimulation remains an ongoing ***,we proposed a strategy for skin scar inhibition by providing electrical stimulation via a multilayer stacked electret(MS-electret),which can generate direct current(DC)electric field(EF)without any power supply *** addition,the MS-electret can easily control the intensity of EFs by simply stacking electret layers and maintain stable EF with the surface potential of 3400 V over 5 days owing to the injected charges on the electret *** confirmed inhibition of type 1 collagen andα-SMA expression of human dermal fibroblasts(hDFs)by 90%and 44%in vitro,indicating that the transition of hDFs to myofibroblasts was restricted by applying stable electrical *** further revealed a 20%significant decrease in the ratio of myofibroblasts caused by the MS-electret in *** findings present that the MS-electret is an outstanding candidate for effective skin scar inhibition with a battery-free,physiological electrical microenvironment,and noninvasive treatment that allows it to prevent external infection.

关键词： DC electric field dermal fibroblasts electret scar formation restriction self-creation of electrical stimulation

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