Effects of Liquid Viscosity on Laser-Induced Shock Dynamics

2019 ◽  
Author(s):  
Hiroki Kurahara ◽  
Keita Ando
Keyword(s):  
Pulse Laser ◽  
High Speed ◽  
Water Solution ◽  
Plasma Pressure ◽  
Rapid Expansion ◽  
Glycerol Concentration ◽  
Glycerol Water ◽  
Initial Plasma ◽  
Front Position ◽  
532 Nm

Abstract We experimentally study the effects of viscosity on laser-induced shockwave in glycerol-water solution. A shockwave is generated through rapid expansion of plasma, which is induced by focusing a 6 ns pulse laser (532 nm) of energy fixed at 1.66 ± 0.22 mJ into 80, 90, 100 wt% glycerol-water solution. The shockwave propagation is recorded by an ultra-high-speed camera taken at 100 Mfps together with a pulse laser stroboscope. The photographs are used to determine the shock front position as a function of time, which allows for calculating the shock pressure according to the stiffened-gas type Rankine-Hugoniot relation. It turns out that the initial plasma pressure is reduced by having higher glycerol concentration (i.e., higher viscosity); therefore, wave steepening effect is deemphasized, resulting in a smaller decay rate.

Characteristics of air entrainment during dynamic wetting failure along a planar substrate

2014 ◽  
Vol 747 ◽  
pp. 119-140 ◽  
Author(s):  
E. Vandre ◽  
M. S. Carvalho ◽  
S. Kumar
Keyword(s):  
High Speed ◽  
Water Solution ◽  
Air Entrainment ◽  
Dynamic Contact ◽  
Operating Conditions ◽  
Dynamic Wetting ◽  
Glycerol Water ◽  
Planar Substrate ◽  
Wide Range ◽  
Stationary Plate

AbstractCharacteristic substrate speeds and meniscus shapes associated with the onset of air entrainment are studied during dynamic wetting failure along a planar substrate. Using high-speed video, the behaviour of the dynamic contact line (DCL) is recorded as a tape substrate is drawn through a bath of a glycerol/water solution. Air entrainment is identified by triangular air films that elongate from the DCL above some critical substrate speed. Meniscus confinement within a narrow gap between the substrate and a stationary plate is shown to delay air entrainment to higher speeds for a wide range of liquid viscosities, expanding upon the findings of Vandre, Carvalho & Kumar (J. Fluid Mech., vol. 707, 2012, pp. 496–520). A pressurized liquid reservoir controls the meniscus position within the confinement gap. It is found that liquid pressurization further postpones air entrainment when the meniscus is located near a sharp corner along the stationary plate. Meniscus shapes recorded near the DCL demonstrate that operating conditions influence the size of entrained air films, with smaller films appearing in the more viscous solutions. Regardless of size, air films become unstable to thickness perturbations and ultimately rupture, leading to the entrainment of air bubbles. Recorded critical speeds and air-film sizes compare well to predictions from a hydrodynamic model for dynamic wetting failure, suggesting that strong air stresses near the DCL trigger the onset of air entrainment.

Linear and Nonlinear Optical Properties of Natural Dyes Freestanding Films and Application in Optical Limiting

2020 ◽  
pp. 139-143
Keyword(s):  
Absorption Coefficient ◽  
Water Solution ◽  
Optical Limiting ◽  
Refraction Index ◽  
Laser Wavelength ◽  
Solid State Laser ◽  
Natural Dyes ◽  
Linear And Nonlinear ◽  
532 Nm ◽  
Absorbance Spectra

Natural dyes were followed and prepared from a pomegranate, purple carrot, and eggplant peel. The absorbance spectra was measured in the wavelength range 300-800 nm. The linear properties measurements of the prepared natural dye freestanding films were determined include absorption coefficient (α0), extinction coefficient (κ), and linear refraction index (n). The nonlinear refractive index n2 and nonlinear absorption coefficient β2 of the natural dyes in the water solution were measured by the optical z-scan technique under a pumped solid state laser at a laser wavelength of 532 nm. The results indicated that the pomegranate dye can be promising candidates for optical limiting applications with significantly low optical limiting of 3.5 mW.

scholarly journals Energetic-Materials-Driven Synthesis of Graphene-Encapsulated Tin Oxide Nanoparticles for Sodium-Ion Batteries

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2550
Author(s):  
Yingchun Wang ◽  
Jinxu Liu ◽  
Min Yang ◽  
Lijuan Hou ◽  
Tingting Xu ◽  
...  
Keyword(s):  
Tin Oxide ◽  
Energetic Materials ◽  
High Speed ◽  
Coulombic Efficiency ◽  
Sno2 Nanoparticles ◽  
Direct Synthesis ◽  
Exothermic Reaction ◽  
Rate Capability ◽  
Rapid Expansion ◽  
Core Shell

By evenly mixing polytetrafluoroethylene-silicon energetic materials (PTFE-Si EMs) with tin oxide (SnO2) particles, we demonstrate a direct synthesis of graphene-encapsulated SnO2 (Gr-SnO2) nanoparticles through the self-propagated exothermic reaction of the EMs. The highly exothermic reaction of the PTFE-Si EMs released a huge amount of heat that induced an instantaneous temperature rise at the reaction zone, and the rapid expansion of the gaseous SiF4 product provided a high-speed gas flow for dispersing the molten particles into finer nanoscale particles. Furthermore, the reaction of the PTFE-NPs with Si resulted in a simultaneous synthesis of graphene that encapsulated the SnO2 nanoparticles in order to form the core-shell nanostructure. As sodium storage material, the graphene-encapsulated SnO2 nanoparticles exhibit a good cycling performance, superior rate capability, and a high initial Coulombic efficiency of 85.3%. This proves the effectiveness of our approach for the scalable synthesis of core-shell-structured graphene-encapsulated nanomaterials.

High-Speed Synthesis and Electric Properties of Magnesium Doped Lead Titanate Ceramics

2007 ◽  
Vol 121-123 ◽  
pp. 149-152
Author(s):  
Liang Sheng Qiang ◽  
Dong Yan Tang ◽  
Xing Hong Zhang ◽  
L. Jin
Keyword(s):  
Lead Titanate ◽  
High Speed ◽  
Sintering Temperature ◽  
Water Solution ◽  
Sol Gel ◽  
Electric Properties ◽  
Synthesis Process ◽  
Pure Lead ◽  
Alcohol Water ◽  
Titanate Ceramics

By adding methyl alcohol/water solution with certain concentration into sol to hydrolysis directly and sintering the fresh sol directly, lead titanate(PbTiO3) ceramics doped with magnesium are prepared by using magnesium acetate as doper to prohibit the disadvantages contained in conventional sol-gel method, such as low hydrolytic rate, high sintering temperature, long preparation period. The changes of structure, microstructure, synthesis process and electric properties of modified ceramics are studied in detail. The sizes and morphology of high purely and high density magnesium doped lead titanate nanocrystals thus obtained are observed by TEM photographs and the structures and affection of sintering temperature of to lattice constant and sizes of nanocrystals are detected by XRD. Electric properties detection results show that doped lead titanate ceramics exhibite excellent dielectric, ferroelectric and pyroelectric properties compare with pure lead titanate.

Effect of Tube Diameter on Flow Phenomena of Gas-Liquid Two-Phase Flow in Microchannels

2015 ◽  
Author(s):  
Hideo Ide ◽  
Eiji Kinoshita ◽  
Ryo Kuroshima ◽  
Takeshi Ohtaka ◽  
Yuichi Shibata ◽  
...  
Keyword(s):  
Pressure Drop ◽  
High Speed ◽  
Water Solution ◽  
Flow Direction ◽  
Flow Characteristics ◽  
Tube Diameter ◽  
Two Phase ◽  
Frictional Pressure Drop ◽  
Flow Phenomena ◽  
The Waves

Gas-liquid two-phase flows in minichannels and microchannels display a unique flow pattern called ring film flow, in which stable waves of relatively large amplitudes appear at seemingly regular intervals and propagate in the flow direction. In the present work, the velocity characteristics of gas slugs, ring films, and their features such as the gas slug length, flow phenomena and frictional pressure drop for nitrogen-distilled water and nitrogen-30 wt% ethanol water solution have been investigated experimentally. Four kinds of circular microchannels with diameters of 100 μm, 150 μm, 250 μm and 518 μm were used. The effects of tube diameter and physical properties, especially the surface tension and liquid viscosity, on the flow patterns, gas slug length and the two-phase frictional pressure drop have been investigated by using a high speed camera at 6,000 frames per second. The flow characteristics of gas slugs, liquid slugs and the waves of ring film are presented in this paper.

scholarly journals Responses of human sensory characteristics to 532 nm pulse laser stimuli

2016 ◽  
Vol 24 (s2) ◽  
pp. S697-S705 ◽  
Author(s):  
Ji-Sun Kim ◽  
Han-Byeol Oh ◽  
A-Hee Kim ◽  
Jun-Sik Kim ◽  
Eun-Suk Lee ◽  
...  
Keyword(s):  
Pulse Laser ◽  
Sensory Characteristics ◽  
532 Nm

scholarly journals Flashboiling atomization in nozzles for GDI engines

2017 ◽  
Author(s):  
Sebastian Bornschlegel ◽  
Chris Conrad ◽  
Lisa Eichhorn ◽  
Michael Wensing
Keyword(s):  
Penetration Depth ◽  
High Speed ◽  
Aerodynamic Drag ◽  
Ambient Pressure ◽  
Rapid Expansion ◽  
Gasoline Direct Injection ◽  
Coolant Temperature ◽  
Concentrated Mass ◽  
Flash Boiling ◽  
Gdi Engines

Flashboiling denotes the phenomenon of rapid evaporation and atomization at nozzles, which occurs when fluidsare injected into ambient pressure below their own vapor pressure. It happens in gasoline direct injection (GDI) engines at low loads, when the cylinder pressure is low during injection due to the closed throttle valve. The fuel temperature at the same time approaches cylinder head coolant temperature due to the longer dwell time of the fuel inside the injector. Flash boiling is mainly beneficial for atomization quality, since it produces small droplet sizes and relative broad and homogenous droplet distributions within the spray. Coherently, the penetration depth normally decreases due to the increased aerodynamic drag. Therefore the thermal properties of injectors are often designed to reach flash boiling conditions as early as possible. At the same time, flash boiling significantly increases the risk of undesired spray collapsing. In this case, neighbouring jets converge and form a single jet. Due to the now concentrated mass, penetration depth is enhanced again and can lead to liner or piston wetting in addition to the overall diminished mixture formation.In order to understand the underlying physics, it is important to study the occurring phenomena flashboiling and jet-to-jet interacting i.e. spray collapsing separately. To this end, single hole injectors are built up to allow for an isolated investigation of flashboiling. The rapid expansion at the nozzle outlet is visualized with a microscopic high speed setup and the forces that lead to the characteristic spray expansion are discussed. Moreover, the results on the macroscopic spray in terms of penetration, cone angles and vapor phase are shown with a high speed Schlieren setup. Resulting droplet diameters and velocities are measured using LDA/PDA.As a result, we find a comprehensive picture of flash boiling. The underlying physics can be described and discussed for the specific case of high pressure injection at engine relevant nozzle geometries and conditions, but independently from neighbouring jets. These findings provide the basis to understand and investigate flashboilingand jet-to-jet interaction as distinct, but interacting subjects rather than a combined phenomenon.DOI: http://dx.doi.org/10.4995/ILASS2017.2017.4750 

scholarly journals Feeding mechanics and bite force modelling of the skull of Dunkleosteus terrelli , an ancient apex predator

2006 ◽  
Vol 3 (1) ◽  
pp. 77-80 ◽  
Author(s):  
Philip S.L Anderson ◽  
Mark W Westneat
Keyword(s):  
High Speed ◽  
Prey Capture ◽  
Mouth Opening ◽  
Biomechanical Model ◽  
Bite Force ◽  
Rapid Expansion ◽  
Large Individual ◽  
Linkage Mechanism ◽  
Feeding Mechanics ◽  
Four Bar Linkage

Placoderms are a diverse group of armoured fishes that dominated the aquatic ecosystems of the Devonian Period, 415–360 million years ago. The bladed jaws of predators such as Dunkleosteus suggest that these animals were the first vertebrates to use rapid mouth opening and a powerful bite to capture and fragment evasive prey items prior to ingestion. Here, we develop a biomechanical model of force and motion during feeding in Dunkleosteus terrelli that reveals a highly kinetic skull driven by a unique four-bar linkage mechanism. The linkage system has a high-speed transmission for jaw opening, producing a rapid expansion phase similar to modern fishes that use suction during prey capture. Jaw closing muscles power an extraordinarily strong bite, with an estimated maximal bite force of over 4400 N at the jaw tip and more than 5300 N at the rear dental plates, for a large individual (6 m in total length). This bite force capability is the greatest of all living or fossil fishes and is among the most powerful bites in animals.

scholarly journals Synthesis of α-CaSO4·0.5H2O from flue gas desulfurization gypsum regulated by C4H4O4Na2·6H2O and NaCl in glycerol-water solution

RSC Advances ◽  
2017 ◽  
Vol 7 (44) ◽  
pp. 27807-27815 ◽  
Author(s):  
Qing-Jun Guan ◽  
Wei Sun ◽  
Yue-Hua Hu ◽  
Zhi-Gang Yin ◽  
Chang-Ping Guan
Keyword(s):  
Phase Transition ◽  
Flue Gas ◽  
Water Solution ◽  
Flue Gas Desulfurization ◽  
New Method ◽  
Glycerol Water ◽  
Aspect Ratios

A brand new method to prepare α-CaSO4·0.5H2O with low aspect ratios from flue gas desulfurization gypsum in glycerol-water solution was presented, in which NaCl was used as the phase transition accelerator and C4H4O4Na2·6H2O as the crystal modifier.

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