scholarly journals Influence of Gaseous Environment on Reaction Behavior and Phase Formation in Ti/2B Reactive Multilayer Foils

2012 ◽  
Vol 1405 ◽  
Author(s):  
Robert V. Reeves ◽  
Mark A. Rodriguez ◽  
Eric D. Jones ◽  
David P. Adams
Keyword(s):  
High Speed ◽  
Ambient Pressure ◽  
Product Formation ◽  
Atmospheric Conditions ◽  
Bilayer Thickness ◽  
X Ray Diffraction ◽  
High Speed Imaging ◽  
Reaction Behavior ◽  
Gaseous Environment ◽  
Sputter Deposited

ABSTRACTThe effects of surrounding gaseous environment on the reaction behaviors and product formation for sputter-deposited Ti/2B reactive multilayers are reported. With the surrounding environment set to different air pressures, from atmospheric conditions to 10-4 Torr, Ti/2B samples were reacted in a self-propagating mode, and the average reaction wave velocities were determined through high-speed imaging. Propagation speeds for 3.0 μm-thick multilayers were in the range of 10.89 to 0.05 m/s depending on bilayer thickness (i.e., reactant layer periodicity) and ambient pressure. X-ray diffraction analysis showed that single-phase TiB2 forms within multilayers that have small bilayer thickness. Multilayers that have a large bilayer thickness developed a mixture of TiB2, TiB and TiO2.

Characterization of a Superheated Fuel Jet in a Crossflow

2010 ◽  
Vol 133 (1) ◽  
Author(s):  
May L. Corn ◽  
Jeffrey M. Cohen ◽  
Jerry C. Lee ◽  
Donald J. Hautman ◽  
Scott M. Thawley ◽  
...  
Keyword(s):  
High Speed ◽  
Ambient Pressure ◽  
Design Feature ◽  
Dew Point ◽  
Fuel Temperature ◽  
High Speed Imaging ◽  
Fuel Atomization ◽  
Phase Doppler Interferometry ◽  
Fuel Jet ◽  
Submicron Droplets

An experiment was conducted to characterize a superheated fuel jet (Jet-A) injected into an unheated crossflow of air. The liquid phase of the fuel jet was characterized with high speed imaging and phase Doppler interferometry. The transition from a shear-atomized to a flash-atomized spray at a fuel temperature of 513 K (465°F) was observed at an ambient pressure of 1 atm, which is consistent with the bubble and dew point curves predicted for JP-8. The explosive breakup that was seen in the flash-atomized spray produced submicron droplets with a high radial momentum. This unique behavior makes superheated fuels an attractive design feature for fuel preparation devices that can employ flash boiling to enhance fuel atomization and mixing in a compact volume.

Experimental Study on Laminar Flame Speeds and Markstein Length of Methane-Air Mixtures at Atmospheric Conditions

2014 ◽  
Vol 699 ◽  
pp. 714-719
Author(s):  
Alaeldeen Altag Yousif ◽  
Shaharin Anwar Sulaiman
Keyword(s):  
High Speed ◽  
Equivalence Ratio ◽  
Laminar Flame ◽  
Burning Velocity ◽  
Ambient Pressure ◽  
Flame Speed ◽  
Laminar Flame Speed ◽  
Atmospheric Conditions ◽  
Laminar Burning Velocity ◽  
Markstein Length

Accurate value of laminar flame speed is an important parameter of combustible mixtures. In this respect, experimental data are very useful for modeling improvement and validating chemical kinetic mechanisms. To achieve this, an experimental characterization on spherically expanding flames propagation of methane-air mixtures were carried out. Tests were conducted in constant volume cylindrical combustion chamber to measure stretched, unstretched laminar flame speed, laminar burning velocity, and flame stretch effect as quantified by the associated Markstein lengths. The mixtures of methane-air were ignited at extensive ranges of lean-to-rich equivalence ratios, under ambient pressure and temperature. This is achieved by high speed schlieren cine-photography for flames observation in the vessel. The results showed that the unstretched laminar burning velocity increased and the peak value of the unstretched laminar burning velocity shifted to the richer mixture side with the increase of equivalence ratio. The flame propagation speed showed different trends at different equivalence ratio for tested mixtures. It was found that the Markstein length was increased with the increase of equivalence ratio.

Characterization of a Superheated Fuel Jet in a Crossflow

2009 ◽  
Author(s):  
May Corn ◽  
Jeff Cohen ◽  
Don Hautman ◽  
Scott Thawley ◽  
Christopher Brown ◽  
...  
Keyword(s):  
High Speed ◽  
Ambient Pressure ◽  
Design Feature ◽  
Dew Point ◽  
Vapor Concentration ◽  
Fuel Vapor ◽  
Fuel Temperature ◽  
High Speed Imaging ◽  
Phase Doppler Interferometry ◽  
Fuel Jet

An experiment was conducted to characterize a superheated fuel jet (Jet-A) injected into an unheated crossflow. The liquid phase of the fuel jet was characterized with high speed imaging and phase Doppler interferometry while the vapor phase of the fuel was measured with infrared scattering and extinction methods. The transition from a shear-atomized to flash-atomized spray at a fuel temperature of 465°F (513K) was observed at an ambient pressure of 1 atm, which is consistent with the bubble and dew point curves predicted for JP-8. The explosive breakup that was seen in the flash-atomized spray produced sub-micron droplets with a high radial and transverse momentum that resulted in an increasing fuel vapor concentration for the same penetration height when compared with the shear-atomized case. This unique behavior makes superheated fuels an attractive design feature for fuel preparation devices that can employ flash boiling to enhance fuel atomization and mixing in a compact volume.

scholarly journals We -T classification of diesel fuel droplet impact regimes

2018 ◽  
Vol 474 (2215) ◽  
pp. 20170759 ◽  
Author(s):  
Hesamaldin Jadidbonab ◽  
Ilias Malgarinos ◽  
Ioannis Karathanassis ◽  
Nicholas Mitroglou ◽  
Manolis Gavaises
Keyword(s):  
Surface Temperature ◽  
High Speed ◽  
Ambient Pressure ◽  
Dynamic Contact Angle ◽  
Dynamic Contact ◽  
High Speed Imaging ◽  
Two Phase ◽  
Post Impact ◽  
T Classification ◽  
The Impact

A combined experimental and computational investigation of micrometric diesel droplets impacting on a heated aluminium substrate is presented. Dual view high-speed imaging has been employed to visualize the evolution of the impact process at various conditions. The parameters investigated include wall-surface temperature ranging from 140 to 400°C, impact Weber and Reynolds numbers of 19–490 and 141–827, respectively, and ambient pressure of 1 and 2 bar. Six possible post-impact regimes were identified, termed as Stick, Splash, Partial-Rebound, Rebound, Breakup-Rebound and Breakup-Stick , and plotted on the We-T map. Additionally, the temporal variation of the apparent dynamic contact angle and spreading factor have been determined as a function of the impact Weber number and surface temperature. Numerical simulations have also been performed using a two-phase flow model with interface capturing, phase-change and variable physical properties. Increased surface temperature resulted to increased maximum spreading diameter and induced quicker and stronger recoiling behaviour, mostly attributed to the change of liquid viscosity.

Structure and Phase Formation in SHS_FGM

2006 ◽  
Vol 45 ◽  
pp. 1067-1074 ◽  
Author(s):  
A.S. Rogachev
Keyword(s):  
High Speed ◽  
Mutual Influence ◽  
Video Recording ◽  
Product Formation ◽  
Functionally Graded ◽  
X Ray Diffraction ◽  
Concentration Gradients ◽  
Graded Materials ◽  
High Temperature Synthesis ◽  
Short Time

Self-propagating high-temperature synthesis (SHS), also known as combustion synthesis, is one of the most prospective methods for production functionally graded materials (FGM). The advantages of SHS include short time of reaction and product formation, which allow retaining pre-determined concentration gradient in the synthesized material. In the present work, the following challenges remaining in the field of FGM production by SHS are discussed. First, main features of combustion of multilayer samples are considered from the viewpoint of mutual influence of the combustible and inert layers. Second, evolution of the concentration gradients (profiles) during the combustion is outlined and different methods for controlling this process, such as mechanical pre-activation of the reactants are examined. Third, processes of the product phase and microstructure formation in multilayer SHSmaterials are described. The problem of creating very thin gradient samples and coatings by SHS is also discussed. The consideration includes data of high-speed video recording, timeresolved X-ray diffraction, SEM, EPMA and other experimental techniques.

TEM studies of solid-state reactions in sputter-deposited Nb/Al multilayer thin films

1996 ◽  
Vol 54 ◽  
pp. 1020-1021
Author(s):  
F. Ma ◽  
S. Vivekanand ◽  
K. Barmak ◽  
C. Michaelsen
Keyword(s):  
Thin Films ◽  
Solid State ◽  
Stoichiometric Composition ◽  
Analytical Electron Microscopy ◽  
Grain Structure ◽  
Solid State Reactions ◽  
Multilayer Thin Films ◽  
X Ray Diffraction ◽  
X Ray ◽  
Sputter Deposited

Solid state reactions in sputter-deposited Nb/Al multilayer thin films have been studied by transmission and analytical electron microscopy (TEM/AEM), differential scanning calorimetry (DSC) and X-ray diffraction (XRD). The Nb/Al multilayer thin films for TEM studies were sputter-deposited on (1102)sapphire substrates. The periodicity of the films is in the range 10-500 nm. The overall composition of the films are 1/3, 2/1, and 3/1 Nb/Al, corresponding to the stoichiometric composition of the three intermetallic phases in this system.Figure 1 is a TEM micrograph of an as-deposited film with periodicity A = dA1 + dNb = 72 nm, where d's are layer thicknesses. The polycrystalline nature of the Al and Nb layers with their columnar grain structure is evident in the figure. Both Nb and Al layers exhibit crystallographic texture, with the electron diffraction pattern for this film showing stronger diffraction spots in the direction normal to the multilayer. The X-ray diffraction patterns of all films are dominated by the Al(l 11) and Nb(l 10) peaks and show a merging of these two peaks with decreasing periodicity.

Experimental Measurement of In-Plane Rolling Nonpneumatic Tire Vibrations Using High-Speed Imaging

2019 ◽  
Vol 47 (3) ◽  
pp. 196-210
Author(s):  
Meghashyam Panyam ◽  
Beshah Ayalew ◽  
Timothy Rhyne ◽  
Steve Cron ◽  
John Adcox
Keyword(s):  
High Speed ◽  
Image Correlation ◽  
Dynamic Mode Decomposition ◽  
Dynamic Mode ◽  
High Speed Imaging ◽  
Correlation Algorithm ◽  
Mode Decomposition ◽  
Series Of Experiments ◽  
Plane Deformations ◽  
Dominant Frequencies

ABSTRACT This article presents a novel experimental technique for measuring in-plane deformations and vibration modes of a rotating nonpneumatic tire subjected to obstacle impacts. The tire was mounted on a modified quarter-car test rig, which was built around one of the drums of a 500-horse power chassis dynamometer at Clemson University's International Center for Automotive Research. A series of experiments were conducted using a high-speed camera to capture the event of the rotating tire coming into contact with a cleat attached to the surface of the drum. The resulting video was processed using a two-dimensional digital image correlation algorithm to obtain in-plane radial and tangential deformation fields of the tire. The dynamic mode decomposition algorithm was implemented on the deformation fields to extract the dominant frequencies that were excited in the tire upon contact with the cleat. It was observed that the deformations and the modal frequencies estimated using this method were within a reasonable range of expected values. In general, the results indicate that the method used in this study can be a useful tool in measuring in-plane deformations of rolling tires without the need for additional sensors and wiring.

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