scholarly journals Studies of reactive and nonreactive metals–ejecta–transporting nonreactive and reactive gases and vacuum

2020 ◽  
Author(s):  
W. T. Buttler ◽  
J. C. Cooley ◽  
J. E. Hammerberg ◽  
R. K. Schulze ◽  
J. D. Schwarzkopf ◽  
...  
Keyword(s):  
Reactive Gases

scholarly journals Hydrodynamic limits of kinetic equations for polyatomic and reactive gases

2017 ◽  
Vol 8 (1) ◽  
pp. 23-42 ◽  
Author(s):  
M. Bisi ◽  
G. Spiga
Keyword(s):  
Degrees Of Freedom ◽  
Continuum Limit ◽  
Fluid Dynamic ◽  
Energy Levels ◽  
Kinetic Equations ◽  
Navier Stokes ◽  
Bgk Model ◽  
Hydrodynamic Limits ◽  
Stress Diffusion ◽  
Reactive Gases

Abstract Starting from a kinetic BGK-model for a rarefied polyatomic gas, based on a molecular structure of discrete internal energy levels, an asymptotic Chapman-Enskog procedure is developed in the asymptotic continuum limit in order to derive consistent fluid-dynamic equations for macroscopic fields at Navier-Stokes level. In this way, the model allows to treat the gas as a mixture of mono-atomic species. Explicit expressions are given not only for dynamical pressure, but also for shear stress, diffusion velocities, and heat flux. The analysis is shown to deal properly also with a mixture of reactive gases, endowed for simplicity with translational degrees of freedom only, in which frame analogous results can be achieved.

scholarly journals Self-organized graphene-like boron nitride containing nanoflakes on copper by low-temperature N2 + H2 plasma

RSC Advances ◽  
2016 ◽  
Vol 6 (90) ◽  
pp. 87607-87615 ◽  
Author(s):  
B. B. Wang ◽  
D. Gao ◽  
I. Levchenko ◽  
K. Ostrikov ◽  
M. Keidar ◽  
...  
Keyword(s):  
Low Temperature ◽  
Boron Nitride ◽  
Chemical Vapour Deposition ◽  
Efficient Method ◽  
Vapour Deposition ◽  
Chemical Vapour ◽  
Self Organized ◽  
Reactive Gases ◽  
Hot Filament

A simple and efficient method for synthesizing complex graphene-inspired BNCO nanoflakes by plasma-enhanced hot filament chemical vapour deposition using B4C as a precursor and N2/H2 reactive gases is reported.

Reactive Gases as Reagents for Polymer Films Chemical Modifications

1997 ◽  
pp. 21-30 ◽  
Author(s):  
J. F. Pilichowski ◽  
S. Commereuc ◽  
I. Lukac ◽  
G. Teissedre ◽  
J. Lacoste
Keyword(s):  
Polymer Films ◽  
Chemical Modifications ◽  
Reactive Gases

The determination of the Henry’s Coefficient of reactive gases – An example of CO2 in aqueous solutions of monoethanolamine (MEA)

2017 ◽  
Vol 173 ◽  
pp. 474-482 ◽  
Author(s):  
Lichun Li ◽  
Robert C. Burns ◽  
Marcel Maeder ◽  
Graeme Puxty ◽  
Shujuan Wang ◽  
...  
Keyword(s):  
Aqueous Solutions ◽  
Reactive Gases

The transient start of supersonic jets

2007 ◽  
Vol 578 ◽  
pp. 331-369 ◽  
Author(s):  
MATEI I. RADULESCU ◽  
CHUNG K. LAW
Keyword(s):  
Numerical Simulations ◽  
Ambient Air ◽  
Hydrogen Gas ◽  
Shock Interactions ◽  
Round Jets ◽  
Reactive Gases ◽  
Acoustic Instabilities ◽  
Diffusive Fluxes ◽  
Experimental Findings ◽  
Good Agreement

This study investigates the initial transient hydrodynamic evolution of highly under-expanded slit and round jets. A closed-form analytic similarity solution is derived for the temporal evolution of temperature, pressure and density at the jet head for vanishing diffusive fluxes, generalizing a previous model of Chekmarev using Chernyi's boundary-layer method for hypersonic flows. Two-dimensional numerical simulations were also performed to investigate the flow field during the initial stages over distances of ~ 1000 orifice radii. The parameters used in the simulations correspond to the release of pressurized hydrogen gas into ambient air, with pressure ratios varying between approximately 100 and 1000. The simulations confirm the similarity laws derived theoretically and indicate that the head of the jet is laminar at early stages, while complex acoustic instabilities are established at the sides of the jet, involving shock interactions within the vortex rings, in good agreement with previous experimental findings. Very good agreement is found between the present model, the numerical simulations and previous experimental results obtained for both slit and round jets during the transient establishment of the jet. Criteria for Rayleigh–Taylor instability of the decelerating density gradients at the jet head are also derived, as well as the formulation of a model addressing the ignition of unsteady expanding diffusive layers formed during the sudden release of reactive gases.

Acoustic Noise Reduction Under Distributed Combustion

2017 ◽  
Author(s):  
Ahmed E. E. Khalil ◽  
Ashwani K. Gupta
Keyword(s):  
Carbon Dioxide ◽  
Heat Release ◽  
Noise Reduction ◽  
Oxygen Concentration ◽  
Acoustic Signal ◽  
Thermal Field ◽  
Field Uniformity ◽  
Pollutants Emission ◽  
Reactive Gases ◽  
Swirl Flame

Colorless Distributed Combustion (CDC) has been shown to provide unique benefits on ultra-low pollutants emission, enhanced combustion stability, and thermal field uniformity. To achieve CDC conditions, fuel-air mixture must be properly prepared and mixed with hot reactive gases from within the combustor prior to the mixture ignition. The hot reactive gases reduce the oxygen concentration in the mixture while increasing its temperature, resulting in a reaction zone that is distributed across the reactor volume, with lower reaction rate to result in the same fuel consumption. The conditions to achieve distributed combustion were previously studied using methane and other fuels with focus on pollutants emission and thermal field uniformity. In this paper, the impact of distributed combustion on noise reduction and increased stability is investigated. Such reduced noise is critical in mitigating the coupling between flame and heat release perturbations and acoustic signal to enhance the overall flame stability and reduce the propensity of flame instabilities which can cause equipment failure. Nitrogen-carbon dioxide mixture is used to simulate the reactive entrained gases from with the combustor. Increasing the amounts of nitrogen and carbon dioxide reduced the oxygen concentration within the oxidizing mixture, fostering distributed combustion. Upon achieving distributed combustion, the overall flame noise signature decreased from 80 dB to only 63 dB, as the flame transitioned from traditional swirl flame to distributed combustion. The flow noise under these conditions was 54 dB, indicating that distributed combustion has only 9 dB increase over isothermal case as compared to 26 dB for standard swirl flame. In addition, the dominant flame frequency around 490Hz disappeared under distributed combustion. For the traditional swirl flame, both the acoustic signal and heat release fluctuations (detected through CH∗ chemiluminescence) had a peak around 150Hz, indicating coupling between the heat release fluctuations and pressure variation. However, upon transitioning to distributed combustion, this common peak disappeared, outlining the enhanced stability of distributed combustion as there is no feedback between the heat release fluctuations and the recorded acoustic signal.

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