Measurement of heavy particle temperature in a radiofrequency air discharge at atmospheric pressure from the numerical simulation of the NO ? system

1992 ◽  
Vol 7 (7) ◽  
pp. 1103 ◽  
Author(s):  
Anne-Marie Gomes ◽  
Jean Bacri ◽  
Jean-Philippe Sarrette ◽  
Jacques Salon
Keyword(s):  
Numerical Simulation ◽  
Atmospheric Pressure ◽  
Particle Temperature ◽  
Heavy Particle ◽  
Air Discharge

scholarly journals Thermal behavior of ceramic particles in a gaseous medium at high temperature

2020 ◽  
Vol 307 ◽  
pp. 01056
Author(s):  
Abderrahmane AISSA ◽  
Abdel-Nour ZAIM ◽  
M SAHNOUN ◽  
Redouane FARES ◽  
M ABDELOUHAB ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Spherical Particle ◽  
Atmospheric Pressure ◽  
Computational Analysis ◽  
Gaseous Medium ◽  
Plasma Jet ◽  
Spray Process ◽  
Plasma Spray Process ◽  
Proposed Model ◽  
Computational Fluid Dynamics Cfd

Numerical simulation of the interaction between the spherical particle and plasma gas is carried out. The aim of this study is to investigatethermal transfer between the plasma gas and solid particle during the plasma spray process and to validate the well-known empirical correlation of the Ranz and Marshall. In the conditions of molten or semi-molten states of prepared substrate, the medium (plasma jet) can affect the high velocities of particles. On the basis of direct numerical simulation, the computational analysis has been carried out by using computational fluid dynamics (CFD) of heat transfer in atmospheric pressure and mid-temperature range (3000k–12000k) of a plasma flow over a spherical particle. Our proposed model improves correlation with experiments compared to the existing approaches in the literature.

Numerical Simulation of Heavy Particle Dispersion—Scale Ratio and Flow Decay Considerations

1994 ◽  
Vol 116 (1) ◽  
pp. 154-163 ◽  
Author(s):  
Lian-Ping Wang ◽  
David E. Stock
Keyword(s):  
Numerical Simulation ◽  
Time Scale ◽  
Dispersion Coefficient ◽  
Fluid Velocity ◽  
Heavy Particle ◽  
Particle Dispersion ◽  
Heavy Particles ◽  
Velocity Scale ◽  
Scale Ratio ◽  
Diffusivity Ratio

Lagrangian statistical quantities related to the dispersion of heavy particles were studied numerically by following particle trajectories in a random flow generated by Fourier modes. An experimental fluid velocity correlation was incorporated into the flow. Numerical simulation was performed with the use of nonlinear drag. The simulation results for glass beads in a nondecaying turbulent air showed a difference between the horizontal dispersion coefficient and vertical dispersion coefficient. This difference was related to the differences of both the velocity scale and the time scale between the two direction. It was shown that for relatively small particle sizes the particle time scale ratio dominates the value of the diffusivity ratio. For large particles, the velocity scale ratio reaches a value of 1/2 and thus fully determines the diffusivity ratio. Qualitative explanation was provided to support the numerical findings. The dispersion data for heavy particles in grid-generated turbulences were successfully predicted by the simulation when flow decay was considered. As a result of the reduction in effective inertia and the increase in effective drift caused by the flow decay, the particle dispersion coefficient in decaying flow decreases with downstream location. The particle rms fluctuation velocity has a slower decay rate than the fluid rms velocity if the drift parameter is large. It was also found that the drift may substantially reduce the particle rms velocity.

scholarly journals Backward runaway electrons in a subnanosecond air discharge at atmospheric pressure

2015 ◽  
Vol 34 (1) ◽  
pp. 23-30 ◽  
Author(s):  
Victor F. Tarasenko ◽  
Igor' D. Kostyrya ◽  
Dmitry V. Beloplotov
Keyword(s):  
High Voltage ◽  
Atmospheric Pressure ◽  
Exposure Dose ◽  
X Rays ◽  
Runaway Electrons ◽  
Full Width ◽  
Half Maximum ◽  
X Ray ◽  
Grid Cathode ◽  
Air Discharge

AbstractIn the paper, we study the conditions for the generation of backward runaway electrons through a grounded grid cathode in atmospheric pressure air at high-voltage pulses with a full width at half maximum of 1 ns and risetime of 0.3 ns applied to the gap from a SLEP-150 pulser. The study confirms that backward runaway electrons and X-rays do arise near grid cathodes in atmospheric pressure air. It is shown that the current of the backward beam and the X-rays from the gas diode depend differently on the interelectrode distance. The average X-ray exposure dose in a pulse is more than 3.5 mR.

Numerical Simulation of Heavy Particle Dispersion Time Step and Nonlinear Drag Considerations

1992 ◽  
Vol 114 (1) ◽  
pp. 100-106 ◽  
Author(s):  
Lian-Ping Wang ◽  
D. E. Stock
Keyword(s):  
Numerical Simulation ◽  
Numerical Experiments ◽  
Heavy Particle ◽  
Free Fall ◽  
Particle Dispersion ◽  
Integration Time ◽  
Fall Velocity ◽  
Time Step ◽  
Physical Experiments ◽  
Total Integration

Numerical experiments can be used to study heavy particle dispersion by tracking particles through a numerically generated instantaneous turbulent flow field. In this manner, data can be generated to supplement physical experiments. To perform the numerical experiments efficiently and accurately, the time step used when tracking the particles through the fluid must be chosen correctly. After finding a suitable time step for one particular simulation, the time step must be reduced as the total integration time increases and as the free-fall velocity of the particle increases. Based on the numerical calculations, we suggest that the nonlinear drag be included in a numerical simulation if the ratio of the particle’s Stokes free-fall velocity to the fluid rms velocity is greater than two.

Nichtgleichgewichtscffekte im Argonkaskadenbogen im Druckbereich von 0,2 atm bis 5,0 atm / Non-LTE Effects in an Argon Cascade Arc in the Pressure Range from 0.2 atm to 5.0 atm

1973 ◽  
Vol 28 (9) ◽  
pp. 1459-1467 ◽  
Author(s):  
D. Garz
Keyword(s):  
Particle Temperature ◽  
Energy Levels ◽  
Heavy Particle ◽  
Electrical Current ◽  
Mean Free Path ◽  
Electrical Field Strength ◽  
Intensity Measurements ◽  
Plasma State ◽  
Significant Intensity

An analysis of the plasma state was performed by determination of the electron temperature and the distribution temperature from end -on intensity measurements in the arc axis and by determination of the heavy particle temperature from measurements of the electrical field strength. The electrical current of the arc was varied between 1.5 amp and 60 amp and the argon pressure was varied from 0.2 atm to 5.0 atm. It turned out that not the electron density but the mean free path of the electrons is the essential parameter for the adjustment of LTE. Moreover radial end-on intensity measurements of Ar-I lines with different upper energy levels revealed significant intensity anomalies spreading from the axis of the arc to the walls. These effects could be explained assuming that a diffusion of Ar atoms, which are excited to 4s-levels, takes place out of the arc axis. The diffusion equation and its solution led to a satisfying explanation of the observed radial non-LTE effects.

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