scholarly journals Benefits of Hydrogen in a Segmented-Anode Plasma Torch in Suspension Plasma Spraying

2021 ◽  
Author(s):  
Alice Dolmaire ◽  
Enni Hartikainen ◽  
Simon Goutier ◽  
Emilie Béchade ◽  
Michel Vardelle ◽  
...  
Keyword(s):  
Plasma Spraying ◽  
Gas Turbines ◽  
Gas Flow ◽  
Plasma Jet ◽  
Plasma Jets ◽  
Suspension Plasma Spraying ◽  
Mechanical And Thermal Properties ◽  
Mean Velocity ◽  
Zone Length ◽  
Plasma Torches

AbstractSuspension plasma spraying (SPS) enables the production of various coating microstructures with unique mechanical and thermal properties. Aeronautical manufacturers have been working for fifty years to improve the thermal barrier coating (TBC) performances in gas turbines. Commercial plasma torches with a segmented anode that are characterized by stable plasma jets should enable a better control of the TBC microstructure. The addition of diatomic gases such as hydrogen in the plasma-forming gas affects the plasma jet formation and causes some instabilities. However, it enhances the thermal conductivity of the gas flow, the plasma mass enthalpy and the heat transfer to particles. This study aims to characterise and describe the coating microstructure changes of yttria-stabilised zirconia when gradually adding hydrogen with argon into the plasma gas mixture. The effect of hydrogen is weighted out due to the gas mass enthalpy, mean velocity at the nozzle exit and “hot zone” length of the plasma jet. The coating microstructures, which depend on these plasma jet parameters, will be mapped from feathery and porous to dense and cracked deposits depending on the spraying conditions.

scholarly journals High-Speed Video Analysis of the Process Stability in Plasma Spraying

2021 ◽  
Author(s):  
K. Bobzin ◽  
M. Öte ◽  
M. A. Knoch ◽  
I. Alkhasli ◽  
H. Heinemann
Keyword(s):  
Plasma Spraying ◽  
High Speed ◽  
Plasma Jet ◽  
Plasma Jets ◽  
Time Dependent ◽  
Acquisition Time ◽  
Fast Fourier Transformation ◽  
Frequency Spectra ◽  
Dependent Signal ◽  
The Stability

AbstractIn plasma spraying, instabilities and fluctuations of the plasma jet have a significant influence on the particle in-flight temperatures and velocities, thus affecting the coating properties. This work introduces a new method to analyze the stability of plasma jets using high-speed videography. An approach is presented, which digitally examines the images to determine the size of the plasma jet core. By correlating this jet size with the acquisition time, a time-dependent signal of the plasma jet size is generated. In order to evaluate the stability of the plasma jet, this signal is analyzed by calculating its coefficient of variation cv. The method is validated by measuring the known difference in stability between a single-cathode and a cascaded multi-cathode plasma generator. For this purpose, a design of experiment, covering a variety of parameters, is conducted. To identify the cause of the plasma jet fluctuations, the frequency spectra are obtained and subsequently interpreted by means of the fast Fourier transformation. To quantify the significance of the fluctuations on the particle in-flight properties, a new single numerical parameter is introduced. This parameter is based on the fraction of the time-dependent signal of the plasma jet in the relevant frequency range.

Plasma Spraying Using Ar-He-H2 Gas Mixtures

1998 ◽  
Author(s):  
S. Janisson ◽  
A. Vardelle ◽  
J.F. Coudert ◽  
B. Pateyron ◽  
P. Fauchais ◽  
...  
Keyword(s):  
Plasma Spraying ◽  
Gas Flow ◽  
Plasma Jet ◽  
Gas Mixtures ◽  
Gas Velocity ◽  
Gas Flow Rate ◽  
Static Behavior ◽  
Operating Variables ◽  
Arc Current ◽  
Plasma Guns

Abstract In D.C. plasma guns used for plasma spraying, the properties of the plasma forming-gas control, to a great extent, the characteristics of the plasma jet and the momentum, heat and mass transfer to the particles injected in the flow. This paper deals with mixtures of argon, helium and hydrogen and the effect of the volume composition of these mixtures on the dynamic and static behavior of the plasma jet. Both were investigated from the measurements of arc voltage and gas velocity. Correlations between these parameters and the operating variables (arc current, gas flow rate, gas mixture composition) were established from a dimensional analysis. The results were supported by the calculation of the thermodynamic and transport properties of the ternary gas mixtures used in this study.

scholarly journals Interaction of Cold Atmospheric Argon and Helium Plasma Jets with Bio-Target with Grounded Substrate Beneath

2019 ◽  
Vol 9 (21) ◽  
pp. 4528 ◽  
Author(s):  
Irina Schweigert ◽  
Dmitry Zakrevsky ◽  
Pavel Gugin ◽  
Elena Yelak ◽  
Ekaterina Golubitskaya ◽  
...  
Keyword(s):  
Cancer Cells ◽  
Gas Flow ◽  
Fluid Model ◽  
Plasma Jet ◽  
Plasma Jets ◽  
Atmospheric Plasma ◽  
Maximum Efficiency ◽  
Embryonic Cells ◽  
Plasma Parameters

The cold atmospheric pressure plasma jet interaction with the bio-target is studied in the plasma experiment, 2D fluid model simulations, and with MTT and iCELLigence assays of the viability of cancer cells. It is shown, for the first time, that the use of the grounded substrate under the media with cells considerably amplifies the effect of plasma cancer cell treatment in vitro. Plasma devices with cylindrical and plane geometries generating cold atmospheric plasma jets are developed and tested. The sequence of the streamers which forms the plasma jet is initiated with a voltage of 2.5–6.5 kV applied with the frequency 40 kHz. We suggest using the grounded substrate under the bio-target during the plasma jet treatment of cancer cells. The analysis of the measured plasma spectra and comparison of OH-line intensity for different voltages and gas flow rates allows us to find a range of optimal plasma parameters for the enhanced OH generation. The time-dependent viability is measured for human cell lines, A431 (skin carcinoma), HEK 293 (kidney embryonic cells), and A549 (human lung adenocarcinoma cells) after the plasma jet treatment. The results with cell-based experiments (direct treatment) performed with various plasma jet parameters confirm the maximum efficiency of the treatment with the optimal plasma parameters.

Simulation and Modeling of Turbulent Plasma Jet Based on Axisymetric LBGK Model

2011 ◽  
Vol 312-315 ◽  
pp. 1167-1171 ◽  
Author(s):  
Ridha Djebali ◽  
Mohammed El Ganaoui ◽  
Bernard Pateyron ◽  
Habib Sammouda
Keyword(s):  
Plasma Spraying ◽  
High Performance ◽  
Plasma Jet ◽  
Experimental Tests ◽  
Solution Procedure ◽  
Industrial Applications ◽  
Plasma Jets ◽  
Diffusion Parameters ◽  
Complex Phenomena ◽  
Economic Constraints

The coating of surfaces by plasma spraying is an important manufacturing process with many industrial applications. In the last several decades, numerical modeling of plasma spraying processes has met with considerable attention [1,2,3]. That is in order to well understand the complex phenomena the plasma spray involves, for economic constraints and to well predict the plasma-inflight-particles exchanges since this affects directly the coating formability and microstructure. This study deals with the investigation of plasma jets using an axisymmetric LB thermal model. Plasma jets have been very successful in many applications (such as spraying, cutting, welding,…). The excellent choice of high performance plasma gases and spraying materials has been the subject of several experimental and numerical efforts. An excellent choice will be the response of efficient numerical studies and the results of experimental tests. Plasma jets are high temperature flows (>8000K). Therefore, all diffusion parameters involved in conservation equations are temperature dependent. In the following, we present a plasma jet investigation in an axisymmetric LBM (Jian’s model [4]). In the context of our knowledge, it is the first attempt to tackle this field by using the LBM. Further reading on solution procedure, the model implementation and assumptions may be found in [5,6].

scholarly journals Mechanisms of heat transfer between a droplet and a plasma jet in Suspension Plasma Spraying

2014 ◽  
Vol 550 ◽  
pp. 012022 ◽  
Author(s):  
F Girard ◽  
E Meillot ◽  
S Vincent ◽  
L Bianchi ◽  
J P Caltagirone
Keyword(s):  
Heat Transfer ◽  
Plasma Spraying ◽  
Plasma Jet ◽  
Suspension Plasma Spraying

Contributions to heat and mass transfer between a plasma jet and droplets in suspension plasma spraying

2015 ◽  
Vol 268 ◽  
pp. 278-283 ◽  
Author(s):  
F. Girard ◽  
E. Meillot ◽  
S. Vincent ◽  
J.P. Caltagirone ◽  
L. Bianchi
Keyword(s):  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Plasma Spraying ◽  
Plasma Jet ◽  
Suspension Plasma Spraying

Patterns of plasma jet arrays in the gas flow field of non-thermal atmospheric pressure plasma jets

2019 ◽  
Vol 26 (1) ◽  
pp. 013505 ◽  
Author(s):  
M. Hasnain Qaisrani ◽  
Congyun Li ◽  
Pei Xuekai ◽  
M. Khalid ◽  
Xian Yubin ◽  
...  
Keyword(s):  
Flow Field ◽  
Atmospheric Pressure ◽  
Gas Flow ◽  
Atmospheric Pressure Plasma ◽  
Plasma Jet ◽  
Plasma Jets ◽  
Pressure Plasma ◽  
Gas Flow Field

scholarly journals Plasma-generated reactive oxygen and nitrogen species can lead to closure, locking and constriction of the Dionaea muscipula Ellis trap

2019 ◽  
Vol 16 (150) ◽  
pp. 20180713
Author(s):  
Alexander G. Volkov ◽  
Kunning G. Xu ◽  
Vladimir I. Kolobov
Keyword(s):  
Gas Flow ◽  
Uv Light ◽  
Reactive Oxygen ◽  
Plasma Jet ◽  
Plasma Jets ◽  
Nitrogen Species ◽  
Atmospheric Air ◽  
Venus Flytrap ◽  
Production Of Hydrogen

Reactive oxygen and nitrogen species (RONS) can influence plant signalling, physiology and development. We have previously observed that an argon plasma jet in atmospheric air can activate plant movements and morphing structures in the Venus flytrap and Mimosa pudica similar to stimulation of their mechanosensors in vivo. In this paper, we found that the Venus flytrap can be activated by plasma jets without direct contact of plasma with the lobe, midrib or cilia. The observed effects are attributed to RONS, which are generated by argon and helium plasma jets in atmospheric air. We also found that application of H 2 O 2 or HNO 3 aqueous solutions to the midrib induces propagation of action potentials and trap closing similar to plasma effects. Control experiments showed that UV light or neutral gas flow did not induce morphing or closing of the trap. The trap closing by plasma is thus likely to be associated with the production of hydrogen peroxide by the cold plasma jet in air. Understanding plasma control of plant morphing could help design adaptive structures and bioinspired intelligent materials.

Effect of Processing Parameters on Plasma Jet and In-flight Particles Characters in Supersonic Plasma Spraying

2016 ◽  
Vol 35 (8) ◽  
pp. 775-786 ◽  
Author(s):  
Pei Wei ◽  
Zhengying Wei ◽  
Guangxi Zhao ◽  
Y. Bai ◽  
Chao Tan
Keyword(s):  
Plasma Spraying ◽  
Flow Rate ◽  
Gas Flow ◽  
Plasma Jet ◽  
Processing Parameters ◽  
Current Intensity ◽  
Maximum Temperature ◽  
Gas Flow Rate ◽  
Average Maximum ◽  
Supersonic Plasma

AbstractIn supersonic plasma spraying system (SAPS), heat transfer from arc plasma is characterized by several distinct features, such as transport of dissociation and ionization energy and of electrical charges in addition to mass transport. The thermodynamic and transport properties of plasma jet were influenced by several main parameters such as primary gas flow rate, the H2 vol.% and current intensity A. This paper first analyzes the effect of these parameters on the temperature and velocity of plasma jet theoretically. Further, the loading particles were melted and accelerated by plasma jet. Effects of several main parameters such as carrier gas flow rate, the H2 vol.%, the current intensity, the voltage and the spraying distance on temperature and velocity of in-flight particle were studied experimentally. The average maximum temperature and velocity of in-flight particle at any given parameters were systematically quantified. Optimal SAPS process parameters were given in this paper. In general, increasing the particles impacting velocity and surface temperature can improve the maximum spreading factor and decrease the coating porosity.

Influence of Injector Geometry on Particle Trajectories: Analysis of Particle Dynamics in the Injector and Plasma Jet

1998 ◽  
Author(s):  
M. Vardelle ◽  
A. Vardelle ◽  
B. Dussoubs ◽  
P. Fauchais ◽  
T.J. Roemer ◽  
...  
Keyword(s):  
Gas Flow ◽  
Computational Study ◽  
Plasma Jet ◽  
Particle Dynamics ◽  
Plasma Jets ◽  
Space Distribution ◽  
Straight Tube ◽  
Size Segregation ◽  
Particle Size Range ◽  
Particle Injection

Abstract The conditions of particle injection into the side of plasma jets play an important role in determining the microstructure and properties of sprayed deposits. However, few investigations have been carried out on this topic. The current work presents the results of an experimental and computational study of the influence of injector geometry and gas mass flow rate on particle dynamics at injector exit and in the plasma jet. Two injector geometries were tested: a straight tube and a curved tube with various radii of curvature. Zirconia powders with different particle size range and morphology were used. A possible size segregation effect in the injector was analyzed from the space distribution of particles collected on a stick tape. The spray pattern in the plasma jet was monitored from the thermal radiation emitted by particles. An analysis of the particle behavior in the injector and mixing of the carrier-gas flow with the plasma jet was carried out using a 3-D computational fluids dynamics code.

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