National Repository of Grey Literature 89 records found  beginprevious59 - 68nextend  jump to record: Search took 0.01 seconds. 
Interakce částic s plazmatem při plazmové gasifikaci
Hlína, Michal ; Hrabovský, Milan ; Kopecký, Vladimír ; Konrád, Miloš
The kinetics of high temperature gasification in plasma flow is analyzed on the basis of solution of equations of heat transfer from plasma to particles through their surface as well as the gas sheath that is created by newly produced gas and the modified Arrhenius equation describing volatilization process. The equation for the rate of gasification is deduced.
PIV study of the controlled pulsatile jets
Pírková, L. ; Kopecký, V. ; Trávníček, Zdeněk
The aim of this paper is to describe an experimental study of controlled pulsating jets using PIV method. The present synchronization of PIV data with the pulsating process enables to measure vector maps of the flow field with the time steps under 1ms. Principle of PIV method and the present experimental set up are described. Main part of the paper discusses vector and scalar maps of the flow.
Experimental study of of time development of pulsatile jets using classical PIV method
Kopecký, V. ; Kotek, M. ; Pírková, L. ; Jašíková, D. ; Trávníček, Zdeněk ; Hlína, Jan
This paper describes a quantitative visualization of pulsatile flow fields using classical PIV method. A synchronization of PIV measurement with the control signal allows to acquire flow fields maps with time steps less than 1ms. The results are presented for jets from weaving nozzles, for controlled jets, and for plasma arks for electrostatic spinning.
Experimentální studium bifurkačních proudů metodou PIV
Pírková, L. ; Kopecký, V. ; Trávníček, Zdeněk
This paper describes an experimental study of bifurcating jets using PIV method. Principle of PIV method is shortly explained, and the present experimental set up (mainly settings of the laser and measurement system) is described. Second part of this paper discusses results, which are shown as vector and scalar maps of the flow.
Zplyňování dřeva v plazmatu a produkce plynu s nízkým obsahem dehtů
Hlína, Michal ; Hrabovský, Milan ; Kopecký, Vladimír ; Konrád, Miloš ; Kavka, Tetyana ; Skoblja, S.
Tar content in gas produced by the gasification of biomass always plays an important role because high tar content disables some potentialities of the further treatment of the produced gas. There is a strong effort to produce gas with low tar content from this point of view. High concentrations of hydrogen and carbon monoxide also advance possibilities of the usage of the produced gas. Experiments were carried out in a reactor for plasma gasification equipped with hybrid gas-water stabilized DC torch. They confirmed that the reactor is absolutely suitable for this purpose mainly due to extremely low flow of plasma composed of argon, hydrogen and oxygen and its high inner temperature. The measurements of the tar content, using wood as a treated material, were based on SPE method and the determination of benzene and toluene in a gas phase revealed really low concentrations of tar, mostly below 10 mg/Nm3.
Ofukování termického proudu plazmatu generovaného plazmatronem
Kavka, Tetyana ; Hrabovský, Milan ; Chumak, Oleksiy ; Kopecký, Vladimír
The ambient air is entrained intensively into atmospheric pressure thermal plasma jets. A system for shielding plasma jet has been used to improve jet characteristics and reduce oxygen content. Different gases have been applied as a shroud gas – argon, acetylene, methane, mixtures of acetylene-nitrogen and hydrogen-nitrogen. All shroud gases used in experiments affected plasma jet making the profiles of the jet characteristics flattened with higher temperatures and velocities and reduced amount of oxygen.
Difuzní proud v hraniční oblasti oblouku měřený elektrickými sondami
Chumak, Oleksiy ; Hrabovský, Milan ; Kavka, Tetyana ; Kopecký, Vladimír
Electric probes were used for investigation of an intermediate layer between the arc and anode surface in regions outside the main current channel. Distributions of a diffuse current and the potential were measured. Resistance and heating of the intermediate layer by diffuse current were evaluated. It was found that not only the value of diffuse current strongly depends on distance from the arc but also the shape of the distribution and the position of the maximum of the current change with the distance. These trends can be explained by expanding of the plasma jet. Evaluated equivalent intermediate layer resistance shows widening of the conductive region in a stream wise direction. Variation of resistivity of the intermediate layer is much higher than variation of the potential drop on the layer. That means that distributed current as well as Joule heating of the layer are generally controlled by distributed resistance.
Měření potenciálu plazmatu a elektronového a iontového proudu v obloukovém proudu plazmatu pomocí elektrických sond
Hurba, Oleksiy ; Hrabovský, Milan ; Kopecký, Vladimír ; Chumak, Oleksiy
The results of studying of a plasma jet with use electric probes are presented. Distribution of potential in anode region of plasma jet and distribution of currents to positively biased probes were received. Distribution of electric field intensity in sheath of cold gas between the anode surface and the jet and distribution of density of power dissipated in the sheath are calculated.
Studium difuzního proudu na hranici oblouku pomocí elektrických sond
Chumak, Oleksiy ; Hrabovský, Milan ; Kavka, Tetyana ; Kopecký, Vladimír
Electric probes were used for investigation of an intermediate layer between the arc and anode surface in regions outside the main current channel. Distributions of a diffuse current and the potential were measured. Resistance and heating of the intermediate layer by diffuse current were evaluated.It was found that not only the value of diffuse current strongly depends on distance from the arc but also the shape of the distribution and the position of the maximum of the current change with the distance. These trends can be explained by expanding of the plasma jet. Evaluated equivalent intermediate layer resistance shows widening of the conductive region in a stream wise direction. Variation of resistivity of the intermediate layer is much higher than variation of the potential drop on the layer. That means that distributed current as well as Joule heating of the layer are generally controlled by distributed resistance.
Use of image-processing toolbox for powder particle diagnostics in plasma spray process
Chumak, Oleksiy ; Kopecký, Vladimír
For measurement of distribution of powder particles and their velocities on plasma spraying, imagigng by CCD camera is used.It is difficult to identify the particles injected into plasma jet on photos, because of high brightness of background light source, noises of CCD camera and low contrast of particle images.Filtering of the photos by a function of two-dimensional convolution.

National Repository of Grey Literature : 89 records found   beginprevious59 - 68nextend  jump to record:
See also: similar author names
1 Kopecký, V.
3 Kopecký, Vladimír
4 Kopecký, Vojtěch
4 Kopecký, Václav
1 Kopecký, Vít
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