Národní úložiště šedé literatury Nalezeno 156 záznamů.  1 - 10dalšíkonec  přejít na záznam: Hledání trvalo 0.00 vteřin. 
Redukce šumu z experimentálních časových řad
Chára, Zdeněk ; Kysela, Bohuš
Příspěvek se zabývá redukcí šumu z časových řad. Pozornost je zaměřena především na časové řady získané metodou PIV. Metoda redukce šumu je testována pro PIV data získaná při měření rychlostních polí v míchané nádobě.
32nd Symposium on anemometry: proceedings
Chára, Zdeněk ; Klaboch, L.
Proceedings of 32nd Symposium on Anemometry. The conference was oriented on the experimental techniques applied in fluid mechanics.
Experimental investigation of settling slurry flow in inclined pipe sections
Vlasák, Pavel ; Chára, Zdeněk ; Matoušek, Václav ; Kesely, Mikoláš ; Konfršt, Jiří
Narrow particle size distribution glass beads-water slurry flow in the pipe sections of different inclination were investigated on an experimental pipe loop of inner diameter D = 100 mm. The study refers to the effect of pipe inclination and slurry velicity on local concentration distribution, pressure drop-velocity relationship, and deposition limit. The study revealed that the glass beads-water mixtures in the inclined pipe sections were significantly stratified: the solid particles moved principally close to the pipe invert, and for flow velocities close to the deposition limit sliding bed or stationary deposit is created even in inclined pipe sections.
31st Symposium on anemometry: proceedings
Chára, Zdeněk ; Klaboch, L.
Proceedings of 31st Symposium on Anemometry. The conference was oriented on the experimental techniques applied in fluid mechanics.
Flow of heterogeneous slurry in horizontal and inclined pipes
Vlasák, Pavel ; Chára, Zdeněk ; Konfršt, Jiří ; Kysela, Bohuš
Narrow particle size distribution heterogeneous slurries were investigated on an experimental pipe loop with the horizontal and inclined pipe sections of inner diameter 100 mm. The investigation was focused on the effect of the pipe inclination, average slurry velocity and overall concentration and on the local concentration distribution, pressure drop, deposition limit and carrier liquid-particle slip velocity. The local concentration distribution was studied with the application of a gamma-ray densitometer. Mixture flow-behaviour and particles motion were investigated in a pipe viewing section. The study revealed that the heterogeneous slurries in the horizontal and inclined pipe sections were significantly stratified, the solid particles moved principally close to the pipe invert, and particle saltation becomes the dominant mode of particle conveying for higher and moderate flow velocities. Carrier liquid-particle slip velocity depends not only on the mixture velocity, but also on particle position in the pipe cross-section. The effect of pipe inclination on the frictional pressure drop in inclined pipe sections depends on mixture velocity, in ascending pipe section decreases with increasing mixture velocity and in descending pipe section the frictional pressure drop gradually decreased with increasing pipe inclination.
In-situ measurement of particle size distribution in an agitated vessel
Kysela, Bohuš ; Konfršt, Jiří ; Chára, Zdeněk ; Šulc, R. ; Ditl, P.
Agitation of solid-liquid suspension or two immiscible liquids is a frequent operation in chemical and metallurgical industries (suspension/emulsion polymerization, catalytic chemical reaction, hydrometallurgical solvent extraction). The product quality, yield and economy of the processes are significantly affected by a mixing process. Prediction of mean particle/drop size and particle/drop size distribution (PSD) during the agitation is fundamental for emulsification, suspension polymerization, solid particle dispersion or crystallization. \nThe aim of this contribution is to propose a simple method of in-situ measurement of particle size distribution. The particle size measurement is based on an image analysis performed on raw image records. Evaluation method based on the best focused particles with sharp detected boundaries enhanced by the analysis of particle circularity was developed. Precise spherical mono-disperse steel and plastic particles were used to verify accuracy of evaluation method. The method has been proposed for the measurement of the time evolution of the drop size distribution in liquid-liquid dispersion in an agitated tank. The effect of droplet size distribution on the impeller speed in wateroil dispersion in agitated vessel was obtained.
Měření velikosti kapek ve dvoufázovém systému
Kysela, Bohuš ; Konfršt, Jiří ; Chára, Zdeněk ; Kotek, M. ; Šulc, R.
The in-situ measurement method of droplet size in an agitated vessel based on droplet visualisation and image analysis were developed. The image analysis was enhanced by the finding edges algorithm and circularity analysis. The proposed method was validated by the measurements of precise solid particles and used for liquid-liquid mesurements in an agitated vessel.
Řízený pohyb kulové částice v kanále s volnou hladinou
Chára, Zdeněk ; Kysela, Bohuš ; Konfršt, Jiří
V příspěvku jsou prezentovány experimentální výsledky proudění kolem kulovité částice, kdy částice je umístěna na tenké tyčce a její pohyb je řízen asynchronním motorkem. Pro určení rychlostních polí kolem pohybující se částice byla použita metoda 2D PIV. Měření se uskutečnila v kanále s volnou hladinou, jehož dno bylo pokryto jednou vrstvou skleněných tyček o průměru 6mm.

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