No (503)
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503
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non-invasive methods for sensing solids concentration distribution in liquid flowing through pipe
Krupička, Jan; Krčmařík, D.; Matoušek, Václav
2014 - Czech
The paper deals with a measurement of solids concentration in aqueous slurry flowing in a pipe. A radiometric method is currently in use on a testing pipe lop of Institute of Hydrodynamics AS CZ. Results using the method are summarized and compared to our first results using another method, electrical impedance tomography, which was recently tested on the same loop. Příspěvek se zabývá měřením rozložení koncentrace pevných částic ve směsi s kapalinou proudící potrubím. Na potrbním okruhu Ústavu pro hydrodynamiku AV ČR je k tomuto měření využívána radiometrická metoda. Jsou shrnuty naše dosavadní výsledky s touto metodou a porovnány s první zkušeností s měřením pomocí elektrické impedanční tomografie, která byla nedávno testována na tomtéž potrubním okruhu.
Keywords:
slurry pipe flow; radiometry; electrical impedance tomography
Available on request at various institutes of the ASCR
non-invasive methods for sensing solids concentration distribution in liquid flowing through pipe
The paper deals with a measurement of solids concentration in aqueous slurry flowing in a pipe. A radiometric method is currently in use on a testing pipe lop of Institute of Hydrodynamics AS CZ. ...
Měření a analýza proudu z radiálního míchadla
Kysela, Bohuš; Konfršt, Jiří; Chára, Zdeněk
2014 - Czech
Mixing is in proces engineering very important operation and has the task of creating a homogeneous mixture, homonegeous suspension, to better debond material in the dispersion, and the like. Míchání je v procesní technice velice důležitá operace, která má z úkol vytvořit homogenní směs, homogenní suspenzi, lépe rozdružit materiál v disperzních, atp. Pokud se zaměříme na míchané aparáty představované míchanou nádobou s rychloběžným míchadlem, lze celý objem nádoby dle funkce rozdělit na dvě části tj. na část pracovního objemu s vysokámi smykovými silami a velkou disipaci energie, kde k výše zmíněným procesům dochází (oblast v blízkosti míchadla), a druhou část, která by se dala nazvat části zásobní nebo cirkulační, ze které se vlivem proudění směs dostává do části pracovního objemu. Při modelování a zvětšování měřítka je snahou poměry v malých modelových nádobách dodržet i u velkých zvýšené energetické náročnosti procesu míchání. Tyto parametry lze analyzovat především na základě znalostí proudového pole a rozložení disipace energie v míchaném objemu, případně dalších parametrů.
Keywords:
LDA; radial impeller; turbulent flow
Available on request at various institutes of the ASCR
Měření a analýza proudu z radiálního míchadla
Mixing is in proces engineering very important operation and has the task of creating a homogeneous mixture, homonegeous suspension, to better debond material in the dispersion, and the like.
Numerical simulations of flow over stationary deposit
Chára, Zdeněk; Vlasák, Pavel; Kysela, Bohuš; Konfršt, Jiří
2014 - English
The paper deals with a water flow in a horizontal, circular pipe of inner diameter 40 mm with a stationary deposit. The deposit was formed by spheres of diameter d=6 mm. The thickness of the deposit was about two sphere diameters. The flow was experimentally studied by the PIV method and COMSOL Multiphysics 4.4 was used as tool for numerical simulations as well. Two approaches were used to create the stationary deposit. In the first one was the deposit was replaced by a rough wall with different values of the roughness parameter ks. In the second case the deposit was created from the identical spherical particles. The results of the simulations and the experimental data are compared.
Keywords:
stationary deposit; PIV method; numerical simulations
Available on request at various institutes of the ASCR
Numerical simulations of flow over stationary deposit
The paper deals with a water flow in a horizontal, circular pipe of inner diameter 40 mm with a stationary deposit. The deposit was formed by spheres of diameter d=6 mm. The thickness of the deposit ...
Stationary- and sliding beds in pipe flows of settling slurry
Matoušek, Václav; Krupička, Jan; Chára, Zdeněk
2014 - English
Investigations are discussed on the effect of stationary- and sliding beds on a behavior of settling slurry flows. Results are presented of our recent experiments with two fractions of ballotini in a 100-mm-pipe loop. Experimental work contained measurements of concentration profiles and velocity profiles. The experimental results for flows with stationary deposits are compared with predictions using our formulae for solids transport and bed friction in layered flows. CFD simulations are included to validate the velocityprofile measurements and to verify the bed roughness predictions in the flows with stationary beds. Furthermore, the measured velocity profiles are compared to profiles predicted using the log law of the wall with boundary shear velocities determined from the linear distribution of shear stress across the pipe flow. The approach is successful in the flow below the upper wall of the pipe but fails above the top of the deposit where the stress distribution is different as verified by the CFD simulation. The concept of the linear-distribution of shear stress is well applicable in flows with sliding beds. An example is given of a solution for a partially-stratified flow with sliding bed using the 1-D Stress- Distribution based Model.
Keywords:
experiment; hydraulic transport; concentration profile; velocity profile; sheet flow
Available on request at various institutes of the ASCR
Stationary- and sliding beds in pipe flows of settling slurry
Investigations are discussed on the effect of stationary- and sliding beds on a behavior of settling slurry flows. Results are presented of our recent experiments with two fractions of ballotini in a ...
3D measurement of particle movement using one camera
Chára, Zdeněk; Kysela, Bohuš
2013 - Czech
Article is focused on analysis of measuring 3D particle motion with one camera and light knife. The 3D spherical particle movement is measured using standard particle tracking method (two velocity components) combined with simple method based on light intensity of scattered light by the moving spherical particle. V příspěvku je analyzována možnost měření 3D pohybu kulovitých částic pomocí jedné kamery a světelného nože. Zatímco pro určení 2D rychlostního pole částic byla použita standardní sledovací technika (Particle-Tracking-Velocimetry), pro měření třetí složky rychlosti kolmé na rovinu objektivu kamery byla použita jednoduchá metoda založená na měření intenzity světla dopadajícího na pohybující se částici.
Keywords:
3D particles; particle motion; measurements
Available at various institutes of the ASCR
3D measurement of particle movement using one camera
Article is focused on analysis of measuring 3D particle motion with one camera and light knife. The 3D spherical particle movement is measured using standard particle tracking method (two velocity ...
Long-term hydroecological monitoring in the Krkonoše Mts
Tesař, Miroslav; Šír, Miloslav
2013 - English
The cloud and fog water deposition proved to be important delivery mechanism for both water and pollutants in mountainous headwater regions. A fogwater study has been conducted in the Krkonoše Mts. since 1999 till the present time. The sampling site for the observation and evaluation occult precipitation in the Western region was established in the Modrý potok basin (1010–1554 m a.s.l., 2.62 km2) at the highest point of the watershed (passive cloud and fog water collector) while the bulk precipitation and throughfall samplers were installed near to the closure profile of the basin. Rain gauges are evenly situated at six altitudes of the watershed (from 1020 to 1365 m a. s. l.). In the Eastern region the both passive and active collectors were installed close to the Labská bouda chalet (1325 m a.s.l). The active collector (Eigenbrodt, Germany) is operated automatically by the PWD-11 sensor (Vaisala, Finland). Collected samples were stored in polyethylene bottles and transported as soon as possible to the laboratories of the Czech Geological Survey and Geological Institute of ASCR to the chemical analyses. The results for 1999–2011 will be presented in this article. A wide range of concentrations were encountered, most typically exceeding concentrations occurring in rain (so-called enrichment factors were evaluated) and the estimated wet deposition of the most important chemical compounds were calculated and compared with respect to weighted means of bulk precipitation collected in the open area. Based on the model predictions and on the water balance of the forest canopy the annual occult precipitation total for the Krkonoše Mts. was estimated by 20–25 % of the annual falling precipitation total. The research is supported by the Czech Science Foundation (205/09/1918).
Keywords:
occult precipitation; cloud and fog water deposition; water chemistry
Available at various institutes of the ASCR
Long-term hydroecological monitoring in the Krkonoše Mts
The cloud and fog water deposition proved to be important delivery mechanism for both water and pollutants in mountainous headwater regions. A fogwater study has been conducted in the Krkonoše Mts. ...
Evaluation of the dissipation of the turbulent kinetic energy from gradients measured in mixing vessel
Kysela, Bohuš; Konfršt, Jiří; Chára, Zdeněk; Kotek, M.
2013 - Czech
Dissipation of the turbulent kinetic energy in mixing vessels is important parameter in mixing process. According to the latest findings it is also in the most cases the control process. This study shows a limits of dissipation rate evaluation using the velocity field obtained from the PIV (Particle Image Velocimetry) results. Disipace turbulentní kinetické energie v míchaných nádobách je důležitým parametrem v procesu míchání. A dle posledních poznatků je také ve většině případů procesem řídícím. Jelikož metoda přímého měření disipace turbulentní kinetické energie a její distribuce v míchané nádobě není dostupná, používají se různé postupy pro její výpočet na základě teorií o turbulenci. Pro míchané nádoby se v praxi využívá hlavně střední hodnota vypočtená z poměru příkonu na hřídeli míchadla vztaženého k celkovému objemu nádoby.
Keywords:
kinetic energy; gradients; LDA measuring; TR PIV measuring; Time Resolved Particle Image Velocimetry
Available at various institutes of the ASCR
Evaluation of the dissipation of the turbulent kinetic energy from gradients measured in mixing vessel
Dissipation of the turbulent kinetic energy in mixing vessels is important parameter in mixing process. According to the latest findings it is also in the most cases the control process. This study ...
Fine set-up of the Ar-Ion laser and fibre loader
Konfršt, Jiří; Kysela, Bohuš; Chára, Zdeněk
2013 - Czech
Use of lasers in the measuring systems, which use LDA/PDA devices, expects good knowledge of physical characteristics of used light source namely for multicomponent measurements. This article is focused on the experimental parameter analysis of individually separated light wavelength from Ar-Ion plasma tube, working in multiline “ML” mode. The best laser source parameters: aperture size, power input and quality of the utilized separate wavelengths were obtained and beams were adjusted to the optical fibres. Použití laserů v měřících systémech využívajících zařízení LDA (Laser Doppler Anemometry)/PDA (Phase Doppler Anemometry) předpokládá dobrou znalost fyzikálních charakteristik používaného světelného zdroje. Tento příspěvek se zabývá experimentální analýzou parametrů jednotlivě separovaných světelných vlnových délek u Ar-Ion plazmové trubice, pracující v multi-vlnném „ML“ režimu. Motivací práce byla snaha o co nejkvalitnější zavedení světla do světelných vláken a minimalizace ztrát světelného výkonu pro účel dvou-, příp. tří-složkového měření proudového pole v míchané nádobě. Vyšetřovány byly parametry jednotlivých vlnových délek, a to světelný výkon, průběh emise a interference ve vztahu k nastavení apertury laseru a ve vazbě na nastavení proudového / světelného výkonu laseru. V dalším kroku bylo provedeno zavedení světelného záření z laseru pracujícího v „ML“ režimu do transmitteru a dále pomocí optických zavaděčů do mono-modových optických vláken. Do optických vláken byly zavedeny dvě nejsilnější vlnové délky, zelená - 514,5 nm a modrá - 488 nm. Pro současné zavedení oboru barev bylo nutné provést úpravu optické trasy v transmitteru přizvednutím středového hranolového páru u modré barvy.
Keywords:
Ar-Ion laser; Laser Doppler Anemometry (LDA); Phase Doppler Anemometry (PDA)
Available at various institutes of the ASCR
Fine set-up of the Ar-Ion laser and fibre loader
Use of lasers in the measuring systems, which use LDA/PDA devices, expects good knowledge of physical characteristics of used light source namely for multicomponent measurements. This article is ...
Coarse-grained particles conveying along a pipe bed
Vlasák, Pavel; Chára, Zdeněk; Konfršt, Jiří; Kysela, Bohuš
2013 - English
The paper describes the results of a flow visualisation of model coarse-grained fully stratified particle-water mixtures. Investigation was focussed on study of the particle behaviour and carrier liquid and conveyed particles local velocities. Glass balls and washed graded pebble gravel of mean diameter of 6 mm were conveyed by water in a horizontal smooth pipe loop with a transparent pipe viewing section of inner diameter 40 mm. Particle movement along the pipe invert and particulate stationary bed, created by two layers of spherical particles of the same size as the conveyed particles, was studied. The effect of stationary bed on local velocity values of the carrier liquid and conveyed particles were determined. It was conducted that the maximum liquid velocity is significantly shifted from pipe centre to a higher position in the flow pattern with stationary bed.
Keywords:
coarse-grained slurry; flow structure; visualisation; liquid local velocity; particle velocity; rychlost; částice
Available at various institutes of the ASCR
Coarse-grained particles conveying along a pipe bed
The paper describes the results of a flow visualisation of model coarse-grained fully stratified particle-water mixtures. Investigation was focussed on study of the particle behaviour and carrier ...
27th Symposium on anemometry: proceedings
Chára, Zdeněk; Klaboch, L.
2013 - Czech
Proceedings of 27th Symposium on Anemometry. The conference was oriented on the experimental techniques applied in fluid mechanics. Sborník z konference 27th symposium o anemometrii. Konference byla zaměřena na experimentální techniky používané v mechanice tekutin.\n
Keywords:
anemometry; conference; proceedings
Available at various institutes of the ASCR
27th Symposium on anemometry: proceedings
Proceedings of 27th Symposium on Anemometry. The conference was oriented on the experimental techniques applied in fluid mechanics.
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