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Tomáš Navrátil - One of the best experts on this subject based on the ideXlab platform.
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Sedimentary archive of contamination in the Confined Channel of the Ohře River, Czech Republic
Journal of Soils and Sediments, 2017Co-Authors: Tomáš Matys Grygar, Jitka Elznicová, Tereza Lelková, Timea Kiss, Márton Balogh, Ladislav Strnad, Tomáš NavrátilAbstract:Purpose The Ohře River has received contamination from metal mining and metallurgy (mainly Cu, Pb, Sn, U, Zn) over the previous five centuries. This contamination history has been poorly documented. Contamination has entered the river system in its middle reach, where the Channel is incised and bedrock Confined, which impedes overbank deposition. Our objective was to locate and describe a sedimentary record in this unfavourable depositional setting. Materials and methods Three former Channel bars that have coalesced with the riverbank were revealed by examination of historical and current maps and a digital terrain model. Manual coring in the bar and in situ (handheld) X-ray fluorescence (XRF) spectroscopy provided data for developing a contamination chemostratigraphy, which was correlated with the mining history in the region. Detailed topographic examination of the bar and valley edge was important to understanding the evolution of one of the bars. Optically stimulated luminescence (OSL) dating was used to verify the timing of deposition. Results and discussion Handheld XRF for in situ analysis of element composition is efficient for studying contaminated sediment bodies with complex stratigraphy, which require extensive coring and stratigraphic correlation. Despite the unfavourable settings, the Channel bars trapped sufficient sediment to produce a record that correlates with the history of contamination in the drainage basin. In the bar studied in greatest detail, we observed a surprising amount of contamination passing through the Ohře River Channel (up to 300 mg kg^−1 of Cu, 340 mg kg^−1 of Pb and 630 mg kg^−1 of Sn in fine sand and silt deposits) associated with a pollution climax in the sixteenth and seventeenth centuries. Modern contamination (Hg and U deposited in the nineteenth and twentieth centuries) was entrapped with low efficiency based on comparable concentrations of Hg and U located 90 km downstream. Conclusions The efficacy of the use of historical maps and detailed fieldwork was demonstrated by identification of unique depositional meso-environments, which are rare in bedrock-Confined fluvial systems. The contamination chemostratigraphy of the bar deposits was correlated with the local mining and pollution history and contributed to an understanding of the bar evolution. The approach used in our study may be applicable to other montane rivers with historic ore mining and processing in their basins.
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Sedimentary archive of contamination in the Confined Channel of the Ohře River, Czech Republic
Journal of Soils and Sediments, 2017Co-Authors: Tomáš Matys Grygar, Jitka Elznicová, Tereza Lelková, Timea Kiss, Márton Balogh, Ladislav Strnad, Tomáš NavrátilAbstract:The Ohře River has received contamination from metal mining and metallurgy (mainly Cu, Pb, Sn, U, Zn) over the previous five centuries. This contamination history has been poorly documented. Contamination has entered the river system in its middle reach, where the Channel is incised and bedrock Confined, which impedes overbank deposition. Our objective was to locate and describe a sedimentary record in this unfavourable depositional setting. Three former Channel bars that have coalesced with the riverbank were revealed by examination of historical and current maps and a digital terrain model. Manual coring in the bar and in situ (handheld) X-ray fluorescence (XRF) spectroscopy provided data for developing a contamination chemostratigraphy, which was correlated with the mining history in the region. Detailed topographic examination of the bar and valley edge was important to understanding the evolution of one of the bars. Optically stimulated luminescence (OSL) dating was used to verify the timing of deposition. Handheld XRF for in situ analysis of element composition is efficient for studying contaminated sediment bodies with complex stratigraphy, which require extensive coring and stratigraphic correlation. Despite the unfavourable settings, the Channel bars trapped sufficient sediment to produce a record that correlates with the history of contamination in the drainage basin. In the bar studied in greatest detail, we observed a surprising amount of contamination passing through the Ohře River Channel (up to 300 mg kg−1 of Cu, 340 mg kg−1 of Pb and 630 mg kg−1 of Sn in fine sand and silt deposits) associated with a pollution climax in the sixteenth and seventeenth centuries. Modern contamination (Hg and U deposited in the nineteenth and twentieth centuries) was entrapped with low efficiency based on comparable concentrations of Hg and U located 90 km downstream. The efficacy of the use of historical maps and detailed fieldwork was demonstrated by identification of unique depositional meso-environments, which are rare in bedrock-Confined fluvial systems. The contamination chemostratigraphy of the bar deposits was correlated with the local mining and pollution history and contributed to an understanding of the bar evolution. The approach used in our study may be applicable to other montane rivers with historic ore mining and processing in their basins.
Shen Tian-rong - One of the best experts on this subject based on the ideXlab platform.
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The effect of jet array arrangement on the flow characteristics of the outlet hole in short Confined Channels
Heat Transfer—Asian Research, 2007Co-Authors: Liu Haiyong, Kong Manzhao, Liu Song-ling, Shen Tian-rongAbstract:This experimental study is part of the research program related to the aerodynamic characteristics of impingement in a Confined Channel. Experimental research on better understanding flow structure in Confined Channel with impingement cooling is rarely found in open literature. The main purposes of this project are (1) gaining greater insight into the structure of the impingement jet flow and flow in the outlet hole; (2) understanding the effect of impingement hole arrangement build up on the flow structure and aerodynamic parameters within holes and Channels with different aspect ratios. The test models are two Confined Channels with three staggered circular jet holes, and a single large size outlet hole placed downstream of the jet plate. The structure parameters of these orifices are different. In this paper, detailed flow field in the outlet hole was measured with a straight five-hole probe, and the discharge coefficient of outlet holes with different aspect ratios was also studied in each Channel. Experimental data shows that the jet arrangement has little influence on the flow behavior of the outlet hole when the aspect ratio of the passage was 1, but it played an important role on the discharge coefficient. Distinctively different flow patterns were found in two models with the aspect ratios of 3 and 5, while the variation of the discharge coefficient showed a slight influence on impingement hole arrangement. © 2007 Wiley Periodicals, Inc. Heat Trans Asian Res, 37(1): 20–28, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20188
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Flow field measurements in a Confined Channel and outlet hole with staggered jet array impingement
Journal of Propulsion Technology, 2006Co-Authors: Shen Tian-rongAbstract:Experimental results were presented to describe the flow behavor in low aspect ratio Confined Channel and outlet hole.Flow impinges target wall from twelve staggered jet holes and pours out with a sharp turning from a bigger outlet hole.Measurements were performed using a five-hole probe.Important results of the research include: Jet-induced swirl flow were found in the Channel,which tended to push high velocity flow moving toward side walls or even to the top wall.A strong counter-clockwise vortex was observed in the outlet hole which led to serious flow separation and low discharge coefficient of around 0.3.Static pressure in Channel and jet holes droped more rapidly in the downstream region,and Channel pressure has shown a little recovery near the outlet hole.
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Investigation of Flow Fields in a Short Confined Channel with Staggered Jet Impingement
2006Co-Authors: Shen Tian-rongAbstract:Experimental and numerical simulation results were presented to describe the flow behavior in the Channel with staggered jet impingement arrangement.Measurements of flow characteristics at different Reynolds numbers and different Channel heights were performed using a five-hole probe.Important results are:(1) there are complicated vortices in the Channel;(2) with the same Channel height,Reynolds number does not play an important role to the Channel flow characteristics;(3) the change of Channel heights has significant effect on flow characteristics.
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Effect of jet arrangement on the flow characteristics of the outlet hole in short Confined Channel
2006Co-Authors: Shen Tian-rongAbstract:Experimental investigation was carried out to study the flow fields of the outlet hole in two Confined passages with different staggered jet arrangement.Detailed flow field measurements were conducted with a five-hole probe.The influence of jet arrangement on the flow field and discharge coefficient of the outlet hole was investigated.Experimental data show that the jet arrangement has little influence on flow behavior in the passage of low aspect ratio,but play important role on discharge coefficient.Distinctively different flow transformation was found when the aspect ratio increased to 3 and 5,while the variation of discharge coefficient showed similar results.
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Investigation of flow fields in a short Confined Channel and jet hole with staggered jet impingement
Machinery Design and Manufacture, 2005Co-Authors: Shen Tian-rongAbstract:Experimental and numerical simulation results were presented to describe the flow behavior of outlet holes with staggered jet impingement arrangement.Measurements were performed using a five-hole prove,and study the flow characteristics at different Reynolds number and different Channel high.Important aspects of the study show that:1) There were complicated vortexs in the outlet holes;2) In the same Channel height,Reynolds number does not play important role to the Channel flow characteristics.3) The flow characteristics of the Channel and impinging holes were influencing with different Channel height.
Jing-zhou Zhang - One of the best experts on this subject based on the ideXlab platform.
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convective heat transfer of a row of air jets impingement excited by triangular tabs in a Confined crossflow Channel
International Journal of Heat and Mass Transfer, 2015Co-Authors: Jing-zhou Zhang, Yong ShanAbstract:Abstract Computational and experimental studies were conducted to investigate the conjugated convective heat transfer produced by single row of impinging jets inside a Confined Channel with non-uniform initial crossflow issued from discrete holes. The effects of the crossflow-to-jet Reynolds number ratio and crossflow holes arrangement (inline or staggered in relative to the impinging jet holes) on the jet impingement behaviors were studied providing the same total cooling air mass flowrate. Particular attention was paid to examine the tab-excited jet impingement behaviors in a Confined Channel with non-uniform crossflow. The results show that the tabbed excitation on the improvement of convective heat transfer in the vicinity of impingement region is not as well as the situation where no initial crossflow is present. For the inline arrangement of crossflow holes, the location corresponding to the peak laterally-averaged Nusselt number is moved downstream and the peak laterally-averaged Nusselt number is decreased significantly under larger crossflow-to-jet Reynolds number ratios. While for the staggered arrangement of crossflow holes, the location corresponding to the peak laterally-averaged Nusselt number is not affected by the crossflow but the peak laterally-averaged Nusselt number is decreased monotonously with the increase of crossflow-to-jet Reynolds number ratio. Under small crossflow-to-jet Reynolds number ratio, the initial crossflow arrangement has little influence on the laterally-averaged Nusselt number distribution. Among three crossflow-to-jet Reynolds number ratios ranged from 0.5 to 2, the maximum relative difference of peak laterally-averaged Nusselt numbers between two different crossflow arrangements is occurred under crossflow-to-jet Reynolds number ratio of 1.
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Jet impingement on a rib-roughened wall inside semi-Confined Channel
International Journal of Thermal Sciences, 2014Co-Authors: Lei Tan, Jing-zhou ZhangAbstract:Abstract Convective heat transfer on the rib-roughened wall impinged by a row of air jets inside semi-Confined Channel was experimentally investigated. Four rows of transverse ribs were arranged in the wall-jet zone downstream from the impinging jet stagnation to enhance heat transfer. Three typical rib configurations, including orthogonal ribs, V-shaped ribs and inverted V-shaped ribs, were considered under different non-dimensional jet-to-target distances ranging from 1 to 3 diameters and impinging jet Reynolds numbers ranging from 6000 to 30,000. The results show that the rib-roughened wall enhances the convective heat transfer up to 30% in the ribbed region by comparison with the smooth wall under the same jet Reynolds number. Among three rib configurations, the inverted V-shaped rib seems to be advantageous on the convective heat transfer enhancement, especially at lower jet-to-target spacing. The ribs on the impinging target do provide stronger convective heat transfer in the wall-jet region, but at greater expense of pressure drop inside the Channel. At the jet-to-target spacing ratio of 1, the flow coefficient of the rib-roughened Channel is decreased 5%–10% in related to the smooth Channel.
Cun-liang Liu - One of the best experts on this subject based on the ideXlab platform.
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Numerical investigation on the flow structures in a narrow Confined Channel with staggered jet array arrangement
Chinese Journal of Aeronautics, 2015Co-Authors: Haiyong Liu, Cun-liang LiuAbstract:Abstract A series of numerical analyses have been performed to investigate the flow structures in a narrow Confined Channel with 12 staggered circular impingement holes and one bigger exit hole. The flow enters the Channel through the impingement holes and exits through the far end outlet. The flow fields corresponding to two jet Reynolds numbers (25000 and 65000) and three Channel configurations with different ratios of the Channel height to the impingement hole diameter (Zr = 1, 3, 5) are analyzed by solving the Reynolds averaged Navier–Stokes equations with the realizable k–e turbulence model. Detailed flow field information including the secondary flow, the interaction between the jets and the cross flow, and flow distribution along the Channel has been obtained. Comparisons between the numerical and experimental results of the flow fields at the four planes along the Channel are performed to validate the numerical method. The calculated impingement pattern, high velocity flow distribution, low velocity separation region and vortices are in good agreement with the experimental data, implying the validity and effectiveness of the employed numerical approach for analyzing relevant flow field.
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Aerodynamic investigation of impingement cooling in a Confined Channel with staggered jet array arrangement
Experimental Thermal and Fluid Science, 2013Co-Authors: Haiyong Liu, Songling Liu, Hongfu Qiang, Cun-liang LiuAbstract:Abstract An enlarged model of a Confined Channel with staggered circular impingement jet holes and an exit hole was built. The cross flow was induced in the passage by the outflow of the exit hole. Experiments were performed to measure the flow field in the passage. The variations of mass flux distribution, static pressure and discharge coefficient were also studied. Jet Reynolds number of 10,000, 25,000 and 65,000 with Zr (ratio of passage height to diameter of impingement hole) of 1, 3 and 5 were considered. Experimental results showed that the jets impinged the target wall effectively along the entire passage of Zr = 1. But they were deflected by the cross flow in the downstream region of passage of Zr = 3 and 5. The impingement induced strong secondary flows in the passage that caused high velocity flow moving to the side and top walls. The flow structure in the passage changed distinctly with the increases of Zr . Mass flux distribution, static pressure and discharge coefficient were mostly dominated by Zr under the present test condition.
Tereza Lelková - One of the best experts on this subject based on the ideXlab platform.
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Sedimentary archive of contamination in the Confined Channel of the Ohře River, Czech Republic
Journal of Soils and Sediments, 2017Co-Authors: Tomáš Matys Grygar, Jitka Elznicová, Tereza Lelková, Timea Kiss, Márton Balogh, Ladislav Strnad, Tomáš NavrátilAbstract:Purpose The Ohře River has received contamination from metal mining and metallurgy (mainly Cu, Pb, Sn, U, Zn) over the previous five centuries. This contamination history has been poorly documented. Contamination has entered the river system in its middle reach, where the Channel is incised and bedrock Confined, which impedes overbank deposition. Our objective was to locate and describe a sedimentary record in this unfavourable depositional setting. Materials and methods Three former Channel bars that have coalesced with the riverbank were revealed by examination of historical and current maps and a digital terrain model. Manual coring in the bar and in situ (handheld) X-ray fluorescence (XRF) spectroscopy provided data for developing a contamination chemostratigraphy, which was correlated with the mining history in the region. Detailed topographic examination of the bar and valley edge was important to understanding the evolution of one of the bars. Optically stimulated luminescence (OSL) dating was used to verify the timing of deposition. Results and discussion Handheld XRF for in situ analysis of element composition is efficient for studying contaminated sediment bodies with complex stratigraphy, which require extensive coring and stratigraphic correlation. Despite the unfavourable settings, the Channel bars trapped sufficient sediment to produce a record that correlates with the history of contamination in the drainage basin. In the bar studied in greatest detail, we observed a surprising amount of contamination passing through the Ohře River Channel (up to 300 mg kg^−1 of Cu, 340 mg kg^−1 of Pb and 630 mg kg^−1 of Sn in fine sand and silt deposits) associated with a pollution climax in the sixteenth and seventeenth centuries. Modern contamination (Hg and U deposited in the nineteenth and twentieth centuries) was entrapped with low efficiency based on comparable concentrations of Hg and U located 90 km downstream. Conclusions The efficacy of the use of historical maps and detailed fieldwork was demonstrated by identification of unique depositional meso-environments, which are rare in bedrock-Confined fluvial systems. The contamination chemostratigraphy of the bar deposits was correlated with the local mining and pollution history and contributed to an understanding of the bar evolution. The approach used in our study may be applicable to other montane rivers with historic ore mining and processing in their basins.
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Sedimentary archive of contamination in the Confined Channel of the Ohře River, Czech Republic
Journal of Soils and Sediments, 2017Co-Authors: Tomáš Matys Grygar, Jitka Elznicová, Tereza Lelková, Timea Kiss, Márton Balogh, Ladislav Strnad, Tomáš NavrátilAbstract:The Ohře River has received contamination from metal mining and metallurgy (mainly Cu, Pb, Sn, U, Zn) over the previous five centuries. This contamination history has been poorly documented. Contamination has entered the river system in its middle reach, where the Channel is incised and bedrock Confined, which impedes overbank deposition. Our objective was to locate and describe a sedimentary record in this unfavourable depositional setting. Three former Channel bars that have coalesced with the riverbank were revealed by examination of historical and current maps and a digital terrain model. Manual coring in the bar and in situ (handheld) X-ray fluorescence (XRF) spectroscopy provided data for developing a contamination chemostratigraphy, which was correlated with the mining history in the region. Detailed topographic examination of the bar and valley edge was important to understanding the evolution of one of the bars. Optically stimulated luminescence (OSL) dating was used to verify the timing of deposition. Handheld XRF for in situ analysis of element composition is efficient for studying contaminated sediment bodies with complex stratigraphy, which require extensive coring and stratigraphic correlation. Despite the unfavourable settings, the Channel bars trapped sufficient sediment to produce a record that correlates with the history of contamination in the drainage basin. In the bar studied in greatest detail, we observed a surprising amount of contamination passing through the Ohře River Channel (up to 300 mg kg−1 of Cu, 340 mg kg−1 of Pb and 630 mg kg−1 of Sn in fine sand and silt deposits) associated with a pollution climax in the sixteenth and seventeenth centuries. Modern contamination (Hg and U deposited in the nineteenth and twentieth centuries) was entrapped with low efficiency based on comparable concentrations of Hg and U located 90 km downstream. The efficacy of the use of historical maps and detailed fieldwork was demonstrated by identification of unique depositional meso-environments, which are rare in bedrock-Confined fluvial systems. The contamination chemostratigraphy of the bar deposits was correlated with the local mining and pollution history and contributed to an understanding of the bar evolution. The approach used in our study may be applicable to other montane rivers with historic ore mining and processing in their basins.