The flow choking may occur for weir flow slit-type flip buckets trader common operation conditions. An estimation method is developed through introducing a comprehensive coefficient to determine the approach flow Frou...The flow choking may occur for weir flow slit-type flip buckets trader common operation conditions. An estimation method is developed through introducing a comprehensive coefficient to determine the approach flow Froude number for the flow choking to occur in those flip buckets. The error of the present method relative to the experimental data is less than 5%. The results show that, the Froude number for the flow choking to occur is related to the contraction ratio and the contraction angle of the flip buckets. When the flow choking occurs, the upper jet trajectory decreases and the lower one is almost not affected, and the dynamic pressures on the bottom and the sidewalls increase due to the flow profile rising on the flip buckets.展开更多
Tundish is an important metallurgical reactor in the continuous castingprocess. In order to control the fluid flow in tundish and thus take full advantage of the residencetime available for the removal of inclusions f...Tundish is an important metallurgical reactor in the continuous castingprocess. In order to control the fluid flow in tundish and thus take full advantage of the residencetime available for the removal of inclusions from molten steel, the effect of weir and dam on thefluid flow has been studied in a water model based on the characteristic number Froude and Reynoldnumber similarity criteria. The residence time distribution curves of the flow were measured bySG800. The optimum arrangement of darn and weir and the nonstationary flow in tundish werediscussed. The results show that the combination of weir and dam is benefit for the flow pattern intundish, weir can prevent the upper recirculating flow, dam can cut off the bottom flow and turn toupwards, it is advantageous to separate the nonmetallic inclusions. Furthermore, it is important toexceed the critical depth of bath during exchange ladles, not only for the inclusion floatation butalso for avoiding tundish slag drainage earlier.展开更多
The water flow over a semicircular weir is investigated numerically and experimentally in this paper. The numerical model solves the Reynolds equation for a mean flow field with thek-ε-turbulent model. To trace the m...The water flow over a semicircular weir is investigated numerically and experimentally in this paper. The numerical model solves the Reynolds equation for a mean flow field with thek-ε-turbulent model. To trace the motion of the free surface, the COF method with geometric reconstruction is employed. The velocity of the flow is measured by means of LDV technique. Four types of flow patterns, the position of the separation and reattachment point, the distribution of shear stress on the bed at downstream of the weir are presented and discussed. The numerical results agree well with the experiment data.展开更多
A modified piano key weir with a rounded nose and a parapet wall (MPKW) can improve the discharge capacity significantly compared to a standard piano key weir. However, the optimum of the inlet/outlet width ratio (Wi/...A modified piano key weir with a rounded nose and a parapet wall (MPKW) can improve the discharge capacity significantly compared to a standard piano key weir. However, the optimum of the inlet/outlet width ratio (Wi/Wo) on the discharge efficiency of MPKW is still not investigated numerically. The present work utilized the numerical modeling to investigate and analyze the effects of the inlet/outlet key width ratios on the hydraulic characteristics and discharge capacity of the MPKW. To validate the numerical model with the experimental data, the results indicate that the average relative error is 2.96%, which confirms that the numerical model is fairly well to predictthe specifications of flow over on the MPKW. Numerical simulation results indicated that the discharge capacity of the MPKW can be improved up to 8.5% by optimizing the Wi/Wo ratio ranging from 1.53 to 1.67 even if the other parameters of the MPKW keep unchanged. A big Wi/Wo ratio generally leads to an increase in discharge capacity at low heads and a little effect on the discharge efficiency at high heads. The discharge efficiency of the inlet and outlet crests increases up to 9.6% for high heads, while discharge efficiency of the lateral crest decreases up to 23.5% compared with the reference model. The findings of the study revealed that the intrinsic influencing mechanism of the Wi/Wo ratio on the discharge performance of MPKWs.展开更多
The fluid flow phenomena in tundish have a strong influence not only on theuniform of composition and temperature of bath, but also on the separation of non-metallicinclusions, especially for the multi-strand tundish....The fluid flow phenomena in tundish have a strong influence not only on theuniform of composition and temperature of bath, but also on the separation of non-metallicinclusions, especially for the multi-strand tundish. A water model of a multi-strand tundish hasbeen set up based on the Froude number and Reynold number similarity criteria. The effect ofdam+weir and baffle on the uniform of composition and temperature of bath for different nozzles hasbeen studied. The residence time distribution curves of the fluid flow were measured by SG800.Comparing the photos of the flow pattern in tundish, the optimum arrangement of baffle+dam wasobtained. This new structure is benefit not only to uniform the temperature among different SENs(submerge entry nozzles) but also to separate the non-inclusions from the liquid steel, it can bewidely used in multi-strand tundish.展开更多
In the water modeling experiments, three cases were considered, i. e, , a bare tundish, a tundish equipped with a turbulence inhibitor, and a rectangular tundish equipped with weirs （dams） and a turbulence inhibitor...In the water modeling experiments, three cases were considered, i. e, , a bare tundish, a tundish equipped with a turbulence inhibitor, and a rectangular tundish equipped with weirs （dams） and a turbulence inhibitor. Comparing the RTD curves, inclusion separation, and the result of the streamline experiment, it can be found that the tundish equipped with weirs （dams） and a turbulence inhibitor has a great effect on the flow field and the inclusion separation when compared with the sole use or no use of the turbulent inhibitor or weirs （dams）. In addition, the enlargement of the distance between the weir and dam will result in a better effect when the tundish equipped with weirs （dam） and a turbulence inhibitor was used.展开更多
This study is an experimental study to analyze the dissipation effect of a baffle shape installed to reduce the scour problem downstream of a weir. The hydraulic experiment on the flow dissipation effect created by ba...This study is an experimental study to analyze the dissipation effect of a baffle shape installed to reduce the scour problem downstream of a weir. The hydraulic experiment on the flow dissipation effect created by baffle installation was an experiment under a fixed bed condition to investigate the flow dissipation effect based on changes in flow in the apron downstream caused by?changes in baffle shape. The experimental analysis was conducted by measuring the flow rate at the apron downstream with and without the installation of a baffle on the basis of the flow dissipation effect. This experiment compared the flow dissipation effect achieved with five baffle shapes to analyze the effect of the baffle shape. Two conditions of flow rate were considered: when a water level in the area of super-critical flow was lower than the baffle height, and when it?flowed over the baffle. Overall, the flow dissipation effect was found to be?good when a square baffle with a large flow blocking area was used. The analysis also found that hydraulic jump was facilitated when the front part of the baffle was inclined, as flow was induced to the upper direction. The result of the experiment showed that when performing flow dissipation through the use of a baffle, the effect of flow blocking and flow duration alteration should be considered.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant No.51179056)the PAPD(Grant No.3014-SYS1401)the Fundamental Research Funds for the Central Universities of China(Grant No.2014B03114)
文摘The flow choking may occur for weir flow slit-type flip buckets trader common operation conditions. An estimation method is developed through introducing a comprehensive coefficient to determine the approach flow Froude number for the flow choking to occur in those flip buckets. The error of the present method relative to the experimental data is less than 5%. The results show that, the Froude number for the flow choking to occur is related to the contraction ratio and the contraction angle of the flip buckets. When the flow choking occurs, the upper jet trajectory decreases and the lower one is almost not affected, and the dynamic pressures on the bottom and the sidewalls increase due to the flow profile rising on the flip buckets.
文摘Tundish is an important metallurgical reactor in the continuous castingprocess. In order to control the fluid flow in tundish and thus take full advantage of the residencetime available for the removal of inclusions from molten steel, the effect of weir and dam on thefluid flow has been studied in a water model based on the characteristic number Froude and Reynoldnumber similarity criteria. The residence time distribution curves of the flow were measured bySG800. The optimum arrangement of darn and weir and the nonstationary flow in tundish werediscussed. The results show that the combination of weir and dam is benefit for the flow pattern intundish, weir can prevent the upper recirculating flow, dam can cut off the bottom flow and turn toupwards, it is advantageous to separate the nonmetallic inclusions. Furthermore, it is important toexceed the critical depth of bath during exchange ladles, not only for the inclusion floatation butalso for avoiding tundish slag drainage earlier.
文摘The water flow over a semicircular weir is investigated numerically and experimentally in this paper. The numerical model solves the Reynolds equation for a mean flow field with thek-ε-turbulent model. To trace the motion of the free surface, the COF method with geometric reconstruction is employed. The velocity of the flow is measured by means of LDV technique. Four types of flow patterns, the position of the separation and reattachment point, the distribution of shear stress on the bed at downstream of the weir are presented and discussed. The numerical results agree well with the experiment data.
文摘A modified piano key weir with a rounded nose and a parapet wall (MPKW) can improve the discharge capacity significantly compared to a standard piano key weir. However, the optimum of the inlet/outlet width ratio (Wi/Wo) on the discharge efficiency of MPKW is still not investigated numerically. The present work utilized the numerical modeling to investigate and analyze the effects of the inlet/outlet key width ratios on the hydraulic characteristics and discharge capacity of the MPKW. To validate the numerical model with the experimental data, the results indicate that the average relative error is 2.96%, which confirms that the numerical model is fairly well to predictthe specifications of flow over on the MPKW. Numerical simulation results indicated that the discharge capacity of the MPKW can be improved up to 8.5% by optimizing the Wi/Wo ratio ranging from 1.53 to 1.67 even if the other parameters of the MPKW keep unchanged. A big Wi/Wo ratio generally leads to an increase in discharge capacity at low heads and a little effect on the discharge efficiency at high heads. The discharge efficiency of the inlet and outlet crests increases up to 9.6% for high heads, while discharge efficiency of the lateral crest decreases up to 23.5% compared with the reference model. The findings of the study revealed that the intrinsic influencing mechanism of the Wi/Wo ratio on the discharge performance of MPKWs.
文摘The fluid flow phenomena in tundish have a strong influence not only on theuniform of composition and temperature of bath, but also on the separation of non-metallicinclusions, especially for the multi-strand tundish. A water model of a multi-strand tundish hasbeen set up based on the Froude number and Reynold number similarity criteria. The effect ofdam+weir and baffle on the uniform of composition and temperature of bath for different nozzles hasbeen studied. The residence time distribution curves of the fluid flow were measured by SG800.Comparing the photos of the flow pattern in tundish, the optimum arrangement of baffle+dam wasobtained. This new structure is benefit not only to uniform the temperature among different SENs(submerge entry nozzles) but also to separate the non-inclusions from the liquid steel, it can bewidely used in multi-strand tundish.
文摘In the water modeling experiments, three cases were considered, i. e, , a bare tundish, a tundish equipped with a turbulence inhibitor, and a rectangular tundish equipped with weirs （dams） and a turbulence inhibitor. Comparing the RTD curves, inclusion separation, and the result of the streamline experiment, it can be found that the tundish equipped with weirs （dams） and a turbulence inhibitor has a great effect on the flow field and the inclusion separation when compared with the sole use or no use of the turbulent inhibitor or weirs （dams）. In addition, the enlargement of the distance between the weir and dam will result in a better effect when the tundish equipped with weirs （dam） and a turbulence inhibitor was used.
文摘This study is an experimental study to analyze the dissipation effect of a baffle shape installed to reduce the scour problem downstream of a weir. The hydraulic experiment on the flow dissipation effect created by baffle installation was an experiment under a fixed bed condition to investigate the flow dissipation effect based on changes in flow in the apron downstream caused by?changes in baffle shape. The experimental analysis was conducted by measuring the flow rate at the apron downstream with and without the installation of a baffle on the basis of the flow dissipation effect. This experiment compared the flow dissipation effect achieved with five baffle shapes to analyze the effect of the baffle shape. Two conditions of flow rate were considered: when a water level in the area of super-critical flow was lower than the baffle height, and when it?flowed over the baffle. Overall, the flow dissipation effect was found to be?good when a square baffle with a large flow blocking area was used. The analysis also found that hydraulic jump was facilitated when the front part of the baffle was inclined, as flow was induced to the upper direction. The result of the experiment showed that when performing flow dissipation through the use of a baffle, the effect of flow blocking and flow duration alteration should be considered.
