The physical and mathematical model of an operating electrowinning cell was established, and the flow of electrolyte was numerically simulated by the commercial software Fluent. The results indicate that there are two...The physical and mathematical model of an operating electrowinning cell was established, and the flow of electrolyte was numerically simulated by the commercial software Fluent. The results indicate that there are two circulations at the surface flow where part of electrolyte backflows to the inlet from the side of cell, and the rest flows directly to the outlet, and the separation of two circulations with opposite direction occurs at the 20th pair of anode-cathode. This phenomenon was observed in the real operation. The electrolyte flows into the space between anode and cathode from the side portion of the cell. Meanwhile, the interelectrode effective flow rate （IEFR） is put forward to describe quantitively the flow field characteristics and is defined as the ratio of electrolyte flow between the anode and cathode to the total flow area. The influences of structure parameters and operating conditions on IEFR, such as the inlet angle, the volumetric flow rate, the inlet position and the height of steel baffles were simulated. The inlet position has a significant influence on the IEFR and its optimal value is 0.9 m below free surface. The inlet angle should be in the range from -10° to 10°. IEFR is in linear proportion with the volumetric flow rate, and the height of the steel baffle has little influence on the flow field.展开更多
The outcome of the cutting blasting in a one-step shaft excavation is heavily related to the cutting parameters used for parallel cutting method. In this study, the relationships between the cutting parameters（such a...The outcome of the cutting blasting in a one-step shaft excavation is heavily related to the cutting parameters used for parallel cutting method. In this study, the relationships between the cutting parameters（such as the hole spacing L and the empty hole diameter D） and damage zones were investigated by numerical simulation. A damage state index γ was introduced and used to characterize the crushing and crack damage zones through a user-defined subroutine. Two indices, i.e., η1 and η2 that can reflect the cutting performance, were also introduced. The simulation results indicate that an optimal value of L can be obtained so that the η1 and η2 can reach their optimal states for the best cutting performance. A larger D results in better cutting performance when the L value maintains its best. In addition, the influences of the loading rate and the in-situ stress on the cutting performance were investigated. It is found that an explosive with a high loading rate is suit for cutting blasting. The propagation direction and the length of the tensile cracks are affected by the direction and the magnitude of the maximum principal stress.展开更多
Seven adjustments of convergent-type Vortex Tube （VT） with different throttle angles were applied. The adjustments were made to analyze the influences of such angles on cold and hot temperature drops as well as flow...Seven adjustments of convergent-type Vortex Tube （VT） with different throttle angles were applied. The adjustments were made to analyze the influences of such angles on cold and hot temperature drops as well as flow structures inside the VTs. An experimental setup was designed, and tests were performed on different convergent VT configurations at injection pressures ranging from 0.45 to 0.65 MPa. The angles of the throttle valve were arranged between 30° to 90°, and the numbers of injection nozzles ranged between 2 and 6. Laboratory results indicated that the maximum hot and cold temperature drops ranged from 23.24 to 35 K and from 22.87 to 32.88 K, respectively, at four injection nozzles. Results also showed that temperature drop is a function of hot throttle valve angle with the maximum hot and cold temperature drops depending on the angle applied. We used graphs to demonstrate the changes in the cold and hot temperature drops with respect to hot throttle angle values. These values were interpreted and evaluated to determine the optimum angle, which was 60°. The CFD outputs agreed very well with the laboratory results. The proposed CFD results can help future researchers gain good insights into the complicated separation process taking place inside the VTs.展开更多
基金Project(2011AA061003)supported by the National High-Tech Research and Development Program of China
文摘The physical and mathematical model of an operating electrowinning cell was established, and the flow of electrolyte was numerically simulated by the commercial software Fluent. The results indicate that there are two circulations at the surface flow where part of electrolyte backflows to the inlet from the side of cell, and the rest flows directly to the outlet, and the separation of two circulations with opposite direction occurs at the 20th pair of anode-cathode. This phenomenon was observed in the real operation. The electrolyte flows into the space between anode and cathode from the side portion of the cell. Meanwhile, the interelectrode effective flow rate （IEFR） is put forward to describe quantitively the flow field characteristics and is defined as the ratio of electrolyte flow between the anode and cathode to the total flow area. The influences of structure parameters and operating conditions on IEFR, such as the inlet angle, the volumetric flow rate, the inlet position and the height of steel baffles were simulated. The inlet position has a significant influence on the IEFR and its optimal value is 0.9 m below free surface. The inlet angle should be in the range from -10° to 10°. IEFR is in linear proportion with the volumetric flow rate, and the height of the steel baffle has little influence on the flow field.
基金Projects(2016YFC0600706,2016YFC0600802) supported by the National Key Research and Development Program of ChinaProject(2017zzts186) supported by Cultivating Excellent Doctors of Central South University,China
文摘The outcome of the cutting blasting in a one-step shaft excavation is heavily related to the cutting parameters used for parallel cutting method. In this study, the relationships between the cutting parameters（such as the hole spacing L and the empty hole diameter D） and damage zones were investigated by numerical simulation. A damage state index γ was introduced and used to characterize the crushing and crack damage zones through a user-defined subroutine. Two indices, i.e., η1 and η2 that can reflect the cutting performance, were also introduced. The simulation results indicate that an optimal value of L can be obtained so that the η1 and η2 can reach their optimal states for the best cutting performance. A larger D results in better cutting performance when the L value maintains its best. In addition, the influences of the loading rate and the in-situ stress on the cutting performance were investigated. It is found that an explosive with a high loading rate is suit for cutting blasting. The propagation direction and the length of the tensile cracks are affected by the direction and the magnitude of the maximum principal stress.
文摘Seven adjustments of convergent-type Vortex Tube （VT） with different throttle angles were applied. The adjustments were made to analyze the influences of such angles on cold and hot temperature drops as well as flow structures inside the VTs. An experimental setup was designed, and tests were performed on different convergent VT configurations at injection pressures ranging from 0.45 to 0.65 MPa. The angles of the throttle valve were arranged between 30° to 90°, and the numbers of injection nozzles ranged between 2 and 6. Laboratory results indicated that the maximum hot and cold temperature drops ranged from 23.24 to 35 K and from 22.87 to 32.88 K, respectively, at four injection nozzles. Results also showed that temperature drop is a function of hot throttle valve angle with the maximum hot and cold temperature drops depending on the angle applied. We used graphs to demonstrate the changes in the cold and hot temperature drops with respect to hot throttle angle values. These values were interpreted and evaluated to determine the optimum angle, which was 60°. The CFD outputs agreed very well with the laboratory results. The proposed CFD results can help future researchers gain good insights into the complicated separation process taking place inside the VTs.
