Improved fluid dynamics can enhance the separation efficiency of flotation methods. A Computational Fluid Dynamics simulation using FLUENT was performed to model the fluid environment of a cyclonic-sta- tic micro bubb...Improved fluid dynamics can enhance the separation efficiency of flotation methods. A Computational Fluid Dynamics simulation using FLUENT was performed to model the fluid environment of a cyclonic-sta- tic micro bubble flotation column. The simulation results visually show the interior flow and illustrate mix- ing of the different flows within the apparatus. An analysis of the distribution in velocity and vorticity was used to analyze the separation mechanism and the synergism of the component parts and to strengthen the design of each unit. The conclusions are that axial back mixing and vortexes still exist in the separation unit even in the presence of packing media. The inverted cone structure near the tangential inlet （cone 1 ） within the cyclonic unit is the main reason for this. The cone 1 structure enhances swirling and focuses energy within the inner area of the cone where there are abundant bubbles. As a result slowly floating minerals are forcibly recovered and railings are effectively separated within this unit. However, cone 1 also reduces the vorticity downstream from it, which reduces the efficiency of railings separation within this part. Therefore, the design of cone 1 should be based on the principles of lessening disturbances to the column unit while strengthening the separation effect of the cyclonic unit. Also, the axial distance between the paired cyclonic structures at the bottom of the column （cone 2） and cone 1 poses tough requirements because of an interaction between separation of the middlings and railings.展开更多
It is hypothesized that steady anguilliform swimming motion of aquatic animals is purely reactive such that no net vortex wake is left downstream. This is versus carangiform and tunniform swimming of fish, where vorte...It is hypothesized that steady anguilliform swimming motion of aquatic animals is purely reactive such that no net vortex wake is left downstream. This is versus carangiform and tunniform swimming of fish, where vortex streams are shed from tail, fins, and body. But there the animal movements are such to produce partial vortex cancellation downstream in maximizing propulsive efficiency. In anguilliform swimming characteristic of the eel family, it is argued that the swimming motions are configured by the animal such that vortex shedding does not occur at all. However, the propulsive thrust in this case is higher order in the motion amplitude, so that relatively large coils are needed to produce relatively small thrust; the speeds of anguilliform swimmers are less than the carangiform and tunniforrn, which develop first order thrusts via lifting processes. Results of experimentation on live lamprey are compared to theoretical prediction which assumes the no-wake hypothesis. Two-dimensional analysis is first performed to set the concept. This is followed by three-dimensional analysis using slender-body theory. Slender-body theory has been applied by others in studying anguilliform swimming, as it is ideally suited to the geometry of the lamprey and other eel-like animals. The agreement between this new approach based on the hypothesis of wakeless swimming and the experiments is remarkably good in spite of the physical complexities.展开更多
API RP 19B《油气井射孔器评价的推荐作法》作为行业内射孔器评价的权威标准,对科研、生产和应用具有重要的指导作用。随着油气勘探开发和射孔完井作业认识的不断深入,为了更加准确地了解井下射孔的实际穿透深度,该标准结合行业最新的...API RP 19B《油气井射孔器评价的推荐作法》作为行业内射孔器评价的权威标准,对科研、生产和应用具有重要的指导作用。随着油气勘探开发和射孔完井作业认识的不断深入,为了更加准确地了解井下射孔的实际穿透深度,该标准结合行业最新的研究成果,完善了在应力条件下的岩石靶射孔试验方法和操作规范。本文在2014年版API RP 19B标准的基础上,全面分析了其与最新版本油气井射孔器评价标准之间的差异,并详细解读了第二部分关于应力条件下岩石靶射孔试验方法的要求、测试装置及相关安全事项等内容。通过对该修订标准的解读,为油气井射孔产品研发和测试技术人员提供重要参考,增强标准的操作性,为油气完井设计提供更为可靠的数据支持。展开更多
基金supported by the National Natural Science Foundation of China (No. 51074157)the Foundation of China University of Mining and Technology (No. 2011QNA08)
文摘Improved fluid dynamics can enhance the separation efficiency of flotation methods. A Computational Fluid Dynamics simulation using FLUENT was performed to model the fluid environment of a cyclonic-sta- tic micro bubble flotation column. The simulation results visually show the interior flow and illustrate mix- ing of the different flows within the apparatus. An analysis of the distribution in velocity and vorticity was used to analyze the separation mechanism and the synergism of the component parts and to strengthen the design of each unit. The conclusions are that axial back mixing and vortexes still exist in the separation unit even in the presence of packing media. The inverted cone structure near the tangential inlet （cone 1 ） within the cyclonic unit is the main reason for this. The cone 1 structure enhances swirling and focuses energy within the inner area of the cone where there are abundant bubbles. As a result slowly floating minerals are forcibly recovered and railings are effectively separated within this unit. However, cone 1 also reduces the vorticity downstream from it, which reduces the efficiency of railings separation within this part. Therefore, the design of cone 1 should be based on the principles of lessening disturbances to the column unit while strengthening the separation effect of the cyclonic unit. Also, the axial distance between the paired cyclonic structures at the bottom of the column （cone 2） and cone 1 poses tough requirements because of an interaction between separation of the middlings and railings.
文摘It is hypothesized that steady anguilliform swimming motion of aquatic animals is purely reactive such that no net vortex wake is left downstream. This is versus carangiform and tunniform swimming of fish, where vortex streams are shed from tail, fins, and body. But there the animal movements are such to produce partial vortex cancellation downstream in maximizing propulsive efficiency. In anguilliform swimming characteristic of the eel family, it is argued that the swimming motions are configured by the animal such that vortex shedding does not occur at all. However, the propulsive thrust in this case is higher order in the motion amplitude, so that relatively large coils are needed to produce relatively small thrust; the speeds of anguilliform swimmers are less than the carangiform and tunniforrn, which develop first order thrusts via lifting processes. Results of experimentation on live lamprey are compared to theoretical prediction which assumes the no-wake hypothesis. Two-dimensional analysis is first performed to set the concept. This is followed by three-dimensional analysis using slender-body theory. Slender-body theory has been applied by others in studying anguilliform swimming, as it is ideally suited to the geometry of the lamprey and other eel-like animals. The agreement between this new approach based on the hypothesis of wakeless swimming and the experiments is remarkably good in spite of the physical complexities.
文摘API RP 19B《油气井射孔器评价的推荐作法》作为行业内射孔器评价的权威标准,对科研、生产和应用具有重要的指导作用。随着油气勘探开发和射孔完井作业认识的不断深入,为了更加准确地了解井下射孔的实际穿透深度,该标准结合行业最新的研究成果,完善了在应力条件下的岩石靶射孔试验方法和操作规范。本文在2014年版API RP 19B标准的基础上,全面分析了其与最新版本油气井射孔器评价标准之间的差异,并详细解读了第二部分关于应力条件下岩石靶射孔试验方法的要求、测试装置及相关安全事项等内容。通过对该修订标准的解读,为油气井射孔产品研发和测试技术人员提供重要参考,增强标准的操作性,为油气完井设计提供更为可靠的数据支持。
