The melt stirring in a large copper smelting oxygen bottom-blown furnace is caused by the large amount of gas movement blown in by two rows of oxygen lances.At present,the two rows of oxygen lances provide oxygen of e...The melt stirring in a large copper smelting oxygen bottom-blown furnace is caused by the large amount of gas movement blown in by two rows of oxygen lances.At present,the two rows of oxygen lances provide oxygen of equal strength,and the stirring in the central area of the melt is insufficient,which restricts the efficient progress of the smelting reaction.This study proposes a strong-weak coupling oxygen supply method and establishes an equivalent model based on a large bottom-blown furnace(LBBF)of an enterprise to simulate the bubble characteristics and flow characteristics of the molten pool.The results show that adjusting the flow ratio between the two rows of oxygen lances can create a“strong”and a“weak”coexisting source of disturbance in an LBBF.It is worth noting that when the flow rate ratio of the two rows of oxygen lances is 1.6,the peak velocity generated by the“strong”distur bance source in the molten pool increases by 18.92%,and the disturbance range increases.This method effectively strengthens the stirring in the central area of the molten pool,improves smelting efficiency,and does not produce harmful melt splashes.It provides important guidance for optimizing production practice.展开更多
Rivers are classified into two types.One is the outer river which flows into ocean and the other is the inner river which does not flow into the ocean but into desert or lake.The inner rivers are the erosive rivers th...Rivers are classified into two types.One is the outer river which flows into ocean and the other is the inner river which does not flow into the ocean but into desert or lake.The inner rivers are the erosive rivers that have been seldom studied so far.Based on the field survey data,the analysis on the characteristics of the flow and sediment in the inner rivers' broad-shallow shifting (IRBS) reach.The IRBS reach often bears such the properties as:high gradient bed,usually 10‰or greater;small flow dischar...展开更多
There is a relatively complex flow state inside the high speed on-off valve,which often produces low pressure area and oil reflux in the high-speed opening and closing process of the spool,causing cavitation and vorte...There is a relatively complex flow state inside the high speed on-off valve,which often produces low pressure area and oil reflux in the high-speed opening and closing process of the spool,causing cavitation and vortex and other phenomena.These phenomena will affect the stability of the internal flow field of the plate valve and the flow characteristics of the high speed on-off valve.Aiming at the problems of small flow rate and instability of internal flow field,a new spool structure was designed.The flow field models of two-hole and three-hole plate spools with different openings were established,and software ANSYS Workbench was chosen to mesh the model.The standard k−εturbulence model was selected for numerical simulation using FLUENT software.The pressure distribution and velocity distribution under the same pressure and different opening degree were obtained.The structure and parameters of the optimization model were also obtained.The stability analysis of flow field under different pressure was carried out.The results demonstrate that the three-hole spool has a similar flow field change with the two-hole spool,but it does not create a low pressure zone,and the three-hole spool can work stably at 2 MPa or less.This method improves the appearance of low pressure area and oil backflow in the process of high speed opening and closing of spool.The stability of flow field and the flow rate of high speed switch valve are improved.Finally,the products designed in this paper are compared with existing hydraulic valve products.The results show that the three-hole plate type high speed on-off valve designed in this paper maintains the stability of the internal flow field under the condition of 200 Hz and large opening degree,and realizes the increase of flow rate.展开更多
In order to reduce pressure pulsation of vortex pumps,the mantis shrimp was chosen as biological prototype and a bionic engineering model was developed from its abdominal segment grooves.Bionic mantis shrimp groove vo...In order to reduce pressure pulsation of vortex pumps,the mantis shrimp was chosen as biological prototype and a bionic engineering model was developed from its abdominal segment grooves.Bionic mantis shrimp groove volute vortex pump models with different numbers of grooves were developed,and numerical simulation methods were used to calculate the models to study the effects of the volute grooves on the pressure pulsation of a vortex pump.The results show that a bionic groove volute could effectively improve the pressure pulsation of a vortex pump outlet,and reduce the pressure pulsation around the pump’s tongue and other internal points.The pressure pulsation under different conditions is impacted by shaft frequency and blade frequency.The bionic groove structure has little effect on the external characteristics of the pump,but could improve the static pressure,velocity distribution,and vortex structure of the flow field.Additionally,pressure pulsation of the whole vortex pump is reduced.展开更多
Flashover on polluted insulators is the most common accident occuring in power system.A great amount of work has been done to study the flashover characteristics on various kinds of insulators with several theoretical...Flashover on polluted insulators is the most common accident occuring in power system.A great amount of work has been done to study the flashover characteristics on various kinds of insulators with several theoretical models proposed.In these models,the amount and the distribution of the pollution on the insulator is critical to the flashover performance.However,very few simulation works has been carried out to study the pollution accumulation characteristics on the insulators.In this paper,both experimental and numerical efforts were given to study the pollution accumulation characteristics in order to evaluate the flashover probability.Experiments were performed first to have a bird view on the overall pollution distributions considering several crucial influential factors such as the wind speed and wind direction.AC porcelain insulators(XWP_2-160 type) were selected as the experimental samples and the equivalent salt deposit density(ESDD) was measured after the total predetermined amount of pollution was reached.Then, aerodynamic simulation was carried out to study the airflow and velocity distributions on each part of the insulator in clean air with regard to different wind speed and direction.It was found that the amount of the pollution on each section of the insulator has clear connections to the wind speed or air pressure distribution on the insulator surface.These distributions coincide to the pollution distribution obtained from experiments.Besides,the wind speed and air pressure distribution along the insulator chain was also studied.This work has shown that the numerical simulation may predict the pollution distribution on the insulators with practical accuracy.It is also possible to design new insulator shapes to reduce the pollution accumulation on critical areas according to the analysis in this work.展开更多
基金Project(2022YFC3901501)supported by the National Key R&D Program of ChinaProject(U20A20273)supported by the National Natural Science Foundation of China+1 种基金Project(2022JJ10078)supported by the Natural Science Foundation for Distinguished Young Scholars of Hunan Province,ChinaProject(2021RC3005)supported by the Science and Technology Innovation Program of Hunan Province,China。
文摘The melt stirring in a large copper smelting oxygen bottom-blown furnace is caused by the large amount of gas movement blown in by two rows of oxygen lances.At present,the two rows of oxygen lances provide oxygen of equal strength,and the stirring in the central area of the melt is insufficient,which restricts the efficient progress of the smelting reaction.This study proposes a strong-weak coupling oxygen supply method and establishes an equivalent model based on a large bottom-blown furnace(LBBF)of an enterprise to simulate the bubble characteristics and flow characteristics of the molten pool.The results show that adjusting the flow ratio between the two rows of oxygen lances can create a“strong”and a“weak”coexisting source of disturbance in an LBBF.It is worth noting that when the flow rate ratio of the two rows of oxygen lances is 1.6,the peak velocity generated by the“strong”distur bance source in the molten pool increases by 18.92%,and the disturbance range increases.This method effectively strengthens the stirring in the central area of the molten pool,improves smelting efficiency,and does not produce harmful melt splashes.It provides important guidance for optimizing production practice.
文摘Rivers are classified into two types.One is the outer river which flows into ocean and the other is the inner river which does not flow into the ocean but into desert or lake.The inner rivers are the erosive rivers that have been seldom studied so far.Based on the field survey data,the analysis on the characteristics of the flow and sediment in the inner rivers' broad-shallow shifting (IRBS) reach.The IRBS reach often bears such the properties as:high gradient bed,usually 10‰or greater;small flow dischar...
基金Project(51975164)supported by the National Natural Science Foundation of ChinaProject(201908230358)supported by the China Scholarship CouncilProject supported by the Fundamental Research Foundation for Universities of Heilongjiang Province,China。
文摘There is a relatively complex flow state inside the high speed on-off valve,which often produces low pressure area and oil reflux in the high-speed opening and closing process of the spool,causing cavitation and vortex and other phenomena.These phenomena will affect the stability of the internal flow field of the plate valve and the flow characteristics of the high speed on-off valve.Aiming at the problems of small flow rate and instability of internal flow field,a new spool structure was designed.The flow field models of two-hole and three-hole plate spools with different openings were established,and software ANSYS Workbench was chosen to mesh the model.The standard k−εturbulence model was selected for numerical simulation using FLUENT software.The pressure distribution and velocity distribution under the same pressure and different opening degree were obtained.The structure and parameters of the optimization model were also obtained.The stability analysis of flow field under different pressure was carried out.The results demonstrate that the three-hole spool has a similar flow field change with the two-hole spool,but it does not create a low pressure zone,and the three-hole spool can work stably at 2 MPa or less.This method improves the appearance of low pressure area and oil backflow in the process of high speed opening and closing of spool.The stability of flow field and the flow rate of high speed switch valve are improved.Finally,the products designed in this paper are compared with existing hydraulic valve products.The results show that the three-hole plate type high speed on-off valve designed in this paper maintains the stability of the internal flow field under the condition of 200 Hz and large opening degree,and realizes the increase of flow rate.
基金Projects(51779226,51476144)supported by the National Natural Science Foundation of ChinaProject(2017C31025)supported by Zhejiang Province Department Public Welfare Industrial Projects,China+1 种基金Project(2016M601736)supported by Postdoctoral Science Foundation of ChinaProject(1601028C)supported by Postdoctoral Research Funding Plan in Jiangsu Province,China
文摘In order to reduce pressure pulsation of vortex pumps,the mantis shrimp was chosen as biological prototype and a bionic engineering model was developed from its abdominal segment grooves.Bionic mantis shrimp groove volute vortex pump models with different numbers of grooves were developed,and numerical simulation methods were used to calculate the models to study the effects of the volute grooves on the pressure pulsation of a vortex pump.The results show that a bionic groove volute could effectively improve the pressure pulsation of a vortex pump outlet,and reduce the pressure pulsation around the pump’s tongue and other internal points.The pressure pulsation under different conditions is impacted by shaft frequency and blade frequency.The bionic groove structure has little effect on the external characteristics of the pump,but could improve the static pressure,velocity distribution,and vortex structure of the flow field.Additionally,pressure pulsation of the whole vortex pump is reduced.
基金Supported by East China Grid Company Ltd(200933- 04316C156)
文摘Flashover on polluted insulators is the most common accident occuring in power system.A great amount of work has been done to study the flashover characteristics on various kinds of insulators with several theoretical models proposed.In these models,the amount and the distribution of the pollution on the insulator is critical to the flashover performance.However,very few simulation works has been carried out to study the pollution accumulation characteristics on the insulators.In this paper,both experimental and numerical efforts were given to study the pollution accumulation characteristics in order to evaluate the flashover probability.Experiments were performed first to have a bird view on the overall pollution distributions considering several crucial influential factors such as the wind speed and wind direction.AC porcelain insulators(XWP_2-160 type) were selected as the experimental samples and the equivalent salt deposit density(ESDD) was measured after the total predetermined amount of pollution was reached.Then, aerodynamic simulation was carried out to study the airflow and velocity distributions on each part of the insulator in clean air with regard to different wind speed and direction.It was found that the amount of the pollution on each section of the insulator has clear connections to the wind speed or air pressure distribution on the insulator surface.These distributions coincide to the pollution distribution obtained from experiments.Besides,the wind speed and air pressure distribution along the insulator chain was also studied.This work has shown that the numerical simulation may predict the pollution distribution on the insulators with practical accuracy.It is also possible to design new insulator shapes to reduce the pollution accumulation on critical areas according to the analysis in this work.
