The top-bottom combined blowing converter mainly adopts the blowing method of top-blowing oxygen and bottom-blowing nitrogen.In the production process,there are some disadvantages,such as a significant temperature dif...The top-bottom combined blowing converter mainly adopts the blowing method of top-blowing oxygen and bottom-blowing nitrogen.In the production process,there are some disadvantages,such as a significant temperature difference between the top and bottom of the molten pool,inadequate gas permeability of bottom blowing,and low decarburization efficiency.Therefore,we propose a novel bottom-blowing gas doped oxygen process to enhance the smelting conditions in the converter.The 500 kg medium frequency induction furnace with top and bottom-blowing function was used to explore the influence of the proportion of bottom-blowing gas doped oxygen on the smelting effect in different smelting cycles.Subsequently,industrial experimental verification was carried out on a 60 t converter.The results of intermediate frequency furnace experiments demonstrate that the bottom-blowing gas doped oxygen process exhibits a superior heating rate and decarburization efficiency during the initial and final stages of blowing compared to pure N2 used for bottom-blowing.Simultaneously,the dephosphorization efficiency exhibited an initial increase followed by a subsequent decrease as the bottom-blowing oxygen content increased.The industrial test of 60 t converter validates the findings above.Moreover,when the oxygen content in bottom-blowing gas is 5%,the average blowing time reduces by 54 s,and the minimum endpoint carbon-oxygen equilibrium reaches 0.00219 under this condition.The results demonstrate that the appropriate amount of oxygen doped in bottom-blowing gas can effectively enhance the metallurgical conditions of the converter and improve production efficiency.展开更多
Blowing snow events in Antarctica play an important role in the climate system,affecting the mass balance of the ice sheet and the radiative effects of the atmosphere.Due to the harsh weather conditions in Antarctica,...Blowing snow events in Antarctica play an important role in the climate system,affecting the mass balance of the ice sheet and the radiative effects of the atmosphere.Due to the harsh weather conditions in Antarctica,ground-based detection data is deficient,making it difficult to accurately obtain both the frequency of blowing snow and the evolution of the height of the blowing snow layer.In this study,we introduce a new method based on the raw signal from the C12 ceilometer to separate clear-sky,cloud,snowfall,and blowing snow conditions within a height of 500 meters above the surface of Zhongshan Station.Research has shown that more than 80%of the blowing snow at Zhongshan Station is affected by cyclonic systems,and less than 20%of the blowing snow is affected by katabatic winds.Further,Antarctic blowing snow is closely related to snowfall.When there is heavy snowfall(even a blizzard),a smaller wind speed can lead to the formation of a deep blowing snow layer within an hour after snowfall.However,as time increases,the threshold wind speed required to generate blowing snow significantly increases,and the thickness of the blowing snow layer becomes shallower.展开更多
Stall flutter poses great challenges to flight safety.To alleviate this problem,a steady blowing control considering the perturbation and wake-induced vibration at a large angle of attack is developed in this paper,wh...Stall flutter poses great challenges to flight safety.To alleviate this problem,a steady blowing control considering the perturbation and wake-induced vibration at a large angle of attack is developed in this paper,where two blowings are configured on upper and lower tail surfaces to suppress the stall flutter.The stall flutter with one-degree-of-freedom is first evaluated by numerical simulation.The equation of motion for stall flutter is solved by the Newmark-β method.Then,the stall flutter responses for five blowing speeds,i.e.,0,4,12,20,and 28 m/s under the airspeed range of 3–9 m/s,are studied in detail.The stall flutter suppression mechanism can be summarized as follows:a large blowing speed can inject energy into the boundary layer and enhance the high-pressure zone,which delays the flow separation on the suction surface.In this way,the formation of the leading-edge separation vortex is suppressed.Thus,the dynamic stall vortex is weakened and accelerates shedding.In addition,the driving moment is reduced,which leads to a decrement in the stall flutter amplitude.When the blowing speed is 28 m/s(stall flutter amplitude=0.1357 rad),compared with uncontrolled case(stall flutter amplitude=0.6002 rad),the amplitude can decrease by 77.39%,which demonstrates the effectiveness of the proposed steady blowing based active control strategy.展开更多
Sea ice and snow are the most sensitive and important crucial components of the global climate system,affecting the global climate by modulating the energy exchange between the ocean and the atmosphere.The sea near Zh...Sea ice and snow are the most sensitive and important crucial components of the global climate system,affecting the global climate by modulating the energy exchange between the ocean and the atmosphere.The sea near Zhongshan Station in Antarctica is covered by landfast sea ice,with snow depth influenced by both thermal factors and wind.This region frequently experiences katabatic winds and cyclones from the westerlies,leading to frequent snow blowing events that redistribute the snow and affects its depth,subsequently impacting the thermodynamic growth of sea ice.This study utilized the one-dimensional thermodynamic model ICEPACK to simulate landfast sea ice thickness and snow depth near Zhongshan Station in 2016.Two parameterization schemes for snow blowing,the Bulk scheme,and the ITDrdg(ITD/ridges)scheme are evaluated for their impact on snow depth.The results show that simulations using snow blowing schemes more closely align with observed results,with the ITDrdg scheme providing more accurate simulations,evidenced by root mean square errors of less than 10 cm for both snow depth and sea ice thickness.Snow blowing also impacts the thermodynamic growth of sea ice,particularly bottom growth.The sea ice bottom increases by 9.0 cm using the ITDrdg scheme compared to simulations without the snow blowing,accounting for 12.5%of total sea ice bottom growth.Furthermore,snow blowing process also influences snow ice formation,highlighting its primary role in affecting snow depth.Continued field observations of snow blowing are necessary to evaluate and improve parameterization schemes.展开更多
The amount of oxygen blown into the converter is one of the key parameters for the control of the converter blowing process,which directly affects the tap-to-tap time of converter. In this study, a hybrid model based ...The amount of oxygen blown into the converter is one of the key parameters for the control of the converter blowing process,which directly affects the tap-to-tap time of converter. In this study, a hybrid model based on oxygen balance mechanism (OBM) and deep neural network (DNN) was established for predicting oxygen blowing time in converter. A three-step method was utilized in the hybrid model. First, the oxygen consumption volume was predicted by the OBM model and DNN model, respectively. Second, a more accurate oxygen consumption volume was obtained by integrating the OBM model and DNN model. Finally, the converter oxygen blowing time was calculated according to the oxygen consumption volume and the oxygen supply intensity of each heat. The proposed hybrid model was verified using the actual data collected from an integrated steel plant in China, and compared with multiple linear regression model, OBM model, and neural network model including extreme learning machine, back propagation neural network, and DNN. The test results indicate that the hybrid model with a network structure of 3 hidden layer layers, 32-16-8 neurons per hidden layer, and 0.1 learning rate has the best prediction accuracy and stronger generalization ability compared with other models. The predicted hit ratio of oxygen consumption volume within the error±300 m^(3)is 96.67%;determination coefficient (R^(2)) and root mean square error (RMSE) are0.6984 and 150.03 m^(3), respectively. The oxygen blow time prediction hit ratio within the error±0.6 min is 89.50%;R2and RMSE are0.9486 and 0.3592 min, respectively. As a result, the proposed model can effectively predict the oxygen consumption volume and oxygen blowing time in the converter.展开更多
The bottom blowing element is the key equipment to ensure the bottom blowing effect of the converter.Three types of bottom blowing elements,dispersive type(D1),double circular seam(D2)and straight cylinder type(D3),we...The bottom blowing element is the key equipment to ensure the bottom blowing effect of the converter.Three types of bottom blowing elements,dispersive type(D1),double circular seam(D2)and straight cylinder type(D3),were built,and the effects of bottom blowing element type on molten bath flow,wall erosion and furnace bottom erosion were simulated.It was found that when the bottom blowing elements of dispersive type(D1)and double circular seam(D2)were used,the dead zone area in the lower part of the molten bath was smaller,and the high-speed zone area was larger;therefore,the stirring effect on the bottom melt was better.When the straight cylinder type(D3)bottom blowing element was used,the gas penetrated the molten bath at a faster rate to reach the surface of molten bath and failed to disperse in the bottom molten bath,and the wall shear stress near the nozzle outlet was larger.When argon was blown by three different bottom blowing elements,the area of the wall shear stress greater than 3 Pa was 4.8,5.6 and 8.7 cm2,respectively,within 0.2 m of the bottom blowing nozzle outlet.展开更多
In this study,the unsteady Reynolds-averaged Navier–Stokes algorithm coupled with the Discrete Phase Model(DPM)was used to study the accumulation of snow in the bogie region of a high-speed train under crosswind cond...In this study,the unsteady Reynolds-averaged Navier–Stokes algorithm coupled with the Discrete Phase Model(DPM)was used to study the accumulation of snow in the bogie region of a high-speed train under crosswind conditions.Moreover,the impact of active blowing schemes on the airflow around the bogie and the dynamics and deposition of snow particles were also assessed.According to the results:in the crosswind environment,active blowing changes the flow field in the bogie area,reducing the flow of air coming from the windward side and bottom of the bogie.The trajectory of snow particles carried by crosswinds is modified due to the reduced airflow into the bogie region.With no active blowing,snow accumulation is mainly concentrated in the bogie cavity,frame,and primary suspension;while it is reduced by nearly an order of magnitude as soon as blowing is enabled.Blowing speeds need to be distributed appropriately in order to achieve the best possible snow protection.Continuously increasing the blowing speed on one side does not improve the amount of snow in the bogie region.The optimal condition for snow prevention of the entire train is achieved with a windward side blowing speed of 4 m/s and a leeward side blowing speed of 6 m/s,resulting in a snow reduction rate of 95.6%.Moreover,higher blowing speeds on the leeward side are beneficial for mitigating snow accumulation in the bogie region.展开更多
In this article,the relevant instruments and techniques for measuring solid precipitation and blowing snow are reviewed,with a focus on the in situ instrument measurements.Moreover,a literature review and specific obs...In this article,the relevant instruments and techniques for measuring solid precipitation and blowing snow are reviewed,with a focus on the in situ instrument measurements.Moreover,a literature review and specific observation activities for solid precipitation are provided,the working principles of several instruments are introduced,and the advantages and disadvantages,measurement performance,and specific application scenarios of the instruments are evaluated.Currently,there are numerous solid precipitation measurement instruments available,and the standardization and sustainability of these measurements also need to be considered.The purpose of the review is not to be exhaustive but to provide readers with information on the current status of the development of relevant technologies and the prospects for their application in the polar regions.展开更多
Nowadays, in China, the bottom-blowing technique plays an important role in accelerating the molten bath stirring and promoting the metallurgical reactions in electric arc furnace (EAF) steelmaking. The innovations of...Nowadays, in China, the bottom-blowing technique plays an important role in accelerating the molten bath stirring and promoting the metallurgical reactions in electric arc furnace (EAF) steelmaking. The innovations of bottom-blowing technologies in EAF steelmaking were reviewed. The optimized bottom-blowing arrangement in EAF based on the furnace structure and the position of electrodes was introduced, and the fluid flow characteristics of EAF molten bath with bottomblowing were analyzed. Furthermore, bottom-blowing CO2 in EAF can facilitate the carbon-oxygen reaction reaching equilibrium and decrease the content of nitrogen in molten steel due to its special metallurgical properties. Pulsating bottom-blowing in EAF can effectively improve the molten bath stirring through the action of the unsteady bottom blowing gas streams, which could make the fluid flow field more disorderly than the steady bottom-blowing. And submerged O2 injection with CO2 in EAF can noticeably strengthen the EAF molten bath stirring, increase the production efficiency and improve the molten steel quality.展开更多
Gas blowing is a valid method to remove the impurities from metallurgical grade silicon（MG-Si） melt.The thermodynamic behavior of impurities Fe,Al,Ca,Ti,Cu,C,B and P in MG-Si was studied in the process of O2 blowing...Gas blowing is a valid method to remove the impurities from metallurgical grade silicon（MG-Si） melt.The thermodynamic behavior of impurities Fe,Al,Ca,Ti,Cu,C,B and P in MG-Si was studied in the process of O2 blowing.The removal efficiencies of impurities in MG-Si were investigated using O2 blowing in ladle.It is found that the removal efficiencies are higher than 90% for Ca and Al and nearly 50% for B and Ti.The morphology of inclusions was analyzed and the phases Al3Ni,NiSi2 and Al3Ni were confirmed in MG-Si by X-ray diffraction.It was found that SiB4 exists in Si？B binary system.The chemical composition of inclusions in MG-Si before and after refining was analyzed by SEM-EDS.It is found that the amount of white inclusion reduces for the removal of most Al and Ca in the forms of molten slag inclusion and the contents of Fe,Ni and Mn in inclusion increase for their inertia in silicon melt with O2 blowing.展开更多
The experiment was carried out in a combined blowing converter.The natural gas was supplied as the cooling medium for the bottom lance.The blow- ing practice of medium P hot metal (0.30-0.85% [P]) indicated that with ...The experiment was carried out in a combined blowing converter.The natural gas was supplied as the cooling medium for the bottom lance.The blow- ing practice of medium P hot metal (0.30-0.85% [P]) indicated that with better stirring at the bottom of the converter and lower P_(CO),this steelmgking process was favorable to reduce the amount of [C] and [O] and increase the (P_2O_5)/[P]. The maximum rate of dephospborization might be high up to 0.0a5%/min and the P content in steel could be reduced to lower than 0.03% by single slag-forming operation.展开更多
Fluid flow characteristics in a four-strand tundish with gas blowing were studied by water modeling experiments.It is found that gas blowing can greatly improve the flow characteristics in the tundish with a turbulenc...Fluid flow characteristics in a four-strand tundish with gas blowing were studied by water modeling experiments.It is found that gas blowing can greatly improve the flow characteristics in the tundish with a turbulence inhibitor.It dramatically increases the peak concentration time,and greatly decreases the dead volume,and reduces the minimum residence time.The gas blowing location,gas flow rate,and porous plug area greatly influence the flow characteristics in the tundish; the gas blowing location near the baffle,smaller gas flow rate,and smaller porous plug area are better for improving the fluid flow characteristics.Using gas blowing can reduce the difference of flows at the middle outlets and side outlets for the multi-strand tundish.Bubbles produced by gas blowing can absorb small inclusions and provide the condition for inclusion collision and aggregation.Therefore,introducing gas blowing into a tundish and combining the turbulence inhibitor can improve inclusion floating and removal,and the cleanness of molten steel can be advanced.展开更多
A three-dimensional mathematical model was developed to investigate the effect of gas blowing nozzle angles on multiphase flow,circulation flow rate,and mixing time during Ruhrstahl-Heraeus(RH) refining process.Also,a...A three-dimensional mathematical model was developed to investigate the effect of gas blowing nozzle angles on multiphase flow,circulation flow rate,and mixing time during Ruhrstahl-Heraeus(RH) refining process.Also,a water model with a geometric scale of 1:4 from an industrial RH furnace of 260 t was built up,and measurements were carried out to validate the mathematical model.The results show that,with a conventional gas blowing nozzle and the total gas flow rate of 40 L·min^(-1),the mixing time predicted by the mathematical model agrees well with the measured values.The deviations between the model predictions and the measured values are in the range of about 1.3%–7.3% at the selected three monitoring locations,where the mixing time was defined as the required time when the dimensionless concentration is within 3% deviation from the bath averaged value.In addition,the circulation flow rate was 9 kg·s^(-1).When the gas blowing nozzle was horizontally rotated by either 30° or 45°,the circulation flow rate was found to be increased by about 15% compared to a conventional nozzle,due to the rotational flow formed in the up-snorkel.Furthermore,the mixing time at the monitoring point 1,2,and 3 was shortened by around 21.3%,28.2%,and 12.3%,respectively.With the nozzle angle of 30° and 45°,the averaged residence time of 128 bubbles in liquid was increased by around 33.3%.展开更多
Recent research proves that wings with leading-edge tubercles have the ability to perform efficiently in post-stall region over the conventional straight wing. Moreover, the conventional straight wing outperforms the ...Recent research proves that wings with leading-edge tubercles have the ability to perform efficiently in post-stall region over the conventional straight wing. Moreover, the conventional straight wing outperforms the tubercled wing at a pre-stall region which is quintessential. Even though tubercled wing offers great performance enhancement, because of the complexity of the flow, the trough region of the tubercled wing is more prone to flow separation. Henceforth, the present paper aims at surface blowing – an active flow control technique over the tubercled wing to enhance the aerodynamic efficiency by positively influencing its lift characteristics without causing any additional drag penalty. Flow parameters like blowing velocity ratios and the location of blowing were chosen to find the optimised configuration keeping the amplitude and frequency of the leading-edge tubercles constant as 0.12 c and 0.25 c respectively. Numerical investigations were carried out over the baseline tubercled wing and tubercled wing with surface blowing at various blowing jet velocity ratios 0.5, 1 and 2 over four different chordwise locations ranging from 0.3 c to 0.8 c.The results confirm that blowing at various x/c with different blowing velocity ratios performs better than the conventional tubercled wing. Comparatively, blowing velocity ratio 2 at 0.3 c shows peak performance of about 28% enhancement in the lift characteristics relative to the baseline model. Particularly, in the pre-stall region, 25–50% increase in aerodynamic efficiency is evident over the tubercled wing with surface blowing compared with the baseline case. Additionally,attempts were made to delineate the physical significance of the flow separation mechanism due to blowing by visualizing the streamline pattern.展开更多
In continuous casting,the argon blowing at the tundish upper nozzle is usually used to prevent nozzle clogging,whose effect is closely related to the migration of argon bubbles and the flow behavior of the liquid stee...In continuous casting,the argon blowing at the tundish upper nozzle is usually used to prevent nozzle clogging,whose effect is closely related to the migration of argon bubbles and the flow behavior of the liquid steel in the nozzle.Here,to investigate the effects of argon blowing at the tundish upper nozzle on multiphase flow behavior in nozzle,a threedimensional model of the tundish–nozzle–mold was established for numerical simulation.The results indicate that the argon bubbles injected from the inner wall of the tundish upper nozzle first move downward along the nozzle wall under the action of the liquid steel.As the distance from the tundish upper nozzle increases,the argon bubbles gradually diffuse to the center of the nozzle.Compared with no argon blowing,the liquid steel velocity increases in the center of the nozzle and decreases near the wall with argon blowing.With increasing the argon flow rate,the concentration of bubbles in the nozzle increases,and the process of bubble group diffusion to the center region of the nozzle speeds up.This in turn increases the liquid steel velocity at the center of the nozzle but reduces near the wall.With increasing the casting speed,the concentration of bubbles in the nozzle decreases,the length of the bubble group near the nozzle wall is extended,and the liquid steel velocity at the center region and near-wall region of the nozzle increases.The mechanism of argon blowing at the tundish upper nozzle to prevent nozzle clogging is mainly realized by the isolation effect of the argon bubble group on the inner wall of the nozzle.展开更多
The fluid flow and the interfacial phenomenon of slag and metal in tundish with gas blowing were studied with mathematical and physical modeling, and the effects of gas flowrate, the placement of porous beam for the g...The fluid flow and the interfacial phenomenon of slag and metal in tundish with gas blowing were studied with mathematical and physical modeling, and the effects of gas flowrate, the placement of porous beam for the generation of bubbles, and the combination of flow control devices on the flow and slag-metal interface were investigated. The results show that the position of gas bubbling has a significant effect on the flow in tundish, and the placement of porous beam and gas flowrate are the two main factors affecting the entrapment of slag in tundish. The closer the porous beam to the weir, the more reasonable is the flow, which is in favor of the control of slag entrapment in tundish.展开更多
The bubble growth and detachment behavior in the bottom blowing process were investigated.Four multi-hole nozzle configurations with different opening ratios were assessed experimentally using high-speed photography a...The bubble growth and detachment behavior in the bottom blowing process were investigated.Four multi-hole nozzle configurations with different opening ratios were assessed experimentally using high-speed photography and digital image processing.For these configurations,the experiments reveal that the bubble growth consists of a petal-like stage,an expansion stage and a detachment stage.The petal-like shape is qualitatively described through the captured images,while the non-spherical bubbles are analyzed by the aspect ratio.The bubble size at the detachment is quantified by the maximum caliper distance and the bubble equivalent diameter.Considering the dependence on the opening ratio,different prediction models for the ratio of maximum caliper distance to hydraulic diameter of the nozzle outlet and the dimensionless bubble diameter are established.The comparative analysis results show that the proposed prediction model can accurately predict the bubble detachment size under the condition of multi-hole nozzles.展开更多
The water modelling experiments of 300 t converter concerning combined blowing parameters, the number, and configuration of bottom nozzles are carried out. The results show that the arrangement of 16 bottom nozzles at...The water modelling experiments of 300 t converter concerning combined blowing parameters, the number, and configuration of bottom nozzles are carried out. The results show that the arrangement of 16 bottom nozzles at 0. 40D and 0. 45D （hearth diameter） concentric circles is the reasonable solution. The combined blowing steel- making technique of 300 t converter has been developed through experiments and studies relating to optimizing the top-bottom combined blowing pattern, the number and configuration of the bottom nozzles, the type selection of bot- tom nozzle, and bottom nozzle maintenance techniques. The results show that the product of w[c] ＂ w[o] at endpoint is reduced from 0. 002 62 to 0. 002 43, average TFe content is decreased by %, phosphorus distribution is raised from 70.85 to 78.95, sulfur distribution is raised from 3.43 to 4.32 and manganese content is raised by 0.02%.展开更多
In order to increase the contact area and promote the mass transfer process of gas and liquid,the process of the bubble refine-ment in a metallurgical reactor with mechanical agitation was studied by physical simulati...In order to increase the contact area and promote the mass transfer process of gas and liquid,the process of the bubble refine-ment in a metallurgical reactor with mechanical agitation was studied by physical simulation.Based on the capillary number,a prediction equation for the bubble refinement was established.The effects of the gas flow rate,the stirring speed and thestirring depth on the bubble refinement in the reactor were discussed in detail.The distribution of the bubble diameter in thereactor was obtained under different conditions.The results show that when the stirring speed reaches 300 r/min,the bubblediamcter mainly distributes in the range of 1-2 mm.A higher gas flow rate may increase the number of bubbles in the meltand promote the bubble refinement process.The mechanism of bubble refinement under mechanical agitation was analyzed.and the results indicated that the stirring speed.,the blade area and the blade inclination are the main influencing factors.展开更多
The effects of operation parameters of combined blowing converter on the volumetric mass transfer coefficient between slag and steel are studied with a cold model with water simulating steel, oil simulating slag and b...The effects of operation parameters of combined blowing converter on the volumetric mass transfer coefficient between slag and steel are studied with a cold model with water simulating steel, oil simulating slag and benzoic acid as the transferred substance between water and oil. The results show that, with lance level of 2.1m and the top blowing rate of 25000Nm3/h, the volumetric mass transfer coefficient changes most significantly when the bottom blowing rate ranges from 384 to 540Nm3/h. The volumetric mass transfer coefficient reaches its maximum when the lance level is 2.1m, the top blowing rates is 30000Nm3/h, and the bottom blowing rate is 384Nm3/h with tuyeres located symmetrically at 0.66D of the converter bottom.展开更多
基金supported by the National Natural Science Foundation of China(No.U21A20317)the National Key Research and Development Program of China(No.2017YFB0304201).
文摘The top-bottom combined blowing converter mainly adopts the blowing method of top-blowing oxygen and bottom-blowing nitrogen.In the production process,there are some disadvantages,such as a significant temperature difference between the top and bottom of the molten pool,inadequate gas permeability of bottom blowing,and low decarburization efficiency.Therefore,we propose a novel bottom-blowing gas doped oxygen process to enhance the smelting conditions in the converter.The 500 kg medium frequency induction furnace with top and bottom-blowing function was used to explore the influence of the proportion of bottom-blowing gas doped oxygen on the smelting effect in different smelting cycles.Subsequently,industrial experimental verification was carried out on a 60 t converter.The results of intermediate frequency furnace experiments demonstrate that the bottom-blowing gas doped oxygen process exhibits a superior heating rate and decarburization efficiency during the initial and final stages of blowing compared to pure N2 used for bottom-blowing.Simultaneously,the dephosphorization efficiency exhibited an initial increase followed by a subsequent decrease as the bottom-blowing oxygen content increased.The industrial test of 60 t converter validates the findings above.Moreover,when the oxygen content in bottom-blowing gas is 5%,the average blowing time reduces by 54 s,and the minimum endpoint carbon-oxygen equilibrium reaches 0.00219 under this condition.The results demonstrate that the appropriate amount of oxygen doped in bottom-blowing gas can effectively enhance the metallurgical conditions of the converter and improve production efficiency.
基金supported by the National Key Research and Development Program of China(Grant No.2021YFC2802501)the National Natural Science Foundation of China(Grant Nos.41875025,62105367,42175154,42305084)+1 种基金the Hunan Provincial Natural Science Foundation of China(Grant Nos.2021JJ10047,2020JJ4662)the Research Project of National University of Defense Technology(Grant No.202401-YJRC-XX-030)。
文摘Blowing snow events in Antarctica play an important role in the climate system,affecting the mass balance of the ice sheet and the radiative effects of the atmosphere.Due to the harsh weather conditions in Antarctica,ground-based detection data is deficient,making it difficult to accurately obtain both the frequency of blowing snow and the evolution of the height of the blowing snow layer.In this study,we introduce a new method based on the raw signal from the C12 ceilometer to separate clear-sky,cloud,snowfall,and blowing snow conditions within a height of 500 meters above the surface of Zhongshan Station.Research has shown that more than 80%of the blowing snow at Zhongshan Station is affected by cyclonic systems,and less than 20%of the blowing snow is affected by katabatic winds.Further,Antarctic blowing snow is closely related to snowfall.When there is heavy snowfall(even a blizzard),a smaller wind speed can lead to the formation of a deep blowing snow layer within an hour after snowfall.However,as time increases,the threshold wind speed required to generate blowing snow significantly increases,and the thickness of the blowing snow layer becomes shallower.
基金co-supported by the National Natural Science Foundation of China(Nos.52472394,52425211,52201327,52272360)。
文摘Stall flutter poses great challenges to flight safety.To alleviate this problem,a steady blowing control considering the perturbation and wake-induced vibration at a large angle of attack is developed in this paper,where two blowings are configured on upper and lower tail surfaces to suppress the stall flutter.The stall flutter with one-degree-of-freedom is first evaluated by numerical simulation.The equation of motion for stall flutter is solved by the Newmark-β method.Then,the stall flutter responses for five blowing speeds,i.e.,0,4,12,20,and 28 m/s under the airspeed range of 3–9 m/s,are studied in detail.The stall flutter suppression mechanism can be summarized as follows:a large blowing speed can inject energy into the boundary layer and enhance the high-pressure zone,which delays the flow separation on the suction surface.In this way,the formation of the leading-edge separation vortex is suppressed.Thus,the dynamic stall vortex is weakened and accelerates shedding.In addition,the driving moment is reduced,which leads to a decrement in the stall flutter amplitude.When the blowing speed is 28 m/s(stall flutter amplitude=0.1357 rad),compared with uncontrolled case(stall flutter amplitude=0.6002 rad),the amplitude can decrease by 77.39%,which demonstrates the effectiveness of the proposed steady blowing based active control strategy.
基金The National Natural Science Foundation of China under contract Nos 42306255 and 41976217the National Key R&D Program of China under contract No.2018YFA0605903。
文摘Sea ice and snow are the most sensitive and important crucial components of the global climate system,affecting the global climate by modulating the energy exchange between the ocean and the atmosphere.The sea near Zhongshan Station in Antarctica is covered by landfast sea ice,with snow depth influenced by both thermal factors and wind.This region frequently experiences katabatic winds and cyclones from the westerlies,leading to frequent snow blowing events that redistribute the snow and affects its depth,subsequently impacting the thermodynamic growth of sea ice.This study utilized the one-dimensional thermodynamic model ICEPACK to simulate landfast sea ice thickness and snow depth near Zhongshan Station in 2016.Two parameterization schemes for snow blowing,the Bulk scheme,and the ITDrdg(ITD/ridges)scheme are evaluated for their impact on snow depth.The results show that simulations using snow blowing schemes more closely align with observed results,with the ITDrdg scheme providing more accurate simulations,evidenced by root mean square errors of less than 10 cm for both snow depth and sea ice thickness.Snow blowing also impacts the thermodynamic growth of sea ice,particularly bottom growth.The sea ice bottom increases by 9.0 cm using the ITDrdg scheme compared to simulations without the snow blowing,accounting for 12.5%of total sea ice bottom growth.Furthermore,snow blowing process also influences snow ice formation,highlighting its primary role in affecting snow depth.Continued field observations of snow blowing are necessary to evaluate and improve parameterization schemes.
基金financially supported by the National Natural Science Foundation of China (Nos.51974023 and52374321)the funding of State Key Laboratory of Advanced Metallurgy,University of Science and Technology Beijing,China (No.41620007)。
文摘The amount of oxygen blown into the converter is one of the key parameters for the control of the converter blowing process,which directly affects the tap-to-tap time of converter. In this study, a hybrid model based on oxygen balance mechanism (OBM) and deep neural network (DNN) was established for predicting oxygen blowing time in converter. A three-step method was utilized in the hybrid model. First, the oxygen consumption volume was predicted by the OBM model and DNN model, respectively. Second, a more accurate oxygen consumption volume was obtained by integrating the OBM model and DNN model. Finally, the converter oxygen blowing time was calculated according to the oxygen consumption volume and the oxygen supply intensity of each heat. The proposed hybrid model was verified using the actual data collected from an integrated steel plant in China, and compared with multiple linear regression model, OBM model, and neural network model including extreme learning machine, back propagation neural network, and DNN. The test results indicate that the hybrid model with a network structure of 3 hidden layer layers, 32-16-8 neurons per hidden layer, and 0.1 learning rate has the best prediction accuracy and stronger generalization ability compared with other models. The predicted hit ratio of oxygen consumption volume within the error±300 m^(3)is 96.67%;determination coefficient (R^(2)) and root mean square error (RMSE) are0.6984 and 150.03 m^(3), respectively. The oxygen blow time prediction hit ratio within the error±0.6 min is 89.50%;R2and RMSE are0.9486 and 0.3592 min, respectively. As a result, the proposed model can effectively predict the oxygen consumption volume and oxygen blowing time in the converter.
基金funded by the Joint Fund Project of Shaanxi(Grant No.2021JLM-32)the General Project of National Natural Science Foundation of China(Grant No.52374346).
文摘The bottom blowing element is the key equipment to ensure the bottom blowing effect of the converter.Three types of bottom blowing elements,dispersive type(D1),double circular seam(D2)and straight cylinder type(D3),were built,and the effects of bottom blowing element type on molten bath flow,wall erosion and furnace bottom erosion were simulated.It was found that when the bottom blowing elements of dispersive type(D1)and double circular seam(D2)were used,the dead zone area in the lower part of the molten bath was smaller,and the high-speed zone area was larger;therefore,the stirring effect on the bottom melt was better.When the straight cylinder type(D3)bottom blowing element was used,the gas penetrated the molten bath at a faster rate to reach the surface of molten bath and failed to disperse in the bottom molten bath,and the wall shear stress near the nozzle outlet was larger.When argon was blown by three different bottom blowing elements,the area of the wall shear stress greater than 3 Pa was 4.8,5.6 and 8.7 cm2,respectively,within 0.2 m of the bottom blowing nozzle outlet.
基金funded by the National Natural Science Foundation of China(Grant No.12172308)the Provincial Natural Science Foundation of Hunan(Grant No.2023JJ40260).
文摘In this study,the unsteady Reynolds-averaged Navier–Stokes algorithm coupled with the Discrete Phase Model(DPM)was used to study the accumulation of snow in the bogie region of a high-speed train under crosswind conditions.Moreover,the impact of active blowing schemes on the airflow around the bogie and the dynamics and deposition of snow particles were also assessed.According to the results:in the crosswind environment,active blowing changes the flow field in the bogie area,reducing the flow of air coming from the windward side and bottom of the bogie.The trajectory of snow particles carried by crosswinds is modified due to the reduced airflow into the bogie region.With no active blowing,snow accumulation is mainly concentrated in the bogie cavity,frame,and primary suspension;while it is reduced by nearly an order of magnitude as soon as blowing is enabled.Blowing speeds need to be distributed appropriately in order to achieve the best possible snow protection.Continuously increasing the blowing speed on one side does not improve the amount of snow in the bogie region.The optimal condition for snow prevention of the entire train is achieved with a windward side blowing speed of 4 m/s and a leeward side blowing speed of 6 m/s,resulting in a snow reduction rate of 95.6%.Moreover,higher blowing speeds on the leeward side are beneficial for mitigating snow accumulation in the bogie region.
基金supported by the National Key Research and Development Program of China(Grant no.2021YFC2802501).
文摘In this article,the relevant instruments and techniques for measuring solid precipitation and blowing snow are reviewed,with a focus on the in situ instrument measurements.Moreover,a literature review and specific observation activities for solid precipitation are provided,the working principles of several instruments are introduced,and the advantages and disadvantages,measurement performance,and specific application scenarios of the instruments are evaluated.Currently,there are numerous solid precipitation measurement instruments available,and the standardization and sustainability of these measurements also need to be considered.The purpose of the review is not to be exhaustive but to provide readers with information on the current status of the development of relevant technologies and the prospects for their application in the polar regions.
基金The authors would like to express their thanks for the support by the National Natural Science Foundation of China (No.51734003).
文摘Nowadays, in China, the bottom-blowing technique plays an important role in accelerating the molten bath stirring and promoting the metallurgical reactions in electric arc furnace (EAF) steelmaking. The innovations of bottom-blowing technologies in EAF steelmaking were reviewed. The optimized bottom-blowing arrangement in EAF based on the furnace structure and the position of electrodes was introduced, and the fluid flow characteristics of EAF molten bath with bottomblowing were analyzed. Furthermore, bottom-blowing CO2 in EAF can facilitate the carbon-oxygen reaction reaching equilibrium and decrease the content of nitrogen in molten steel due to its special metallurgical properties. Pulsating bottom-blowing in EAF can effectively improve the molten bath stirring through the action of the unsteady bottom blowing gas streams, which could make the fluid flow field more disorderly than the steady bottom-blowing. And submerged O2 injection with CO2 in EAF can noticeably strengthen the EAF molten bath stirring, increase the production efficiency and improve the molten steel quality.
基金Projects(51104080,u1137601) supported by the National Natural Science Foundation of ChinaProject(2009CD027) supported by the Natural Science Foundation of Yunnan Province,ChinaProject(14118557) supported by the Personnel Training Foundation of Kunming University of Science and Technology,China
文摘Gas blowing is a valid method to remove the impurities from metallurgical grade silicon（MG-Si） melt.The thermodynamic behavior of impurities Fe,Al,Ca,Ti,Cu,C,B and P in MG-Si was studied in the process of O2 blowing.The removal efficiencies of impurities in MG-Si were investigated using O2 blowing in ladle.It is found that the removal efficiencies are higher than 90% for Ca and Al and nearly 50% for B and Ti.The morphology of inclusions was analyzed and the phases Al3Ni,NiSi2 and Al3Ni were confirmed in MG-Si by X-ray diffraction.It was found that SiB4 exists in Si？B binary system.The chemical composition of inclusions in MG-Si before and after refining was analyzed by SEM-EDS.It is found that the amount of white inclusion reduces for the removal of most Al and Ca in the forms of molten slag inclusion and the contents of Fe,Ni and Mn in inclusion increase for their inertia in silicon melt with O2 blowing.
文摘The experiment was carried out in a combined blowing converter.The natural gas was supplied as the cooling medium for the bottom lance.The blow- ing practice of medium P hot metal (0.30-0.85% [P]) indicated that with better stirring at the bottom of the converter and lower P_(CO),this steelmgking process was favorable to reduce the amount of [C] and [O] and increase the (P_2O_5)/[P]. The maximum rate of dephospborization might be high up to 0.0a5%/min and the P content in steel could be reduced to lower than 0.03% by single slag-forming operation.
文摘Fluid flow characteristics in a four-strand tundish with gas blowing were studied by water modeling experiments.It is found that gas blowing can greatly improve the flow characteristics in the tundish with a turbulence inhibitor.It dramatically increases the peak concentration time,and greatly decreases the dead volume,and reduces the minimum residence time.The gas blowing location,gas flow rate,and porous plug area greatly influence the flow characteristics in the tundish; the gas blowing location near the baffle,smaller gas flow rate,and smaller porous plug area are better for improving the fluid flow characteristics.Using gas blowing can reduce the difference of flows at the middle outlets and side outlets for the multi-strand tundish.Bubbles produced by gas blowing can absorb small inclusions and provide the condition for inclusion collision and aggregation.Therefore,introducing gas blowing into a tundish and combining the turbulence inhibitor can improve inclusion floating and removal,and the cleanness of molten steel can be advanced.
基金financially supported by the National Natural Science Foundation of China(No.51704062)the Fundamental Research Funds for the Central Universities,China(No.N2025019)。
文摘A three-dimensional mathematical model was developed to investigate the effect of gas blowing nozzle angles on multiphase flow,circulation flow rate,and mixing time during Ruhrstahl-Heraeus(RH) refining process.Also,a water model with a geometric scale of 1:4 from an industrial RH furnace of 260 t was built up,and measurements were carried out to validate the mathematical model.The results show that,with a conventional gas blowing nozzle and the total gas flow rate of 40 L·min^(-1),the mixing time predicted by the mathematical model agrees well with the measured values.The deviations between the model predictions and the measured values are in the range of about 1.3%–7.3% at the selected three monitoring locations,where the mixing time was defined as the required time when the dimensionless concentration is within 3% deviation from the bath averaged value.In addition,the circulation flow rate was 9 kg·s^(-1).When the gas blowing nozzle was horizontally rotated by either 30° or 45°,the circulation flow rate was found to be increased by about 15% compared to a conventional nozzle,due to the rotational flow formed in the up-snorkel.Furthermore,the mixing time at the monitoring point 1,2,and 3 was shortened by around 21.3%,28.2%,and 12.3%,respectively.With the nozzle angle of 30° and 45°,the averaged residence time of 128 bubbles in liquid was increased by around 33.3%.
基金supported by the Science Engineering Research Board(SERB)Department of Science&Technology(DST)+1 种基金Government of India(No.ECR/2017/001199)SERB/DST for their financial assistance in carrying out this research work through Early Career Research Award
文摘Recent research proves that wings with leading-edge tubercles have the ability to perform efficiently in post-stall region over the conventional straight wing. Moreover, the conventional straight wing outperforms the tubercled wing at a pre-stall region which is quintessential. Even though tubercled wing offers great performance enhancement, because of the complexity of the flow, the trough region of the tubercled wing is more prone to flow separation. Henceforth, the present paper aims at surface blowing – an active flow control technique over the tubercled wing to enhance the aerodynamic efficiency by positively influencing its lift characteristics without causing any additional drag penalty. Flow parameters like blowing velocity ratios and the location of blowing were chosen to find the optimised configuration keeping the amplitude and frequency of the leading-edge tubercles constant as 0.12 c and 0.25 c respectively. Numerical investigations were carried out over the baseline tubercled wing and tubercled wing with surface blowing at various blowing jet velocity ratios 0.5, 1 and 2 over four different chordwise locations ranging from 0.3 c to 0.8 c.The results confirm that blowing at various x/c with different blowing velocity ratios performs better than the conventional tubercled wing. Comparatively, blowing velocity ratio 2 at 0.3 c shows peak performance of about 28% enhancement in the lift characteristics relative to the baseline model. Particularly, in the pre-stall region, 25–50% increase in aerodynamic efficiency is evident over the tubercled wing with surface blowing compared with the baseline case. Additionally,attempts were made to delineate the physical significance of the flow separation mechanism due to blowing by visualizing the streamline pattern.
基金the National Natural Science Foundation of China(Nos.51874215 and 51974213).
文摘In continuous casting,the argon blowing at the tundish upper nozzle is usually used to prevent nozzle clogging,whose effect is closely related to the migration of argon bubbles and the flow behavior of the liquid steel in the nozzle.Here,to investigate the effects of argon blowing at the tundish upper nozzle on multiphase flow behavior in nozzle,a threedimensional model of the tundish–nozzle–mold was established for numerical simulation.The results indicate that the argon bubbles injected from the inner wall of the tundish upper nozzle first move downward along the nozzle wall under the action of the liquid steel.As the distance from the tundish upper nozzle increases,the argon bubbles gradually diffuse to the center of the nozzle.Compared with no argon blowing,the liquid steel velocity increases in the center of the nozzle and decreases near the wall with argon blowing.With increasing the argon flow rate,the concentration of bubbles in the nozzle increases,and the process of bubble group diffusion to the center region of the nozzle speeds up.This in turn increases the liquid steel velocity at the center of the nozzle but reduces near the wall.With increasing the casting speed,the concentration of bubbles in the nozzle decreases,the length of the bubble group near the nozzle wall is extended,and the liquid steel velocity at the center region and near-wall region of the nozzle increases.The mechanism of argon blowing at the tundish upper nozzle to prevent nozzle clogging is mainly realized by the isolation effect of the argon bubble group on the inner wall of the nozzle.
基金Item Sponsored by National Natural Science Foundation of China (50674020)Program for New Century Excellent Talents in University (NCET-04-0285)
文摘The fluid flow and the interfacial phenomenon of slag and metal in tundish with gas blowing were studied with mathematical and physical modeling, and the effects of gas flowrate, the placement of porous beam for the generation of bubbles, and the combination of flow control devices on the flow and slag-metal interface were investigated. The results show that the position of gas bubbling has a significant effect on the flow in tundish, and the placement of porous beam and gas flowrate are the two main factors affecting the entrapment of slag in tundish. The closer the porous beam to the weir, the more reasonable is the flow, which is in favor of the control of slag entrapment in tundish.
基金Project(51676211)supported by the National Natural Science Foundation of ChinaProject(2015zzts044)supported by Innovation Foundation for Postgraduate of Central South University,ChinaProject(2017SK2253)supported by the Key R&D Plan of Hunan Province,China
文摘The bubble growth and detachment behavior in the bottom blowing process were investigated.Four multi-hole nozzle configurations with different opening ratios were assessed experimentally using high-speed photography and digital image processing.For these configurations,the experiments reveal that the bubble growth consists of a petal-like stage,an expansion stage and a detachment stage.The petal-like shape is qualitatively described through the captured images,while the non-spherical bubbles are analyzed by the aspect ratio.The bubble size at the detachment is quantified by the maximum caliper distance and the bubble equivalent diameter.Considering the dependence on the opening ratio,different prediction models for the ratio of maximum caliper distance to hydraulic diameter of the nozzle outlet and the dimensionless bubble diameter are established.The comparative analysis results show that the proposed prediction model can accurately predict the bubble detachment size under the condition of multi-hole nozzles.
文摘The water modelling experiments of 300 t converter concerning combined blowing parameters, the number, and configuration of bottom nozzles are carried out. The results show that the arrangement of 16 bottom nozzles at 0. 40D and 0. 45D （hearth diameter） concentric circles is the reasonable solution. The combined blowing steel- making technique of 300 t converter has been developed through experiments and studies relating to optimizing the top-bottom combined blowing pattern, the number and configuration of the bottom nozzles, the type selection of bot- tom nozzle, and bottom nozzle maintenance techniques. The results show that the product of w[c] ＂ w[o] at endpoint is reduced from 0. 002 62 to 0. 002 43, average TFe content is decreased by %, phosphorus distribution is raised from 70.85 to 78.95, sulfur distribution is raised from 3.43 to 4.32 and manganese content is raised by 0.02%.
基金supported by the National Natural Science Foundation of China(U1508217,U1702253 and 51774078)the Fundamental Research Funds for the Central Universities(N172506009 and N170908001).
文摘In order to increase the contact area and promote the mass transfer process of gas and liquid,the process of the bubble refine-ment in a metallurgical reactor with mechanical agitation was studied by physical simulation.Based on the capillary number,a prediction equation for the bubble refinement was established.The effects of the gas flow rate,the stirring speed and thestirring depth on the bubble refinement in the reactor were discussed in detail.The distribution of the bubble diameter in thereactor was obtained under different conditions.The results show that when the stirring speed reaches 300 r/min,the bubblediamcter mainly distributes in the range of 1-2 mm.A higher gas flow rate may increase the number of bubbles in the meltand promote the bubble refinement process.The mechanism of bubble refinement under mechanical agitation was analyzed.and the results indicated that the stirring speed.,the blade area and the blade inclination are the main influencing factors.
文摘The effects of operation parameters of combined blowing converter on the volumetric mass transfer coefficient between slag and steel are studied with a cold model with water simulating steel, oil simulating slag and benzoic acid as the transferred substance between water and oil. The results show that, with lance level of 2.1m and the top blowing rate of 25000Nm3/h, the volumetric mass transfer coefficient changes most significantly when the bottom blowing rate ranges from 384 to 540Nm3/h. The volumetric mass transfer coefficient reaches its maximum when the lance level is 2.1m, the top blowing rates is 30000Nm3/h, and the bottom blowing rate is 384Nm3/h with tuyeres located symmetrically at 0.66D of the converter bottom.
