During the harvesting process,rigid materials are prone to causing damage to the cotton stalks,which will increase the risk of stalk breakage.A cotton stalk pulling component that blends stiff and flexible materials w...During the harvesting process,rigid materials are prone to causing damage to the cotton stalks,which will increase the risk of stalk breakage.A cotton stalk pulling component that blends stiff and flexible materials was devised to lower the breaking rate.The cotton stalk pulling component was made up of rollers and flexible belts that pull the stalks using clamping force and the forward speed of the tractor.The influence of various factors in the equipment on the harvesting effect of cotton stalks were analyzed through response surface experiments,and a multiple quadratic regression response surface model with missing pulling rate and breakage rate as response values was established.The significant of influencing factors on the breaking rate of cotton stalks are in a descending order as:the angle of cotton stalk pulling,tractor’s forward speed,and the clamping speed of the cotton stalk component.The working parameters of the wheel-belt type cotton stalk pulling machine have been optimized using the response surface combination experimental method,and the optimal parameter combination was obtained as:tractor forward speed of 4.5 km/h,cotton stalk pulling angle of 60°,and clamping speed of the cotton stalk pulling component of 349 r/min.The results of validation experiments showed that the missing pulling rate of cotton stalks was 5.06%and the breakage rate was 13.12%,indicating a good harvesting effect of the cotton stalks.The model was reasonable and the performance parameters could meet the relevant inspection requirements.The results can provide a reference for further research on the technology of flexible cotton stalk pulling.展开更多
The unstable fluid flow and severe free surface fluctuations in the wheel and belt caster can affect the quality of the cast bar.The lower level height tends to entrap inclusions in the molten metal.On the other hand,...The unstable fluid flow and severe free surface fluctuations in the wheel and belt caster can affect the quality of the cast bar.The lower level height tends to entrap inclusions in the molten metal.On the other hand,the higher level height makes the production process more dangerous due to the overflow of high temperature fluid from the mold.A computational model of the molten metal pouring process was established.The transient fluid flow and free surface fluctuations behavior were calculated using the three-dimensional large eddy simulation model and the volume of fluid model.The results show that the flow velocity of the main jet gradually decreases under the influence of the low kinetic energy fluid in the mold.There is an obvious oscillation in the tail of the jet,while the flow field is asymmetric in space.The jet is closer to the inside radius side due to the Coanda effect,and there is a recirculation zone on the inside radius and the outside radius respectively,according to the 10 s time-averaged results.Compared with the industrial observation and simulation results,the shape of the free surface is a wave that varies with time.In addition,the free surface height is lowest and the flow velocity is highest in the region near the jet.展开更多
基金financially supported by the National Nature Foundation Project(Grant No.52365038)the National Nature Foundation Project(Grant No.51865058)+3 种基金the Xinjiang Uygur Autonomous Region Agricultural Science and Technology Extension and Service Project(Grant No.NTFW-2022-17)the Xinjiang Uygur Autonomous Region Key R&D Project(Grant No.2022B02022-2)the Xinjiang Uygur Autonomous Region Key R&D Project(Grant No.2022B02023-3)the Xinjiang Uygur Autonomous Region Youth Science Fund(Grant No.2022D01B91).
文摘During the harvesting process,rigid materials are prone to causing damage to the cotton stalks,which will increase the risk of stalk breakage.A cotton stalk pulling component that blends stiff and flexible materials was devised to lower the breaking rate.The cotton stalk pulling component was made up of rollers and flexible belts that pull the stalks using clamping force and the forward speed of the tractor.The influence of various factors in the equipment on the harvesting effect of cotton stalks were analyzed through response surface experiments,and a multiple quadratic regression response surface model with missing pulling rate and breakage rate as response values was established.The significant of influencing factors on the breaking rate of cotton stalks are in a descending order as:the angle of cotton stalk pulling,tractor’s forward speed,and the clamping speed of the cotton stalk component.The working parameters of the wheel-belt type cotton stalk pulling machine have been optimized using the response surface combination experimental method,and the optimal parameter combination was obtained as:tractor forward speed of 4.5 km/h,cotton stalk pulling angle of 60°,and clamping speed of the cotton stalk pulling component of 349 r/min.The results of validation experiments showed that the missing pulling rate of cotton stalks was 5.06%and the breakage rate was 13.12%,indicating a good harvesting effect of the cotton stalks.The model was reasonable and the performance parameters could meet the relevant inspection requirements.The results can provide a reference for further research on the technology of flexible cotton stalk pulling.
基金supported by Innovative Research Groups Project of the Natural Science Foundation of Hebei Province(No.E2021203011)Central Government Guides Local Science and Technology Development Fund Projects(No.206Z1601G).
文摘The unstable fluid flow and severe free surface fluctuations in the wheel and belt caster can affect the quality of the cast bar.The lower level height tends to entrap inclusions in the molten metal.On the other hand,the higher level height makes the production process more dangerous due to the overflow of high temperature fluid from the mold.A computational model of the molten metal pouring process was established.The transient fluid flow and free surface fluctuations behavior were calculated using the three-dimensional large eddy simulation model and the volume of fluid model.The results show that the flow velocity of the main jet gradually decreases under the influence of the low kinetic energy fluid in the mold.There is an obvious oscillation in the tail of the jet,while the flow field is asymmetric in space.The jet is closer to the inside radius side due to the Coanda effect,and there is a recirculation zone on the inside radius and the outside radius respectively,according to the 10 s time-averaged results.Compared with the industrial observation and simulation results,the shape of the free surface is a wave that varies with time.In addition,the free surface height is lowest and the flow velocity is highest in the region near the jet.
