The one dimensional mathematical model of the air drag in melt blowing process, which had been put forward by Uyttendaele and Shambaugh is improved. The influence of the density and the specific heat capacity of polym...The one dimensional mathematical model of the air drag in melt blowing process, which had been put forward by Uyttendaele and Shambaugh is improved. The influence of the density and the specific heat capacity of polymer melt at constant pressure changing with polymer temperature on fiber diameter are studied. The power - law model is introduced as the constitutive equation. The influences of polymer volume flow rate, initial polymer temperature, initial air velocity and initial air temperature on fiber diameter are discussed.展开更多
Oxygen rich combustion is a mean to increase the energy efficiency and to contribute to CO2 capture. Influence of oxygen enriched air on the stability of methane flames from non premixed laminar jets has been investig...Oxygen rich combustion is a mean to increase the energy efficiency and to contribute to CO2 capture. Influence of oxygen enriched air on the stability of methane flames from non premixed laminar jets has been investigated experimentally. The burner consists of two coaxial jets: methane flowing out of the inner, oxidizer from the outer. The flame behavior is studied according to the proportion of oxygen in the oxidizer jet, the oxidizer and the methane jets velocities. The flame is either anchored to the burner, lifted, stationary or not or blown-out. The addition of oxygen produces a decrease of the lift height, a reduction of the length of the reaction zone and an increase in the soot emission. These results have been reported into diagrams of stability where the flame configurations are connected to the competition between the dynamic effect of the injection velocity and the chemical effect of oxygen addition.展开更多
Compressed air is an integral utility part of industrial utility systems. Any improvement in compressed air system will lead to reduction in utility cost. The effectiveness of utilization side of compressed air is usu...Compressed air is an integral utility part of industrial utility systems. Any improvement in compressed air system will lead to reduction in utility cost. The effectiveness of utilization side of compressed air is usually dependent upon operator’s discretion. There are no performance testing methods available for testing existing end use equipments. A test apparatus for estimation of compressed air flow based on measurement of pressure reduction in a fixed volume cylinder in a given time is developed. The test apparatus is easy to build and simple to operate in an industrial environment. This can be used for measuring performance of any pneumatic end-use equipment and for benchmarking the performance. The test apparatus was used in a foundry for quantifying the performance of the old and new blow guns.展开更多
Panax notoginseng is grown mainly in Yunnan Province.Under the present high-density planting patterns for the plant,to solve the problems of a high rate of seed damage and the inability to use a traditional single air...Panax notoginseng is grown mainly in Yunnan Province.Under the present high-density planting patterns for the plant,to solve the problems of a high rate of seed damage and the inability to use a traditional single air-blowing metering device,this paper designs a six-row air-blowing centralized precision seed-metering device for P.notoginseng to realize mechanized precision seeding of this species.This paper describes the working principle of the seed-metering device,and the main structural parameters are determined by combining theoretical calculations with simulation analysis.A mechanics model of the seed filling,cleaning and pressing processes of the seed-metering device was constructed.The seeds of P.notoginseng in Yunnan Province were selected as experimental subjects.An experimental study on the seed-metering performance of the seed-metering device was carried out using the quadratic rotation orthogonal combination test method.The outlet pressure of the air nozzle,forward velocity and cone angle of the hole were selected as test factors.Mathematical models of the grain spacing qualified index,miss index,multiple index and the coefficient of variation of the row displacement consistency were established to analyze the order of factors affecting indicators.Through parameter optimization,the optimum combination of parameters was determined as follows:the cone angle of the hole is 50°,the forward velocity is less than 0.73 m/s,and the outlet pressure of the air nozzle is 0.32-0.52 kPa.The qualified index of grain spacing is higher than 94%,the miss index is less than 3%,the multiple index is less than 5%,and the coefficient of variation of the row displacement consistency is less than 5%.The test results are essentially consistent with the optimization results.The metering device meets the requirements of precision seeding of P.notoginseng.This study provides a basis for the design of a six-row air-blowing centralized precision seed-metering device for P.notoginseng.展开更多
The paper sheds light on the idle lean blow off(LBO)problem for high fuel air ratio(FAR)com⁃bustor,which is impossible to be addressed with traditional aero combustor design.A significant improvement in aero combustor...The paper sheds light on the idle lean blow off(LBO)problem for high fuel air ratio(FAR)com⁃bustor,which is impossible to be addressed with traditional aero combustor design.A significant improvement in aero combustor design is required to resolve the idle LBO issue.The authors detailed a practical and efficient solu⁃tion,which not only solved the idle LBO issue but also defined the aero-thermal design for high-FAR combustor.The design will usher in a new era of aero combustor.展开更多
文摘The one dimensional mathematical model of the air drag in melt blowing process, which had been put forward by Uyttendaele and Shambaugh is improved. The influence of the density and the specific heat capacity of polymer melt at constant pressure changing with polymer temperature on fiber diameter are studied. The power - law model is introduced as the constitutive equation. The influences of polymer volume flow rate, initial polymer temperature, initial air velocity and initial air temperature on fiber diameter are discussed.
文摘Oxygen rich combustion is a mean to increase the energy efficiency and to contribute to CO2 capture. Influence of oxygen enriched air on the stability of methane flames from non premixed laminar jets has been investigated experimentally. The burner consists of two coaxial jets: methane flowing out of the inner, oxidizer from the outer. The flame behavior is studied according to the proportion of oxygen in the oxidizer jet, the oxidizer and the methane jets velocities. The flame is either anchored to the burner, lifted, stationary or not or blown-out. The addition of oxygen produces a decrease of the lift height, a reduction of the length of the reaction zone and an increase in the soot emission. These results have been reported into diagrams of stability where the flame configurations are connected to the competition between the dynamic effect of the injection velocity and the chemical effect of oxygen addition.
文摘Compressed air is an integral utility part of industrial utility systems. Any improvement in compressed air system will lead to reduction in utility cost. The effectiveness of utilization side of compressed air is usually dependent upon operator’s discretion. There are no performance testing methods available for testing existing end use equipments. A test apparatus for estimation of compressed air flow based on measurement of pressure reduction in a fixed volume cylinder in a given time is developed. The test apparatus is easy to build and simple to operate in an industrial environment. This can be used for measuring performance of any pneumatic end-use equipment and for benchmarking the performance. The test apparatus was used in a foundry for quantifying the performance of the old and new blow guns.
基金This research was supported by the National Natural Science Foundation of China(51975265,31960366)the Key Grant Project of Yunnan Province(2018ZC001-3,2018ZC001-4,2018ZC001-5)the Yunnan Province University Engineering Research Center Construction Plan Project.
文摘Panax notoginseng is grown mainly in Yunnan Province.Under the present high-density planting patterns for the plant,to solve the problems of a high rate of seed damage and the inability to use a traditional single air-blowing metering device,this paper designs a six-row air-blowing centralized precision seed-metering device for P.notoginseng to realize mechanized precision seeding of this species.This paper describes the working principle of the seed-metering device,and the main structural parameters are determined by combining theoretical calculations with simulation analysis.A mechanics model of the seed filling,cleaning and pressing processes of the seed-metering device was constructed.The seeds of P.notoginseng in Yunnan Province were selected as experimental subjects.An experimental study on the seed-metering performance of the seed-metering device was carried out using the quadratic rotation orthogonal combination test method.The outlet pressure of the air nozzle,forward velocity and cone angle of the hole were selected as test factors.Mathematical models of the grain spacing qualified index,miss index,multiple index and the coefficient of variation of the row displacement consistency were established to analyze the order of factors affecting indicators.Through parameter optimization,the optimum combination of parameters was determined as follows:the cone angle of the hole is 50°,the forward velocity is less than 0.73 m/s,and the outlet pressure of the air nozzle is 0.32-0.52 kPa.The qualified index of grain spacing is higher than 94%,the miss index is less than 3%,the multiple index is less than 5%,and the coefficient of variation of the row displacement consistency is less than 5%.The test results are essentially consistent with the optimization results.The metering device meets the requirements of precision seeding of P.notoginseng.This study provides a basis for the design of a six-row air-blowing centralized precision seed-metering device for P.notoginseng.
文摘The paper sheds light on the idle lean blow off(LBO)problem for high fuel air ratio(FAR)com⁃bustor,which is impossible to be addressed with traditional aero combustor design.A significant improvement in aero combustor design is required to resolve the idle LBO issue.The authors detailed a practical and efficient solu⁃tion,which not only solved the idle LBO issue but also defined the aero-thermal design for high-FAR combustor.The design will usher in a new era of aero combustor.