An air-lift has been more recently applied in the dredging, deep-seated beach placer mining and underground mining engineering. However, the influence and mechanism of various parameters on the air-lift performance ar...An air-lift has been more recently applied in the dredging, deep-seated beach placer mining and underground mining engineering. However, the influence and mechanism of various parameters on the air-lift performance are not quite clear, especially the influence of flow pattern on lifting efficiency. Focusing on the problems mentioned above, the key part of the air-lift （namely, the air injector） was proposed aimed to reduce friction loss in the inner pipe according to improving flow field performance, thus increase the lifting efficiency. The study of relative factors of the performance of an air-lift is performed and the river sand is used as simulation of underground ore bed. The total lifting height of the experimental system is 3 m, the water flux, mass flow of solid particles, concentration of particles and lifting efficiency are measured under the same submergence ratios by changing the air injector, which is divided into nine specifications of air injection in this research. The experimental results indicate that the optimal air flow rate corresponding to excellent performance of the air-lift can be obtained in the range of 35-40 m3/h. The air injection method has a great effect on the performance of the air-lift, the air injector with three nozzles is better than that in the case of one or two nozzles. Further more, the air injection angle and arrangement of air injection pipes also have great effect on the performance of an air-lift. The proposed research results have guiding significance for engineering application.展开更多
To date,no experimental study has been done on eliminating the energy consumption of the flapping wing rotor(FWR;caused by inertial force)based on an energy capture mechanism(such as a spring).Also,the effect of the v...To date,no experimental study has been done on eliminating the energy consumption of the flapping wing rotor(FWR;caused by inertial force)based on an energy capture mechanism(such as a spring).Also,the effect of the variation amplitude of the twist angles on the FWR remains unknown.In this study,a 19.2-g FWR model is designed and manufactured.Three different kinds of springs are then selected and assembled onto the FWR to reduce the energy consumption caused by the inertial forces.Afterward,a motion capture system and a lift measurement system are built to test the aerodynamic and kinematic performance of the FWR.Then,the influence of the variation range of the twist angles and the dimensions of the spring on the motion parameters and lift efficiency of the FWR is analyzed.If the rigid twist angle variation range is set to 10°–70°instead of 10°–50°,the FWR can generate 3 to 10 g of greater average lifts under the same input voltage.In most cases,the introduction of the spring also improves the average lifting rate by 1-4 g.The lift enhancement effect induced by the spring is more pronounced when the main frequency with the maximum amplitude is close to or coincides with the resonant frequency of the FWR structure.If the main frequency is greater than the resonance frequency of the FWR structure,the lift enhancement effect is hardly observed.In conclusion,according to experimental analyses,both the selection of 10°-70°preset twist angles and the application of springs can improve the lift efficiency of FWR and overcome the weight of the FWR system(37.8 g)assembled with a flight control system.Free-flight test results show that the FWR system(including the 19.2-g FWR model and an 18.6-g flight control system)has sufficient lifting margin to successfully perform a take-off mission and achieve a stable hovering action.展开更多
基金supported by Ministry of Science and Technology of China (Grant No. 2008DFA70300)
文摘An air-lift has been more recently applied in the dredging, deep-seated beach placer mining and underground mining engineering. However, the influence and mechanism of various parameters on the air-lift performance are not quite clear, especially the influence of flow pattern on lifting efficiency. Focusing on the problems mentioned above, the key part of the air-lift （namely, the air injector） was proposed aimed to reduce friction loss in the inner pipe according to improving flow field performance, thus increase the lifting efficiency. The study of relative factors of the performance of an air-lift is performed and the river sand is used as simulation of underground ore bed. The total lifting height of the experimental system is 3 m, the water flux, mass flow of solid particles, concentration of particles and lifting efficiency are measured under the same submergence ratios by changing the air injector, which is divided into nine specifications of air injection in this research. The experimental results indicate that the optimal air flow rate corresponding to excellent performance of the air-lift can be obtained in the range of 35-40 m3/h. The air injection method has a great effect on the performance of the air-lift, the air injector with three nozzles is better than that in the case of one or two nozzles. Further more, the air injection angle and arrangement of air injection pipes also have great effect on the performance of an air-lift. The proposed research results have guiding significance for engineering application.
基金supported by the Natural Science Foundation of Zhejiang Province(Grant No.LQ22A020006)the National Natural Science Foundation of China(Grant No.52105285)+3 种基金the Aeronautical Science Foundation Program(Grant No.ASFC-20230023052001)China Postdoctoral Science Foundation(Grant No.2024M754237)Science and Technology Project of Jiangxi Education Department(Grant No.GJJ200452)Basic Public Welfare Research Program of Wenzhou(Grant No.G2023046)。
文摘To date,no experimental study has been done on eliminating the energy consumption of the flapping wing rotor(FWR;caused by inertial force)based on an energy capture mechanism(such as a spring).Also,the effect of the variation amplitude of the twist angles on the FWR remains unknown.In this study,a 19.2-g FWR model is designed and manufactured.Three different kinds of springs are then selected and assembled onto the FWR to reduce the energy consumption caused by the inertial forces.Afterward,a motion capture system and a lift measurement system are built to test the aerodynamic and kinematic performance of the FWR.Then,the influence of the variation range of the twist angles and the dimensions of the spring on the motion parameters and lift efficiency of the FWR is analyzed.If the rigid twist angle variation range is set to 10°–70°instead of 10°–50°,the FWR can generate 3 to 10 g of greater average lifts under the same input voltage.In most cases,the introduction of the spring also improves the average lifting rate by 1-4 g.The lift enhancement effect induced by the spring is more pronounced when the main frequency with the maximum amplitude is close to or coincides with the resonant frequency of the FWR structure.If the main frequency is greater than the resonance frequency of the FWR structure,the lift enhancement effect is hardly observed.In conclusion,according to experimental analyses,both the selection of 10°-70°preset twist angles and the application of springs can improve the lift efficiency of FWR and overcome the weight of the FWR system(37.8 g)assembled with a flight control system.Free-flight test results show that the FWR system(including the 19.2-g FWR model and an 18.6-g flight control system)has sufficient lifting margin to successfully perform a take-off mission and achieve a stable hovering action.
