This experiment is to study the special resistant induced by the high-speed evaporation surrounding themoving high-temperature particles. An observable equipment was designed, in which the first 11 experiments wereper...This experiment is to study the special resistant induced by the high-speed evaporation surrounding themoving high-temperature particles. An observable equipment was designed, in which the first 11 experiments wereperformed by pouring one or several Zirconia spheres with various high-temperature and a diameter of 3～ 10 mminto a water pool. The particles falling-down speeds were recorded by high-speed photographic instrumentation,and pressures and water temperatures were measured. A comparison between the experiments with cold and hotspheres respectively, employing three different sphere types each, was presented. The experimental data, com-pared with the theory of the evaporation drag model, are nearly identical.展开更多
The importance to industry of non-contact bearings is growing rapidly as the demand for highspeed and high-precision manufacturing equipment increases.As a recently developed non-contact technology,near-field acoustic...The importance to industry of non-contact bearings is growing rapidly as the demand for highspeed and high-precision manufacturing equipment increases.As a recently developed non-contact technology,near-field acoustic levitation(NFAL)has drawn much attention for the advantages it offers,including no requirement for an external pressurized air supply,its compact structure,and its ability to adapt to its environment.In this paper,the working mechanism of NFAL is introduced in detail and compared to all existing non-contact technologies to demonstrate its versatility and potential for practical applications in industry.The fundamental theory of NFAL,including gas film lubrication theory and acoustic radiation pressure theory is presented.Then,the current stateof-the-art of the design and development of squeeze film air bearings based on NFAL is reviewed.Finally,future trends and obstacles to more widespread use are discussed.展开更多
文摘This experiment is to study the special resistant induced by the high-speed evaporation surrounding themoving high-temperature particles. An observable equipment was designed, in which the first 11 experiments wereperformed by pouring one or several Zirconia spheres with various high-temperature and a diameter of 3～ 10 mminto a water pool. The particles falling-down speeds were recorded by high-speed photographic instrumentation,and pressures and water temperatures were measured. A comparison between the experiments with cold and hotspheres respectively, employing three different sphere types each, was presented. The experimental data, com-pared with the theory of the evaporation drag model, are nearly identical.
基金the financial support from the National Natural Science Foundation of China(Nos.51575170 and 51875185)the National Key R&D Program of China(2018YFB2000100)the Foundation of Hunan Province(2018JJ1006).
文摘The importance to industry of non-contact bearings is growing rapidly as the demand for highspeed and high-precision manufacturing equipment increases.As a recently developed non-contact technology,near-field acoustic levitation(NFAL)has drawn much attention for the advantages it offers,including no requirement for an external pressurized air supply,its compact structure,and its ability to adapt to its environment.In this paper,the working mechanism of NFAL is introduced in detail and compared to all existing non-contact technologies to demonstrate its versatility and potential for practical applications in industry.The fundamental theory of NFAL,including gas film lubrication theory and acoustic radiation pressure theory is presented.Then,the current stateof-the-art of the design and development of squeeze film air bearings based on NFAL is reviewed.Finally,future trends and obstacles to more widespread use are discussed.
