The Double-Jet Film-Cooling （DJFC） technology is invented by the authors and comprises a significant enhancement of the adiabatic film-cooling effectiveness due to the formation of anti-kidney vortices. The DJFC tec...The Double-Jet Film-Cooling （DJFC） technology is invented by the authors and comprises a significant enhancement of the adiabatic film-cooling effectiveness due to the formation of anti-kidney vortices. The DJFC technology places a second ejection hole with compound angle in a double-hole arrangement downstream the first hole. The second hole creates a second jet with another dominating vortex rotating in opposite direction to the first one and then combines both jets to one jet. The basic applicability and function of the DJFC technology has been proven by the numerical studies and testing in a test rig. The comparison of the experimental results of the adiabatic film cooling effectiveness to the numerical results for the same blowing ratio （M=（pc）c/（pc）h） shows qualitatively similar distributions. However, the experimental results show enhanced mixing-out of the cooling air and, thus, the experimental values of the adiabatic film cooling effectiveness are lower compared to the numerical values.展开更多
In this work, commercially pure Zr sheets were subjected to β air cooling and then rolled to different reductions(10% and 50%)at room temperature. Microstructures of both the β-air-cooled and the rolled specimens we...In this work, commercially pure Zr sheets were subjected to β air cooling and then rolled to different reductions(10% and 50%)at room temperature. Microstructures of both the β-air-cooled and the rolled specimens were well characterized by electron channelling contrast imaging and electron backscatter diffraction techniques, with special attentions paid to their misorientation characteristics. Results show that the β-air-cooled specimen owns a Widmanst?tten structure featured by lamellar grains with typical phase transformation misorientations. The 10% rolling allows prismatic slip and tensile twinning({11-21}<11-2-6> and{10-12}<10-11>) to be activated profusely, which produce new low-angle(~3°–5°) and high-angle(~35° and ~85°) misorientation peaks, respectively. After increasing the rolling reduction to 50%, twinning is suppressed and dislocation slip becomes the dominant deformation mode, with the lamellar grains highly elongated and aligned towards the rolling direction.Meanwhile, only one strong low-angle misorientation peak related to the prismatic slip is presented in the 50%-rolled specimen,with all other peaks disappeared. Analyses on local misorientations reveal that hardly any residual strains exist in the β-air-cooled specimen, which should be related to their sufficient relaxation during slow cooling. Residual strains introduced by 10% rolling are heterogeneously distributed near grain/twin boundaries while heavier deformation(50% rolling) produces much larger residual strains pervasively existing throughout the specimen microstructure.展开更多
Cryogenic electron microscopy(cryo-EM)has extensively boosted structural biology research since the“resolution revolution”in the year of 2013 which was soon awarded the Nobel Prize in Chemistry in 2017.The advances ...Cryogenic electron microscopy(cryo-EM)has extensively boosted structural biology research since the“resolution revolution”in the year of 2013 which was soon awarded the Nobel Prize in Chemistry in 2017.The advances in camera techniques and software algorithms enabled cryoEM to routinely characterize the three-dimensional structures of biomolecules at near-atomic resolution.Biomolecules are basically sensitive to electron irradiation damage,which can be minimized at cryo-temperature.This principle has inspired material scientists to characterize electron beam-or air-sensitive materials by cryo-EM,such as the electrodes in the lithium-ion battery,metal-organic frameworks(MOFs),covalent-organic frameworks(COFs)and zeolites.In addition,the reaction systems can be fast-frozen at vitreous ice in cryoEM,which correspondingly preserves the materials at the close-to-native state.Herein,we summarized the development and applications of both the cryo-EM technique and other emerging cryo-techniques in materials science,and energy storage and conversion.Cryo-EM techniques,capable of the direct observation of sensitive materials and electrochemical reaction processes,will greatly renew our understanding of materials science and related mechanisms.展开更多
The collision of a supercooled water droplet with a surface result an object creates ice accretion on the surface. The icing problem in any cold environments leads to severe damages on aircrafts, and a lot of studies ...The collision of a supercooled water droplet with a surface result an object creates ice accretion on the surface. The icing problem in any cold environments leads to severe damages on aircrafts, and a lot of studies on prevention and prediction techniques for icing have been conducted so far. Therefore, it is very important to know the detail of freezing mechanism of supercooled water droplets to improve the anti-and de-icing devices and icing simulation codes. The icing mechanism of a single supercooled water droplet impacting on an object surface would give us great insights for the purpose. In the present study, we develop a dual-luminescent imaging technique to measure the time-resolved temperature of a supercooled water droplet impacting on the surface under different temperature conditions. We apply this technique to measure the exact temperature of a water droplet, and to discuss the detail of the freezing process.展开更多
文摘The Double-Jet Film-Cooling （DJFC） technology is invented by the authors and comprises a significant enhancement of the adiabatic film-cooling effectiveness due to the formation of anti-kidney vortices. The DJFC technology places a second ejection hole with compound angle in a double-hole arrangement downstream the first hole. The second hole creates a second jet with another dominating vortex rotating in opposite direction to the first one and then combines both jets to one jet. The basic applicability and function of the DJFC technology has been proven by the numerical studies and testing in a test rig. The comparison of the experimental results of the adiabatic film cooling effectiveness to the numerical results for the same blowing ratio （M=（pc）c/（pc）h） shows qualitatively similar distributions. However, the experimental results show enhanced mixing-out of the cooling air and, thus, the experimental values of the adiabatic film cooling effectiveness are lower compared to the numerical values.
基金supported by the Fundamental and Cutting-Edge Research Plan of Chongqing(Grant Nos.cstc2017jcyj AX0114&cstc2016jcyj A0434)the National Natural Science Foundation of China(Grant Nos.51401040,51601075&51601165)
文摘In this work, commercially pure Zr sheets were subjected to β air cooling and then rolled to different reductions(10% and 50%)at room temperature. Microstructures of both the β-air-cooled and the rolled specimens were well characterized by electron channelling contrast imaging and electron backscatter diffraction techniques, with special attentions paid to their misorientation characteristics. Results show that the β-air-cooled specimen owns a Widmanst?tten structure featured by lamellar grains with typical phase transformation misorientations. The 10% rolling allows prismatic slip and tensile twinning({11-21}<11-2-6> and{10-12}<10-11>) to be activated profusely, which produce new low-angle(~3°–5°) and high-angle(~35° and ~85°) misorientation peaks, respectively. After increasing the rolling reduction to 50%, twinning is suppressed and dislocation slip becomes the dominant deformation mode, with the lamellar grains highly elongated and aligned towards the rolling direction.Meanwhile, only one strong low-angle misorientation peak related to the prismatic slip is presented in the 50%-rolled specimen,with all other peaks disappeared. Analyses on local misorientations reveal that hardly any residual strains exist in the β-air-cooled specimen, which should be related to their sufficient relaxation during slow cooling. Residual strains introduced by 10% rolling are heterogeneously distributed near grain/twin boundaries while heavier deformation(50% rolling) produces much larger residual strains pervasively existing throughout the specimen microstructure.
基金supported by the National Natural Science Foundation of China(52171219 and 91963113)。
文摘Cryogenic electron microscopy(cryo-EM)has extensively boosted structural biology research since the“resolution revolution”in the year of 2013 which was soon awarded the Nobel Prize in Chemistry in 2017.The advances in camera techniques and software algorithms enabled cryoEM to routinely characterize the three-dimensional structures of biomolecules at near-atomic resolution.Biomolecules are basically sensitive to electron irradiation damage,which can be minimized at cryo-temperature.This principle has inspired material scientists to characterize electron beam-or air-sensitive materials by cryo-EM,such as the electrodes in the lithium-ion battery,metal-organic frameworks(MOFs),covalent-organic frameworks(COFs)and zeolites.In addition,the reaction systems can be fast-frozen at vitreous ice in cryoEM,which correspondingly preserves the materials at the close-to-native state.Herein,we summarized the development and applications of both the cryo-EM technique and other emerging cryo-techniques in materials science,and energy storage and conversion.Cryo-EM techniques,capable of the direct observation of sensitive materials and electrochemical reaction processes,will greatly renew our understanding of materials science and related mechanisms.
文摘The collision of a supercooled water droplet with a surface result an object creates ice accretion on the surface. The icing problem in any cold environments leads to severe damages on aircrafts, and a lot of studies on prevention and prediction techniques for icing have been conducted so far. Therefore, it is very important to know the detail of freezing mechanism of supercooled water droplets to improve the anti-and de-icing devices and icing simulation codes. The icing mechanism of a single supercooled water droplet impacting on an object surface would give us great insights for the purpose. In the present study, we develop a dual-luminescent imaging technique to measure the time-resolved temperature of a supercooled water droplet impacting on the surface under different temperature conditions. We apply this technique to measure the exact temperature of a water droplet, and to discuss the detail of the freezing process.
