In this study, kerosene fuel-rich gas produced by the combustion in the gas generator was used as the fuel and oxygen-rich air was used as the oxidant to investigate the propagation characteristics of the rotating det...In this study, kerosene fuel-rich gas produced by the combustion in the gas generator was used as the fuel and oxygen-rich air was used as the oxidant to investigate the propagation characteristics of the rotating detonation wave (RDW). The initiation of the kerosene fuel-rich gas and propagation process of the RDW were analyzed. The influences of the oxygen content in the oxidizer, kerosene mass flow rate of the gas generator, and temperature of the kerosene fuel-rich gas on the propagation process of the RDW were studied. The experimental results revealed that the propagation velocity of the RDW could be improved by increasing the three parameters mentioned above with the kerosene mass flow rate as the strongest factor. The minimum oxygen content that could successfully initiate and maintain the stable propagation of the RDW was 32%, achieving the RDW velocity of 1141.9 m/s. The RDW mainly propagated as two-counter rotating waves and a single wave when the equivalent ratios were 0.62–0.79 and 0.85–0.87, respectively. The highest RDW velocity of 1637.2 m/s was obtained when the kerosene mass flow rate, oxygen content, and equivalent ratio were 74.6 g/s, 44%, and 0.87, respectively.展开更多
Kinetics of oxygen adsorption on single crystal Mn<sub>5</sub>Si<sub>3</sub> （111） surface and initial surface oxidation were investigated. Oxygen chemisorbs dissociatively at room temperatur...Kinetics of oxygen adsorption on single crystal Mn<sub>5</sub>Si<sub>3</sub> （111） surface and initial surface oxidation were investigated. Oxygen chemisorbs dissociatively at room temperature on Mn and Si atoms. A fast oxidation of Si atoms occurs followed by oxidation of Mn atoms at RT. The MnO<sub>2</sub> was reduced by Si atoms and the SiO was oxidized further to SiO<sub>2</sub> during the sample heating.展开更多
Low initial Coulombic efficiency (ICE) is an important impediment to practical application of Li-rich layered oxides (LLOs), which is due to the irreversible oxygen release. It is generally considered that surface oxy...Low initial Coulombic efficiency (ICE) is an important impediment to practical application of Li-rich layered oxides (LLOs), which is due to the irreversible oxygen release. It is generally considered that surface oxygen vacancies are conducive to the improvement of ICE of LLOs. To reveal the relation of oxygen vacancies and ICE, sample PLO (Li-Mn-Cr-O) and its treated product (TLO) are comprehensive investigated in this work. During the treated process, part of oxygen atoms return to original constructed vacancies. It makes oxygen vacancies in sample TLO much poorer than those in sample PLO, and induces the formation of Li-poor spinel-layered integrated structure. Electrochemical measurement indicates the ICE of sample PLO is only 80.8%, while sample TLO is almost full reversible with the ICE of ~97.1%. In term of high-energy X-ray diffraction, scanning transmission electron microscopy, X-ray photoelectron spectroscopy and synchrotron hard/soft X-ray absorption spectroscopy, we discover that the ICE is difficult to be improved significantly just by building oxygen vacancies. LLOs with high ICE not only have to construct suitable oxygen vacancies, but also require other components with Li-poor structure to stabilize oxygen. This work provides deep insight into the mechanism of high ICE, and will contribute to the design and development of LLOs for next-generation high-energy lithium-ion batteries.展开更多
In the mid of the 1970s,China began to develop its first oxygen/hydrogen rocket engine,which is designated as YF-73 and used for the third stage of the Long March 3 launch vehicle (LM-3).After successful flight tests ...In the mid of the 1970s,China began to develop its first oxygen/hydrogen rocket engine,which is designated as YF-73 and used for the third stage of the Long March 3 launch vehicle (LM-3).After successful flight tests of the LM-3,the development of a new engine-YF-75 engine started,which is for the third stage of the LM-3A.This paper describes these two engines and the development of China’s cryogenic technology.It also discusses some tentative ideas about the future development of oxygen/hydrogen engine.展开更多
The pulse detonation rocket engine （PDRE） requires periodic supply of oxidizer, fuel and purge gas. A rotary-valve assembly is fabricated to control the periodic supply in this research. Oxygen and liquid aviation k...The pulse detonation rocket engine （PDRE） requires periodic supply of oxidizer, fuel and purge gas. A rotary-valve assembly is fabricated to control the periodic supply in this research. Oxygen and liquid aviation kerosene are used as oxidizer and fuel respectively. An ordinary automobile spark plug, with ignition energy as low as 50 mJ, is used to initiate combustion. Steady operation of the PDRE is achieved with operating frequency ranging from 1 Hz to 10 Hz. Experimentally measured pressure is lower than theoretical value by 13% at 1 Hz and 37% at 10 Hz, and there also exists a velocity deficit at different operating frequencies. Both of these two phenomena are believed mainly due to droplet size which depends on atomization and vaporiza-tion of liquid fuel.展开更多
文摘In this study, kerosene fuel-rich gas produced by the combustion in the gas generator was used as the fuel and oxygen-rich air was used as the oxidant to investigate the propagation characteristics of the rotating detonation wave (RDW). The initiation of the kerosene fuel-rich gas and propagation process of the RDW were analyzed. The influences of the oxygen content in the oxidizer, kerosene mass flow rate of the gas generator, and temperature of the kerosene fuel-rich gas on the propagation process of the RDW were studied. The experimental results revealed that the propagation velocity of the RDW could be improved by increasing the three parameters mentioned above with the kerosene mass flow rate as the strongest factor. The minimum oxygen content that could successfully initiate and maintain the stable propagation of the RDW was 32%, achieving the RDW velocity of 1141.9 m/s. The RDW mainly propagated as two-counter rotating waves and a single wave when the equivalent ratios were 0.62–0.79 and 0.85–0.87, respectively. The highest RDW velocity of 1637.2 m/s was obtained when the kerosene mass flow rate, oxygen content, and equivalent ratio were 74.6 g/s, 44%, and 0.87, respectively.
文摘Kinetics of oxygen adsorption on single crystal Mn<sub>5</sub>Si<sub>3</sub> （111） surface and initial surface oxidation were investigated. Oxygen chemisorbs dissociatively at room temperature on Mn and Si atoms. A fast oxidation of Si atoms occurs followed by oxidation of Mn atoms at RT. The MnO<sub>2</sub> was reduced by Si atoms and the SiO was oxidized further to SiO<sub>2</sub> during the sample heating.
基金We thank the funding supports of the National Natural Science Foundation of China(Project Nos.51874104 and 52004070)the Key Technology and Supporting Platform of Genetic Engineering of Materials under States Key Project of Research and Development Plan of China(Project No.2016YFB0700600).The authors thank Cheng-Hao Chuang for the assistant with X-ray spectroscopy measurement.
文摘Low initial Coulombic efficiency (ICE) is an important impediment to practical application of Li-rich layered oxides (LLOs), which is due to the irreversible oxygen release. It is generally considered that surface oxygen vacancies are conducive to the improvement of ICE of LLOs. To reveal the relation of oxygen vacancies and ICE, sample PLO (Li-Mn-Cr-O) and its treated product (TLO) are comprehensive investigated in this work. During the treated process, part of oxygen atoms return to original constructed vacancies. It makes oxygen vacancies in sample TLO much poorer than those in sample PLO, and induces the formation of Li-poor spinel-layered integrated structure. Electrochemical measurement indicates the ICE of sample PLO is only 80.8%, while sample TLO is almost full reversible with the ICE of ~97.1%. In term of high-energy X-ray diffraction, scanning transmission electron microscopy, X-ray photoelectron spectroscopy and synchrotron hard/soft X-ray absorption spectroscopy, we discover that the ICE is difficult to be improved significantly just by building oxygen vacancies. LLOs with high ICE not only have to construct suitable oxygen vacancies, but also require other components with Li-poor structure to stabilize oxygen. This work provides deep insight into the mechanism of high ICE, and will contribute to the design and development of LLOs for next-generation high-energy lithium-ion batteries.
文摘In the mid of the 1970s,China began to develop its first oxygen/hydrogen rocket engine,which is designated as YF-73 and used for the third stage of the Long March 3 launch vehicle (LM-3).After successful flight tests of the LM-3,the development of a new engine-YF-75 engine started,which is for the third stage of the LM-3A.This paper describes these two engines and the development of China’s cryogenic technology.It also discusses some tentative ideas about the future development of oxygen/hydrogen engine.
基金National Natural Science Foundation of China (50976094)Doctoral Program Foundation of Education Ministry of China (20096102110022)+1 种基金Doctorate Foundation of Northwestern Polytechnical University (CX201112)Graduate Innovation Lab Center of Northwestern Polytechnical University (10006,10013)
文摘The pulse detonation rocket engine （PDRE） requires periodic supply of oxidizer, fuel and purge gas. A rotary-valve assembly is fabricated to control the periodic supply in this research. Oxygen and liquid aviation kerosene are used as oxidizer and fuel respectively. An ordinary automobile spark plug, with ignition energy as low as 50 mJ, is used to initiate combustion. Steady operation of the PDRE is achieved with operating frequency ranging from 1 Hz to 10 Hz. Experimentally measured pressure is lower than theoretical value by 13% at 1 Hz and 37% at 10 Hz, and there also exists a velocity deficit at different operating frequencies. Both of these two phenomena are believed mainly due to droplet size which depends on atomization and vaporiza-tion of liquid fuel.
