Laminar methane/air premixed flames at different pressures in a newly developed high-pressure laminar burner are studied through Cantera simulation and filtered Rayleigh scattering(FRS).Different gas component fractio...Laminar methane/air premixed flames at different pressures in a newly developed high-pressure laminar burner are studied through Cantera simulation and filtered Rayleigh scattering(FRS).Different gas component fractions are obtained through the detailed numerical simulations.And this approach can be used to correct the FRS images of large variations in a Rayleigh cross section in different flame regimes.The temperature distribution above the flat burner is then presented without stray light interference from soot and wall reflection.Results also show that the extent of agreement with the single point measurement by the thermocouple is<6%.Finally,this study concludes that the relative uncertainty of the presented filtered Rayleigh scattering diagnostics is estimated to be below 10%in single-shot imaging.展开更多
Interferometric Rayleigh scattering diagnostic technique for the time-resolved measurement of flow velocity is studied. Theoretically, this systematic velocity-measured accuracy can reach up to 1.23 m/s. Measurement a...Interferometric Rayleigh scattering diagnostic technique for the time-resolved measurement of flow velocity is studied. Theoretically, this systematic velocity-measured accuracy can reach up to 1.23 m/s. Measurement accuracy is then evaluated by comparing with hot wire anemometry results. Moreover, the distributions of velocity and turbulence intensity in a supersonic free jet from a Laval nozzle with a Mach number of 1.8 are also obtained quantitatively. The sampling rate in this measurement is determined to be approximately 10 k Hz.展开更多
Proton exchange membrane fuel cells(PEMFCs)represent a promising technology to overcome the current energy and environmental issues,where high-performance cathodic catalysts are badly needed due to the sluggish kineti...Proton exchange membrane fuel cells(PEMFCs)represent a promising technology to overcome the current energy and environmental issues,where high-performance cathodic catalysts are badly needed due to the sluggish kinetics of oxygen reduction reaction(ORR).By far Pt stands for the best ORR catalyst,however,considering the scarcity and high cost,it is imperative to further improve its catalytic activity and atomic efficiency to reduce the loading amount.In view of the key issues,this review concentrates on recent advances on developing high-performance Pt-based nanocatalysts for ORR.The catalytic ORR mechanism was first described,followed by presenting the major principles to regulate ORR activity involving ligand effect and geometric effect.Guided by the principles,typical design strategies of Pt-based nanocatalysts were detailedly summarized,with emphasis on increasing intrinsic activity of single active site and electrochemical active surface area.We finally concluded by providing the remaining challenges and future directions in this field.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant No.91641118)the Fenglei Youth Innovation Fund of China Aerodynamics and Research Development Center,China(Grant Nos.FLYIF20160017 and PJD20180131).
文摘Laminar methane/air premixed flames at different pressures in a newly developed high-pressure laminar burner are studied through Cantera simulation and filtered Rayleigh scattering(FRS).Different gas component fractions are obtained through the detailed numerical simulations.And this approach can be used to correct the FRS images of large variations in a Rayleigh cross section in different flame regimes.The temperature distribution above the flat burner is then presented without stray light interference from soot and wall reflection.Results also show that the extent of agreement with the single point measurement by the thermocouple is<6%.Finally,this study concludes that the relative uncertainty of the presented filtered Rayleigh scattering diagnostics is estimated to be below 10%in single-shot imaging.
基金Project supported by the National Natural Science Foundation of China(Grant No.11272337)
文摘Interferometric Rayleigh scattering diagnostic technique for the time-resolved measurement of flow velocity is studied. Theoretically, this systematic velocity-measured accuracy can reach up to 1.23 m/s. Measurement accuracy is then evaluated by comparing with hot wire anemometry results. Moreover, the distributions of velocity and turbulence intensity in a supersonic free jet from a Laval nozzle with a Mach number of 1.8 are also obtained quantitatively. The sampling rate in this measurement is determined to be approximately 10 k Hz.
基金National Key Research and Development Program of China(No.2021YFA1502000)NSFC(No.U2032149 and 22102052)+1 种基金Science and Technology Innovation Program of Hunan Province(No.2021RC3065 and 2021RC2053)Hunan Provincial Natural Science Foundation of China(No.2020JJ2001).
文摘Proton exchange membrane fuel cells(PEMFCs)represent a promising technology to overcome the current energy and environmental issues,where high-performance cathodic catalysts are badly needed due to the sluggish kinetics of oxygen reduction reaction(ORR).By far Pt stands for the best ORR catalyst,however,considering the scarcity and high cost,it is imperative to further improve its catalytic activity and atomic efficiency to reduce the loading amount.In view of the key issues,this review concentrates on recent advances on developing high-performance Pt-based nanocatalysts for ORR.The catalytic ORR mechanism was first described,followed by presenting the major principles to regulate ORR activity involving ligand effect and geometric effect.Guided by the principles,typical design strategies of Pt-based nanocatalysts were detailedly summarized,with emphasis on increasing intrinsic activity of single active site and electrochemical active surface area.We finally concluded by providing the remaining challenges and future directions in this field.
