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Your search keyword '"Li, Jiagang"' showing total 17 results
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17 results on '"Li, Jiagang"'

13. Simulation of Cathode-Spot on Hydrogen Titanium Cathode with Various Impregnation Degree

Author

Wang Lijun, Li Jiagang, Zhang Xiao, and Zhang Zhefeng

Subjects
Materials science, Number density, Hydrogen, Diffusion, Analytical chemistry, chemistry.chemical_element, Electron, Cathode, Ion, law.invention, chemistry, law, Current density, Titanium
Abstract

In this paper, the formation process of single cathode spot on hydrogen titanium cathode is simulated. The influence of impregnation degree α(H content per metal atom) on the formation and development of craters was studied by the control variable method. In this model, hydrogen diffusion in the cathode is calculated, and the deformation of cathode metal is simulated by hydrodynamic model. The components considered in the model include electrons, titanium atoms, H atoms, Ti ions (Ti+, Ti2+ and Ti3+) and H+ ions. The simulation results show that the impregnation degree has a great effect on the cathode spot process. The average charge state on the pure titanium cathode is larger, while the total ion number density on the hydrogen titanium cathode is larger because of the extra hydrogen ions. Low impregnation hydrogen (impregnation degree less than 1) can reduce the surface temperature and ablation of the cathode. With the increase of impregnation degree, the proportion of titanium ions in the plasma cloud decreases gradually, resulting in the decrease of the total energy current density and the decrease of the radius and depth of cathode spots. The simulation results are broadly consistent with the work of other researchers.

Published
2021

16. Research on the characteristics of fluid flow and heat transfer of Al2O3-water nanofluid in an L-shaped chaotic channel.

Author

Wang, Dan, Wei, Yabing, Pan, Kang, Li, Jiagang, and Jiao, Miaoxin

Subjects
NANOFLUIDICS, LASER Doppler velocimeter, HEAT transfer fluids, NANOFLUIDS, HEAT transfer coefficient, REYNOLDS number
Abstract

Purpose: This paper aims to investigate the effects of different volume fractions of Al2O3-water nanofluid on flow and heat transfer under chaotic convection conditions in an L-shaped channel, comparing the difference of numerical simulation results between single-phase and Eulerian–Lagrangian models. Design/methodology/approach: The correctness and accuracy of the two calculation models were verified by comparing with the experimental values in literature. An experimental model of the L-shaped channel was processed, and the laser Doppler velocimeter was used to measure the velocities of special positions in the channel. The simulated values were compared with the experimental results, and the correctness and accuracy of the simulation method were verified. Findings: The calculated results using the two models are basically consistent. Under the condition of Reynolds number is 500, when the volume fractions of nanofluid range from 1% to 4%, the heat transfer coefficients simulated by single-phase model are 1.49%–25.80% higher than that of pure water, and simulated by Eulerian–Lagrangian model are 3.19%–27.48% higher than that of pure water. Meanwhile, the friction coefficients are barely affected. Besides, there are obvious secondary flow caused by lateral oscillations on the cross sections, and the appearance of secondary flow makes the temperature distributions uniform on the cross section and takes more heat away, thus the heat transfer performance is enhanced. Originality/value: The originality of this work is to reveal the differences between single-phase and two-phase numerical simulations under different flow states. The combination of chaotic convection and nanofluid indicates the direction for further improving the heat transfer threshold. [ABSTRACT FROM AUTHOR]

Published
2022
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