L.F. Zhang
,
K.K. Cai
,
Y. Qu and Y.S. Shen Postdoctoral Fellow of Japan Science Promotion Society Taniguchi Lab.
,
Department of Metallurgy
,
Graduate School of Engineering
,
Tohoku University
,
Sendai980-8579
,
Japan School of Metallurgy
,
University of Science and Technology Beijing
,
Beijing 100083
,
China
金属学报(英文版)
In the present paper, based on the two-phase model (Eulerian model), the two dimensional fluid flow liz air-stirred water systems is simulated, and the effect of interphase lift force on the fluid flow is specially discussed. In the Eulerian two-phase model, gas and liquid phase are considered to be two different continuous fluids interacting with each other through the finite inter-phase areas. The exchange between the phases is represented by source terms in conversation equations. Turbulence is assumed to be a property of the liquid phase, k - ε model is used to describe the behavior of the liquid phase. The dispersion of phases due to turbulence is represented by introducing a diffusion term in mass consecrvation equation. The contribution of bubble movement to the turbulent energy and its dissipation rate is taken into accounted by adding extra volumetric source terms to the equations of turbulent enemy and its dissipation rate. The comparison between the mathematical simulation and experiment data indicates that the interphase lift force has a big effect on the flow behavior, and considering both drug force and lift force as interphase forces is important to accurately simulate the gas-water two-phase fluid flow in air-stirred systems. The interphase lift force makes bubbles move away from the centerline, the gas concentration is decreased near the centerline, and increased near the wall. The lift force is smaller than drug force at the same place, especially far away from the centerline.
关键词:
two-phase Eulerian model
,
null
,
null
,
null
N. Tada
,
T. Kitamura
,
R. Ohtani and E. Nakayama (Department of Engineering Physics and Mechanics
,
Graduate School of Engineering
,
Kyoto University
,
Yoshida-hommachi
,
Sakyo-ku
,
Kyoto
,
606-8501
,
Japan)
金属学报(英文版)
Creep-fatigue test was carried out using smooth round bar specimens of Type 304 stainless steel. Cavities and small cracks on the cross-section of the specimen were carefully observed by a scanning laser microscope. Moreover, direct current electrical potential method (DC-EPM) was applied in order to evaluate non-destructively the distribution of internal cracks. The distribution evaluated by DC-EPM agreed well with the actual one.
关键词:
creep-fatigue
,
null
,
null
,
null
,
null
M.Morinaga and H. Yukawa Department of Materials Science and Engineering
,
Graduate School of Engineering
,
Nagoya University
,
Furo-cho
,
Chikusa-ku
,
Nagoya 464-8603
,
Japan
金属学报(英文版)
The electronic structures are calculated by the DV-Xa molecular orbital method employing small model clusters in order to clarify the roles of the hydride forming elements, A, (e.g., La, Zr Ti, Mg) and non-forming elements, B, (e.g., Ni, Mn, Fe) in hydrogen storage alloys. It is confirmed from this calculation that hydrogen interacts more strongly with hydride non-forming elements, B, than hydride forming elements, A, in agreement with our previous calculations. However,the B-H interaction is enhanced only when some A element exists in the neighborhood. Otherwise, such a B-H interaction never operates in the alloy. In this sense,the coexistence of A and B elements are essential in the constitution of hydrogen storage alloys. Also, it is shown that the A/B compositional ratio of hydrogen storage alloys is understood in terms of a simple parameter, 2Bo(A - B) / /Bo(A - A)+ Bo(B-B)], where the Bo(A-B), Bo(A-A) and the Bo(B-B) are the bond strengths between atoms given in the parentheses.
关键词:
electronic structure
,
null
,
null
,
null
,
null
,
null
,
null
