This paper is concerned with theoretical and experimental study on the conical swirling water jet flow. Based upon the theoretical analysis, the experiment on the structural characteristics of swirling water jet flow ...This paper is concerned with theoretical and experimental study on the conical swirling water jet flow. Based upon the theoretical analysis, the experiment on the structural characteristics of swirling water jet flow including the velocity and pressure distribution laws, on which the parameters of the jet, nozzle and directional blades have more or less influence, was carried out in CSSRC by using a 3-D LDV in order to optimize a new high-efficiency jet instead of swirling drilling bit for rock-breaking and continuously drilling, and to meet the demand of radial horizontal drilling technology. Meanwhile based on the experimental results, the numerical simulation was conducted for the conical swirling water jet in the immersed well-bottom flow by solving the RANS equations in the 3-D body-fitted coordinate system with the k-e. turbulence model. The numerical results are consistent with the experimental data, and lead to some conclusions which are important for applying the conical swirling water jet to the petroleum drilling engineering.展开更多
We pioneered a study about how the geometric relationship of single-walled carbon nanotubes(SWCNT) is influenced by curvature factor and non-planar geometry factor in cylindrical coordinate system based on the assumpt...We pioneered a study about how the geometric relationship of single-walled carbon nanotubes(SWCNT) is influenced by curvature factor and non-planar geometry factor in cylindrical coordinate system based on the assumption of complete symmetry. The bond length and angle of every carbon-carbon bonds are determined by using the principle of the minimum energy. The results of the paper include(1) From the calculation result, the symmetry breaking appears for chiral carbon nanotubes, while the part symmetry appears for achiral carbon nanotubes with increasing curvature.(2) The synergistic effect of bond lengths and bond angles is first found.(3) We conclude that the influence of non-planar geometry factor can be completely ignored on bond lengths and bond angles when the curvature parameter has been included in the model.(4)The two fractal dimensions are given from the nanoscale to the macroscale for zigzag topology and armchair topology respectively. Fractal dimensions of SWCNT show special characteristics, varying with the length of SWCNT until the lengths approach infinity. The close and inevitable correlations among curvature, symmetry breaking and stability of SWCNTs can be summed up as: the increase of curvature causes symmetry breaking,and such symmetry breaking will further reduce the structural stability.展开更多
文摘This paper is concerned with theoretical and experimental study on the conical swirling water jet flow. Based upon the theoretical analysis, the experiment on the structural characteristics of swirling water jet flow including the velocity and pressure distribution laws, on which the parameters of the jet, nozzle and directional blades have more or less influence, was carried out in CSSRC by using a 3-D LDV in order to optimize a new high-efficiency jet instead of swirling drilling bit for rock-breaking and continuously drilling, and to meet the demand of radial horizontal drilling technology. Meanwhile based on the experimental results, the numerical simulation was conducted for the conical swirling water jet in the immersed well-bottom flow by solving the RANS equations in the 3-D body-fitted coordinate system with the k-e. turbulence model. The numerical results are consistent with the experimental data, and lead to some conclusions which are important for applying the conical swirling water jet to the petroleum drilling engineering.
基金National Natural Science Foundation of China (No. 10602028)Student Research Train Program of BeiHang University
文摘We pioneered a study about how the geometric relationship of single-walled carbon nanotubes(SWCNT) is influenced by curvature factor and non-planar geometry factor in cylindrical coordinate system based on the assumption of complete symmetry. The bond length and angle of every carbon-carbon bonds are determined by using the principle of the minimum energy. The results of the paper include(1) From the calculation result, the symmetry breaking appears for chiral carbon nanotubes, while the part symmetry appears for achiral carbon nanotubes with increasing curvature.(2) The synergistic effect of bond lengths and bond angles is first found.(3) We conclude that the influence of non-planar geometry factor can be completely ignored on bond lengths and bond angles when the curvature parameter has been included in the model.(4)The two fractal dimensions are given from the nanoscale to the macroscale for zigzag topology and armchair topology respectively. Fractal dimensions of SWCNT show special characteristics, varying with the length of SWCNT until the lengths approach infinity. The close and inevitable correlations among curvature, symmetry breaking and stability of SWCNTs can be summed up as: the increase of curvature causes symmetry breaking,and such symmetry breaking will further reduce the structural stability.
