[1] [1] Zhong Minlin, Liu Wenjin. Leading areas and hot topics on global laser materials processing research [J]. Chinese J. Lasers, 2008, 35(11):1653～1659

[2] [2] T. T. Wohlers. Wohlers Report [M]. USA: Wohlers Associates, Inc. 2006. 13～43

[3] [3] Zhang Anfeng, Li Dichen, Lu Bingheng. Development of research on laser direct metal rapid prototyping technology [J]. Ordnance Material Science and Engineering, 2007, 30(5):68～72

[4] [4] S. Zekovic, R. Dwivedi, R. Kovacevic. Numerical simulation and experimental investigation of gas-powder flow from radially symmetrical nozzles in laser-based direct metal deposition [J]. Int. J. Mach. Tool. & Manuf., 2007, 47:112～123

[5] [5] J. Lin. Numerical simulation of the focused powder streams in coaxial laser cladding [J]. J. Mater. Proc. Technol., 2000, 105:17～23

[6] [6] Yang Nan, Yang Xichen. Numerical simulation of flow field of nozzle in laser cladding [J]. Chinese J. Lasers, 2008, 35(3):452～455

[7] [7] Jin Xiaoshu, Yang Xichen, Feng Liwei et al.. Numerical simulation of coaxial powder flow with carrying gas in laser manufacturing [J]. Chinese J. Mechanical Engineering, 2007, 43(5):161～166

[8] [8] Zhang Anfeng, Zhou Zhimin, Li Dichen et al.. Numerical simulation of gas-solid two-phase flow field on coaxial powder nozzle in laser metal direct manufacturing [J]. J. Xi’an Jiaotong University, 2008, 42(9):1169～1173

[9] [9] T. Tanaka, Y. Tsuji. Numerical simulation of gas-solid two-phase flow in a vertical pipe [J]. Gas-Solid Flows ASME, 1991, 121(2):123～128

[10] [10] B. E. Launder, D. B. Spalding. Lectures in Mathematical Models of Turbulence [M]. London: Academic Press, 1972. 127～133

[11] [11] Wang Fujun. Computational Fluid Dynamics Analysis-Principles and Application of CFD Software [M]. Beijing: Tsinghua University Press, 2004. 120～124

[12] [12] Li Wenchun. Direct numerical simulation of three-dimensional gas-solid two-phase wake of a circular cylinder [D]. Hangzhou: Zhejiang University, 2005. 32～34

[13] [13] J. M. Lin. Concentration mode of the powder stream in coaxial laser cladding [J]. Opt. & Laser Technol., 1999, 31(3):251～257

[14] [14] A. J. Pinkerton, L. Li. Modelling powder concentration distribution from a coaxial deposition nozzle for laser-based rapid tooling [J]. J. Manu. Science and Engineer.-Trans. ASME, 2004, 126(1):33～41

[15] [15] Yang Xichen, Lei Jianbo, Liu Yunwu et al.. Experimental measurement of metal powder stream [J]. Chinese J. Lasers, 2006, 33(7):993～997