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论文类型：期刊论文

发表时间：2013-10-01

发表刊物：SURFACE & COATINGS TECHNOLOGY

收录刊物：SCIE、EI、Scopus

卷号：232

页面范围：290-297

ISSN号：0257-8972

关键字：Cold spraying; Computational fluid dynamics (CFD); Numerical simulation; Impact velocity; Total pressure; Divergent length

摘要：This study investigates the effect of total pressure (P-o) and nozzle divergent length (L-a) on the flow character and particle impact velocity in cold spraying. Computational fluid dynamic (CFD) approach is employed in the present work to achieve this objective. The simulated results indicate that P-o and L-d significantly influence the flow regime and particle acceleration. With gradually increasing P-o, the nozzle exit Mach number (M-e) firstly increases and then fluctuates after P-o exceeds a critical value, finally M-e reaches the maximum value and maintains stable. Differing from M-e, the particle impact velocity (V-p) continually goes up with P-o due to the increasing gas density which can improve the drag force, but the growth rate levels out gradually. Besides, it is also found that Me shows a downward trend with increasing L-d. However, as for V-p, there exists an optimal L-d which can guarantee the particle achieving the maximum V-p. Moreover, for nozzles with larger expansion ratio, the optimal L-d is longer. This optimal length is considered as a consequence of the competition between the particle acceleration time and drag force on the particle surface. (C) 2013 Elsevier B.V. All rights reserved.