Numerical investigations on cold gas dynamic spray process with nano- and microsize particles
- Authors: Jen, Tien-Chien , Li, Longjian , Cui, Wenzhi , Chen, Qinghua , Zhang, Xinming
- Date: 2005
- Subjects: Numerical simulation , Cold gas dynamic spraying , Microparticles , Copper particles , Platinum particles
- Type: Article
- Identifier: uj:5265 , http://hdl.handle.net/10210/14934
- Description: The particle velocity in cold gas dynamic spraying (CGDS) is one of the most important factors that can determine the properties of the bonding to the substrate. In this paper, the acceleration process of microscale and sub-microscale copper (Cu) and platinum (Pt) particles inside and outside De-Laval-Type nozzle is investigated. A numerical simulation is performed for the gas-particle two phase flow with particle diameter ranging from 100 nm to 50 lm, which are accelerated by carrier gas nitrogen and helium in a supersonic De-Laval-type nozzle. The carrier gas velocity and pressure distributions in the nozzle and outside the nozzle are illustrated. The centerline velocity for two types of particles, Pt and Cu, are demonstrated. It is observed that the existence of the bow shocks near the substrate prevents the smaller size particles (less than 0.5 lm) from penetrating, thus leads to poor coating in the actual practices. Furthermore, the extended straight section may have different optimal length for different size particles, and even may be unnecessary for sub-microsize particles.
- Full Text:
The acceleration of micro- and nano-particles in supersonic De-Laval-Type nozzle
- Authors: Jen, Tien-Chien , Li, Longjian , Chen, Qinghua , Wenzhi cui , Zhang, Xinming
- Date: 2003
- Subjects: Nanoparticles , De-Laval-Type nozzle
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/15769 , uj:15698 , Jen, Tien-Chien et al. 2003. The acceleration of micro- and nano-particles in supersonic De-Laval-Type nozzle. Proceedings of IMECE'03, 2003 ASME International Mechanical Engineering Congress, Washington D.C., November 15-21 2003
- Description: The particle velocity in cold gas dynamic spraying (CGDS) is one of the most important factors that can determine the properties of the bonding to the substrate. The acceleration of gas to particles is strongly dependent on the densities of particles and the particle size. In this paper, the acceleration process of micro-scale and nano-scale copper (Cu) and platinum (Pt) particles in De-Laval-Type nozzle is investigated. A numerical simulation is performed for the gas-particle two phase flow with particle diameter ranging from 100nm to 50µm, which are accelerated by carrier gas Nitrogen in a supersonic DeLaval-type nozzle. The results show that cone-shape weak shocks (compression waves) occur at the exit of divergent section and the particle density has significant effect on the accele ration of micro-scale particles. At same inlet condition, the velocity of the smaller particles is larger than the larger particles at the exit of the divergent section of the nozzle.
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