1206 A NUMBERICAL STUDY OF SUPERSONIC POWDER-LADEN JET FLOW IN COLD GAS DYNAMIC SPRAY PROCESS

In this paper, numerical simulations were performed for the gas-particle two phase flow in the cold gas dynamic spray process to investigate the acceleration of micro- and nanoparticles with diameters ranging from 100nm to 50μm. Nitrogen (N2) and Helium (He) were chosen as the carrier gas, respectively. The acceleration of carrier gas to particles in the De-Laval-Type supersonic nozzle was strongly dependent on the characteristics of flow field, as well as the densities and the size of the particles. Two kind of particles Copper (Cu) and Platinum (Pt) were chosen as the spraying materials. The computed results showed that the flow structures of the carrier gas were very different for different gas and different spraying distance, which resulted in consequently different accelerating features. The cone-shape weak shocks (compression waves) occurred at the exit of divergent section, and the bow-shaped strong shock wave was found right before the substrate, which played a resistance role to the particles and prevented the smaller particles from approaching on the substrate.

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Optimization of Cold Gas Dynamic Spray Processes by Computational Simulation

Volume 1: Symposia, Parts A and B ◽

10.1115/fedsm2007-37081 ◽

2007 ◽

Author(s):

Hidemasa Takana ◽

Kazuhiro Ogawa ◽

Tetsuo Shoji ◽

Hideya Nishiyama

Keyword(s):

Shock Wave ◽

Electrostatic Force ◽

Particle Diameter ◽

Integrated Model ◽

Viscous Drag ◽

Spray Process ◽

Gas Dynamic ◽

Cold Gas Dynamic Spray ◽

Gas Dynamic Spray ◽

Cold Gas

An integrated model of compressible thermofluid, splat formation and coating formation for a cold dynamic spray process has been established. In-flight behavior of nano-micro particles and the interaction between the shock wave and the particles in a supersonic jet flow impinging onto the substrate and further particle acceleration with electrostatic force are clarified in detail by considering viscous drag force, flow acceleration, added mass, gravity, Basset history force, Saffman lift force, Brownian motion, thermophoresis and electrostatic force. The effect of electrostatic acceleration becomes more significant with the decrease in particle diameter even in the presence of unavoidable shock wave. As a result, electrostatic acceleration can broaden the application range of operating particle diameter in a cold gas dynamic spray process to form a robust and activated coating. Finally, based on the integrated model, the coating thickness characteristics in an electrostatic assisted cold dynamic spray process are evaluated.

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The Use of Particle/Substrate Material Models in Simulation of Cold-Gas Dynamic-Spray Process

Journal of Thermal Spray Technology ◽

10.1007/s11666-013-0051-4 ◽

2013 ◽

Vol 23 (3) ◽

pp. 530-540 ◽

Cited By ~ 37

Author(s):

Saeed Rahmati ◽

Abbas Ghaei

Keyword(s):

Substrate Material ◽

Material Models ◽

Spray Process ◽

Gas Dynamic ◽

Cold Gas Dynamic Spray ◽

Gas Dynamic Spray ◽

Cold Gas

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Study of thermite mixture consolidated by the cold gas dynamic spray process

Journal of Physics Conference Series ◽

10.1088/1742-6596/500/5/052003 ◽

2014 ◽

Vol 500 (5) ◽

pp. 052003 ◽

Cited By ~ 3

Author(s):

A Bacciochini ◽

G Maines ◽

C Poupart ◽

H Akbarnejad ◽

M Radulescu ◽

...

Keyword(s):

Spray Process ◽

Thermite Mixture ◽

Gas Dynamic ◽

Cold Gas Dynamic Spray ◽

Gas Dynamic Spray ◽

Cold Gas

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The Effects of the Distance Between Nozzle and Substrate on Cold Gas Dynamic Spray Process

Volume 9: Heat Transfer, Fluid Flows, and Thermal Systems, Parts A, B and C ◽

10.1115/imece2009-10501 ◽

2009 ◽

Author(s):

Longjian Li ◽

Qinghua Chen ◽

Wenzhi Cui ◽

Tien-Chien Jen ◽

Yi-Hsin Yen ◽

...

Keyword(s):

Supersonic Nozzle ◽

Strong Shock ◽

Two Phase ◽

Carrier Gas ◽

Compression Waves ◽

Spray Process ◽

Gas Dynamic ◽

Cold Gas Dynamic Spray ◽

Gas Dynamic Spray ◽

Cold Gas

In this paper, numerical simulations were performed for the gas-particle two phase flow in the Cold Gas Dynamic Spray (CGDS) process to investigate the acceleration of micro- and nanoparticles with diameters ranging from 100nm to 50μm. Nitrogen (N2) and Helium (He) were chosen as the carrier gas, respectively. The acceleration of carrier gas to particles in the De-Laval-Type supersonic nozzle was strongly dependent on the characteristics of flow field, as well as the densities and the size of the particles. Copper particles (Cu) were chosen as the spraying materials. The computed results showed that the flow structures of the carrier gas were very different for different gas and different spraying distance, which resulted in consequently different accelerating features. The cone-shape weak shocks (compression waves) occurred at the exit of divergent section, and the bow-shaped strong shock wave was found right before the substrate, which played a resistance role to the particles and prevented the smaller particles from approaching on the substrate.

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Computational Simulation on Performance Enhancement of Cold Gas Dynamic Spray Processes With Electrostatic Assist

Journal of Fluids Engineering ◽

10.1115/1.2907417 ◽

2008 ◽

Vol 130 (8) ◽

Cited By ~ 8

Author(s):

Hidemasa Takana ◽

Kazuhiro Ogawa ◽

Tetsuo Shoji ◽

Hideya Nishiyama

Keyword(s):

Shock Wave ◽

Electrostatic Force ◽

Computational Simulation ◽

Viscous Drag ◽

Formation Model ◽

Spray Process ◽

Gas Dynamic ◽

Cold Gas Dynamic Spray ◽

Gas Dynamic Spray ◽

Cold Gas

A real-time computational simulation on the entire cold spray process is carried out by the integrated model of compressible flow field, splat formation model, and coating formation model, in order to provide the fundamental data for the advanced high performance cold gas dynamic spray process with electrostatic acceleration. In this computation, viscous drag force, flow acceleration added mass, gravity, Basset history force, Saffman lift force, Brownian motion, thermophoresis, and electrostatic force are all considered in the particle equation of motion for the more realistic prediction of in-flight nano∕microparticle characteristics with electrostatic force and also for the detailed analysis of particle-shock-wave-substrate interaction. Computational results show that electrostatic acceleration can broaden the smallest size of applicable particle diameter for successful adhesion; as a result, wider coating can be realized. The utilization of electrostatic acceleration enhances the performance of cold dynamic spray process even under the presence of unavoidable shock wave.

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