The Acceleration of Micro- and Nano-Particles in Supersonic De-Laval-Type Nozzle

2003 ◽  
Author(s):  
Tien-Chien Jen ◽  
Longjian Li ◽  
Qinghua Chen ◽  
Wenzhi Cui ◽  
Xinming Zhang
Keyword(s):  
Particle Density ◽  
Particle Diameter ◽  
Nano Particles ◽  
Cold Gas Dynamic Spraying ◽  
Acceleration Process ◽  
Two Phase ◽  
Micro Scale ◽  
Compression Waves ◽  
Gas Dynamic ◽  
Weak Shocks

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 De-Laval-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.

Effects of Shock Waves on the Particle Acceleration for Cold Gas Dynamic Spray

2004 ◽  
Author(s):  
Tien-Chien Jen ◽  
Longjian Li ◽  
Wenzhi Cui ◽  
Qinghua Chen ◽  
Xinming Zhang
Keyword(s):  
Particle Diameter ◽  
Cold Gas Dynamic Spraying ◽  
Acceleration Process ◽  
Two Phase ◽  
Carrier Gas ◽  
Micro Scale ◽  
Gas Dynamic ◽  
Bow Shocks ◽  
Cold Gas Dynamic Spray ◽  
Cold Gas

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 micro-scale and sub micro-scale 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 100nm to 50μm, which are accelerated by carrier gas Nitrogen in a supersonic De-Laval-type nozzle. The carrier gas velocity and pressure distributions in the nozzle and outside the nozzle are illustrated. The center-line 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 μm) from penetrating, thus leads to poor coating in the actual practices.

Visualizing Test on the Distribution Rule of Coarse Particles in a Double Blade Pump

2019 ◽  
Author(s):  
Xianfang Wu ◽  
Xiao Tian ◽  
Minggao Tan ◽  
Houlin Liu
Keyword(s):  
Particle Concentration ◽  
Two Phase Flow ◽  
Particle Density ◽  
Particle Diameter ◽  
Phase Flow ◽  
Coarse Particles ◽  
Two Phase ◽  
Solid Liquid ◽  
Blade Pump ◽  
Flow Pump

Abstract As a typical fluid mechanics problem, pump blockage has always been a hot research topic. The obtaining of the distribution of coarse particles in the solid-liquid two-phase flow pump is the basis of improving its non-blocking performance. High-speed photography technique is applied to do visualizing test and research on the distribution of coarse particles in a double blade pump. The effects of particle concentration, particle density and particle diameter on the distribution of coarse particles in the solid-liquid two-phase flow pump at different phases are studied. Besides, the variation of hydraulic performance of the double blade pump under different parameters is also analyzed. The results show that the particles in the impeller mainly located in the vicinity of the blade pressure surface, and the distribution of the particles in each section of the volute is quite different. The great difference in particle density can result in obviously uneven distribution of particles. With the increase of particle diameter, particle density and particle concentration, the pump head and efficiency both decrease while the shaft power increase on the contrary. This research results can also provide a basis for the optimization design of solid-liquid two-phase flow pumps.

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

2005 ◽  
Author(s):  
Longjian Li ◽  
Wenzhi Cui ◽  
Qinghua Chen ◽  
Tien-Chien Jen ◽  
Quan Liao
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 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.

Operation Performance of a Small Air-Lift Pump for Conveying Solid Particles

2003 ◽  
Vol 125 (1) ◽  
pp. 17-25 ◽  
Author(s):  
Hitoshi Fujimoto ◽  
Satoshi Ogawa ◽  
Hirohiko Takuda ◽  
Natsuo Hatta
Keyword(s):  
Particle Density ◽  
Gas Injection ◽  
Particle Diameter ◽  
Solid Particles ◽  
Operation Performance ◽  
Two Phase ◽  
Experimental Conditions ◽  
Injection Point ◽  
Pump Performance ◽  
Air Lift

The pump performance of a small air-lift system for conveying solid particles is investigated experimentally. The total length of the vertical lifting pipe is 3200 mm, and the inner diameter of the pipe is 18 mm. The gas injector is set at a certain point of the pipe. The flows in the lifting pipe are water/solid two-phase mixtures below the gas injection point, and air/water/solid three-phase mixtures above it. The time-averaged characteristics of the flows are examined for various experimental conditions. The effects of particle diameter, particle density, the gas-injection point, and the volume flux of air on the pump performance are studied systematically. The critical boundary at which the particles can be lifted is discussed in detail based upon one-dimensional mixture model.

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

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.

Two Phase Analysis of Heat Transfer and Dispersion of Nano Particles in a Microchannel

2008 ◽  
Author(s):  
Seyed Mojtaba Mousavi Nayinian ◽  
Mehrzad Shams ◽  
Hossein Afshar ◽  
Goodarz Ahmadi
Keyword(s):  
Particle Motion ◽  
Slip Flow ◽  
Particle Diameter ◽  
Momentum Equation ◽  
Considerable Effect ◽  
Nano Particles ◽  
Two Phase ◽  
Starting Position ◽  
Brownian Force ◽  
Saffman Lift Force

The effect of different parameters on dispersion of nanoparticles in a microchannel in slip flow regime is studied. The equations of particle motion and energy balance are solved numerically and the effect of particle diameter, starting position of particles in microchannel, and slip coefficient on dispersion of particles is discussed. Radiative heat flux in energy equation and drag force, Saffman lift force, Brownian force and gravitational force in momentum equation are included. The results show that the Brownian force has considerable effect on particle motion in microchannel. Particles temperature at the outlet can be controlled by variation of their diameter and starting position in microchannel.

Numerical Simulation of Flow Field Characteristics of Free Falling Particle Plume Affected by Particle Diameter and Density

2014 ◽  
Vol 894 ◽  
pp. 163-166 ◽  
Author(s):  
Ze Qin Liu ◽  
Ling Yu Liu ◽  
Xiao Jian Li
Keyword(s):  
Numerical Simulation ◽  
Flow Field ◽  
Particle Density ◽  
Fluid Dynamic ◽  
Particle Diameter ◽  
Ambient Air ◽  
Two Phase ◽  
Flow Field Characteristics ◽  
Computational Fluid Dynamic Software ◽  
Free Falling

The study of flow field characteristics of free falling particle plume is part of the basic application research of gas-solid two phase flow. The Computational Fluid Dynamic Software FLUENT was adopted in this paper. The numerical simulation was carried out to study the influence of particle diameter and particle density to the particle flow field characteristics of free falling particle plume. The results of the numerical simulation showed that, with the increasing of particle diameter and the increasing of particle density, the disturbance of ambient air to the particle plume decreased, and the entrainment ability of particle plume to the ambient air was diminished.

Functional protective coatings of nickel-based alloys

2019 ◽  
pp. 110-114
Author(s):  
D. A. Gerashchenkov ◽  
T. I. Bobkova ◽  
A. F. Vasiliev ◽  
P. A. Kuznetsov ◽  
E. A. Samodelkin ◽  
...  
Keyword(s):  
Environmental Influence ◽  
Protective Coatings ◽  
Cold Gas Dynamic Spraying ◽  
Functional Elements ◽  
Corrosion Resistant ◽  
Gas Dynamic ◽  
Precision Alloy ◽  
Wear And Corrosion ◽  
High Level ◽  
Corrosion Resistant Coatings

A composition of a precision alloy based on the Ni–Cr–Mo system for wear and corrosion-resistant coatings by supersonic cold gas dynamic spraying has been developed. The optimum coatings composition provides high level of operational properties; its application is very promising for protection of structural and functional elements of marine equipment from aggressive environmental influence.

Nanostructured powders based on aluminum reinforced by silicon nitride designed for spraying of multifunctional strengthened coatings

2019 ◽  
pp. 65-73
Author(s):  
T. I. Bobkova ◽  
B. V. Farmakovsky ◽  
N. A. Sokolova
Keyword(s):  
Silicon Nitride ◽  
Composite Powder ◽  
High Energy ◽  
Cold Gas Dynamic Spraying ◽  
Powder Materials ◽  
Structure And Properties ◽  
Gas Dynamic ◽  
Composition Structure ◽  
New Phase ◽  
Nanostructured Powders

The work deals with topical issues such as development of composite nanostructured powder materials. The results of creating powders based on the system “aluminum–nitride of silicon” are presented. Complex investigations of the composition, structure and properties of powder materials, as well as coatings formed on their basis by supersonic cold gas dynamic spraying, were carried out. It has been found that the high-energy treatment of a powder mixture of aluminum with nanofibers of silicon nitride provides the formation of a composite powder in which a new phase of the Si(1-х)AlхO(1-х)Nх type is formed, which additionally increases the hardness in the coatings to be sprayed.

Measurement of Liquid Film Thickness in Micro Tube Annular Flow

2010 ◽  
Author(s):  
Hiroshi Kanno ◽  
Youngbae Han ◽  
Yusuke Saito ◽  
Naoki Shikazono
Keyword(s):  
Heat Transfer ◽  
Film Thickness ◽  
Liquid Film ◽  
Annular Flow ◽  
Liquid Film Thickness ◽  
Phase Flow ◽  
Two Phase ◽  
Micro Scale ◽  
Film Model ◽  
Annular Film

Heat transfer in micro scale two-phase flow attracts large attention since it can achieve large heat transfer area per density. At high quality, annular flow becomes one of the major flow regimes in micro two-phase flow. Heat is transferred by evaporation or condensation of the liquid film, which are the dominant mechanisms of micro scale heat transfer. Therefore, liquid film thickness is one of the most important parameters in modeling the phenomena. In macro tubes, large numbers of researches have been conducted to investigate the liquid film thickness. However, in micro tubes, quantitative information for the annular liquid film thickness is still limited. In the present study, annular liquid film thickness is measured using a confocal method, which is used in the previous study [1, 2]. Glass tubes with inner diameters of 0.3, 0.5 and 1.0 mm are used. Degassed water and FC40 are used as working fluids, and the total mass flux is varied from G = 100 to 500 kg/m2s. Liquid film thickness is measured by laser confocal displacement meter (LCDM), and the liquid-gas interface profile is observed by a high-speed camera. Mean liquid film thickness is then plotted against quality for different flow rates and tube diameters. Mean thickness data is compared with the smooth annular film model of Revellin et al. [3]. Annular film model predictions overestimated the experimental values especially at low quality. It is considered that this overestimation is attributed to the disturbances caused by the interface ripples.

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