An Investigation of Particle Injection and Resulting In-Flight Particle Behavior During Air Plasma Spraying

2006 ◽  
Author(s):  
W. Zhang ◽  
V. Srinivasan ◽  
L. L. Zheng ◽  
S. Sampath
Keyword(s):  
Gas Flow ◽  
Process Parameter ◽  
Diagnostic Tools ◽  
Particle State ◽  
Plasma Diagnostic ◽  
Air Plasma ◽  
Particle Injection ◽  
Carrier Gas ◽  
Particle Behavior ◽  
Particle Characteristics

In this article we present our studies on the role of particle injection on the in-flight particle characteristics in an external orthogonally injected air plasma spray system. The influence of carrier gas on the in-flight particle state has been investigated, experimentally and using simulation, for Yttria Stabilized Zirconia (YSZ) thermal spray powder processed in an Ar-H2 plasma. Diagnostic tools such as IPP and SPT have been used to measure the plume characteristics and ensemble temperature while DPV-2000 has been used to measure the distributions of individual particle characteristics such as temperature, velocity and size, at the point of the maximum particle flux and at various points (square grid) in the plume cross-section. Three-dimensional simulations have been performed for the cases presented in the experiments. Specifically, the effects of carrier gas flow rate on the in-flight particle characteristics were studied at multiple stand-off distances. Simulation results agree well with the experimental observation that the particle velocity and temperature will increase with the plume angle and then decrease after reaching a maxima for a given process parameter combination and stand-off distance. This maxima has been observed at the same plume angle for different process parameter combinations. The results of this study are currently being used to 'optimize' the particle injection and trajectory, which enables better understanding of the influence of plasma forming and stabilizing parameters (gas flows and arc current) on the in-flight particle behavior.

More on the Influence of Injector Geometry and Carrier Gas Flow Rate on Spray Pattern and Particle Temperature

2000 ◽  
Author(s):  
J.R. Fincke ◽  
W.D. Swank ◽  
D.C. Haggard
Keyword(s):  
Gas Flow ◽  
Particle Temperature ◽  
Gas Jet ◽  
Injection Velocity ◽  
Minor Effect ◽  
Gas Bubble ◽  
Particle Injection ◽  
Spray Pattern ◽  
Carrier Gas ◽  
Cold Gas

Abstract Recently it has been suggested that the carrier gas jet interaction with the plasma can have a large effect on the resulting particle temperature. The postulated interaction is through deflection of the main plasma jet and by delaying the heating of particles by the formation of a "cold" gas bubble. We have examined the effect of the gas jet itself on the temperature of the particles by attempting to artificially form a cold gas bubble using a separate, closely oriented gas jet. The effect of the "twin" co-flowing jet was evaluated by measuring its effect on the mean and standard deviation of the particle injection velocity and the resulting spray pattern and particle temperature. Additionally we have used alternative carrier gases with similar density but with specific heats that are higher than argon by a factor of two. A measurable but minor effect on particle temperature is observed.

The Influence of Injector Geometry and Carrier Gas Flow Rate on Spray Pattern

1997 ◽  
Author(s):  
J.R. Fincke ◽  
W.D. Swank ◽  
D.C. Haggard
Keyword(s):  
Flow Rate ◽  
Gas Flow ◽  
Functionally Graded ◽  
Injection Velocity ◽  
Average Particle ◽  
Gas Flow Rate ◽  
Particle Injection ◽  
Spray Pattern ◽  
Carrier Gas ◽  
Carrier Gas Flow

Abstract The performance (particle velocity and velocity distribution) of a typical injector, and the resulting particle spray pattern for metallic (NiCrAlY) and ceramic (ZrO2) particles are examined as a function of carrier gas flow rate and the effect of varying the geometry immediately upstream of the injector. Injector performance is also examined for a 1:1 mixture of ceramic and metallic particles such as is used in the spraying of functionally graded materials. The upstream geometries tested included a 90° "tee," a 90° elbow, and a straight entrance. The elbow geometry was tested in both "up" and "down" orientation to determine the influence of gravity. The upstream geometry can alter the average particle injection velocity by 10-15% influencing both the spray pattern trajectory and width.

Process Maps for Plasma Spray Part I: Plasma-Particle Interactions

2000 ◽  
Author(s):  
D.L. Gilmore ◽  
R.A. Neiser ◽  
Y. Wan ◽  
S. Sampath
Keyword(s):  
Plasma Spray ◽  
Gas Flow ◽  
Operating Conditions ◽  
Injection Velocity ◽  
Microstructural Development ◽  
Spray Parameters ◽  
Particle Interactions ◽  
Plasma Particle ◽  
Particle Injection ◽  
Process Maps

Abstract This is the first paper of a two part series based on an integrated study carried out at Sandia National Laboratories and the State University of New York at Stony Brook. The aim of the study is to develop a more fundamental understanding of plasma-particle interactions, droplet-substrate interactions, deposit formation dynamics and microstructural development as well as final deposit properties. The purpose is to create models that can be used to link processing to performance. Process maps have been developed for air plasma spray of molybdenum. Experimental work was done to investigate the importance of such spray parameters as gun current, auxiliary gas flow, and powder carrier gas flow. In-flight particle diameters, temperatures, and velocities were measured in various areas of the spray plume. Samples were produced for analysis of microstructures and properties. An empirical model was developed, relating the input parameters to the in-flight particle characteristics. Multi-dimensional numerical simulations of the plasma gas flow field and in-flight particles under different operating conditions were also performed. In addition to the parameters which were experimentally investigated, the effect of particle injection velocity was also considered. The simulation results were found to be in good general agreement with the experimental data.

scholarly journals High Flow Closed Circuit Anaesthesia

1994 ◽  
Vol 22 (4) ◽  
pp. 426-434 ◽  
Author(s):  
A. P. K. Verkaaik ◽  
G. Van Dijk
Keyword(s):  
Nitrous Oxide ◽  
Time Constant ◽  
Gas Flow ◽  
High Flow ◽  
Controlled Delivery ◽  
Closed Circuit ◽  
Clinical Use ◽  
Volatile Anaesthetics ◽  
Carrier Gas ◽  
Flow Systems

We present an automatic closed circuit anaesthesia ventilator designed for routine clinical use. The ventilator combines the benefits of high flow systems and true closed circuits, without their disadvantages. The system can be used with any FiO2, with air or nitrous oxide as carrier gas. Servo controlled delivery of modern volatile anaesthetics is regulated on endtidal value. The time constant for increase or decrease of concentrations is only a few minutes. There is no need to open the system at any time, nor is it necessary to increase the fresh gas flow. An automatic flush procedure prevents accumulation of unwanted gases. Operation is as easy as contemporary non-closed circuit ventilators. With this machine, closed circuit anaesthesia is possible from the beginning to the end of the procedure.

scholarly journals Simulation and experimental research based on carrier gas flow rate on the influence of four-channel coaxial nozzle flow field

2020 ◽  
pp. 002029402096423
Author(s):  
Shi Rui Guo ◽  
Qian Qian Yin ◽  
Lu Jun Cui ◽  
Xiao Lei Li ◽  
Ying Hao Cui ◽  
...  
Keyword(s):  
Flow Field ◽  
Gas Flow ◽  
Simulation Analysis ◽  
Two Phase ◽  
Carrier Gas ◽  
Coaxial Nozzle ◽  
Convergence Point ◽  
Flow Convergence ◽  
Fluent Software ◽  
Carrier Gas Flow

This paper investigates the influence of carrier gas flow on the external flow field of coaxial powder feeding nozzle. FLUENT software was adopted to establish gas-solid two-phase flow. The simulation of powder stream field under different carrier gas flow was also carried out. Results show that the larger the flow of carrier gas is, the higher the gas flow field velocity at the nozzle outlet is. At the same time, the concentration at the convergence point is lower, and the convergent point is maintained at 0.015 m. Under the condition of 4 L/min, the powder flow convergence is good. When it exceeds 4 L/min, powder spot diameter increases. The experiment of powder aggregation and laser cladding forming were completed, which shows that the forming effect is the best one under the condition of 4 L/min. It is consistent with the simulation analysis results and has a high reference to the optimization of the process parameters of coaxial nozzle.

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