Particle velocities, sizes and flux distribution in plasma spray with two powder injection ports

Wang, P.; Yu, S. C. M.; Ng, H. W.

doi:10.1016/j.msea.2004.02.037

Cited by 20 publications

(11 citation statements)

References 15 publications

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“…3a) respectively under different plasma spraying parameters as listed in Table 5. The difference between the influence of these two powder injection schemes and the plasma spray parameters on the in-flight particle characteristics and the properties of the plasma sprayed coatings has already been discussed elsewhere [17].…”

Section: Correlation Of the Measured Volume Flux With Actual Depositmentioning

confidence: 99%

“…The PDA measurement volume was put under the orifice of the atomizer at a standoff distance of 10 mm, where the sprayed water droplets should assume perfect spherical shape due to the surface tension effect. NiCrAlY and YSZ powders were plasma sprayed under their respective common operation conditions in which a coating with acceptable DE could be produced according to our previous experience [15][16][17], i.e., power current (A), power voltage (V) and powder feeder rate were maintained at 622 A, 317 V and 0.54 · 10EÀ3 Kg/s respectively. The PDA measurement volume was located at the standoff distance of 80 mm from the exit of the plasma torch and on the mean trajectory of the particle plume for the two kinds of powders, where the possibility that particles could be melted was higher.…”

Section: Phase Doppler Anemometer (Pda)mentioning

confidence: 99%

“…YSZ powders with particle diameter lower than 80 lm were utilized in this investigation and the spraying conditions are listed in Table 5. The twoinjector configuration for plasma spraying has been discussed in detail previously in [17]. The measurement volume of the PDA was traversed throughout the entire cross-sectional plane of the particle plume at the standoff distance of 80 mm from the nozzle exit.…”

Section: Phase Doppler Anemometer (Pda)mentioning

confidence: 99%

“…In the plasma spraying process, the local particle density and the possibility of the multi-particle coincidence occurred in the PDA measurement volume can be numerically evaluated with the aid of Poisson statistics equations. It has been demonstrated that the possibility of the multi-particle coincident inside the PDA measurement volume is very low and its effect on the PDA measurement should be negligible [17]. As for the morphology of the sprayed particles, even those fabricated by atomization and spray drying may not necessarily achieve the perfect spherical shape and smooth surface.…”

Section: Introductionmentioning

confidence: 99%

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Correlation of Plasma Sprayed Coating Deposition Efficiency with Volume Flux Measurements by Phase Doppler Anemometry (PDA)

Wang

2007

Plasma Chem Plasma Process

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The use of phase-Doppler anemometry (PDA) to characterize the detail inflight plasma sprayed particle behavior has been demonstrated previously [Ma et al. Plasma Chem Plasma Process 24(1):85; 25 (1):56] The present articles shows further that a direct relationship may exist between the PDA measured particle volume flux and the coating microstructure and deposition efficiency (DE). In the situation when the precise particle temperature information is not available, the PDA measured particle volume flux may provide an alternative to predict quantitatively the variation of the coating microstructure and the DE. By monitoring the in-flight particle volume flux variations, instead of the particle velocity, size and temperature individually and simultaneously, the optimal settings of the plasma spraying parameters may also be determined conveniently. However, it is noted that the effective applications of such approach depend largely on the particle surface morphology and the pre-determination of the particle size range.

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Section: Correlation Of the Measured Volume Flux With Actual Depositmentioning

confidence: 99%

Section: Phase Doppler Anemometer (Pda)mentioning

confidence: 99%

Section: Phase Doppler Anemometer (Pda)mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Correlation of Plasma Sprayed Coating Deposition Efficiency with Volume Flux Measurements by Phase Doppler Anemometry (PDA)

Wang

2007

Plasma Chem Plasma Process

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“…The PDA measurement volume was put under the orifice of the atomizer at a standoff distance of 10 mm, where the sprayed water droplets were believed to assume perfect spherical shape due to the surface tension effect. NiCrAlY and YSZ powders were plasma sprayed under their respective common operation conditions in which a coating with acceptable deposition efficiency could be produced according to our previous experience [131,132]. The PDA measurement volume was located at the standoff distance of 80 mm from the exit of the plasma torch and on the mean trajectory of the particle plume for the two kinds of powders respectively, where the possibility that particles could be melted was higher.…”

Section: Signals Of Light Generated From Non-spherical Particlesmentioning

confidence: 99%

Measurement of the in-flight particle characteristics in plasma spraying by phase Doppler anemometry (PDA)

Wang¹

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The author would like to take this opportunity to express his great appreciation and gratitude to his supervisor, Associate Professor Yu Ching Man Simon for his advice and guidance extended throughout the project. He would also like to thank Associate Professor Ng Heong Wah for his kind assistance and continuous support during his entire experiments. The author would also like to thank his best friends and colleagues, Ma Jian and Kang Chang Wei. The former has greatly helped him with the PDA fundamentals while the latter has worked with him in many of the plasma spraying experiments. He would also like to thank all the Technicians in Thermal and Fluids Research Lab, Ceramic Processing Lab, Wind Tunnel Lab and Material Lab A for their help whenever required. At the same time, gratitude is due to the Nanyang Technological University (NTU) for providing the financial support in carrying out this research work, without which this research work would not have been possible. Finally, the author has to express his appreciation to his lovely wife, Han Qing, who has always being so considerate and supportive to his work. And he would also thank his parents and sister for their kind understanding and support. The author thanks all mentioned above once again from the bottom of his heart.

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PDA measurements in a three‐phase bubble column

Gan

Law

2013

AIChE Journal

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Phase Doppler anemometry was used to quantify the flow characteristic of a three phases (liquid, solid, and bubbles) cylindrical bubble column driven by a point air source made of a 30‐mm diameter perforated air stone centrally mounted at the bottom. The cylindrical bubble column had an inner diameter of 152 mm and was filled with liquid up to 1 m above the point source. Acrylic beads with a nominal diameter of 3 mm were used as the solid phase. To match the density of the solid phase which was 1.05 kg/m3, the liquid density was raised to about 1.0485 kg/m3 by added salt. The bubble diameters generated were within the range of 600–2400 µm. The detailed turbulent characteristics of the liquid‐phase velocity, bubble diameter, bubble velocity, and solid velocity were measured at three different air rates, namely 0.4, 0.8, and 1.2 L/min (corresponding to average gas volume fraction of 0.0084, 0.0168, and 0.0258, respectively) for the homogeneous bubble column regime. With the addition of the solid phase, the flow field was found to be relatively steady compared to the two‐phase column referencing the probability density functions for both the liquid and bubble velocities. An analysis based on the determination of the drag forces and transversal lift forces was performed to examine the flow stability in the three‐phase bubble column. The analysis illustrated that how the added solid phase effectively stabilized the flow field to achieve a steady circulation in the bubble column and a generalized criterion for the flow stability in the three‐phase bubble column was derived. Further investigation for the transition and the heterogeneous bubble column regime with air rates at 2.0 and 4.0 L/min shown that this criterion can also be used as a general prediction of flow stability in this three‐phase bubble column. © 2013 American Institute of Chemical Engineers AIChE J, 59: 2286–2307, 2013

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Particle velocities, sizes and flux distribution in plasma spray with two powder injection ports

Cited by 20 publications

References 15 publications

Correlation of Plasma Sprayed Coating Deposition Efficiency with Volume Flux Measurements by Phase Doppler Anemometry (PDA)

Correlation of Plasma Sprayed Coating Deposition Efficiency with Volume Flux Measurements by Phase Doppler Anemometry (PDA)

Measurement of the in-flight particle characteristics in plasma spraying by phase Doppler anemometry (PDA)

PDA measurements in a three‐phase bubble column

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