Modeling the impact, flattening and solidification of a molten droplet on a solid substrate during plasma spraying

2014 ◽  
Vol 317 ◽  
pp. 526-533 ◽  
Author(s):  
Y.Z. Zheng ◽  
Q. Li ◽  
Z.H. Zheng ◽  
J.F. Zhu ◽  
P.L. Cao
Keyword(s):  
Plasma Spraying ◽  
Solid Substrate ◽  
Molten Droplet ◽  
The Impact

scholarly journals Numerical Simulations of the Impact and Spreading of a Particulate Drop on a Solid Substrate

2012 ◽  
Vol 2012 ◽  
pp. 1-10
Author(s):  
Hyun Jun Jeong ◽  
Wook Ryol Hwang ◽  
Chongyoup Kim
Keyword(s):  
Numerical Simulations ◽  
Solid Surface ◽  
Reynolds Numbers ◽  
Suspended Particles ◽  
Solid Substrate ◽  
Oscillatory Behavior ◽  
Navier Stokes ◽  
Droplet Spreading ◽  
Navier Stokes Equation ◽  
The Impact

We present two-dimensional numerical simulations of the impact and spreading of a droplet containing a number of small particles on a flat solid surface, just after hitting the solid surface, to understand particle effects on spreading dynamics of a particle-laden droplet for the application to the industrial inkjet printing process. The Navier-Stokes equation is solved by a finite-element-based computational scheme that employs the level-set method for the accurate interface description between the drop fluid and air and a fictitious domain method for suspended particles to account for full hydrodynamic interaction. Focusing on the particle effect on droplet spreading and recoil behaviors, we report that suspended particles suppress the droplet oscillation and deformation, by investigating the drop deformations for various Reynolds numbers. This suppressed oscillatory behavior of the particulate droplet has been interpreted with the enhanced energy dissipation due to the presence of particles.

Experiments on the breakup of drop-impact crowns by Marangoni holes

2018 ◽  
Vol 844 ◽  
pp. 162-186 ◽  
Author(s):  
Abdulrahman B. Aljedaani ◽  
Chunliang Wang ◽  
Aditya Jetly ◽  
S. T. Thoroddsen
Keyword(s):  
Surface Tension ◽  
Lower Surface ◽  
High Viscosity ◽  
Solid Substrate ◽  
Immiscible Liquid ◽  
Hole Formation ◽  
Low Viscosity ◽  
Stress Changes ◽  
Lower Surface Tension ◽  
The Impact

We investigate experimentally the breakup of the Edgerton crown due to Marangoni instability when a highly viscous drop impacts on a thin film of lower-viscosity liquid, which also has different surface tension than the drop liquid. The presence of this low-viscosity film modifies the boundary condition, giving effective slip to the drop along the solid substrate. This allows the high-viscosity drop to form a regular bowl-shaped crown, which rises vertically away from the solid and subsequently breaks up through the formation of a multitude of Marangoni holes. Previous experiments have proposed that the breakup of the crown results from a spray of fine droplets ejected from the thin low-viscosity film on the solid, e.g. Thoroddsen et al. (J. Fluid Mech., vol. 557, 2006, pp. 63–72). These droplets can hit the inner side of the crown forming spots with lower surface tension, which drives a thinning patch leading to the hole formation. We test the validity of this assumption with close-up imaging to identify individual spray droplets, to show how they hit the crown and their lower surface tension drive the hole formation. The experiments indicate that every Marangoni-driven patch/hole is promoted by the impact of such a microdroplet. Surprisingly, in experiments with pools of higher surface tension, we also see hole formation. Here the Marangoni stress changes direction and the hole formation looks qualitatively different, with holes and ruptures forming in a repeatable fashion at the centre of each spray droplet impact. Impacts onto films of the same liquid, or onto an immiscible liquid, do not in general form holes. We furthermore characterize the effects of drop viscosity and substrate-film thickness on the overall evolution of the crown. We also measure the three characteristic velocities associated with the hole formation: i.e. the Marangoni-driven growth of the thinning patches, the rupture speed of the resulting thin films inside these patches and finally the growth rate of the fully formed holes in the crown wall.

scholarly journals Spreading and oscillation dynamics of drop impacting liquid film

2019 ◽  
Vol 881 ◽  
pp. 859-871 ◽  
Author(s):  
Xiaoyu Tang ◽  
Abhishek Saha ◽  
Chao Sun ◽  
Chung K. Law
Keyword(s):  
Film Thickness ◽  
Liquid Film ◽  
Liquid Surface ◽  
Strong Dependence ◽  
Solid Substrate ◽  
Spreading Dynamics ◽  
Viscous Loss ◽  
Shape Oscillation ◽  
Oscillation Dynamics ◽  
The Impact

We herein report an experimental study to explore the effects of impact inertia, film thickness and viscosity on the dynamics of shape deformation of a drop impacting a liquid film. We have identified that the spreading dynamics shows a weak dependence on impact inertia, but strongly depends on the film thickness. For a thick film, the liquid surface deforms and absorbs part of the impact energy, and hence inhibits spreading of the drop. For a thin film, the drop motion is restricted by the bottom solid substrate, promoting spreading. The periodicity of the capillary controlled shape oscillation, on the other hand, is found to be independent of impact inertia and film thickness. The damping of the shape oscillation shows strong dependence on the film thickness, in that the oscillation decays faster for smaller film thicknesses, due to the enhanced viscous loss.

Analysis of Madejski Splat-Quench Solidification Model With Modified Initial Conditions

2004 ◽  
Vol 126 (3) ◽  
pp. 485-489 ◽  
Author(s):  
D. Sivakumar ◽  
H. Nishiyama
Keyword(s):  
Present Model ◽  
Initial Conditions ◽  
Substrate Surface ◽  
Solid Substrate ◽  
Droplet Radius ◽  
Time Interval ◽  
Solidification Model ◽  
Numerical Predictions ◽  
Model Predictions ◽  
The Impact

The initial conditions of Madejski’s splat-quench solidification model for the impact of molten droplets on a solid substrate surface are modified by eliminating the adjustable parameter “ε” used in the estimation of initial spreading droplet radius. In the present model, the initial conditions are estimated after a definite time interval from the start of impact. Numerical predictions obtained from an improved Madejski model with different ε and the corresponding experimental measurements published in the literature are used for the comparison of the present model predictions. The improvements noted from the model predictions are reported.

scholarly journals Experimental Study of the Impact of Substrate Shape and Tilting on Particle Velocity in Suspension Plasma Spraying

2020 ◽  
Vol 29 (3) ◽  
pp. 358-367
Author(s):  
A. Dolmaire ◽  
S. Goutier ◽  
A. Joulia ◽  
P-M. Geffroy ◽  
M. Vardelle ◽  
...  
Keyword(s):  
Experimental Study ◽  
Plasma Spraying ◽  
Particle Velocity ◽  
Suspension Plasma Spraying ◽  
The Impact

A Study of Impacting Droplets of an Emulsion or Surfactant Solution on Solid Substrates

1996 ◽  
Vol 464 ◽  
Author(s):  
M. Vignes-Adler ◽  
B. Prunet-Foch ◽  
F. Legay ◽  
N. Mourougou
Keyword(s):  
Surfactant Solution ◽  
Liquid Films ◽  
Solid Substrate ◽  
Solid Surfaces ◽  
Equilibrium Surface Tension ◽  
Solid Substrates ◽  
Surface Active ◽  
The Impact ◽  
Kinetics Of ◽  
Bounce Back

ABSTRACTCoating of solid surfaces with uniform, thin liquid films occurs in many industrial processes. A common process consists of spraying some liquids or emulsions on a freshly created solid surface. In this context, we have investigated the impact of a single droplet of various emulsions and surface-active solutions on a solid substrate using a high frequency fluorescent visualization technique (1 picture every 0.25 ms). Whatever the materials in presence, the drop spreads and then retracts under the action of inertia and capillarity respectively. Inertia induces spreading and generates a peripheral rim which is unstable to fingering. Then contact line instabilities appear under the form of festoons with pure liquids which are damped with surface-active solutions and amplified with emulsions. When the adsorption kinetics of the surfactant is slow, the equilibrium surface tension is not restored during the duration of the experiment and the drop can bounce back.

scholarly journals Evaluation of Rhodotorula growth on solid substrate via a linear mixed effects model

2011 ◽  
Vol 29 (No. 4) ◽  
pp. 400-410 ◽  
Author(s):  
T. Krulikovská ◽  
E. Jarošová ◽  
P. Patáková
Keyword(s):  
Growth Rate ◽  
Confidence Intervals ◽  
Solid Substrate ◽  
Mixed Effects ◽  
Repeated Measurements ◽  
Mixed Effects Model ◽  
Cultivation Conditions ◽  
Linear Mixed Effects Model ◽  
Linear Mixed Effects ◽  
The Impact

The growth of Rhodotorula glutinis and Rhodotorula mucilaginosa was studied under optimal and stress cultivation conditions at 10°C and 20°C for 14 days. The method of image analysis was used to determine the size of colonies. The linear mixed effects model implemented in the statistical program S-PLUS was applied to analyse the repeated measurements. Two-phase kinetics was confirmed and the mean growth rates in the second linear phase under various stress conditions were estimated. The results indicated a higher growth rate of R. mucilaginosa than was that of R. glutinis under all cultivation conditions. The highest growth rate of was observed during the cultivation of R. mucilaginosa in media with 2% of NaCl at 20°C. The impact of neglecting the fact that repeated data are not independent and using the classical regression model instead of the mixed effects model was demonstrated through the comparison of the confidence intervals for the parameters based on both approaches. While the point estimates of the corresponding parameters were similar, the width of the confidence intervals differed substantially.

Numerical study of the melting and resolidification of the substrate during the impact of a ceramic droplet in a plasma spraying process

2019 ◽  
Vol 88 (2) ◽  
pp. 20901 ◽  
Author(s):  
Mouloud Driouche ◽  
Tahar Rezoug ◽  
Mohammed El Ganaoui
Keyword(s):  
Numerical Model ◽  
Phase Change ◽  
Solid Phase ◽  
Numerical Study ◽  
Solid Substrate ◽  
Navier Stokes ◽  
Droplet Spreading ◽  
Substrate Melting ◽  
Volume Method ◽  
The Impact

The substrate melting can significantly improve the properties of plasma spray coatings. Indeed the adhesion of the projected particles to the substrate can be ameliorated by the substrate melting. In this article, a numerical model is developed to study the dynamics of fluids and heat transfer with liquid/solid phase change during impact of a fully melted alumina particle on an aluminum solid substrate, taking into account of the substrate melting. The model is based on solving the Navier-Stokes and energy equations with liquid / solid phase change. These equations are coupled with the fluid of volume method (VOF), to follow the free surface of the particle during its spreading and solidification. The finite volume method is used to discretize the equations in a 2D axisymmetric domain. A comparison with the published experimental results was carried out to validate this numerical model. Simulations were performed for different initial droplet diameters to study its effect on droplet spreading as well as on substrate melting. It has been observed that the substrate melting begins before the droplet spreads completely; the substrate melting reaches its maximum when the droplet is close to its total solidification. Droplet spreading and substrate melting are more important for large sizes droplets.

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