Droplet impacts on granular monolayers transition from horizontal spreading to corona splashing

Scilight ◽  
2021 ◽  
Vol 2021 (44) ◽  
pp. 441109
Author(s):  
Adam Liebendorfer
Keyword(s):  
Droplet Impacts

scholarly journals A Staged Approach to Erosion Analysis of Wind Turbine Blade Coatings

Coatings ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 681
Author(s):  
David Nash ◽  
Grant Leishman ◽  
Cameron Mackie ◽  
Kirsten Dyer ◽  
Liu Yang
Keyword(s):  
Computed Tomography ◽  
Wind Turbine ◽  
Incubation Period ◽  
Leading Edge ◽  
X Ray ◽  
Erosion Testing ◽  
Staged Approach ◽  
X Ray Computed ◽  
Droplet Impacts ◽  
Rain Erosion

The current wind turbine leading-edge erosion research focuses on the end of the incubation period and breakthrough when analysing the erosion mechanism. This work presented here shows the benefits of splitting and describing leading-edge erosion progression into discrete stages. The five identified stages are: (1) an undamaged, as-new, sample; (2) between the undamaged sample and end of incubation; (3) the end of incubation period; (4) between the end of incubation and breakthrough, and (5) breakthrough. Mass loss, microscopy and X-ray computed tomography were investigated at each of the five stages. From this analysis, it was observed that notable changes were detected at Stages 2 and 4, which are not usually considered separately. The staged approach to rain erosion testing offers a more thorough understanding of how the coating system changes and ultimately fails due to rain droplet impacts. It is observed that during microscopy and X-ray computed tomography, changes unobservable to the naked eye can be tracked using the staged approach.

Splashing of Nickel Droplets During Plasma Spraying

2000 ◽  
Author(s):  
V. Pershin ◽  
I. Thomson ◽  
S. Chandra ◽  
J. Mostaghimi
Keyword(s):  
Substrate Temperature ◽  
Nickel Powder ◽  
Steel Substrate ◽  
Spray Coating ◽  
Building Blocks ◽  
Thermal Spray Coating ◽  
Substrate Heating ◽  
Polished Stainless Steel ◽  
Plasma Sprayed ◽  
Droplet Impacts

Abstract Individual splats are the building blocks of any thermal spray coating. Near the coating-substrate interface, they affect coating properties like adhesion strength. This article examines the effect of substrate heating on droplet splashing. Nickel powder was plasma-sprayed onto a polished stainless steel substrate at various temperatures and the resulting splats were analyzed. Droplet splashing was observed experimentally for three different cases: low substrate temperature, high substrate temperature, and droplet-splat interaction. Mechanisms for splashing were explained with the help of computer-generated nickel droplet impacts. The article proposes that the jetting of molten metal is not triggered by the formation of a central splat but rather a solidified ring on the periphery of the splat. It was observed that, on substrates below 350 deg C, splashing is triggered by solidification at the edge of the spreading droplet. Interactions with previously deposited splats also cause droplets to splash.

scholarly journals Droplet impacts onto soft solids entrap more air

Soft Matter ◽  
2020 ◽  
Vol 16 (24) ◽  
pp. 5702-5710
Author(s):  
Kenneth R. Langley ◽  
Alfonso A. Castrejón-Pita ◽  
Sigurdur T. Thoroddsen
Keyword(s):  
Liquid Drop ◽  
Rigid Surface ◽  
Soft Solids ◽  
Droplet Impacts

A liquid drop impacting onto a soft solid will entrap more air in the central air disc than an equivalent drop impacting onto a rigid surface.

Cratering response during droplet impacts on granular beds

2019 ◽  
Vol 42 (8) ◽  
Author(s):  
Emmanuel Wyser ◽  
Dario Carrea ◽  
Michel Jaboyedoff ◽  
Shiva P. Pudasaini
Keyword(s):  
Droplet Impacts

A discussion on deformation of solids by the impact of liquids, and its relation to rain damage in aircraft and missiles, to blade erosion in steam turbines, and to cavitation erosion - The application of dislocation etching techniques to the study of liquid impacts

1966 ◽  
Vol 260 (1110) ◽  
pp. 101-120 ◽  
Keyword(s):  
Liquid Droplet ◽  
Effective Area ◽  
Optical Microscope ◽  
Dislocation Loops ◽  
Steam Turbines ◽  
Liquid Drops ◽  
Dislocation Etching ◽  
Chemical Etch ◽  
The Impact ◽  
Droplet Impacts

Erosion damage is very often the cumulative result of a series of liquid droplet impacts which individually do not produce any deformation visible under the optical microscope. Such collisions do, however, produce dislocations in the crystalline structure surrounding the area of impact, and in suitable materials these dislocations can be revealed by chemical etch pitting. The technique is particularly easy to apply to freshly cleaved lithium fluoride crystals, and it has been used to study several types of impact. The impact of solid balls produces symmetrical rosettes of dislocations lying on {110} planes, and the dimensions of the rosettes can be related to the area of contact and stress distribution calculated from the theory of the collision of elastic/plastic bodies. Similar, but less symmetrical, rosettes are produced by liquid impacts and, by comparison of the extent and distribution of the dislocation loops in the two cases, it has been possible to make an estimate of the pressure and effective area of contact for liquid drops of various sizes, quantities which are otherwise difficult to measure. The behaviour of liquids other than water has also been investigated.

Waterjet Peening and Surface Preparation at 600MPa: A Preliminary Experimental Study

2006 ◽  
Vol 129 (4) ◽  
pp. 485-490 ◽  
Author(s):  
A. Chillman ◽  
M. Ramulu ◽  
M. Hashish
Keyword(s):  
Experimental Study ◽  
Plastic Deformation ◽  
High Pressure ◽  
Subsurface Layer ◽  
Surface Preparation ◽  
Material Surface ◽  
Ultra High Pressure ◽  
Shock Peening ◽  
Droplet Impacts ◽  
Compressive Residual Stresses

An experimental study was conducted to explore the surface preparation as well as the effects of high-pressure waterjet peening at 600MPa on the surface integrity and finish of metals. The concept of larger droplet size and multiple droplet impacts resulting from an ultra-high-pressure waterjet was used to explore and develop the peening process. A combination of microstructure analysis, microhardness measurements, and profilometry were used in determining the depth of plastic deformation and surface finish that result from the surface treatment process. It was found that waterjet peening at 600MPa induces plastic deformation to greater depths in the subsurface layer of metals than laser shock peening. The degree of plastic deformation and the state of the material surface were found to be strongly dependent on the peening conditions and desired surface roughness. Based on these first investigation results, water peening at 600MPa may serve as a new method for introducing compressive residual stresses in engineering components.

scholarly journals Charge separation and isolation in strong water droplet impacts

2015 ◽  
Vol 17 (10) ◽  
pp. 6858-6864 ◽  
Author(s):  
F. Wiederschein ◽  
E. Vöhringer-Martinez ◽  
A. Beinsen ◽  
F. Postberg ◽  
J. Schmidt ◽  
...  
Keyword(s):  
Charge Separation ◽  
Water Droplet ◽  
Condensed Matter ◽  
High Energy ◽  
Droplet Formation ◽  
Charged Droplet ◽  
Energy Impact ◽  
Droplet Impacts

A schematic picture of the phenomenon of charge separation and charged droplet formation after high-energy impact in condensed matter.

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