High-speed shadow imagery to characterize the size and velocity of the secondary droplets produced by drop impacts onto a heated surface

Castanet, Guillaume; Dunand, Pierre; Caballina, Ophélie; Lemoine, Fabrice

doi:10.1007/s00348-013-1489-3

Cited by 39 publications

(29 citation statements)

References 31 publications

(39 reference statements)

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“…To handle non-spherical droplets they developed a computational method, which calculated the second derivative of the filtered gray level function to detect the boundaries of the drops. Castanet et al (2013) developed an approach based on a Laplacian of the Gaussian method used in particular for blob structures (Acharya and Ray 2005), to detect the outline of the drops, measure their size and track their trajectories in time. The method was applied in the secondary drops generated from drops impacting onto a heated surface.…”

Section: Drop Size and Data Treating Algorithmsmentioning

confidence: 99%

Optical measurements in evolving dispersed pipe flows

Voulgaropoulos

Angeli

2017

Exp Fluids

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Section: Drop Size and Data Treating Algorithmsmentioning

confidence: 99%

Optical measurements in evolving dispersed pipe flows

Voulgaropoulos

Angeli

2017

Exp Fluids

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“…The droplet tracking algorithm (Section 2.2.2) used in this study has been adapted from Castanet et al (2013) for a single moving agricultural spray nozzle to compute the velocity of each impacting droplets. Algorithms used in the following sections were run on a personal computer using Matlab (The MathWorks Company, Natick, MA, USA).…”

Section: Image Analysismentioning

confidence: 99%

Spray droplet impaction outcomes for different plant species and spray formulations

et al. 2017

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A track-sprayer combined with a high-speed camera were used to visualize and identify droplet impaction outcomes for three formulations (water, 0.1% LI 700® (lecithin, a mixture of soya oils, propionic acid and surfactants) in water and 0.1% Pulse® (non-ionic surfactant, trisiloxane ethoxylate) in water) on four plant species (bean (Vicia faba L.), avocado (Persea americana L.), barnyard grass (Echinochloa crus-galli L. P. Beauv.) and cabbage (Brassica oleracea L.)) selected to represent a wide range of leaf surface characters. Droplet sizes and velocities were measured by image analysis and a multiple hypothesis tracking algorithm. Impaction outcomes were categorized into adhesion, bounce, or shatter. The probability of each outcome was estimated from logistic regression models related to the dimensionless Weber number. This approach is in contrast to various deterministic threshold criteria for droplet bounce or shatter that have been used to model droplet impaction events on leaves. It also provides a simple visual and numerical presentation of the complexity of impaction processes, and the relative influence of leaf surface character versus formulation for droplets with different impaction energies.

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“…E.3 in Appendix E.1. Similar trends were found by Lee and Kim [84] and by Castanet et al [26]. Since the depth of field starts to decrease when the object size falls below a certain limit, the method is naturally biased towards large droplets and ligaments.…”

Section: Digital Image Analysissupporting

confidence: 82%

“…The method has besides an important advantage over other techniques, such as PDA, since it delivers a visual impression of the spray structure. This allows for detecting liquid fragments of any shape and gives good insight into the breakup process as shown in several studies [5,26,58,59,75,78,82].…”

Section: Methodsmentioning

confidence: 97%

On the atomization and combustion of liquid biofuels in gas turbines : towards the application of biomass-derived pyrolysis oil

Sallevelt¹

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This document was typeset using L A T E X.Cover image: Structure of a water spray produced by a pressure-swirl atomizer. SummaryThe combustion of liquid biofuels in gas turbines is an efficient way of generating heat and power from biomass. Gas turbines play a major role in the global energy supply and are suitable for a wide range of applications. However, biofuels generally have different properties compared to the conventional fossil fuels. This can lead to various problems when biofuels are directly used in existing installations.This thesis aims to provide better insights into the combustion of biomass-derived pyrolysis oil in gas turbines. Pyrolysis oil can be produced from non-edible biomass via the fast pyrolysis process. In this process, the organic matter is thermally decomposed under mild conditions (~500 • C, 1 atm) through rapid heating in an oxygenfree environment. The vapors formed in the reactor are subsequently condensed to obtain a combustible liquid as the main product. In comparison to the most common biofuels of the first generation, i.e. bioethanol and biodiesel, pyrolysis oil has advantages regarding cost and environmental benefits. From a technical point of view, however, it is a less favorable fuel due properties such as a low heating value, high water content, high acidity, high viscosity, increased surface tension and poor stability. Gas turbines therefore need to be modified before they can successfully operate on pyrolysis oil in pure form. One of the essential tasks is to develop a suitable burner for liquid fuels of such low quality. In this thesis, two research objectives have been formulated to support the development of pyrolysis oil combustion technology.The first objective is to describe the evaporation and flame characteristics of pyrolysis oil. This objective has been addressed by developing a CFD model based on the Euler-Lagrange method in ANSYS Fluent. The modeling approach was first applied to simulate the combustion of ethanol in a modified, downscaled diesel burner of the OPRA OP16 gas turbine rated at 1.9 MW e . This part of the numerical work can be regarded as a first step to validate the model against experiments and literature. Ethanol is a suitable replacement of pyrolysis oil for this purpose, since it is a singlecomponent, nonviscous, volatile and clean burning biofuel that has been studied more extensively in the past. In the next step, the model was further developed to simulate the full-scale combustion of pyrolysis oil in a burner that was recently designed by OPRA for biofuel applications. The complex composition of pyrolysis oil has been approximated by means of a surrogate fuel containing seven components: methanol, water, acetic acid, acetol, phenol, eugenol and levoglucosan. Each comv ponent is known to be present in pyrolysis oil and is used to represent a group of constituents with similar properties. The initial mass fractions of the seven components are chosen such that the surrogate fuel matches the volatility, water content, elemental composition...

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High-speed shadow imagery to characterize the size and velocity of the secondary droplets produced by drop impacts onto a heated surface

Cited by 39 publications

References 31 publications

Optical measurements in evolving dispersed pipe flows

Optical measurements in evolving dispersed pipe flows

Spray droplet impaction outcomes for different plant species and spray formulations

On the atomization and combustion of liquid biofuels in gas turbines : towards the application of biomass-derived pyrolysis oil

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