Measurement of Liquid Film Thickness via Light Absorption and Laser Tomography

Mendez, Miguel Alfonso; Németh, Làszló; Buchlin, Jean‐Marie

doi:10.1051/epjconf/201611402072

Cited by 11 publications

(6 citation statements)

References 26 publications

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“…The goal was to obtain a low-cost measurement technique that reduces the data acquisition time and error compared to the manual tracing method and has a fast, efficient, and reliable post-processing method. The algorithm was developed in MATLAB, version R2018b, and it is based on directional image analysis with a grayscale gradient identification, similar to LeDaR [38] (level detection and recording), followed by image binarization and morphological operations to filter out the eventual outliers and to generate the final ice edge profile. The detection process can be adapted to each case by employing several adjustable parameters-which, for good-quality images (with minimal light reflections or shadows), are constant for each ice accretion regime.…”

Section: Image-processing Ice Edge Detection Methodsmentioning

confidence: 99%

“…Looking at possible inexpensive solutions, measurement techniques based on image processing algorithms are used in many fields [36,37], from the research of physical phenomena [38][39][40][41], of environmental events [42][43][44], or medical research [45][46][47] to the assessment of industrial faults [48][49][50]. These types of algorithms provide non-invasive measurement capabilities, efficient ways to process big amounts of data, are cost-efficient, offer improved and reliable detection accuracy, and significantly reduce human error.…”

Section: Introductionmentioning

confidence: 99%

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Ice Accretion: Image Post-Processing Measurement Techniques for 2D Ice Shapes

et al. 2023

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Ice accretion poses substantial safety hazards for the manned and unmanned aviation industries. Its study is essential for icing events risk assessment and for the development of efficient ice protection systems. The existing ice accretion measurement techniques—casting, molding, and laser-scanning—are time-consuming, sometimes cumbersome to use, and highly expensive, while hand tracing is inexpensive, but has lower accuracy and time-consuming post-processing. This work presents two low-cost, fast, and easy-to-use measurement techniques for 2D ice accretion profiles. Both employ algorithms of automatic ice shape detection, one based on unmediated image-processing, another based on the processing of manual ice tracings. The techniques are applied to ice accretion experiments conducted in an icing wind tunnel at low Reynolds numbers, and their results are validated against ice thickness caliper measurements. A comparison of the results shows that both techniques accurately measure the leading-edge ice thickness and the 2D shape of the ice accretion profiles. One technique is faster, with higher measurement accuracy, but produces interrupted-line 2D ice profiles and requires good lighting conditions, while the other generates continuous-line 2D profiles and has no application restriction, but it is slower, with lower accuracy. A discussion is conducted, aiming to help one determine the best applications for each ice accretion measurement technique presented.

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Section: Image-processing Ice Edge Detection Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Ice Accretion: Image Post-Processing Measurement Techniques for 2D Ice Shapes

et al. 2023

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“…Only the right side of the meniscus is shown since the problem is symmetric. The interface is detected by calculating the vertical gradient of the image intensity, similarly to Mendez et al (2016Mendez et al ( , 2018, by searching for the peak in the intensity gradient in each image column. At the end of this process, outliers are removed using a local median filter.…”

Section: Lif Visualization: Set-up and Processingmentioning

confidence: 99%

Analysis of an unsteady quasi-capillary channel flow with Time Resolved PIV and RBF-based super resolution

Ratz¹,

Fiorini²,

Simonini³

et al. 2022

Preprint

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We investigate the behaviour of accelerating contact lines in an unsteady quasi-capillary channel flow. The configuration consists of a liquid column that moves along a vertical 2D channel, open to the atmosphere and driven by a controlled pressure head. Both advancing and receding contact lines were analyzed to test the validity of classic models for dynamic wetting and to study the flow field near the interface. The operating conditions are characterized by a large acceleration, thus dominated by inertia. The shape of the moving meniscus was retrieved using Laser-Induced Fluorescence (LIF)-based image processing while the flow field near was analyzed via Time-Resolved Particle Image Velocimetry (TR-PIV). The TR-PIV measurements were enhanced in the post-processing, using a combination of Proper Orthogonal Decomposition (POD) and Radial Basis Functions (RBF) to achieve superresolution of the velocity field. Large counter-rotating vortices were observed, and their evolution was monitored in terms of the maximum intensity of the Q-field. The results show that classic contact angle laws based on interface velocity cannot describe the evolution of the contact angle at a macroscopic scale. Moreover, the impact of the interface dynamics on the flow field is considerable and extends several capillary lengths below the interface.

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“…To maximize and match the absorption spectra of the liquid with the emission spectra of the light, a methylene blue colorant is diluted in the liquid, with a concentration of 21 mg/Kg. The definition of the optimal colorant concentration for minimizing the measurement uncertainties is presented in [29,40]. An exemplary image of the TR-Labs acquisition is shown in Fig.5 (top), together with the corresponding reference image (bottom) of the dry test section.…”

Section: The Vki Ondule Facilitymentioning

confidence: 99%

Experimental Characterization of the Jet Wiping Process

et al. 2018

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This paper presents an experimental characterization of the jet wiping process, used in continuous coating applications to control the thickness of a liquid coat using an impinging gas jet. Time Resolved Particle Image Velocimetry (TR-PIV) is used to characterize the impinging gas flow, while an automatic interface detection algorithm is developed to track the liquid interface at the impact. The study of the flow interaction is combined with time resolved 3D thickness measurements of the liquid film remaining after the wiping, via Time Resolved Light Absorption (TR-LAbs). The simultaneous frequency analysis of liquid and gas flows allows to correlate their respective instability, provide an experimental data set for the validation of numerical studies and allows for formulating a working hypothesis on the origin of the coat non-uniformity encountered in many jet wiping processes.

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Measurement of Liquid Film Thickness via Light Absorption and Laser Tomography

Cited by 11 publications

References 26 publications

Ice Accretion: Image Post-Processing Measurement Techniques for 2D Ice Shapes

Ice Accretion: Image Post-Processing Measurement Techniques for 2D Ice Shapes

Analysis of an unsteady quasi-capillary channel flow with Time Resolved PIV and RBF-based super resolution

Experimental Characterization of the Jet Wiping Process

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