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Alain H Cartellier - One of the best experts on this subject based on the ideXlab platform.
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Spray Characterization of Gas-Centered Swirl Coaxial Injectors U sing an Optical Probe
2011Co-Authors: Sylvain Marty, Alain H Cartellier, Moongeun Hong, Jean-philippe Matas, Soo Yong LeeAbstract:In order to investigate spray characteristics of gas-centered swirl coaxial injectors, a phase detection Optical Probe is employed to obtain the spatial evolution of the drop size and velocity. From the study on the Optical Probe responses under various impact angles, it is demonstrated that the drop size and velocity can be measured with an uncertainty less than 15% when the Probe axis remains within about ±15° of the drop velocity direction. This typical uncertainty is in good agreement with a previous study. It is also shown that the drop sizes measured by the Optical Probe are in accord with those evaluated by image processing techniques. Finally, the experiments with the Optical Probe are performed in dense sprays, as it were, in the near field of gas-centered swirl coaxial injectors. Some experimental results are presented and discussed to be of help to understanding of spray characteristics of the injectors.
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Spray Characterization of Gas-Centered Swirl Coaxial Injectors Using an Optical Probe
2011Co-Authors: Sylvain Marty, Alain H Cartellier, Moongeun Hong, Jean-philippe Matas, Soo Yong LeeAbstract:In order to investigate spray characteristics of gas-centered swirl coaxial injectors, a phase detection Optical Probe is employed to obtain the spatial evolution of the drop size and velocity. From the study on the Optical Probe responses under various impact angles, it is demonstrated that the drop size and velocity can be mea- sured with an uncertainty less than 15% when the Probe axis remains within about §15± of the drop velocity direction. This typical uncertainty is in good agreement with a previous study. It is also shown that the drop sizes measured by the Optical Probe are in accord with those evaluated by image processing techniques. Finally, the experiments with the Optical Probe are performed in the near ¯eld of dense sprays. Some experimental results are presented and discussed to be of help to understanding of spray characteristics in gas-centered swirl coaxial injectors.
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Measurement accuracy of a mono-fiber Optical Probe in a bubbly flow
International Journal of Multiphase Flow, 2010Co-Authors: Jiří Vejražka, Philippe Sechet, Marek Večeř, Sandra Orvalho, Marek C. Ruzicka, Alain H CartellierAbstract:The measurement accuracy of a mono-fiber Optical Probe is studied experimentally using isolated bubbles rising freely in a still liquid. The dwell time of the Probe tip within the gas phase, which is obtained from both the Optical Probe signal and high-speed visualization, is compared with the value expected for a non-perturbed bubble. The difference originates mainly from the intrusive nature of the Optical Probe, which modifies the bubble behavior when it comes into contact with the Probe tip. This interaction increases the dwell time if the bubble is pierced by the Probe near its pole, and shortens it for piercing near the equator. The mean dwell time, obtained by averaging for various piercing locations, is shortened and the local void fraction indicated by the Probe is thus underestimated. It is shown that the void fraction error can be correlated with a modified Weber number, and this correlation is helpful for sensor selection and for uncertainty estimate. In addition, the distribution of gas dwell time usually differs from the response expected for an ideal Probe. This deviation results from the dependence of the dwell time error on the piercing location. The dwell time distribution can be used to infer the dependence of the dwell time on the piercing location. Finally, the deformation of long fibers during the bubble-Probe interaction significantly increases the measurement error. Observed results are consistent with data of Andreotti (2009), which were measured in an airlift flow, suggesting that present results are applicable also to the case of moving liquid. Conclusions of this study could be applied also to conductivity Probes or more generally to the interaction of a bubble with any kind of thin, intrusive sensor or fiber.
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measurement of gas phase characteristics using a monofibre Optical Probe in a three phase flow
Chemical Engineering Science, 2008Co-Authors: P C Mena, Philippe Sechet, Fernando Rocha, J. A. Teixeira, Alain H CartellierAbstract:The study of gas-liquid-solid systems structure requires reliable measurement tools. In this paper, pre-liminary results on the potential use of a monofibre Optical Probe to investigate such flow are presented. This Probe, manufactured at LEGI, allows the simultaneous measurement of the gas phase residence time and gas phase velocity. This specificity makes this Probe more interesting than classical single tip Probes or double tip Probes. Although extensively used in two-phase gas-liquid, this Probe was never used in gas-liquid-solid systems. First, the Probe signal response is studied for three-phase flow conditions in the presence of solids. Results show that for soft solids, the Probe tips can be contaminated when the Probe pierces the solid. The signal processing procedure was modified accordingly to take into account these events. Second, the Probe results are validated by comparing global results deduced from profile measurements with measurements performed by independent means. Lastly, void fraction profiles and interfacial area are studied more in detail. Depending on the solid loading, these profiles exhibit different behaviours. These features are associated to characteristics of the flow such as the transition from an homogeneous regime to an heterogenous regime, and are consistent with global observation performed by independent means. This demonstrates the ability of the Probe to connect local information to the global behaviour and structure of the flow.
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simultaneous void fraction measurement bubble velocity and size estimate using a single Optical Probe in gas liquid two phase flows
Review of Scientific Instruments, 1992Co-Authors: Alain H CartellierAbstract:Optical Probes are now commonly used in industrial conditions as well as in laboratory experiments. Although they have been primarily devoted to void fraction measurements, additional information could be extracted from the raw signals they deliver. For a stretched Optical Probe, it is shown that the modulus of the ensemble velocity of a bubble ‖V0‖ could be inferred from the rise time Tu associated with the liquid/gas transition. These two parameters are correlated thanks to piercing experiments in which the interface curvature R and the angle β between the Probe and the normal to the interface are controlled. While the influence of R is negligible, the rise time is very sensitive to β. A one‐to‐one relation between Tu and ‖V0‖ is ensured for quasiperpendicular impactions which must be accordingly distinguished among the bubble signatures. The software which includes the adequate signal processing criteria is described. It gives access to void fraction and to the chord‐velocity joint distribution which p...
Robert F. Mudde - One of the best experts on this subject based on the ideXlab platform.
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X-ray measurements on the influence of Optical Probes on gas–solid fluidized beds
International Journal of Multiphase Flow, 2015Co-Authors: Simon Maurer, Evert C. Wagner, Tilman J. Schildhauer, J. Ruud Van Ommen, Serge M.a. Biollaz, Robert F. MuddeAbstract:X-ray tomography is applied to study the influence of an Optical Probe on the hydrodynamic behavior of a gas-solid bubbling fluidized bed. For this purpose, single bubbles were centrally injected at the bottom of a bubbling fluidized bed of Geldart A/B particles, which was set to minimum fluidization velocity. X-ray measurements were conducted with and without the Optical Probe at a measurement plane below and above the Optical Probe. No change in bubble hydrodynamics were observed with employed Optical Probes, which make them useful for permanent monitoring the fluidization of similar catalytic bubbling fluidized reactors within certain limitations.
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four point Optical Probe for measurement of bubble dynamics validation of the technique
Flow Measurement and Instrumentation, 2008Co-Authors: Junli Xue, Milorad P. Dudukovic, Muthanna H Aldahha, Robert F. MuddeAbstract:Abstract The four-point Optical Probe and the developed data processing algorithm for the measurement of bubble dynamics were validated by video imaging. It was found that the distribution of bubble velocities, specific interfacial area and local gas holdup obtained by the Probe match well with the data obtained by video imaging. The bubble chord length obtained by the Probe is also validated indirectly. Therefore, the four-point Optical Probe and the developed algorithm for data processing can be used to characterize the bubble dynamics in multiphase flow systems, to further advance the fundamental understanding of the behavior of such systems.
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bubble dynamics measurements using four point Optical Probe
Canadian Journal of Chemical Engineering, 2008Co-Authors: Junli Xue, Milorad P. Dudukovic, Muthanna H Aldahha, Robert F. MuddeAbstract:By conducting an analysis of the measurement errors it was found that bubble dynamics obtained by two-point Probes can be highly inaccurate. A four-point Optical Probe with appropriate data processing algorithm has been developed so that the bubble velocity vector can be obtained. This Probe provides directly the value of specific gas-liquid interfacial area. However, for obtaining accurate values of bubble velocity and size, the four-point Probe must be calibrated by a CCD camera at the same conditions. Calibration columns have been developed for this purpose where the bubble size and velocity can be varied to calibrate the measurements by the four-point Optical Probe against a CCD camera.
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bubble velocity size and interfacial area measurements in a bubble column by four point Optical Probe
Aiche Journal, 2008Co-Authors: Muthanna H Aldahhan, Milorad P. Dudukovic, Robert F. MuddeAbstract:The four-point Optical Probe is applied in a bubble column with an air–water system to investigate the bubble properties (local gas holdup, velocity, chord length, specific interfacial area, and frequency) over a range of gas superficial velocities. Both bubbles moving upward and downward are recorded and measured as opposed to only upward bubbles measured and reported in other studies involving Probes. The Probe worked efficiently in both bubbly flow and highly churn-turbulent flow at very high superficial gas velocities. Bubble properties at the conditions of churn-turbulent flow are obtained and investigated for the first time. The changes in the bubble velocity distribution, bubble chord length distribution, and specific interfacial area with superficial gas velocity, sparger design, and with axial and radial positions in the column are discussed. © 2007 American Institute of Chemical Engineers AIChE J, 2008
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Bubble velocity, size, and interfacial area measurements in a bubble column by four‐point Optical Probe
Aiche Journal, 2008Co-Authors: Muthanna H. Al-dahhan, Milorad P. Dudukovic, Robert F. MuddeAbstract:The four-point Optical Probe is applied in a bubble column with an air–water system to investigate the bubble properties (local gas holdup, velocity, chord length, specific interfacial area, and frequency) over a range of gas superficial velocities. Both bubbles moving upward and downward are recorded and measured as opposed to only upward bubbles measured and reported in other studies involving Probes. The Probe worked efficiently in both bubbly flow and highly churn-turbulent flow at very high superficial gas velocities. Bubble properties at the conditions of churn-turbulent flow are obtained and investigated for the first time. The changes in the bubble velocity distribution, bubble chord length distribution, and specific interfacial area with superficial gas velocity, sparger design, and with axial and radial positions in the column are discussed. © 2007 American Institute of Chemical Engineers AIChE J, 2008
Pisut Painmanakul - One of the best experts on this subject based on the ideXlab platform.
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Performance of a monofiber Optical Probe in determining the droplet size and velocity in spray systems comparing with a high-speed camera
Industrial and engineering chemistry research, 2019Co-Authors: Kritchart Wongwailikhit, Nicolas Dietrich, Gilles Hébrard, Pisut PainmanakulAbstract:Optical fiber Probe has been recently developed for characterizing the liquid dispersed in gas in droplet form, but its performance has yet been identified for an actual spray system. This work aims to compare the performance of a monofiber Optical Probe in characterizing the hydrodynamics in spray systems with that of a high-speed camera. Initially, both techniques determined the same series of droplets produced by a syringe. The droplet velocities and sizes obtained from the Optical Probe were in accordance with the high-speed camera when the droplet coalescence was filtered out from the data. Second, a full-cone spray nozzle was used and the average velocities from the two techniques were close, but the off-center collision on the Probe and the difference in size limits caused the discrepancy in the size determination. However, the Probe is still beneficial to determine the droplet hydrodynamics and local liquid fraction, the essential characteristics of a spray system.
Peidong Yang - One of the best experts on this subject based on the ideXlab platform.
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Tunable nanowire nonlinear Optical Probe
Nature, 2007Co-Authors: Yuri Nakayama, Robert M. Onorato, Jan Liphardt, Peter J. Pauzauskie, Richard J Saykally, Aleksandra Radenovic, Peidong YangAbstract:One crucial challenge for subwavelength optics has been the development of a tunable source of coherent laser radiation for use in the physical, information and biological sciences that is stable at room temperature and physiological conditions. Current advanced near-field imaging techniques using fibre-optic scattering Probes have already achieved spatial resolution down to the 20-nm range. Recently reported far-field approaches for Optical microscopy, including stimulated emission depletion, structured illumination, and photoactivated localization microscopy, have enabled impressive, theoretically unlimited spatial resolution of fluorescent biomolecular complexes. Previous work with laser tweezers has suggested that Optical traps could be used to create novel spatial Probes and sensors. Inorganic nanowires have diameters substantially below the wavelength of visible light and have electronic and Optical properties that make them ideal for subwavelength laser and imaging technology. Here we report the development of an electrode-free, continuously tunable coherent visible light source compatible with physiological environments, from individual potassium niobate (KNbO3) nanowires. These wires exhibit efficient second harmonic generation, and act as frequency converters, allowing the local synthesis of a wide range of colours via sum and difference frequency generation. We use this tunable nanometric light source to implement a novel form of subwavelength microscopy, in which an infrared laser is used to Optically trap and scan a nanowire over a sample, suggesting a wide range of potential applications in physics, chemistry, materials science and biology.
Micah S Siegel - One of the best experts on this subject based on the ideXlab platform.
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a genetically encoded Optical Probe of membrane voltage
Neuron, 1997Co-Authors: Micah S Siegel, Ehud Y IsacoffAbstract:Measuring electrical activity in large numbers of cells with high spatial and temporal resolution is a fundamental problem for the study of neural development and information processing. To address this problem, we have constructed a novel, genetically encoded Probe that can be used to measure transmembrane voltage in single cells. We fused a modified green fluorescent protein (GFP) into a voltage-sensitive K+ channel so that voltage-dependent rearrangements in the K+ channel would induce changes in the fluorescence of GFP. The Probe has a maximal fractional fluorescence change of 5.1%, making it comparable to some of the best organic voltage-sensitive dyes. Moreover, the fluorescent signal is expanded in time in a way that makes the signal 30-fold easier to detect. A voltage sensor encoded into DNA has the advantage that it may be introduced into an organism noninvasively and targeted to specific developmental stages, brain regions, cell types, and subcellular compartments.
