Bibliografías temáticas / Droplet Size Measurement

Literatura académica sobre el tema "Droplet Size Measurement"

Autor: Grafiati

Publicado: 4 de junio de 2021

Última modificación: 6 de septiembre de 2023

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Artículos de revistas sobre el tema "Droplet Size Measurement":

Ali Othman, Nur Tantiyani y Simreth Kaur Dhalywala. "Simulation Study on Liquid Droplet Size Measurement inside Venturi Scrubber". Jurnal Kejuruteraan 32, n.º 2 (30 de mayo de 2020): 239–46. http://dx.doi.org/10.17576/jkukm-2020-32(2)-08.

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Droplet distribution is an importance factor to observe scrubber’s performance as uniform droplets distribution improved the particle’s collection efficiency at minimal liquid usage. Yet, the optimization problem typically involves complicated model functions to predict particle’s collection efficiency and pressure drop. Since the interaction between liquid droplets and gas phase is complex and difficult to solve by an experimental approach. Thus in this study, the prediction of liquid droplet’s behavior in the venturi scrubber was observed by using computational fluid dynamic. The liquid was injected through two orifices on the throat wall. The droplet size at different position was observed at various range of a gas velocity from 70 to 100 m/s and the ratio of liquid to gas of 0.07 to 2.0 L/m<sup>3</sup> to determine the optimum absorption rate. The droplet’s breakup in the venturi scrubber was observed using ANSYS<sup>©</sup> simulation where two-fluid model Eulerian-Eulerian approach was applied. It shows as the gas passes through the throat section, the velocity increases gradually and as it passes through the divergent section, it decreases causing the droplet diameter to increase. Typically, the gas velocity in the throat section is between 30-120 m/s, however in this simulation, the gas velocity of 70-105 m/s shown an adequate to achieve the optimum absorption rate. Besides, the liquid to gas ratio less than 0.06 was insufficient to cover the throat, and by increasing it up to 1.0 does not significantly improve the particle collection efficiency as the velocity at the scrubber’s throat drops which a larger droplets diameter was formed.

Wittner, Marc, Heike Karbstein y Volker Gaukel. "Pneumatic Atomization: Beam-Steering Correction in Laser Diffraction Measurements of Spray Droplet Size Distributions". Applied Sciences 8, n.º 10 (26 de septiembre de 2018): 1738. http://dx.doi.org/10.3390/app8101738.

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Laser diffraction is among the most widely used methods for spray droplet size measurements. However, the so-called beam-steering effect must be considered when pneumatic atomizers are used for droplet generation. The beam-steering effect is a systematic measurement error, leading to the detection of apparent large spray droplets due to gradients in the refractive index of the gas phase. The established correction method is based on the reduction of the laser diffraction system’s measurement range by deactivation of detectors, relevant for the detection of large droplets. As this method is only applicable when size ranges of real and apparent droplet sizes are clearly different, an alternative method for beam-steering correction is introduced in the presented study. It is based on a multimodal log-normal fit of measured spray droplet sizes. The modality representing the largest droplets is correlated to the beam-steering effect and therefore excluded from the measured size distribution. The new method was successfully applied to previously published droplet size distribution measurements of an internal mixing Air-Core-Liquid-Ring (ACLR) atomizer. In measurements where the method of detector deactivation is applicable, excellent accordance of droplet size distributions, gained by both correction methods, was found. In measurements with overlapping real and apparent parts of the distribution, the new correction method led to a significant reduction of overestimated large droplets. As a consequence, we conclude that the new method presented here for beam-steering correction should be applied in laser diffraction measurements of spray droplet sizes, generated by pneumatic atomizers.

Spiegel, J. K., P. Zieger, N. Bukowiecki, E. Hammer, E. Weingartner y W. Eugster. "Evaluating the capabilities and uncertainties of droplet measurements for the fog droplet spectrometer (FM-100)". Atmospheric Measurement Techniques Discussions 5, n.º 3 (7 de mayo de 2012): 3333–93. http://dx.doi.org/10.5194/amtd-5-3333-2012.

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Abstract. Droplet size spectra measurements are crucial to obtain a quantitative microphysical description of clouds and fog. However, cloud droplet size measurements are subject to various uncertainties. This work focuses on the evaluation of two key measurement uncertainties arising during cloud droplet size measurements with a conventional droplet size spectrometer (FM-100): first, we addressed the precision with which droplets can be sized with the FM-100 on the basis of Mie theory. We deduced error assumptions and proposed how to correct measured size distributions for these errors by redistributing the measured droplet size distribution using a stochastic approach. Second, based on a literature study, we derived corrections for particle losses during sampling with the FM-100. We applied both corrections to cloud droplet size spectra measured at the high alpine site Jungfraujoch for a temperature range from 0 °C to 11 °C. We show that Mie scattering led to spikes in the droplet size distributions using the default sizing procedure, while the stochastic approach reproduced the ambient size distribution adequately. A detailed analysis of the FM-100 sampling efficiency revealed that particle losses were typically below 10% for droplet diameters up to 10 μm. For larger droplets, particle losses can increase up to 90% for the largest droplets of 50 μm at ambient windspeeds below 4.4 m s−1 and even to >90% for larger angles between the instrument orientation and the wind vector (sampling angle) at higher wind speeds. Comparisons of the FM-100 to other reference instruments revealed that the total liquid water content (LWC) measured by the FM-100 was more sensitive to particle losses than to re-sizing based on Mie scattering, while the total number concentration was only marginally influenced by particle losses. As a consequence, for further LWC measurements with the FM-100 we strongly recommend to consider (1) the error arising due to Mie scattering, and (2) the particle losses, especially for larger droplets depending on the set-up and wind conditions.

Spiegel, J. K., P. Zieger, N. Bukowiecki, E. Hammer, E. Weingartner y W. Eugster. "Evaluating the capabilities and uncertainties of droplet measurements for the fog droplet spectrometer (FM-100)". Atmospheric Measurement Techniques 5, n.º 9 (20 de septiembre de 2012): 2237–60. http://dx.doi.org/10.5194/amt-5-2237-2012.

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Abstract. Droplet size spectra measurements are crucial to obtain a quantitative microphysical description of clouds and fog. However, cloud droplet size measurements are subject to various uncertainties. This work focuses on the error analysis of two key measurement uncertainties arising during cloud droplet size measurements with a conventional droplet size spectrometer (FM-100): first, we addressed the precision with which droplets can be sized with the FM-100 on the basis of the Mie theory. We deduced error assumptions and proposed a new method on how to correct measured size distributions for these errors by redistributing the measured droplet size distribution using a stochastic approach. Second, based on a literature study, we summarized corrections for particle losses during sampling with the FM-100. We applied both corrections to cloud droplet size spectra measured at the high alpine site Jungfraujoch for a temperature range from 0 °C to 11 °C. We showed that Mie scattering led to spikes in the droplet size distributions using the default sizing procedure, while the new stochastic approach reproduced the ambient size distribution adequately. A detailed analysis of the FM-100 sampling efficiency revealed that particle losses were typically below 10% for droplet diameters up to 10 μm. For larger droplets, particle losses can increase up to 90% for the largest droplets of 50 μm at ambient wind speeds below 4.4 m s−1 and even to >90% for larger angles between the instrument orientation and the wind vector (sampling angle) at higher wind speeds. Comparisons of the FM-100 to other reference instruments revealed that the total liquid water content (LWC) measured by the FM-100 was more sensitive to particle losses than to re-sizing based on Mie scattering, while the total number concentration was only marginally influenced by particle losses. Consequently, for further LWC measurements with the FM-100 we strongly recommend to consider (1) the error arising due to Mie scattering, and (2) the particle losses, especially for larger droplets depending on the set-up and wind conditions.

Preiss, Felix Johannes, Teresa Dagenbach, Markus Fischer y Heike Petra Karbstein. "Development of a Pressure Stable Inline Droplet Generator with Live Droplet Size Measurement". ChemEngineering 4, n.º 4 (10 de noviembre de 2020): 60. http://dx.doi.org/10.3390/chemengineering4040060.

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For the research on droplet deformation and breakup in scaled high-pressure homogenizing units, a pressure stable inline droplet generator was developed. It consists of an optically accessible flow channel with a combination of stainless steel and glass capillaries and a 3D printed orifice. The droplet size is determined online by live image analysis. The influence of the orifice diameter, the mass flow of the continuous phase and the mass flow of the disperse phase on the droplet diameter were investigated. Furthermore, the droplet detachment mechanisms were identified. Droplet diameters with a small diameter fluctuation between 175 µm and 500 µm could be realized, which allows a precise adjustment of the capillary (Ca) and Weber (We) Number in the subsequent scaled high pressure homogenizer disruption unit. The determined influence of geometry and process parameters on the resulting droplet size and droplet detachment mechanism agreed well with the literature on microfluidics. Furthermore, droplet trajectories in an exemplary scaled high-pressure homogenizer disruption unit are presented which show that the droplets can be reinjected on a trajectory close to the center axis or close to the wall, which should result in different stresses on the droplets.

Li, C., Q. Lv, X. Wu y C. Tropea. "Planar Rainbow Refractometry For Size, Refractive Index And Position Measurement Of Droplets In A Plane". Proceedings of the International Symposium on the Application of Laser and Imaging Techniques to Fluid Mechanics 20 (11 de julio de 2022): 1–13. http://dx.doi.org/10.55037/lxlaser.20th.8.

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Rainbow refractometry can simultaneously measure the temperature and geometric parameters of droplets by analyzing the recorded primary rainbow scattering signal of the droplet. The technique therefore has high potential in measurement applications involving reacting/non-reacting sprays. This study develops the planar rainbow refractometer technique, expanding the measurement dimension from a single "line" measurement to a "planar" measurement. The position of the droplet in the plane is determined by the contour of the rainbow signal, whereas the size and refractive index of the droplet are derived from the extracted rainbow image using the calibrated scattering angle. A simple and compact rainbow optical measurement system is constructed based on horizontal slit modulation, enabling the recording of spatially discrete rainbow signals of droplets in a plane. A novel scattering angle calibration method using a precisely traversed monodisperse droplet stream with a priori parameters is proposed and the algorithm for obtaining the calibration coefficients is evaluated by simulation. Spray verification experiments were carried out. The signal processing consists of image recognition, particle localization, and the rejection of non-spherical droplets. The possibility of estimating droplet number density is also discussed.

D. W. DeBoer, M. J. Monnens y D. C. kincaid. "Measurement of Sprinkler Droplet Size". Applied Engineering in Agriculture 17, n.º 1 (2001): 11–15. http://dx.doi.org/10.13031/2013.1931.

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Jackson, T. A. y G. S. Samuelsen. "Spatially Resolved Droplet Size Measurements". Journal of Engineering for Gas Turbines and Power 108, n.º 1 (1 de enero de 1986): 196–203. http://dx.doi.org/10.1115/1.3239871.

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This paper encompasses initial tests of a droplet sizing technique, providing spatially and temporally resolved measurements within a liquid spray from an air assist nozzle. The method utilizes laser interferometry. The primary size measurement is based upon the signal visibility; it is validated by the peak intensity of the scattered light. As the system is based on the Doppler effect, a single component of velocity is extracted concurrent with the size information. The size of the measurement volume is controlled with off-axis light collection. Beam splitting is accomplished with a rotating diffraction grating, allowing the signal to be frequency shifted. Measurements are compared directly to those of a standard diffraction based sizing system (i.e., Malvern). The diffraction information is processed via Rosin-Rammler (2 parameter) and Model Independent (15 parameter) distribution algorithms. Correspondence between diffraction and interferometric results is satisfactory for the Model Independent algorithm. Differences observed using the Rosin-Rammler distribution are attributed to an inadequate representation of the spray by the two parameter model.

Qian, Jiang Bo, Heng Fan Li y Zhong He Han. "Influence of Large Water Droplets Passing through Microwave Cavity on Steam Wetness Measurement". Applied Mechanics and Materials 339 (julio de 2013): 495–502. http://dx.doi.org/10.4028/www.scientific.net/amm.339.495.

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The steam turbine exhaust contains large secondary droplets, and the droplets show an uneven distribution in space and time. It analyzes the change of resonant frequency and quality factor with different sizes and positions of droplets, and analyzes the influence on the steam wetness measurement. The results show that: when the size of resonant cavity is constant, the resonant frequency and quality factor are related to the size and location of water droplet. For the cylindrical cavity whose length is 40mm and radius is 30mm, when large droplet located in the ring (radius is 13.0mm) onxoyplane, it has great influence on wetness measurement, and the influence is greater with larger size of droplet.

Wang, Xinhao, Yingchun Wu, Dongyan Xu, Botong Wen, Qimeng Lv y Xuecheng Wu. "Synthetic aperture rainbow refractometry". Optics Letters 47, n.º 20 (4 de octubre de 2022): 5272. http://dx.doi.org/10.1364/ol.471103.

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This work proposed a synthetic aperture rainbow refractometry (SARR) by synthesizing rainbow signals of the same droplet with dual-wavelength laser beams, in order to increase the aperture of rainbow refractometry. In this way, the SARR can apply to long distance and small droplets measurement. An achromatic imaging system, which simultaneously records while separating the two rainbow signals in two channels of a color image, is elaborately designed. A data processing algorithm is developed to retrieve the optimal droplet refractive index and size. Numerical simulations of different droplet sizes from 10 μ m to 200 μ m certify the viability of the SARR. Proof-of-concept experiments of micron-sized ethanol droplets are performed with 1650 mm measurement distance. Results show that the SARR can accurately measure droplet refractive index and size with uncertainties of 2.3 × 10−4 and 2 μ m, respectively. The feasibility and accuracy of the proposed SARR are successfully demonstrated, paving the way for rainbow refractometry applied to large-scale industrial applications.

Más fuentes

Tesis sobre el tema "Droplet Size Measurement":

Gomes, Pimentel Rogerio. "Measurement and Prediction of Droplet Size Distribution in Sprays". Thesis, Université Laval, 2006. http://www.theses.ulaval.ca/2006/23623/23623.pdf.

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Gomes, Pimentel Rogério. "Measurement and prediction of droplet size distribution in sprays". Doctoral thesis, Université Laval, 2006. http://hdl.handle.net/20.500.11794/18194.

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Gaic, Pierre. "Developpement et mise au point d'un systeme de mesure couplee des tailles et vitesses des particules au sein d'un ecoulement diphasique disperse". Université Louis Pasteur (Strasbourg) (1971-2008), 1986. http://www.theses.fr/1986STR13300.

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Mise au point et developpement d'une methode optique de mesure couplee des tailles et vitesses des particules au sein d'un ecoulement diphasique disperse. Confection d'un prototype complet utilise pour etudier le nuage de gouttelettes produit par un injecteur pneumatique

Dhungana, Navaraj. "Background discrimination studies and measurements of droplet and bubble size for the Picasso experiment". Thesis, Laurentian University of Sudbury, 2014. https://zone.biblio.laurentian.ca/dspace/handle/10219/2188.

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The Project in Canada to Search for Supersymmetric Objects (PICASSO) searches for cold dark matter through the direct detection of Weakly Interacting Massive Particles (WIMPs) via spin-dependent and spin independent interactions with 19F nuclei. The detection principle is based on the superheated droplet technique; the detectors consist of a gel matrix with millions of liquid droplets of superheated fluorocarbon (C4F10) dispersed in it. In order to reduce the background, it is essential to distinguish the signature of different background particles interacting in the detector. A dedicated setup was developed in order to study the response of the C4F10 droplets in the presence of different backgrounds. The main objectives of this research are to identify the actual size (diameter) of the droplet increases due to phase transition and to check and establish the correlation between the droplet size and the maximum amplitude of the signal. In addition, the alpha-neutron discrimination was studied by observing each event’s image frames and the associated acoustic signal to get the amplitude distribution. The mean ratio of bubble size to droplet size was found to be 5.48, independent of temperature and type of interacting particle. Furthermore, no correlation was found between the droplet size and the maximum amplitude of the signal. As for the discrimination studies, the analysis of the signal events has confirmed that alphas generated outside the active liquid in the gel are much more difficult to discriminate from neutron than when alphas are generated inside the active liquid.

"Measurement and Prediction of Droplet Size Distribution in Sprays". Thesis, Université Laval, 2006. http://www.theses.ulaval.ca/2006/23623/23623.pdf.

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Chen, Wei-Yen y 陳維彥. "The Study of Using SMPS to Measurement Size Distribution of Coughing Droplet". Thesis, 2005. http://ndltd.ncl.edu.tw/handle/70707897691261449027.

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碩士
國立臺灣大學
環境工程學研究所
93
Droplet exhaled from human may carry microorganisms capable of transmitting disease. As a result of the size be smaller than micron scale had been proven to occupy the great part of size distribution . The goal of this study was to establish the nano scale size of droplet exhaled by healthy individuals, and to compare the sexual differences of the coughing velocity and droplet concentration. Using sample bag to collect droplet. The droplets from human subjects performing coughing were measured by scanning mobility particle sizer (SMPS) system, and establish the droplet size distribution. Furthermore, these data were treated with statistical analysis, comparing the difference of different ages and sexual classification. Then computing the evaporation time, falling distances, horizontal traveling distances with some assumptions. The data of SMPS system showed the respiratory droplets ranged from 0.019 to 0.35 mm and 80% of droplets were between 0.03 and 0.2 mm. Most droplets were more than 0.03 mm. The droplets size were not remarkably difference in age and sexual classification, except for group 2 in sexual classification. The data of wind meter showed the velocity ranged from 0.13 to 1.88 m/s. In this study we found the droplet concentration will increase with coughing velocity. In the data of coughing velocity and droplet concentration, male’s is larger than female’s. In the environment of 20℃ and 50% relative humidity, it took only 7.07×10-5 seconds for 0.2 mm droplet to evaporate, and the falling distance was less than 4.40×10-9 cm, the horizontal traveling distance was about 8.58×10-5 cm. It showed the range of droplets produced by coughing was near the source, and evaporating to form droplet nuclei quickly. If droplet nuclei transmit in the environment, there will be the possibility of infection of diseases. Many infectious diseases belong to nano scale size such as SARS. Therefore this study could be understood its distribution in the smaller scale of droplet size.

Lin, Chia-Cheng y 林嘉承. "Measurement of Droplet Size and Velocity in the Mist Flow Using Digital Image Analysis". Thesis, 2014. http://ndltd.ncl.edu.tw/handle/54042224053424959033.

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碩士
國立交通大學
機械工程系所
102
Cooling by mist flow can achieve higher heat transfer rate than cooling by forced convection of single phase flow. The mist flow is produced by mixing the dispersed water droplets with air stream. The heat transfer is affected by the water droplet size and the mist flow velocity. In this investigation, digital image analysis method was used to obtain the droplet size and velocity. The droplet size and velocity were determined by pixel counting and particle tracking method, respectively. Droplets were illuminated with laser light and images were captured by the camera with microscope lens. Noise reduction and image sharpening were applied before image segmentation. The digital images were segmented using thresholding method, and the threshold algorithm used in this study included mean value method, mode method, iterative method, and Otsu method. The channel used in the investigation had the cross-section of 40mm×40mm and the heated length was 240mm. The images were taken at two observation points at the entrance and exit of heated region. Droplet sizes ranging from 30µm to 80µm were produced by adjusting the water and air flow rate. Larger droplets can be generated by combining higher water flow rate and lower air rate. Measurement of droplet size and velocity in the mist flow can be used to analysis the mist cooling performance.

Madival, Deepak Govind. "Droplet Growth in Moist Turbulent Natural Convection in a Tube". Thesis, 2017. http://etd.iisc.ernet.in/2005/3784.

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Droplet growth processes in a cumulus cloud, beginning from its inception at sub-micron scale up to drizzle drop size of few hundred microns, in an average duration of about half hour, has been a topic of intense research. In particular role of turbulence in aiding droplet growth in clouds has been of immense interest. Motivated by this question, we have performed experiments in which turbulent natural convection coupled with phase change is set up inside a tall vertical insulated tube, by heating water located at tube bottom and circulating cold air at tube top. The resulting moist turbulent natural convection flow in the tube is expected to be axially homogeneous. Mixing of air masses of differing temperature and moisture content leads to condensation of water vapor into droplets, on aerosols available inside the tube. We there-fore have droplets in a turbulent flow, in which phase change is coupled to turbulence dynamics, just as in clouds. We obtain a linear mean-temperature pro le in the tube away from its ends. Because there is net flux of water vapor through the tube, there is a weak mean axial flow, but which is small compared to turbulent velocity fluctuations. We have experimented with two setups, the major difference between them being that in one setup, called AC setup, tube is open to atmosphere at its top and hence has higher aerosol concentration inside the tube, while the other setup, called RINAC setup, is closed to atmosphere and due to presence of aerosol filters has lower aerosol concentration inside the tube. Also in the latter setup, cold air temperature at tube top can be reduced to sub-zero levels. In both setups, turbulence attains a stationary state and is characterized by Rayleigh number based on temperature gradient inside the tube away from its ends, which is 107. A significant result from our experiments is that in RINAC setup, we obtain a broadened droplet size distribution at mid-height of tube which includes a few droplets of size 36 m, which in real clouds marks the beginning of rapid growth of droplets due to collisions among them by virtue of their interaction with turbulence. This shows that for broadening of droplet size distribution, high turbulence levels prevalent in clouds is not strictly necessary. Second part of our study comprises two pieces of theoretical work. First, we deal with the problem of a large collector drop settling amidst a population of smaller droplets whose spatial distribution is homogeneous in the direction of fall. This problem is relevant to the last stage of droplet growth in clouds, when the droplets have grown large enough that they interact weakly with turbulence and begin to settle under gravity. We propose a new method to solve this problem in which collision process is treated as a discrete stochastic process, and reproduce Telford's solution in which collision is treated as a homogeneous Poisson process. We then show how our method may be easily generalized to non-Poisson collision process. Second, we propose a new method to detect droplet clusters in images. This method is based on nearest neighbor relationship between droplets and does not employ arbitrary numerical criteria. Also this method has desirable invariance properties, in particular under the operation of uniform scaling of all distances and addition/deletion of empty space in an image, which therefore renders the proposed method robust. This method has advantage in dealing with highly clustered distributions, where cluster properties vary over the image and therefore average of properties computed over the entire image could be misleading.

Santos, Maria Escudeiro dos. "Influence of added type and amount of fatty acids on the stability of pickering emulsions stabilized with precipitated calcium carbonate nanoparticles". Master's thesis, 2014. http://hdl.handle.net/10451/39279.

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Trabalho Final de Mestrado Integrado, Ciências Farmacêuticas, Universidade de Lisboa, Faculdade de Farmácia, 2014
Pickering emulsions were firstly described over 100 years ago, but are still drawing attention. A Pickering emulsion is basically an emulsion stabilized by solid particles adsorbed to the oil-water interface. The properties of emulsions stabilized solely by the adsorption of solid particles in the oil/water interface can be attributed to the free energy of adsorption for particles with intermediate wettability (50˚-θ-130˚). This irreversible adsorption makes them more stable when compared to emulsions stabilized with surfactants. Precipitated calcium carbonate nanoparticles are widely used as solid particles stabilizers. Since the calcium carbonate is hydrophilic, it remains in the aqueous phase and does not form an emulsion, so the answer is to add hydrophobic organic substances, such as fatty acids, which force the particles to migrate and remain at the oil-water interface. Having this in mind, precipitated calcium carbonate nanoparticles (uncoated) and different fatty acids (capric, lauric, myristic, oleic, palmitic and stearic acid) were used in a series of experiments to try to stabilize oil-in-water Pickering emulsions which were afterwards characterized by droplet size measurement, in order to discover which of the fatty acids produces the most stable emulsion.
As emulsões de Pickering foram descritas pela primeira vez há mais de 100 anos, no entanto continuam a suscitar interesse. Uma emulsão de Pickering consiste, sumariamente, numa emulsão estabilizada por partículas sólidas adsorvidas à interface óleo-água. As propriedades das emulsões estabilizadas exclusivamente pela adsorção de partículas sólidas à interface óleo-água podem ser atribuídas à energia livre de adsorção para partículas cuja molhabilidade seja intermédia (50˚-θ-130˚). Esta adsorção irreversível torna-as mais estáveis quando comparadas a emulsões estabilizadas por tensioactivos. As nanopartículas de carbonato de cálcio precipitado são vastamente utilizadas como partículas sólidas estabilizadoras. Uma vez que o carbonato de cálcio é hidrofílico, este permanece na fase aquosa e não forma uma emulsão. A solução encontrada é adicionar substâncias orgânicas hidrofóbicas, como os ácidos gordos, que vão forçar a migração das partículas e a sua permanência na interface óleo-água. Tendo tudo isto em conta, foram realizadas uma série de experiências contendo nanopartículas de carbonato de cálcio precipitado (Uncoated) e diferentes ácidos gordos (cáprico, láurico, mirístico, oleico, palmítico e esteárico) numa tentativa de produzir emulsões de Pickering óleo-água estáveis. Estas emulsões foram posteriormente caracterizadas por medição do tamanho das gotículas, de modo a encontrar qual o ácido gordo que produz a emulsão mais estável.

Tien, Chi-Hsun y 田棨薰. "R-134a/Distilled Water Spray Droplets Size(d32)Distribution and Velocity/Temperature Measurements". Thesis, 2005. http://ndltd.ncl.edu.tw/handle/95296645089509705250.

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碩士
國立中山大學
機械與機電工程學系研究所
93
Water and R-134a sprays as they impinge on the flat endplate of a circle are studied experimentally. In order to optimize water and R-134a sprays cooling efficiency, a detailed characterization and understanding of the spray formation is essentially needed. The effects of the jet exit velocity and Weber number on spray segregation are investigated. An optical image system was used to quantify the droplet size and distribution. LDV measurements were used to characterize the local velocity and velocity fluctuation distribution from a commercial available nozzle in both axial and radial directions. It is found in the water spray that local mean droplet diameter (SMD) decreases as jet exit velocity increases and as jet proceeds further downstream as well. Furthermore, the SMD and radial velocity are found to be the largest at the outer edges of the water spray. In contrast, the radial velocity is found to be the smallest at the outer edges of the R-134a spray. The SMD and radial velocity continuously decrease across both the water spray and R-134a spray toward the jet axis; while the corresponding axial velocity is the maximum there. Moreover, the R-134a spray jet heat transfer in non-boiling regime was shown to be dependent on the velocity of the impinging jets in terms of Weber number and other related parameters which are in good agreement with those of previous studies.

Libros sobre el tema "Droplet Size Measurement":

M, Jurns John, Chato David J y United States. National Aeronautics and Space Administration., eds. LN spray droplet size measurement via ensemble diffraction technique. [Washington, D.C.]: National Aeronautics and Space Administration, 1991.

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Saiyed, N. H. LN₂ spray droplet size measurement via ensemble diffraction technique. Cleveland, Ohio: National Aeronautics and Space Administration, Lewis Research Center, 1991.

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Dynamics, Von Karman Institute for Fluid. Optical diagnostics of particles & droplets: January 25-29, 1999. Rhode St. Genese, Belgium: von Karman Institute for Fluid Dynamics, 1999.

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Capítulos de libros sobre el tema "Droplet Size Measurement":

Saffmann, M., G. Fraidl y G. Wigley. "Application of Phase and Laser Doppler Anemometry to the Measurement of Droplet Size and Velocity in Gasoline and Diesel Fuel Injection Systems". En Applications of Laser Anemometry to Fluid Mechanics, 206–23. Berlin, Heidelberg: Springer Berlin Heidelberg, 1989. http://dx.doi.org/10.1007/978-3-642-83844-6_12.

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Rees, Andreas y Michael Oschwald. "Experimental Investigation of Transient Injection Phenomena in Rocket Combusters at Vacuum with Cryogenic Flash Boiling". En Fluid Mechanics and Its Applications, 211–31. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-031-09008-0_11.

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AbstractThe substitution of the toxic hydrazine in current high-altitude rocket engines like upper stages or reaction control thrusters by green propellants is a major key driver in the current technology development of rocket propulsion systems. Operating these kind of rocket engines at high-altitude leads to a sudden pressure drop in the liquid propellants during their injection into the combustion chamber with a near-vacuum atmosphere prior to ignition. The resulting superheated thermodynamic state of the liquid causes a fast and eruptive evaporation which is called flash boiling. The degree of atomisation is important for a successful ignition and a secure operation of the rocket engine. The development and operation of a cryogenic high-altitude test bench at DLR Lampoldshausen enables the systematical experimental characterization of cryogenic flash boiling due to its ability to adjust and control the injection parameters like temperature, pressure or geometry. Several test campaigns with liquid nitrogen (LN2) were performed using two optical diagnostic methods: First, flash boiling LN2 spray patterns were visualised by means of high-speed shadowgraphy and, secondly, we determined the droplet size and velocity distributions in strongly superheated LN2 sprays with the help of a laser-based Phase Doppler system (PDA). The experimental data generated within these measurement campaigns provide defined boundary conditions as well as a broad data base for the numerical modelling of cryogenic flash boiling like e.g. the publications [8, 9].

Ramirez de Santiago, Mario. "Measurement of Size and Velocity Distributions of Droplets Produced by Bubbles Bursting". En Applications of Laser Techniques to Fluid Mechanics, 203–26. Berlin, Heidelberg: Springer Berlin Heidelberg, 1991. http://dx.doi.org/10.1007/978-3-642-61254-1_11.

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Chávez, Anselmo y Franz Mayinger. "Algorithms for Automatic Measurement of Size and Velocity of Spray Droplets from Holographic Reconstructions". En Fluid Mechanics and Its Applications, 117–43. Dordrecht: Springer Netherlands, 1993. http://dx.doi.org/10.1007/978-94-011-2690-8_7.

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Borrmann, Stephan, Ruprecht Jaenicke, Rolf Maser y Beate Arends. "Instrument Intercomparison Study on Cloud Droplet Size Distribution Measurements: Holography vs. Laser Optical Particle Counter". En The Kleiner Feldberg Cloud Experiment 1990, 253–58. Dordrecht: Springer Netherlands, 1994. http://dx.doi.org/10.1007/978-94-011-0313-8_12.

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Inoue, T. y S. Kotake. "Measurement of Unstationary Size-Distribution of Submicron Droplets in Rarefaction-Wave Condensation by Laser Scattering". En Optical Methods in Dynamics of Fluids and Solids, 121–27. Berlin, Heidelberg: Springer Berlin Heidelberg, 1985. http://dx.doi.org/10.1007/978-3-642-82459-3_16.

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Kawazoe, H., K. Ohsawa y M. Kataoka. "LDA Measurement of Gasoline Droplet Velocities and Sizes at Intake-Valve Annular Passage in Steady Flow State". En Applications of Laser Techniques to Fluid Mechanics, 248–67. Berlin, Heidelberg: Springer Berlin Heidelberg, 1991. http://dx.doi.org/10.1007/978-3-642-61254-1_13.

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Lang, J., R. Zana y N. Lalem. "Droplet Size and Dynamics in Water in Oil Microemulsions. Correlations Between Results from Time-Resolved Fluorescence Quenching, Quasielastic Light Scattering, Electrical Conductivity and Water Solubility Measurements". En The Structure, Dynamics and Equilibrium Properties of Colloidal Systems, 253–78. Dordrecht: Springer Netherlands, 1990. http://dx.doi.org/10.1007/978-94-011-3746-1_18.

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Kleitz, A., A. R. Laali y J. J. Courant. "26. Fog droplet size measurement and calculation in wet steam turbines". En Technology of turbine plant operating with wet steam, 201–6. Thomas Telford Publishing, 1989. http://dx.doi.org/10.1680/totpowws.13957.0029.

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Nelson, G., X. Ni y I. Mustafa. "Experimental Measurement of Droplet Size Distribution of a MMA Suspension in a Batch Oscillatory Baffled Reactor of 0.21m Diameter". En 10th European Conference on Mixing, 509–16. Elsevier, 2000. http://dx.doi.org/10.1016/b978-044450476-0/50064-9.

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Actas de conferencias sobre el tema "Droplet Size Measurement":

Zama, Yoshio, Masaaki Kawahashi y Hiroyuki Hirahara. "Three-Dimensional Velocity and Droplet Size Measurements of Spray Flow (Keynote Paper)". En ASME/JSME 2003 4th Joint Fluids Summer Engineering Conference. ASMEDC, 2003. http://dx.doi.org/10.1115/fedsm2003-45206.

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The present investigation describes an application of a novel technique of simultaneous measurement of droplet size and three-dimensional components of velocity in a high density spray with swirl. The spray has a complicated and three-dimensional structure caused by mixing with surrounding airflow entrained by high speed fuel jet issuing from a nozzle. The breakup process of fuel film to fine-droplet-cloud, the droplet size dispersion and the velocity distribution of droplets are important factors in practical application of fuel spray for combustors. The conventional technique can be applied to local measurement of droplet speed and size. Recent methods, based on optical and image processing techniques, provide measurement of the velocity and droplet size distribution in observation area or volume. Maeda et al. proposed an excellent measurement technique of the size and the velocity distribution of droplet in spray based on interferometric laser imaging in which the fringe pattern is generated at the out of focus plane by interference between 0th order and 1st order refractions of droplet illuminated by high power laser light sheet. And also, in this technique, the separation of overlapping droplets image has been successfully done by optical method. As a practical application, the size and velocity distributions of droplets in a high density spray without swirl have been measured by this technique. In general, the droplet motion in a spray field is highly three-dimensional. Especially, a spray generated by a swirl nozzle shows complicated droplet motion in the three-dimensional field. In order to analyze the configuration of a complicated spray field, three-dimensional velocity measurement of droplets must be required. In the present paper, a combined measurement technique of the size and three velocity components of droplets in three-dimensional spray field based on doublet imaging technique of droplets and stereoscopic PIV method has been developed. And its feasibility and applicability was confirmed by practical application to measurements of spray fields induced by a swirl jet nozzle using in gas turbine.

Wu, Puyuan, Jun Chen, Paul E. Sojka, Yang Li y Hongjun Cao. "Experimental Measurement of Oil Droplets Size and Velocity Above the Rotor/Stator in a Rotary Compressor". En ASME 2021 Fluids Engineering Division Summer Meeting. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/fedsm2021-65874.

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Abstract Hundreds of millions of Air conditioning (AC) systems are produced each year. Many of them, especially small AC appliances, use rotary compressors as the system’s heat pump due to their simple structure and high efficiency in a small system. Lubricant oil is used in the rotary compressor to lubricate the moving parts, such as the crankshaft and the rolling piston, and to seal the clearance between the sliding parts, e.g., the clearance between the rolling piston and the cylinder, and the vane and the cylinder. As the compressed refrigerant vapor is discharged from the cylinder through the discharge port, part of lubricant oil in the cylinder would be carried by the vapor and atomize into small droplets in the lower cavity during the discharge process, which is complicated and highly-coupled. Some of these oil droplets would ultimately be exhausted from the compressor and enter other parts in the system, reducing the compressor reliability and deteriorating the heat transfer of the condenser and the evaporator in the system. Our previous research studied the atomization of the lubricant oil during the discharge process in the compressor’s lower cavity. However, the oil droplets’ behavior downstream of the lower cavity is unknown. Thus, studying the oil droplets’ behavior after passing through the rotor/stator can help understand how the rotor/stator would affect the droplet size distribution and movement, thus controlling the flow rate of escaped oil droplets. In this study, a hot gas bypass test rig is built to run a modified rotary compressor with sapphire windows right above the rotor/stator. The oil droplets’ size distribution and movement along the radial direction are obtained at the shaft’s rotating frequency of 30 and 60 Hz by shadowgraph. It is found that droplet size at 30 and 60 Hz varies little in the inner region of the rotor/stator clearance and would increase sharply above the clearance and keep increasing in the outer region of the clearance. More importantly, droplet velocity has a downward velocity component at the inner region and an upward velocity component at the outer region of the rotor/stator clearance. With the result of droplet size distribution and droplet velocity above the rotor/stator, we propose the model of the oil droplet’s path above the rotor/stator, which can be understood as the coupling of a swirling jet and a rotating disk.

SAIYED, N., D. CHATO y J. JURNS. "LN2 spray droplet size measurement via ensemble diffraction technique". En 26th Thermophysics Conference. Reston, Virigina: American Institute of Aeronautics and Astronautics, 1991. http://dx.doi.org/10.2514/6.1991-1381.

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Chi, Yohan y Eungseo Kim. "Measurement of Droplet Size Distribution of Transient Diesel Spray". En International Pacific Conference On Automotive Engineering. 400 Commonwealth Drive, Warrendale, PA, United States: SAE International, 1993. http://dx.doi.org/10.4271/931949.

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Donnell, Matt O’ y Sumanta Acharya. "Simultaneous Measurements of Droplet Size, Temperature, and Velocity Using an Integrated Phase-Doppler/Rainbow Thermometer". En ASME 2001 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2001. http://dx.doi.org/10.1115/imece2001/htd-24257.

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Abstract This work summarizes efforts to determine the accuracy and performance characteristics of a new and novel laser diagnostic to measure instantaneous, in flight, droplet temperatures. The instrument uses the location of the rainbow peak to deduce the refractive index of the droplet, which in turn is related to the droplet temperature. Preliminary experiments were undertaken in order to understand the fundamental operating principles and limitations of the instrument. These experiments measured the temperature of an isothermal, single stream of monodisperse droplets. These measurements indicate that the mean refractive index can be measured with a standard deviation as low as 0.0001m. Once the operation of the refractometer was proved under isothermal conditions, the measurement of droplet temperatures in a swirl-stabilized combustor was performed. These measurements indicate that the strength of the rainbow signal is significantly hampered by the noise induced by the flame. Preliminary temperature measurements with the combustor equipped with 45° vanes showed relatively constant radial temperature profiles (∼55–60°C) at locations less than 2 inches from the nozzle exit. A detailed examination of the temperature correlation with velocity and diameter revealed that larger and faster moving droplets dominate the distributions. Thus, the smaller droplets that are suspected of having the highest temperatures are inadequately represented in the mean droplet temperature.

Cho, H. K., K. Y. Choi, S. Cho y C. H. Song. "Droplet Measurement in a Rod Bundle Geometry for a Reflood Heat Transfer Test". En 18th International Conference on Nuclear Engineering. ASMEDC, 2010. http://dx.doi.org/10.1115/icone18-30286.

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During the reflood phase of a postulated loss of coolant accident in a nuclear reactor, the entrainment of liquid droplets can occur at a quench front of reflooding water. It is widely recognized that the behavior of the entrained droplet crucially affects the reflood heat transfer phenomena by decreasing the superheated steam temperature and interacting with a rod bundle and spacer grids. For this reason, various experimental and numerical studies have been performed to examine droplet behavior such as the droplet size, velocity and droplet fraction inside a rod array. In this study, an experiment on the droplet behavior inside a heated rod bundle has been performed. The experiment was focused on the break-up of droplets induced by a spacer grid in a rod bundle geometry, which results in the increase of the interfacial heat transfer between droplets and superheated steam. A 6×6 rod bundle test facility in Korea Atomic Energy Research Institute was used for the experiment. Steam was supplied by an external boiler into the bottom of the test channel, and a droplet injection nozzle was equipped instead of simulating a quench front of reflooding water. The major measuring parameters of the experiment were the droplet size and velocity, and these were measured by a high-speed camera and a digital image processing technique. A series of experiments were conducted with various flow conditions of a steam injection velocity, heater temperature, droplet size and droplet flow rate. The experiments provided the data on the change of the Sauter mean diameter of droplets after collision with a spacer grid depending on flow conditions. Moreover, the data was analyzed with a droplet break-up model by a spacer grid which was implemented into a thermal hydraulic analysis code, COBRA-TF.

Okada, O., T. Fujimatsu, Hideomi Fujita y K. Honma. "SOME PROBLEMS ON DROPLET SIZE MEASUREMENT BY IMMERSION LIQUID METHOD". En ICLASS 94. Connecticut: Begellhouse, 2023. http://dx.doi.org/10.1615/iclass-94.520.

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Wang, Maosen, Dandan Zheng y Ying Xu. "Modelling droplet size in annular flow based on fiber optical reflectometer". En 2023 IEEE International Instrumentation and Measurement Technology Conference (I2MTC). IEEE, 2023. http://dx.doi.org/10.1109/i2mtc53148.2023.10175990.

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Park, Kyung-Hee, Jorge A. Olortegui-Yume, Shantanu Joshi, Patrick Kwon, Moon-Chul Yoon, Gyu-Bong Lee y Sung-Bum Park. "Measurement of Droplet Size and Distribution for Minimum Quantity Lubrication (MQL)". En 2008 International Conference on Smart Manufacturing application (ICSMA). IEEE, 2008. http://dx.doi.org/10.1109/icsma.2008.4505598.

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Kim, Hoi-San, Kyong S. Im y Byung Ok Cho. "Development of measurement technique of droplet velocity and size distribution using PMAS". En High-Speed Photography and Photonics: 21st International Congress, editado por Ung Kim, Joon-Sung Chang y Seung-Han Park. SPIE, 1995. http://dx.doi.org/10.1117/12.209545.

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Informes sobre el tema "Droplet Size Measurement":

Lawson, J. R., W. D. Walton y D. D. Evans. Measurement of droplet size in sprinkler sprays. Gaithersburg, MD: National Bureau of Standards, 1988. http://dx.doi.org/10.6028/nbs.ir.88-3715.

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Fairall, C. W. y William Asher. Measurement of the Sea Spray Droplet Size Distributions at High Winds. Fort Belvoir, VA: Defense Technical Information Center, septiembre de 2003. http://dx.doi.org/10.21236/ada628748.

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Asher, William E. y C. W. Fairall. Measurement of the Sea Spray Droplet Size Distributions at High Winds. Fort Belvoir, VA: Defense Technical Information Center, septiembre de 2003. http://dx.doi.org/10.21236/ada622232.

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Trabold, T. A., R. Kumar y P. F. Vassallo. Annular flow of R-134a through a high aspect ratio duct: Local void fraction, droplet velocity and droplet size measurements. Office of Scientific and Technical Information (OSTI), noviembre de 1998. http://dx.doi.org/10.2172/304179.

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Parker, T. E., J. R. Morency, R. R. Foutter y W. T. Rawlins. Infrared measurements of soot formation and droplet sizes in diesel sprays. Final report, June 6, 1987--December 31, 1990. Office of Scientific and Technical Information (OSTI), julio de 1992. http://dx.doi.org/10.2172/10152227.

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