Dissertations / Theses on the topic 'Droplet size distributions'
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Waldmeyer, James Robert. "The evolution of droplet size distributions in high shear complex flows." Thesis, University of Cambridge, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.612191.
Full textSushanta, Mitra. "Breakup Process of Plane Liquid Sheets and Prediction of Initial Droplet Size and Velocity Distributions in Sprays." Thesis, University of Waterloo, 2001. http://hdl.handle.net/10012/931.
Full textFalahati, Hamid. "The Characterization of Bimodal Droplet Size Distributions in the Ultrafiltration of Highly Concentrated Emulsions Applied to the Production of Biodiesel." Thesis, University of Ottawa (Canada), 2010. http://hdl.handle.net/10393/19585.
Full textNatural Sciences and Engineering Research Council of Canada (NSERC)
Rohloff, Martin [Verfasser], Vollmer [Akademischer Betreuer] Jürgen, and Marcus [Akademischer Betreuer] Müller. "Continuously driven phase separation: size distributions and time scales in droplet growth / Martin Rohloff. Gutachter: Marcus Müller ; Vollmer Jürgen. Betreuer: Vollmer Jürgen." Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2015. http://d-nb.info/1076398634/34.
Full textZhuang, Jianqin, and Ruediger Voelkel. "Emulsion droplet size distribution by PFG NMR." Universitätsbibliothek Leipzig, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-195027.
Full textGomes, Pimentel Rogerio. "Measurement and Prediction of Droplet Size Distribution in Sprays." Thesis, Université Laval, 2006. http://www.theses.ulaval.ca/2006/23623/23623.pdf.
Full textGomes, Pimentel Rogério. "Measurement and prediction of droplet size distribution in sprays." Doctoral thesis, Université Laval, 2006. http://hdl.handle.net/20.500.11794/18194.
Full textAmin, Lekhraj Purushotham. "An investigation of droplet stability and droplet size distribution in a continuous oscillatory baffled tube." Thesis, Heriot-Watt University, 2005. http://hdl.handle.net/10399/226.
Full textYao, Juncheng. "Characterization and Prediction of Water Droplet Size in Oil-Water Flow." Ohio University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1470741069.
Full textMarouelli, Waldir Aparecido 1958. "Improving chemigation efficacy by controlling droplet size distribution of oil-based pesticides." Diss., The University of Arizona, 1996. http://hdl.handle.net/10150/282265.
Full textHsieh, Wei-Chun. "Representing droplet size distribution and cloud processes in aerosol-cloud-climate interaction studies." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/29619.
Full textCommittee Chair: Athanasios Nenes; Committee Member: Andrew G. Stack; Committee Member: Irina N. Sokolik; Committee Member: Judith A. Curry; Committee Member: Mike Bergin; Committee Member: Rodney J. Weber. Part of the SMARTech Electronic Thesis and Dissertation Collection.
Shi, Xiaochuan. "Effect of Electron Bombardment on the Size Distribution of Negatively Charged Droplets Produced by Electrospray." Digital WPI, 2012. https://digitalcommons.wpi.edu/etd-dissertations/15.
Full textOpedal, Nils van der Tuuk, Geir Sørland, and Johan Sjöblom. "Methods for droplet size distribution determination of water-inoil emulsions using low-field NMR." Universitätsbibliothek Leipzig, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-192826.
Full textOpedal, Nils van der Tuuk, Geir Sørland, and Johan Sjöblom. "Methods for droplet size distribution determination of water-inoil emulsions using low-field NMR." Diffusion fundamentals 9 (2009) 7, S. 1-29, 2009. https://ul.qucosa.de/id/qucosa%3A14145.
Full textZhuang, Jianqin, and Ruediger Voelkel. "Emulsion droplet size distribution by PFG NMR: high concentrations, small radii, and suspo-emulsions." Diffusion fundamentals 3 (2005) 37, S. 1-2, 2005. https://ul.qucosa.de/id/qucosa%3A14327.
Full textXue, Yan. "Effects of air turbulence and stochastic coalescence on the size distribution of cloud droplets." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 214 p, 2006. http://proquest.umi.com/pqdweb?did=1172112611&sid=2&Fmt=2&clientId=8331&RQT=309&VName=PQD.
Full textSandoval, Kathia a. "Physical and Chemical Characterization of Crude Oil-Water Mixtures: Understanding the Effects of Interfacial Process to Chemical Bioavailability." FIU Digital Commons, 2016. http://digitalcommons.fiu.edu/etd/2464.
Full textGrimes, Matthew, Paul Myrdal, and Poonam Sheth. "Cosolvent Effect on Droplet Evaporation Time, Aerodynamic Particle Size Distribution, and Differential Throat Deposition for Pressurized Metered Dose Inhalers." The University of Arizona, 2015. http://hdl.handle.net/10150/614123.
Full textObjectives: To evaluate the in vitro performance of various pressurized metered dose inhaler (pMDI) formulations by cascade impaction primarily focusing on throat deposition, fine particle fraction (FPF), and mass-median aerodynamic diameter (MMADR) measurements Methods: Ten solution pMDIs were prepared with varying cosolvent species in either low (8% w/w) or high (20% w/w) concentration. The chosen cosolvents were either alcohol (ethanol, n-propanol) or acetate (methyl-, ethyl-, and butyl acetate) in chemical nature. All formulations used HFA-134a propellant and 0.3% drug. The pMDIs were tested by cascade impaction with three different inlets to determine the aerodynamic particle size distribution (APSD), throat deposition, and FPF of each formulation. Theoretical droplet evaporation time (DET), a measure of volatility, for each formulation was calculated using the MMADR. Results: Highly volatile formulations with short DET showed consistently lower throat deposition and higher FPF than their lower volatility counterparts when using volume-constrained inlets. However, FPF values were not significantly different for pMDI testing with a non-constrained inlet. The MMADR values generated with volume-constrained inlets did not show any discernible trends, but MMADR values from the non-constrained inlet correlated with DET. Conclusions: Formulations with shorter DET exhibit lower throat deposition and higher FPF, indicating potentially better inhalational performance over formulations with longer DET. There appear to be predictable trends relating both throat deposition and FPF to DET. The shift in MMADR values for volume-constrained inlets suggests that large diameter drug particles are preferentially collected in these inlets.
Crialesi, Esposito Marco. "Analysis of primary atomization in sprays using Direct Numerical Simulation." Doctoral thesis, Universitat Politècnica de València, 2019. http://hdl.handle.net/10251/133975.
Full text[CAT] La comprensió dels fenòmens físics que succeïxen en la regió densa (també coneguda com a camp pròxim) durant l'atomització dels sprays ha sigut una de les majors incògnites a l'hora d'estudiar les seues aplicacions. En el sector industrial, el rang d'interés comprén des de toveres en aplicacions propulsives a sprays en aplicacions mèdiques, agrícoles o culinàries. Esta evident falta de coneixement obliga a realitzar simplificacions en la modelització, provocant resultats poc precisos i la necessitat de grans caracteritzacions experimentals en la fase de disseny. D'esta manera, els processos de ruptura del spray i atomització primària es consideren problemes físics fonamentals, la complexitat dels quals ve donada com resultat d'un flux multifàsic en un règim altament turbulent, originant escenaris caòtics. L'anàlisi d'este problema és extremadament complex a causa de l'absència substancial de teories validades dels fenòmens físics involucrats com són la turbulència i l'atomització. A més, la combinació de la naturalesa multifàsica del flux i el seu comportament turbulent resulten en una gran dificultat per a afrontar el problema. Durant els últims 10 anys les tècniques experimentals han sigut finalment capaces de visualitzar la regió densa, però la confiança, anàlisi i efectivitat dels experiments en esta regió del spray encara requerix de millores substancials. En este context, esta tesi tracta de contribuir en l'enteniment d'estos processos físics i de proporcionar ferramentes d'anàlisi per a estos fluxos tan complexos. Per a això, per mitjà de Direct Numerical Simulations s'ha afrontat el problema resolent les escales de moviment més menudes, al mateix temps que es capturen totes les escales de turbulència i esdeveniments de ruptura. Un dels objectius de la tesi ha sigut avaluar la influència que les condicions de contorn del flux entrant tenen en l'atomització primària i en el comportament turbulent del spray. Per a això, s'han empleat dos condicions de contorn diferents. En primer lloc s'ha empleat una condició de contorn sintètica per a produir turbulència homogènia a l'entrada, simulant el comportament de la tovera. Una de les característiques més interessants d'este mètod és la possibilitat de retocar els paràmetres dins de l'algoritme. En particular, l'escala de longitud integral s'ha variat per a avaluar la influència de les estructures mes grans de la tovera en l'atomització primària. L'anàlisi de la condició de contorn sintètica també ha permés el disseny òptim de simulacions de les quals s'han derivat estadístiques turbulentes significatives. En este escenari, s'han dut a terme estudis més profunds sobre la influència de propietats de les estructures turbulentes com l'homogeneïtat i l'anisotropia tant en l'espectre dels fluxos com en les estadístiques de les gotes. Per a tal fi, s'han desenrotllat metodologies noves per a computar l'anàlisi espectral i l'estadística de les gotes. Entre els resultats d'esta anàlisi destaca la independència de la condició de contorn d'entrada en les estadístiques de les gotes, mentres que d'altra banda, es recalca que les característiques turbulentes desenrotllades en l'interior de la tovera afecten a la quantitat total de massa atomitzada. Estes consideracions es troben recolzades per l'anàlisi espectral realitzat, per mitjà del qual es conclou que la turbulència multifásica compartix el comportament universal descrit per les teories de Kolmogorov.
[EN] The understanding of the physical phenomena occurring in the dense region (also known as near field) of atomizing sprays has been long seen as one of the biggest unknown when studying sprays applications. The industrial range of interest goes from nozzles in combustion and propulsion applications to medical sprays, agricultural and food process applications. This substantial lack of knowledge is responsible for some important simplification in modeling, that often result to be inaccurate or simply partial, leading to the evident need of large experimental characterization during the design phase. In fact, the spray breakup and primary atomization processes are indeed fundamental problems of physics, which complexity results from the combination of a multiphase flow in a highly turbulent regime that leads to chaotic scenarios. The analysis of this problem is extremely problematic, due to a substantial lack of definitive theories about the physical phenomena involved, namely turbulence and atomization. Furthermore, the combination of the multiphase nature of the flow and its turbulent behavior makes substantially difficult to address the problem. Only within the last 10 years, experimental techniques have been capable of visualizing the dense region, but the experiments reliability, analysis and effectiveness in this region still requires vast improvements. In this scenario, this thesis aims to contribute in the understanding of these physical process and to provide analysis tools for these complex flows. In order to do so, Direct Numerical Simulations have been used for addressing the problem at its smallest scale of motion, while reliably capturing all turbulence scales and breakup events. The multiphase nature of the flow is accounted for by using the Volume of Fluid method. One of the goal of the thesis was to assess the influence of the inflow boundary conditions on the primary atomization and on the spray's turbulence behavior. In order to do so, two different boundary conditions were used. In a first place, a synthetic inflow boundary condition was used in order to produce a homogeneous turbulence inflow, simulating the nozzle behavior. One of the interesting features of this method was the possibility of tweaking the parameters within the algorithm. In particular, the integral length scale was varied in order to assess the influence of nozzle larger turbulent structures on the primary atomization. The analysis on the synthetic boundary condition also allowed to optimally design simulations from which derive meaningful turbulence statistics. On this framework, further studies were carried over on the influence of turbulent structures properties, namely homogeneity and anisotropy, on both the flows spectra and droplets statistics. In order to achieve this goal, novel procedures for both computing the flow spectra and analyzing droplets were developed and are carefully addressed in the thesis. The results of the analysis highlight the independence of droplets statistics from the inflow boundary condition, while, on the other hand, remarking how the total quantity of atomized mass is significantly affected by the turbulence features developed within the nozzle. This considerations are supported by the spectrum analysis performed, which also highlighted how multiphase turbulence shares the universal features described in Kolmogorov theories.
Crialesi Esposito, M. (2019). Analysis of primary atomization in sprays using Direct Numerical Simulation [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/133975
TESIS
Assenhaimer, Cristhiane. "Evaluation of emulsion destabilization by light scattering applied to metalworking fluids." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/3/3137/tde-17062016-131417/.
Full textSem resumo em português.
Silva, Carlos Felipe Bueno da. "Estudo comparativo de técnicas numéricas de inversão para obtenção de distribuição de tamanho de gotas em emulsões." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/3/3137/tde-04072016-152253/.
Full textThe development of computer algorithms to obtain the particle size distributions in dispersions using spectroscopic data in real time and in-line from sensors enable a variety of applications such as monitoring properties in industrial cutting fluids, monitoring of polymerization processes, wastewater, atmospheric sensing and other applications. The aim of this study is to implement techniques for inversion problem solving, by testing algorithms that provide particle size distribution in dispersions from UV-Vis-Nir (Ultraviolet, Visible and Near-Infrared) spectroscopic data. Four techniques have been implemented, one of them being an alternative method without the inversion step. The methods using inversion techniques showed difficulties to obtain droplet size distributions (DSD) with good quality, while the alternative method was the one that was more efficient and reliable. This study is part of a cooperative program between the University of São Paulo and the University of Bremen, within the BRAGECRIM program (Brazilian German Cooperative Research Initiative in Manufacturing) and is financially supported by FAPESP, CAPES, FINEP and CNPq (Brazil) and DFG (Germany).
Postal, Victor. "Estudo da degradação térmica de emulsões via espectroscopia UV-Vis aplicado a fluidos de corte." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/3/3137/tde-23012017-113619/.
Full textThe monitoring of emulsions used in the metal-mechanical industry comprise an important activity to the quality control of the products manufectured, also providing an increase in the working life of the tools and machinery employed in this sector through the lubrication and refrigeration of the cutting zone. In the majority of cases, these emulsions are prepared diluting a metalworking fluid in an aqueous media, constituting a collection of particles stabilized by emulsifiers and undergoing heating and cooling cycles during metalworking processes. Currently, monitoring routines are based on regular analyses of samples taken from the process fluid, and an effective in-line method is not available to monitor emulsion quality in real time. In this context, it is possible to apply techniques related to UV-Vis spectrocopy in order to obtain information concerning the stability of those systems, correlating light scattering intensities to the droplet dimensions. In this study, it was possible to investigate the thermal destabilisation of a commercial metalworking fluid emulsion, which showed, through the evaluation of the wavelength exponent, to be dependant on the exposure time to heating and its time-averaged temperature. It was also noted that the loss of continuous phase by evaporation and its reposition do not affect the emulsion stability. Moreover, it was observed that important emulsion preparation parameters, such as continuous phase temperature and the time span between the addition of the metalworking fluid on the water surface and the stirring, have fundamental roles in defining the initial average droplet size, which made possible to correlate the area under the light extinction spectra with average droplet sizes.
Lima, Maria Gabriela de Oliveira Lima Basto de. "Caracterização reológica e microstrutural de emulsões água em óleo para uso alimentar." Doctoral thesis, Universidade de Évora, 2014. http://hdl.handle.net/10174/13277.
Full textRohloff, Martin. "Continuously driven phase separation: size distributions and time scales in droplet growth." Doctoral thesis, 2015. http://hdl.handle.net/11858/00-1735-0000-0023-9610-E.
Full textLapp, Tobias. "Evolution of Droplet Distributions in Hydrodynamic Systems." Doctoral thesis, 2011. http://hdl.handle.net/11858/00-1735-0000-0006-B541-8.
Full textChen, Cheng-Min, and 陳政旻. "The study of size distribution of coughing droplet." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/21438067820021371687.
Full text國立臺灣大學
環境工程學研究所
92
Droplet exhaled from human may carry microorganisms capable of transmitting disease in short and long distances. The size of droplet will mainly influence the transmission mode of such infectious droplet. The aim of this study was to establish the size distribution of droplet and droplet nuclei exhaled by healthy individuals, and using sample bag and column to collect them. The droplets from human subjects performing coughing were measured by aerodynamic particle sizer (APS) and scanning mobility particle sizer (SMPS) system, and establish the droplet size distribution. Computing the evaporation time, falling distances, horizontal traveling distances with some assumptions. Furthermore, the data was treated with statistical analysis, comparing the difference of different ages and sexual classification. The data of APS monitoring showed the respiratory droplets ranged from 0.5 to 20 mm and 90~95% of droplets were between 2 and 10 mm. The mode of droplet size distribution is between 5 and 7 mm. Most droplets were less than 10 mm. The diameter of droplet nuclei was found to range in diameter from 0.5 to 5 mm, and the most amount was between 0.6 to 2 mm. The droplets size were not significantly difference in age and sexual classification. The SMPS confirmed the existence of droplets ranged from 0.02 to 0.5 mm. In the environment of 20℃ and 50% relative humidity, it took only 0.04 seconds for 5 mm droplet to evaporate, and the falling distance was less than 0.002 cm, the horizontal traveling distance was about 0.008 cm. It showed the range of droplets produced by coughing was near the source, and evaporating to form droplet nuclei quickly. Droplet nuclei could suspend in the environment for a long time, and transport with air current. The microorganisms may transmit disease by air. Besides, if droplet or droplet nuclei fall on the surface of objects, one may be infected by toughing the infectious objects.
"Measurement and Prediction of Droplet Size Distribution in Sprays." Thesis, Université Laval, 2006. http://www.theses.ulaval.ca/2006/23623/23623.pdf.
Full textChen, Wei-Yen, and 陳維彥. "The Study of Using SMPS to Measurement Size Distribution of Coughing Droplet." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/70707897691261449027.
Full text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.
Amighi, Amirreza. "Droplet size distribution for jets in crossflows at high temperature and pressure." 2008. http://link.library.utoronto.ca/eir/EIRdetail.cfm?Resources__ID=772035&T=F.
Full textChen-Dau, Hsieh, and 謝政道. "A Characteristic Analysis on the Droplets Size Distribution of a Diesel Spray." Thesis, 1994. http://ndltd.ncl.edu.tw/handle/15062259812343597135.
Full textTien, Chi-Hsun, and 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.
Full text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.
HUANG, YI-MING, and 黃奕銘. "A Study of the Effects of Discharge Sprinkler Droplet Size and Distribution on Smoke Flow in Fire." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/5kxst3.
Full text國立臺北科技大學
能源與冷凍空調工程系
107
The fire-extinguishing system applying automatic discharge sprinklers for ceiling height above 10 meters has been studied. The focus is on the phenomenon about the effects of the water droplet size and the size distribution of the discharge sprinklers. The effects of discharge droplets on the smoke flow were also. A full-scale experiment was setup to observe the physical phenomena. A 3D modeling was further undertaken to simulate the fire, smoke exhaust, smoke flow and interaction of water droplets and smoke flow. This research applied FDS in the 3D simulation. This study adopted logarithmic normal / Rosin-Rammler distribution for the sprinkler’s droplet size. All the parameters considered include (1) droplet size distribution, and (2) medium droplet diameter. It has been found that the discharge water droplets would induce the downward flow of smoke and has adverse effect on the visibility of smoke. Smaller water droplet size would take longer time to extinguish the fire, specifically for medium size at 1000 μm. The smaller size water droplet would evaporate faster and has to overcome the buoyancy force of fire. At this droplet size, smoke visibility was lower. Three medium droplet size, 1000μm, 1300μm, and 2000μm were studied. With equal fire extinguishing performance 2000μm droplet had a higher smoke visibility. When the sprinklers are actuated quicker in early fire and with less smoke generation, better smoke visibility would be expected so to have better fire safety.
Akberov, Roald. "An improved numerical model for calculations of transport and size distributions of atmospheric aerosols and cloud droplets." 2008. http://hdl.rutgers.edu/1782.2/rucore10001600001.ETD.17095.
Full text