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Sheikhi, Abdolreza. "Laser shadowgraph study of early flame propagation in swirling flows near the lean misfire limit". Thesis, University of Ottawa (Canada), 1995. http://hdl.handle.net/10393/9577.
Pełny tekst źródłaHattori, Tae. "Investigation into Stability, Transition and Turbulence of Thermal Plumes". Thesis, The University of Sydney, 2012. http://hdl.handle.net/2123/9338.
Pełny tekst źródłaZakrzewski, Sam Mechanical & Manufacturing Engineering Faculty of Engineering UNSW. "A Numerical and Experimental Investigation of High-Speed Liquid Jets - Their Characteristics and Dynamics". Awarded by:University of New South Wales. Mechanical and Manufacturing Engineering, 2002. http://handle.unsw.edu.au/1959.4/18653.
Pełny tekst źródłaRobertson, Welsh Bradley. "On the influence of nozzle geometries on supersonic curved wall jets". Thesis, University of Manchester, 2017. https://www.research.manchester.ac.uk/portal/en/theses/on-the-influence-of-nozzle-geometries-on-supersonic-curved-wall-jets(bc8817e4-c812-44bc-8dfb-f5d0fdf62a72).html.
Pełny tekst źródłaDonzelli, G. "Dynamics of spoke patterns in the solutal convective instability of a nanofluid". Doctoral thesis, Università degli Studi di Milano, 2008. http://hdl.handle.net/2434/60010.
Pełny tekst źródłaKnight, Ethan. "Effect of Corrugated Outer Wall On Operating Regimes of Rotating Detonation Combustors". University of Cincinnati / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1523631068586522.
Pełny tekst źródłaYounis, Taha Elamin Obai. "Numerical and experimental study of transient laminar natural convection of high prandtl number fluids in a cubical cavity". Doctoral thesis, Universitat Rovira i Virgili, 2009. http://hdl.handle.net/10803/8496.
Pełny tekst źródłaObai Younis Taha Elamin
La convección natural en espacios cerrados, se encuentra ampliamente en sistemas naturales e industriales. El objetivo general de este trabajo es desarrollar y validar una herramienta de simulación capaz de predecir las tasas de enfriamiento de aceite en un tanque. Esta herramienta ha de tener en cuenta la variación de la viscosidad del aceite para dar información detallada de las tasas de enfriamiento del aceite bajo diferentes condiciones de contorno térmicas realisticas.
En primer lugar, la influencia de diferentes condiciones de contorno térmicas en las paredes, la variación de la viscosidad y la conductividad de la pared en la convección natural del flujo laminar transitorio en una cavidad cúbica con seis paredes térmicamente activo están analizadas.
Para analizar el efecto individual de las paredes laterales de la cavidad en el proceso de enfriamiento, la segunda parte de este estudio considera que, tanto numéricamente como experimentalmente, la transición de la convección natural laminar en una cavidad cúbica con dos paredes opuestas frías y verticales.
Nuevas relaciones de escala que tengan en cuenta la variación de la viscosidad con la temperatura, no publicadas anteriormente en la literatura, se derivan de las velocidades de la capa límite, por el tiempo necesario para la capa límite para alcanzar el estado estacionario y para la velocidad y el espesor de las intrusiones horizontales.
NUMERICAL AND EXPERIMENTAL STUDY OF TRANSIENT LAMINAR NATURAL CONVECTION OF HIGH PRANDTL NUMBER FLUIDS IN A CUBICAL CAVITY
Obai Younis Taha Elamin
Free convection in enclosed spaces is found widely in natural and industrial systems. The general objective of this work is to develop and validate a simulation tool able to predict the cooling rates of oil in a tank. This tool has to take into account the variation of the oil viscosity to give detailed information of the cooling rates of the oil under different realistic thermal boundary conditions.
First, the influence of different thermal wall boundary conditions, the variation of the viscosity and the wall conductivity on the transient laminar natural convection flow in a cubical cavity with the six walls thermally active is studied numerically.
To analyze the individual effect of the side walls of the cavity on the cooling process, the second part of this study considers, numerically and experimentally, the transient laminar natural convection in a cubical cavity with two cold opposite vertical walls. The shadowgraph technique is employed to visualize the development of the transient convective flow. New scaling relations that take into account the viscosity variation with temperature, not reported previously in the literature, are derived for the boundary layer velocities, for the time needed for the boundary layer to reach the steady state and for the velocity and thickness of the horizontal intrusions.
ALLGOOD, DANIEL CLAY. "AN EXPERIMENTAL AND COMPUTATIONAL STUDY OF PULSE DETONATION ENGINES". University of Cincinnati / OhioLINK, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1095259010.
Pełny tekst źródłaTadrous, Ebram. "Experimental investigation of the transition of Marangoni convection around a stationary gas bubble towards turbulent flow". Universitätsverlag Chemnitz, 2020. https://monarch.qucosa.de/id/qucosa%3A74993.
Pełny tekst źródłaIn dieser Arbeit wird die thermokapillare Konvektion um eine Gasblase unter einer horizontal beheizten Wand unter Gravitationsbedingungen experimentell untersucht. Diese thermokapillare konvektive Strömung jenseits des laminaren stationären Zustands in Richtung turbulenter Strömung steht in dieser Arbeit im Fokus. Im Allgemeinen ist die Marangoni-Konvektion unter Schwerelosigkeitsbedingungen kritischer und wichtiger als auf der Erde. Unter geringen Schwerkraftkräften kann diese durch Oberflächenspannung induzierte Strömung sowohl Wärme- als auch Stoffübergangsprozesse maßgeblich bestimmen. Daher sollte die thermokapillare Konvektion bei Materialproduktionsprozessen im Weltraum berücksichtigt werden. Darüber hinaus können Temperaturgradienten gezielt angewendet werden, um in flüssigen Materialien suspendierte Blasen oder Tropfen zu entfernen oder zu bewegen. Außerdem tritt thermokapillare Strömung in vielen anderen Anwendungen auf, beispielsweise bei der Herstellung von einwandigen Kohlenstoffnanoröhren oder der Herstellung von Einkristallen, um nur einige Beispiele zu nennen. Forscher haben die Marangoni-Konvektion immer als ein wichtiges und interessantes Thema für numerische und experimentelle Studien betrachtet. In Bezug auf die Konfiguration der injizierten Blase unter einer horizontal beheizten Wand wird dieses physikalische Problem hauptsächlich durch eine dimensionslose Kennzahl, die das Verhältnis des durch Kapillarkonvektion induzierten konvektiven Wärmeübertragungs zur Wärmeübertragung durch Leitung darstellt und als Marangoni-Zahl (Mg) bezeichnet wird, definiert. In den letzten Jahrzehnten wurden verschiedene Ansätze zur Beschreibung des Strömungs-Verhaltens bei höheren Marangoni-Zahlen verfolgt. Dabei wurde die Thermokapillarströmung grundsätzlich in ein stabiles laminares und ein nicht laminares (oszillierendes) Verhalten, das durch periodische oder nicht periodische Geschwindigkeit- und Temperatur-Fluktuationen gekennzeichnet ist, eingeteilt. Durch frühere Studien wurde das Regime des Übergangs des thermokapillaren Verhaltens von der periodischen Schwingungszone zur nichtperiodischen gut untersucht. Es fehlen jedoch immer noch detaillierte Informationen über das nichtperiodische Verhalten bei sehr hohen Temperaturgradienten. Daher konzentrieren sich unsere experimentellen Untersuchungen in der vorliegenden Studie hauptsächlich auf die Untersuchung verschiedener Faktoren, die die Nichtperiodizität der konvektiven Thermokapillarströmung beeinflussen, und auf eine Klärung, wie sich diese Strömung unter verschiedenen Randbedingungen über der kritischen Marangoni-Zahl (Mg c ) verhält.Die experimentelle Arbeit wurde sowohl mit einer PIV-Technik als auch mit der Shadowgraph- Technik durchgeführt. Darüber hinaus waren Temperaturmessungen auf Sensorbasis an verschiedenen Stellen in der verwendeten Flüssigkeit um die Luftblase geeignet, um die ungestörten Temperaturgradienten bei verschiedenen Randbedingungen zu bestimmen. Die zeitabhängige Messung sowohl von Geschwindigkeiten als auch von Temperaturen an Orten in der Nähe der Blase lieferte Informationen über das Verhalten der Konvektion der thermokapillaren Strömung. Darüber hinaus wurde durch die Shadowgraph-Technik eine qualitative Bewertung der Fluidströmungsperiodizität um die Blase ermöglicht. Die Durchführung von Experimenten in einer Druckkammer unter Überdruck-Bedingungen bildet eine neuartige Methode, um solche Experimente unter höheren Temperaturgradienten durchzuführen und höhere Marangoni-Zahlen zu erreichen. Die thermokapillare Blasenkonvektion wurde in dieser Arbeit in laminaren stetigen Flüssigkeitsströmungen, periodischen und nichtperiodischen oszillierenden Flüssigkeitsströmungen eingeteilt. Die periodischen Fluidströmungsschwingungen wurden in Abhängigkeit von unterschiedlichen Randbedingungen in symmetrische und asymmetrische eingeteilt. Die nichtperiodischen Strömungsoszillationen um die Gasblase wurden auch bei hohen Temperaturgradienten für verschiedene Blasenaspektverhältnisse erreicht. Wir konnten zeigen, dass für jede Blasengröße der nichtperiodische Schwingungszustand der Strömung um die Gasblase vier verschiedene Modi (A-D) besitzen kann. Die letzte (Phase D) ist ein hoch entwickelter turbulenter Zustand, der bei Mg-Zahlen von 75000 für das kleinste Blasenaspektverhältnis von 1,2 bis zur maximal gemessenen Mg-Zahl von 140000 für das Blasenaspektverhältnis von 2,3 beginnt. Der ausgebildete turbulente Zustand der thermokapillaren Strömung konnte mit unserer experimentellen Konfiguration erstmalig erreicht werden. Darüber hinaus konnten die Antriebsgeschwindigkeiten der thermokapillaren Strömung an der Peripherie der Blase bei verschiedenen Randbedingungen gemessen werden. Diese Studie zeigt deutlich, dass es die Höhe der Antriebsgeschwindigkeit ist, welche die Wechselwirkungen zwischen thermokapillaren Strömungswirbeln unterschiedlicher Größe antreibt, die schließlich zu chaotischen Schwingungen der im Folgenden beschriebenen Grenzlinie führen. Diese Studie zeigt auch, dass die Auftriebskonvektion in der beschriebenen Strömungskonfiguration eine untergeordnete Rolle spielt.:1 INTRODUCTION 2 LITERATURE REVIEW 3 EXPERIMENTAL SETUP AND METHODOLOGY 4 RESULTS AND DISCUSSION 5 CONCLUSIONS AND RECOMMENDATIONS
Ferguson, Kevin M. "Design and cold flow evaluation of a miniature Mach 4 Ramjet". Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2003. http://library.nps.navy.mil/uhtbin/hyperion-image/03Jun%5FFerguson.pdf.
Pełny tekst źródłaThesis advisor(s): Garth V. Hobson, Raymond P. Shreeve. Includes bibliographical references (p. 67). Also available online.
Melhem, Amer. "Oxydation par plasma électrolytique : influence des paramètres du procédé sur le comportement des micro-décharges et conséquences sur les couches d’oxydes". Thesis, Vandoeuvre-les-Nancy, INPL, 2011. http://www.theses.fr/2011INPL098N/document.
Pełny tekst źródłaPlasma electrolytic oxidation is a surface treatment process applied to light weight alloys (Al, Mg, V, Ti, etc.) which may advantageously replace conventional anodizing, especially regarding environmental issues. Though this process has been known for many years, the underlying mechanisms that govern this micro-discharge assisted process remain poorly understood. This work aims at better identifying the breakdown and development mechanisms of the micro-discharges and at correlating the micro-discharge characteristics to the properties of the layers grown onto Al2214 aluminium alloy samples. The approach consists in coupling the study of the micro-discharges, the characterization of the grown layers and the breakdown mechanisms. By means of high rate video recording (> 125 000 frames/s) and shadowgraph techniques, the dependence of the evolution of the micro-discharges with the macroscopic process parameters has been clearly established. The important role of counter-electrodes and their respective position with respect to the sample have been identified and studied. It is also shown that the suitable choice of current frequency and anodic current density may greatly improve the quality of the resulting oxide layers. Current frequency in the kHz range seems most appropriate to grow thick and defect-free homogeneous layers.Finally, from synchronous measurements, it has been pointed out a delay in the onset of micro-discharges with respect to the rising edge of the current pulses. Besides this delay is strongly sensitive to the process parameters, it is probably related to the breakdown mechanisms of the insulating layer. Scenarios for these mechanisms have been proposed
Söderberg, Daniel. "Hydrodynamics of plane liquid jets aimed at applications in paper manufacturing". Doctoral thesis, KTH, Mekanik, 1999. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-2839.
Pełny tekst źródłaQC 20100825
Quinn, Mark Kenneth. "Shock diffraction phenomena and their measurement". Thesis, University of Manchester, 2013. https://www.research.manchester.ac.uk/portal/en/theses/shock-diffraction-phenomena-and-their-measurement(4c41f25a-2ba2-4a4b-aa9c-cdb8bb9ba921).html.
Pełny tekst źródłaMakhlouf, Samir. "Contribution à l'étude de l'impact de la cavitation sur les processus physiques de l'atomisation primaire des jets d'injecteurs essence". Thesis, Rouen, INSA, 2015. http://www.theses.fr/2015ISAM0005/document.
Pełny tekst źródłaIn order to get closer to the homogeneous mixture conditions of a gasoline engine, different fluids are injected into the atmosphere at varying upstream pressure and temperature. Five three-hole real injector prototypes from Continental were used. When injection pressure is increased, the internal flow goes through four regimes where the cavitation development level varies from one to another. The discharge coefficient Cd was found mainly dependent on the cavitation number. At the cavitation critical point, two correlations between Cd and the critical cavitation number on one side respectively, and the correspondent Reynolds number on the other side were found. The near field jet is ruled by three dimensionless numbers : Weber, Reynolds and cavitation. The effect of each one of them on the jet angle at the orifice outlet was obtained. By comparing the results of two injectors, it was found that the length over diameter ratio has a first order influence on the jet angle
Cerbino, R. "Shadowgraphic study of convection in a colloidal suspension". Doctoral thesis, Università degli Studi di Milano, 2004. http://hdl.handle.net/2434/35439.
Pełny tekst źródłaSchaefer, Zane Donald. "Ultrafast-time-gated ballistic-photon imaging and shadowgraphy in optically dense rocket sprays". [Ames, Iowa : Iowa State University], 2009. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1464382.
Pełny tekst źródłaGravel, Jean-François. "Analyse chimique par ablation laser et caractérisation du plasma induit par laser par shadowgraphy". Thesis, Université Laval, 2009. http://www.theses.ulaval.ca/2009/26173/26173.pdf.
Pełny tekst źródłaGiraudet, Cédric Michel Marius. "Contributions à l’étude de la thermo diffusion de mélanges binaires en conditions de réservoirs". Thesis, Pau, 2015. http://www.theses.fr/2015PAUU3003/document.
Pełny tekst źródłaThermodiffusion, also called the Soret effect, describes the coupling between temperature gradient and resulting fluxes. This phenomenon is involved in a number of natural and industrial processes. In particular, multi components fluids in petroleum reservoirs are subjected to this phenomenon because of the geo-thermal gradient. Nevertheless, in spite of a lot of advances, there are few available data of this phenomenon and the establishment of a theoretical model, able to give a quantitative estimation of these transport coefficients whatever molecules in presence, is still an open question. The principal aim of this thesis is to develop an experimental approach allowing providing reference data on thermodiffusion as a function of the pressure. During this thesis, we developed a high pressure thermodiffusion cell in free medium, enabling us to study concentration non-equilibrium fluctuations induced by the Soret effect by means of shadowgraph optical technique. With this setup we investigated two binary mixtures representatives of petroleum fluids; namely the equimassic tetralin/dodecane mixture in liquid phase and the carbon dioxide/methane mixture in gaseous and super critical state. Furthermore, molecular dynamic simulations on the second mixture were performed. Using a dynamic image analysis, we have measured molecular diffusion and Soret coefficient for the tetralin/dodecane mixture. Within experimental uncertainties, we observed a linear decrease of these coefficients with the pressure. Furthermore, we were able to observe the effect of confinement (finite size effect induced by cell vertical boundary conditions) on fluctuation dynamics, in good agreement with calculations and simulations based on hydrodynamic fluctuation theory on similar solutal Rayleigh number. Concerning the carbon dioxide/methane mixture, the dynamic analysis revealed a kinetic too fast for our experimental apparatus. Conversely, static analysis revealed a rapid increase of the non-equilibrium fluctuation magnitude as a function of the pressure up to a threshold beyond which it decreases. On this mixture, performed molecular dynamic simulations provided results in good agreement with expected theoretical behaviour
VILLANUEVA, JUAN JOSE CRUZ. "EXPERIMENTAL STUDY OF THE TURBULENT COMBUSTION OF ETHANOL SPRAYS USING OH-PLIF, PIV AND SHADOWGRAPHY". PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2013. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=23360@1.
Pełny tekst źródłaO presente trabalho apresenta uma análise experimental da combustão turbulenta de sprays de etanol, mediante o uso de técnicas de diagnóstico laser, em queimadores tipo obstáculo. São empregadas a fluorescência induzida por plano laser (PLIF) do radical hidroxila (OH), para mapear a frente de chama, a velocimetria por imagens de partículas (PIV), para determinar o campo de velocidades das gotas do spray e Shadowgraphy, para obter o diâmetro e velocidade de gota. Uma caracterização da estrutura do escoamento de ar a jusante do corpo rombudo é realizada com PIV estéreo para diferentes números de Reynolds. Os resultados mostram uma similitude do escoamento na zona de recirculação. As maiores flutuações turbulentas de velocidades são encontradas na região de vórtice e indicam anisotropia no tensor de Reynolds. Os resultados de Shadowgraphy revelam que as gotas do spray não são perfeitamente esféricas em regiões perto do atomizador. O diâmetro médio Sauter (SMD) foi medido em varias posições na região de recirculação. As gotas de maior diâmetro apresentaram as maiores velocidades e as pequenas são ligeiramente desviadas pela zona de recirculação nas regiões mais afastadas da linha central. Os experimentos reativos realizados com diversos valores de vazão de etanol e ar indicam que a frente de chama é descolada do queimador, sua forma é determinada principalmente pela vazão de etanol e a intensidade de luminescência é aumentada com a velocidade do ar. Em alguns casos o escoamento de ar muda a forma do spray. Uma quantidade de gotas apreciável sempre consegue atravessar a frente de chama. O campo de velocidade das gotas é influenciado pelo incremento da velocidade do escoamento anular de ar.
This work presents an experimental analysis of turbulent combustion of ethanol sprays through the use of laser diagnostic techniques in a bluff-body burner. Are employed the planar laser-induced fluorescence (PLIF) of the hydroxyl (OH), to map the flame front, the particle image velocimetry (PIV) to determine the velocity field of the spray droplets and Shadowgraphy to obtain the droplet diameter and velocity. A characterization of the structure of the air flow downstream of the bluff-body is performed with stereo PIV at different Reynolds numbers. The results evidence flow similarity in the recirculation zone. The largest turbulent velocity fluctuations are found in the vortex region, which implies the anisotropy of the Reynolds stresses. The results of Shadowgraphy indicate that the spray droplets are not perfectly spherical near the atomizer. The evolution of Sauter mean diameter (SMD) is measured at various positions at the recirculation region. The largest diameter droplets have the highest velocity and the smaller are slightly deviated by recirculation zone in the far furthest from the centerline. The reactive experiments are performed with different ethanol and air flow rates and indicate that the flame front is detached from the burner, the shape is determined by the ethanol flow rate and the luminescence intensity increases with the air velocity. In some case the air flow changes the shape of the spray. An appreciable number of droplets always passe through the flame front. The velocity of the droplets is influenced by the increase of speed air velocity.
Maquignon, Nicolas. "Vers un modèle multiphases et multicomposants (MPMC) de type Lattice Boltzmann Method (LBM) pour la simulation dynamique d'un fluide cyogénique dans l'eau". Thesis, Littoral, 2015. http://www.theses.fr/2015DUNK0426/document.
Pełny tekst źródłaIn this thesis, a LBM MPMC model with heat exchange is developed. Data assimilation tests and optical flow measurements are made in order to validate the model. The application context of this thesis is the mixture of a cryogenic fluid with water. In the first part, a bibliographical work reminding the Boltzmann equation and its various assumptions and simplifications, as well as the algorithmic aspect of the LBM are exposed. A comparison between SRT and MRT collision operator is performed, and a simulation of turbulent phenomena at different Reynolds numbers is studied, especially with the benchmark of the instability from Von Karman. In the second part, the MPMC model from Shan & Chen is reminded and extended to the case of the inter-component heat exchanges. Quantitative validations are made, especially with the benchmark of a two-phase or two-component Couette fluid. Consistency is tested against Laplace's law rule, or against a benchmark involving heat conduction. Qualitative testing of condensations in a multi-component medium are proposed to validate the heat exchange between components in the presence of a phase transition. In the third part of this thesis, a validation method for data assimilation is introduced, with the ensemble Kalman filter. A state estimation test of a bi-phase fluid is realized, and compatibility of the ensemble Kalman filtering to the LBM MPMC model is assessed. For validation of the behavior of the model for a two-component case, a substitution fluid (non-cryogenic) for LNG, butane, was selected to permit observations in experimental conditions which are accessible. Then, an experimental platform of injection of liquid butane in a pressurised water column is presented. Shadowgraph images from liquid butane experiments in water are exposed and an optical flow calculation algorithm is applied to these images. A qualitative assessment of the velocity field obtaines by application of this algorithm is performed
Mauger, Cyril. "Cavitation dans un micro-canal modèle d'injecteur diesel : méthodes de visualisation et influence de l'état de surface". Phd thesis, Ecole Centrale de Lyon, 2012. http://tel.archives-ouvertes.fr/tel-00747628.
Pełny tekst źródłaSchneck, William Carl III. "Multi-Physics Model of a Dielectric Barrier Discharge Flow Control Actuator with Experimental Support". Diss., Virginia Tech, 2016. http://hdl.handle.net/10919/65004.
Pełny tekst źródłaPh. D.
Jiang, Wenbiao. "Simulation du bullage dans un photobioréacteur". Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLC086/document.
Pełny tekst źródłaThe working principle of a typical photobioreactor is to inject gas bubbles into the culture medium, providing CO2 to the cells and also stirring the liquid. Subsequently, the cells convert inorganic carbon into organic carbon through photosynthesis under illumination. Therefore, physical phenomena, e.g. bubbly flow, mass transfer, radiative transfer, and biological phenomena, e.g. photosynthesis, cell growth and death, coexist in a photobioreactor. More importantly, all the basic phenomena are not completely independent to each other. For example, bubble volume and bubble shape can influence gas-liquid mass transfer according to Young-Laplace equation and Henry's law. Moreover, some recent research revealed that bubble behaviors also directly affect the biological process. In view of the important impact of bubble behaviors on productivity of a phototbioreactor, the bubbly flow was investigated in this thesis by both experimental and numerical methods.In the experimental study, we first manufactured a new photobioreactor in order to study the bubbles and other phenomena. Subsequently, the bubbles were captured by high speed camera by virtue of a shadowgraphy technique and bubble behaviors were obtained by processing and analyzing the images. From the experimental results, we found that both averaged bubble volume and bubbling frequency increased with gas flow rate. Furthermore, we also discovered that the distribution of bubble volume was almost monodisperse at low flow rate, and it became more and more polydisperse with increasing flow rate. Regarding bubble shape evolution, we used two shape factors, viz. aspect ration and circularity, to quantitatively study it. We found that both shape factors dropped rapidly during bubble rising (within the limit of the field of view of our video camera), which implied that bubbles were flattened in the course of rising. Nonetheless, bubbles became more vertically elongated at higher flow rate, partially due to the more frequent bubble coalescence at higher flow rate.In the numerical study, we adopted VOF method and OpenFOAM, an open source CFD library, as our numerical tool to represent bubbly flow. First of all, the robustness of OpenFOAM in simulating two-phase flow was validated by literature survey. Subsequently, 2D simulations were carried out for seeking the appropriate and not very time-consuming numerical parameters, i.e. maximum Courant number and mesh size. We found that mesh size should somehow be smaller than the nozzle diameter to have meaningful results. On the other hand, maximum Courant number had no particular importance in the simulations (as long as between 0 and 1). Furthermore, 3D simulations were in good agreement with the experiments in terms of bubble volume and bubble shape evolution. However, 3D simulations were not able to represent the polydispersity of bubble volume due to the limited computing power. In addition, several hydrodynamic characteristics were also explored by the proposed numerical tool, which gave reasonable results.To conclude, bubble behaviors were successfully captured by experimental methods and represented by numerical methods in this thesis, which will help us go further in understanding the complicated physical-biological phenomena of a photobioreactor
Wilson, Jacob E. "CHARACTERIZATION OF ROTARY BELL ATOMIZERS THROUGH IMAGE ANALYSIS TECHNIQUES". UKnowledge, 2018. https://uknowledge.uky.edu/me_etds/115.
Pełny tekst źródłaIzarra, Grégoire de. "Diagnostic des zones périphériques d’arcs électriques et des décharges hors-équilibre". Thesis, Orléans, 2013. http://www.theses.fr/2013ORLE2025/document.
Pełny tekst źródłaUntil recently, most of electrical arcs applications were dealing with the properties of the centre of the plasma column, a large number of works was then done to develop diagnostic techniques dedicated to those area where the mean temperature is about 10000 K. With the emergence of plasma chemistery, the diagnostic of arc’s peripheral areas and un-equilibrium discharges become a goal of prime importance. Classical diagnostic techniques are not adapted to those objects where the maximum temperature is around 8000 K; the principal aim of this work was to develop and check diagnostic techniques. Two inovating techniques based on refractive index, the quantitative shadowgraphy and the moiré deflectometry were studied extensively and checked on a laminar plasma jet, a perfect model of arc’s peripheral area. To probe unequilibrium discharge, the use of UV OH spectrum was considered. At this occasion, a spectrum simulation software was written. The study of synthetic spectra lead to the creation of simple measurement methods of rotationnal and vibrationnal OH temperature for a large range of resolution. Those methods was checked on a low power electric discharge. It can be shown that result from molecular spectroscopy are close to those obtained by simulation
Louis, Neven. "Numerical simulations of thedecomposition of a greenpropellant". Thesis, KTH, Mekanik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-250021.
Pełny tekst źródłaYuldashev, Petr. "Propagation d'ondes de choc dans les milieux aléatoires avec des inhomogénéités distribuées dans l'espace ou dans une couche mince". Phd thesis, Ecole Centrale de Lyon, 2011. http://tel.archives-ouvertes.fr/tel-00728798.
Pełny tekst źródłaLelong, Nicolas. "Etablissement numérique et expérimental d'un dispositif nébuliseur pour l'aérosolthérapie". Thesis, Tours, 2013. http://www.theses.fr/2013TOUR3309.
Pełny tekst źródłaThe purpose of aerosol therapy is to deliver drugs into respiratory airways. The jet nebulizer is a device used to generate liquid droplets with a diameter lower than 5 μm. However its atomization process was not much analyzed. Nebulizer performances, which are characterized with droplet size and drug mass inhaled by the patient, are empirically optimized and have reached a plateau. Our work consists in setting a 3D diphasic numerical model on ANSYS Fluent, based on a given geometry. Several methods are used to experimentally characterize aerosol generation: shadowgraphy, laser diffractometry and phase Doppler anemometry. Our model is validated by experimental data and helps predicting generation processes. The influence of several geometric and physical parameters on the output is studied. From these data, droplet generation is optimized for the development of a new nebulizer. Droplet transport to the patient lungs is empirically optimized
Weber, Fabian. "Optical Analysis of the Hydrogen Cooling Film in High Pressure Combustion Chambers". Thesis, Luleå tekniska universitet, Rymdteknik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-76872.
Pełny tekst źródłaVotavová, Helena. "Vývoj nových přístupů v odstraňování okují při kontinuální výrobě oceli s využitím vysokotlakého vodního paprsku". Doctoral thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2019. http://www.nusl.cz/ntk/nusl-401607.
Pełny tekst źródłaBiasiori-Poulanges, Luc. "Fragmentation aérodynamique d’une goutte liquide induite par une onde de choc plane High-magnification shadowgraphy for the study of dropbreakup in a high-speed gas flow On the formation and recurrent shedding of ligaments in droplet aerobreakup Data on eosin y solutions for laser-induced fluorescence in water flows Multimodal imaging for intra-droplet gas-cavity observation during droplet fragmentation". Thesis, Chasseneuil-du-Poitou, Ecole nationale supérieure de mécanique et d'aérotechnique, 2021. http://www.theses.fr/2021ESMA0002.
Pełny tekst źródłaThis thesis proposed a groundbreaking description of the shock-induced aerodynamic fragmentation of a water droplet at the transition of the Rayleigh-Taylor Piercing and the Shear-Induced Entrainment regimes. An experimental facility consisting of a shock tube and high-speed imaging diagnostics is used to investigate the fragmentation processes. Experimental results are supported with numerical simulations performed with the open-source code ECOGEN dedicated to multiphase compressible flows. The shock wave effect on the droplet is assessed by a theoretical modelling based on geometrical acoustics which allows for the description of the wave spatio-temporal dynamics and enables to predict the time-dependent location of the highest energy density. Pressure fields are determined using numerical simulations. It appears that the water tensile rupture is reached for a shock wave Mach number of 1.7 from which bubble cloud cavitation may occur by causing signification changes in the fragmentation dynamics. As regards to the interfacial dynamics, both experiments and numerical simulations show the development of a transverse azimutal modulation resulting in the periodic ligament structure at the droplet surface. Contrary to the modulation growth, its initiation seems to be independent of the capillary effects as revealed by a Fourier analysis of the 3-D numerical results. The ligament dynamics is a cyclic process driven by the vortex shedding process in the wake of the droplet. Four cycles have been observed before the residual droplet core breaks up owing to the growth of an air cavity inside the droplet that acts as weak spot, and thus facilitating the droplet split-off
Vallée, Nathalie. "Caractérisation des jets à hautes pressions : étude expérimentale d'injections continues sub-, trans- et super-critiques". Thesis, Normandie, 2018. http://www.theses.fr/2018NORMIR08/document.
Pełny tekst źródłaStudying a fluid flow under high-pressure conditions through reliable experiments is still nowadays a challenge. When the chamber pressure exceeds the critical pressure of working fluids the supercritical state of matter is reached and the distinction between gas and liquid becomes blurred. For such special conditions, experimental data are scarce and need to be consolidated. In the present study, a new test bench has been designed at CORIA Lab to study the non-reactive injection of ethane and propane into nitrogen or helium under sub- and supercritical conditions. Experimental data are collected from four image-based techniques : shadowgraphy, diffused backlight illumination (DBI), radiography and color background oriented schlieren (CBOS). Qualitative information on topology of the jets and their mixing layer are provided. Quantitative measurements of dense core length, jet spreading angle and density field are supported by a phenomenological study based on binary mixing theory
Marinov, Ilya. "Plasmas in liquids and at the interfaces". Phd thesis, Université Paris Sud - Paris XI, 2013. http://tel.archives-ouvertes.fr/tel-00998381.
Pełny tekst źródłaAbdelali, Ahmed. "Etude expérimentale des instabilités thermoconvectives de Rayleigh-Bénard dans les fluides viscoplastiques". Phd thesis, Université de Grenoble, 2012. http://tel.archives-ouvertes.fr/tel-00845453.
Pełny tekst źródłaHamdan, Ahmad. "Microdécharges dans l'heptane liquide : caractérisation et applications au traitement local des matériaux et à la synthèse de nanomatéraux". Thesis, Université de Lorraine, 2013. http://www.theses.fr/2013LORR0119/document.
Pełny tekst źródłaIn this document, we report our work on discharges in heptane. One of the specific conditions selected is the choice of a micrometric gap distance. Typically, gaps were between 10 and 150 µm, corresponding to breakdown voltages between 1 and 15 kV. From breakdown up to 1 µs, the plasma discharge was characterized by shadowgraphy and optical emission spectroscopy (OES). Shadowgraphy results showed that the velocities of shock wave and bubble interface are about 1200 m s-1 and 100 m s-1, respectively. Beyond 1 µs, experimental and theoretical studies of the oscillatory dynamics of the bubble are made. Then, we proposed a new method to estimate the pressure at discharge breakdown. The technique is based on the response of a 'test bubble' present in the acoustic field of a new discharge whose pressure is to be known. It is estimated to be about 80 bar. OES, between 300 and 800 nm, showed a dominance of continuous radiations during the first 200 ns which were attributed to electron-ion recombination processes. Beyond 200 nm, continuous radiations collapse and then, the emission lines dominate the spectrum. The study of the H? line broadening showed that the electron density can reach 1019 cm-3. Regarding the interaction of the discharge with the electrode surfaces, we demonstrated that the diameter of the impact is governed by the quantity of charges deposited by the discharge. However, the impact morphology is determined by a balance between the force exerted by the plasma pressure and the Marangoni's force. Finally, we studied the possibility to synthesize platinum nanoparticles (5 nm in diameter) embedded in a matrix of hydrogenated carbon exhibiting a short range order
Quérel, Arnaud. "Lessivage de l'atmosphère par la pluie : approche microphysique". Phd thesis, Université Blaise Pascal - Clermont-Ferrand II, 2012. http://tel.archives-ouvertes.fr/tel-00859330.
Pełny tekst źródłaMachicoane, Nathanaël. "Particules matérielles en écoulement turbulent. Transport, dynamique aux temps longs et transfert thermique". Phd thesis, Ecole normale supérieure de lyon - ENS LYON, 2014. http://tel.archives-ouvertes.fr/tel-01070651.
Pełny tekst źródłaDépée, Alexis. "Etude expérimentale et théorique des mécanismes microphysiques mis en jeu dans la capture des aérosols radioactifs par les nuages". Thesis, Université Clermont Auvergne (2017-2020), 2019. http://www.theses.fr/2019CLFAC057.
Pełny tekst źródłaAtmospheric particles are a key topic in many social issues. Their presence in this atmosphere is a meteorological and climatic subject, as well as a public health concern since these particles are correlated with the increase of cardiovascular diseases. Specially, radioactive particles emitted as a result of a nuclear accident can jeopardise ecosystems for decades. The recent accident at the Fukushima Daiichi’s nuclear power plant in 2011 reminds us that the risk, even extremely unlikely, exists.After a release of nuclear material in the atmosphere, nanometric particles diffuse and coagulate, while micrometric particles settle due to gravity. Nevertheless, the intermediate size particles can be transported at a global scale when the main mechanism involved in their scavenging comes from the interaction with clouds and their precipitations. To enhance the ground contamination knowledge after such accidental releases, the understanding of the particle in-cloud collection is thus essential. For this purpose, a microphysical model is implemented in this work, including the whole microphysical mechanisms acting on the particle collection by cloud droplets like the electrostatic forces since radionuclides are well-known to become significantly charged. Laboratory measurements are then conducted through In-CASE (In-Cloud Aerosols Scavenging Experiment), a novel experiment built in this work, to get comparisons between modelling and observations, once again at a microphysical scale where every parameter influencing the particle in-cloud collection is controlled. Furthermore, two systems to electrically charge particles and droplets are constructed to set the electric charges carefully while the relative humidity level is also regulated. These new research results related to the particle collection by cloud droplets following the electrostatic forces, among others effects, are thus incorporated into the convective cloud model DESCAM (Detailed SCAvenging Model). This detailed microphysical model describes a cloud from its formation to the precipitations, allowing the study at a meso-scale of the impact of the new data on the particle scavenging. Moreover, some changes are made in DESCAM to expand the study to stratiform clouds since the major part of the French precipitations come from the stratiform ones. Finally, this work paves the way for the enhancement of the atmospheric particle scavenging modelling, including the ground contamination in the crisis model used by the French Institute in Radiological Protection and Nuclear Safety
Chang, Yu-mei, i 張玉梅. "Research on Shadowgraph Teaching in Extracurricular Activities of Elementary School―An Example from Mituo Elementary School, Kaohsiung County". Thesis, 2007. http://ndltd.ncl.edu.tw/handle/47099467166844276701.
Pełny tekst źródła國立臺南大學
戲劇創作與應用學系碩士班
95
This thesis will focuses on learn, create, and play process of students at school shadow play club, Mitou Elementary. After they learn the traditional shadow play Li Nor-cha disturb East China Sea,they make group creative job as Li Nor-cha disturb the Internet Ca’fe. They even design and made the shadow puppies by themselves, then teamwork to perform this campus shadow play. The main purpose of this research is to design a proper course syllabus for elementary shadow play club. This syllabus could be the reference of future campus club operation. Then the research will based on the operation result to provide workable suggestions and problem-resolving strategies. Through this research, researcher promotes the knowledge and understanding of traditional shadow play and campus shadow play. It would help research objects (i.e. elementary students) understand the differences between traditional and campus shadow play on puppet making and performance style. After the teaching of shadow play club, researcher wish students will love shadow play more, and increase the appreciation of shadow play, then achieve purpose of preserve shadow play. Following is the brief research results of this research: 1. The syllabus research of elementary school shadow play club. This research will develop a concrete course. 2. The teaching progress of elementary shadow play include 4 different stages as: preparation, development, operation, and arrangement. 3. Through the teaching of elementary school shadow play club, it would increase students’ favoring and understanding toward traditional shadow play. 4. Through the teaching of elementary school shadow play club, it would increase students’ abilities on script writing, puppet making and playing. It would also trigger student creativeness to innovate the performance skill and content. This will attract more audiences to enjoy the beauty of shadow play. 5. The research probe to resolve the difficulties of elementary shadow play club. This research also suggests school to find more resources to ease problems. It would help the shadow play more prosperous than ever.
Ghaemi, Sina. "Investigation of Effervescent Atomization Using Laser-Based Measurement Techniques". Master's thesis, 2009. http://hdl.handle.net/10048/394.
Pełny tekst źródłaGravel, Jean-François. "Analyse chimique par ablation laser et caractérisation du plasma induit par laser par shadowgraphy /". 2009. http://www.theses.ulaval.ca/2009/26173/26173.pdf.
Pełny tekst źródłaDi, Yuan 1988. "Experimental Observation and Measurements of Pool Boiling Heat Transfer using PIV, Shadowgraphy, RICM Techniques". Thesis, 2012. http://hdl.handle.net/1969.1/148162.
Pełny tekst źródłaKhan, Abdul. "Bubbly Flow Experiment in Channel Using an Optical Probe and Tracking Algorithm". Thesis, 2012. http://hdl.handle.net/1969.1/ETD-TAMU-2012-08-11730.
Pełny tekst źródłaTewari, Sumit. "Study Of Liquid Fuel Film Transport And Its Effect On Cold Start Hydrocarbon Emissions In A Carburetted Engine". Thesis, 2011. http://etd.iisc.ernet.in/handle/2005/1908.
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