Bibliografie tematiche / Shadowgraph

Letteratura scientifica selezionata sul tema "Shadowgraph"

Autore: Grafiati

Pubblicato: 4 giugno 2021

Ultima modifica: 10 marzo 2023

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Articoli di riviste sul tema "Shadowgraph"

Smith, Cary, Mark Gragston, Yue Wu e Zhili Zhang. "Experimental Characterization of Two-Phase Aerated Liquid Ethanol and Jet A Spray Flames". Applied Sciences 10, n. 19 (4 ottobre 2020): 6950. http://dx.doi.org/10.3390/app10196950.

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This work provides an analysis of an air-assisted atomizing nebulizer’s spray characteristics and combustion behaviors via application of various diagnostics. Two-phase far-field flows and flames of liquid ethanol and practical aviation fuel Jet A were characterized for the droplet distributions, fuel concentrations, and flame dynamics by shadowgraph, Mie scattering, and chemiluminescence imaging of CH*, C2*, and CO2*. Both instantaneous and time-averaged measurements of the two-phase flow and flame characteristics were obtained. Shadowgraphs were used to measure the probability distribution of the droplet diameters. Mie scattering was used to map fuel concentration and obtain the liquid spray cone angles. Estimates of the lifted flame height were obtained by both shadowgraph and Mie scattering, which were verified by the chemiluminescence images. The effect of flow rates on parameters such as flow characteristic, spray cone angle, and drop size spectrum were quantitatively characterized for both ethanol and practical aviation fuel Jet A.

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Corbett, J., C. L. S. Lewis, E. Robertson, S. Saadat, P. F. Cunningham, A. Cole, E. Trucu, M. H. Key e S. J. Rose. "Recent experiments at the Rutherford Appleton Laboratory to study the laser driven compression of CH shell targets and the effects of increasing aspect ratio". Laser and Particle Beams 4, n. 3-4 (agosto 1986): 573–76. http://dx.doi.org/10.1017/s0263034600002251.

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Recent experiments to study the laser driven compression of CH shell targets and the effects of increasing aspect ratio using x-ray shadowgraph techniques are described. This work has been carried out at the Rutherford Appleton Laboratory's Central Laser Facility with 12 beam, 0·53 μm, 1·0 ns irradiation. X-ray shadowgraphy techniques have been used with a frame time of ∼100ps and spatial resolution of 5 to lOμm to obtain density profiles for the compressed targets. A systematic study of 150–200 μm targets with aspect ratios from ∼7 to ∼20 has been performed. The x-ray shadowgraphy techniques used are described, results in the form of x-radiographs presented and a discussion of preliminary results given.

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Greer, Adam T. "In-Situ Shadowgraph Imaging". Marine Technology Society Journal 52, n. 6 (1 novembre 2018): 62–65. http://dx.doi.org/10.4031/mtsj.52.6.5.

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AbstractVarious imaging systems are producing complex data that improve our understanding of physical and biological coupling in the ocean. In-situ shadowgraph imaging is one sampling technique that captures detailed biological information for a wide range of plankton with differing body compositions (e.g., gelatinous to crustacean) in their natural orientations, as well as small-scale physical changes. When combined with rapidly advancing computer vision methods and high-resolution oceanographic observations, shadowgraph imagery holds promise for generating new discoveries in ocean science that are only limited by our creativity in asking new questions.

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Mursenkova, I., M. Timokhin, M. Tikhonov, A. Militsina e A. Kuznetsov. "Digital processing of shadowgraph images taking into account the diffraction of light at a shock front". Journal of Physics: Conference Series 2127, n. 1 (1 novembre 2021): 012001. http://dx.doi.org/10.1088/1742-6596/2127/1/012001.

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Abstract The aim of the study is to determine the shock wave position in experimental shadowgraph images and to evaluate the accuracy by digital image processing. The experimental images were obtained with the shock tube with a rectangular channel. The shadowgraph optical system formed a parallel light beam. It passed through the plane-parallel quartz glasses of the shock tube test section. The process synchronization system at the facility allows registering the shadowgraph images of unsteady flows with shock waves with a high-speed camera or with a single frame camera. The obtained spatial intensity profiles were used to determine the coordinates of gas-dynamic discontinuities at different stages of the flow evolution. shadowgraph patterns were analysed taking into account diffraction at the shock front in case of a laser light source.

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Phung, Van Duoc. "DEVELOPING A SHADOWGRAPH EXPERIMENT SYSTEM FOR CHARACTERIZING SPRAY ATOMIZATION". Journal of Science and Technique 17, n. 4 (27 settembre 2022): 22–31. http://dx.doi.org/10.56651/lqdtu.jst.v17.n04.40110.56651/lqdtu.jst.v17.n04.401.

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The development of modern imaging techniques plays an imporatnt role in studying fuel spray atomization. Shadowgraph combines camera, lens and lightsources to experimentally determine micro parametters (droplet size, droplet size distribution, velocity of droplets) and macro parametters (cone angle, breakup length, penetration) of spray structure. To achieve high quality, shadowgraph systems need to be carefully validated to ensure realiability and capability of working under various operating conditions. This articledevelops an experiment system for characterizing spray atomization by shadowgraph imaging technique. A peliminary study on an air-blast atomizer is also provided.

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Liu, Minghui, e John R. de Bruyn. "Traveling-wave convection in a narrow rectangular cell". Canadian Journal of Physics 70, n. 9 (1 settembre 1992): 689–95. http://dx.doi.org/10.1139/p92-111.

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Traveling-wave convection in an ethanol–water mixture confined in a narrow rectangular cell of height:width aspect ratio 1:0.3 is studied using shadowgraph flow visualization. We are able to identify qualitatively the contributions to the shadowgraph intensity due to the concentration field in the convecting mixture. The measured shadowgraph intensities and traveling-wave frequencies share features with the results of numerical calculations, which assume an infinitely wide cell, and of experiments done in wider cells, but there are significant quantitative differences, apparently due to our highly constrained geometry.

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Linehan, Kelly A., e John R. de Bruyn. "Gravity currents and the electrolyte concentration field in electrochemical deposition". Canadian Journal of Physics 73, n. 3-4 (1 marzo 1995): 177–86. http://dx.doi.org/10.1139/p95-025.

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Using shadowgraphs, we visualize local electrolyte concentration variations in quasi-two-dimensional electrochemical deposition experiments. Experiments have been performed in both circular and parallel-electrode geometries. Our results indicate that a region of ion depletion moves from the cathode towards the anode, while a region of enhanced concentration grows in from the anode. Large-scale gravity-driven flows, which drive the growth of these regions, are observed. The growth speed of the metal aggregate at the cathode is the same as the speed at which these flows move anions away from the cathode, except at the earliest stages of growth. By integrating the shadowgraph intensity, we calculate the concentration field in the parallel geometry.

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Watanabe, Ryuta, Takayuki Kikuchi, Takayuki Yamagata e Nobuyuki Fujisawa. "Shadowgraph Imaging of Cavitating Jet". Journal of Flow Control, Measurement & Visualization 03, n. 03 (2015): 106–10. http://dx.doi.org/10.4236/jfcmv.2015.33010.

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Settles, Gary S. "Smartphone schlieren and shadowgraph imaging". Optics and Lasers in Engineering 104 (maggio 2018): 9–21. http://dx.doi.org/10.1016/j.optlaseng.2017.07.002.

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Più fonti

Tesi sul tema "Shadowgraph"

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.

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The effects of swirling flow and spark locations on the specific rate of growth of flame area, the flame speed and the convection velocity are investigated experimentally in a constant volume vessel near the lean misfire limit for an equivalence ratio of 0.645 using the shadowgraph technique. The circular and the elliptical models are used as flame contours to calculate the flame speed and the convection velocity. The circular model indicates that the flame speed decreases as the swirl flow decays and as the spark location is moved towards the center of the combustion chamber. The modified elliptical model shows the same result for the average flame speed $S\sb{ws}$. Both models show an overlap in convection velocity when comparison is made at a given spark location for different swirl levels because of cyclic variation; even though the average is higher for higher swirl level. The specific rate of growth of flame area (${1\over A}{dA\over dt}$) is obtained using three models for flame area A: (i) 2-D flame area $A\sb{f}$ measured from the photographs, (ii) spherical flame geometry model, and (iii) ellipsoidal geometry model. The stretch factor $K=({\delta\sb{l}\over u\sb{l}}) ({1\over A}{dA\over dt})$ at 0.5 ms from ignition time for the 2-D and the spherical models at ${r\over R}=0.68$ was within the range 0.63-0.97 and at ${r\over R}=0.55$ was within the range 0.5-0.59. The stretch factor for the ellipsoidal model at ${r\over R}=0.68$ was within the range 0.53-1.05 and at ${r\over R}=0.55$ was within the range 0.46-0.53. All three models for flame area indicate that the specific rate of growth of flame area and stretch factor at 0.5 ms from ignition time decrease as the swirl flow decays and as the spark location approaches the center of the combustion chamber.

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Hattori, Tae. "Investigation into Stability, Transition and Turbulence of Thermal Plumes". Thesis, The University of Sydney, 2012. http://hdl.handle.net/2123/9338.

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In this thesis, the stability, transition and turbulence of thermal plumes were investigated by numerical simulation. Experiments were also conducted, but only for the validation of the simulation code being used. The effect of variable transport properties on a large eddy simulation of a turbulent axisymmetric plume was examined, and it was shown that an in-house incompressible Navier-Stokes solver, which is based on a standard Smagorinsky LES model, with the effects of variable properties incorporated using a modified Sutherlands law, predicts the correct statistical behaviours of the turbulent plume. The near-field puffing instability in thermal planar plumes, which had received little attention in the literature, was investigated by direct numerical simulation. The associated lapping flow instability, forming bulge structures over a heated floor section, was studied using a channel flow model, which allows the lapping flow velocity to be varied. The parametric dependencies were found for the bulge formation and the oscillation frequencies in the lapping flow. Further, the Prandtl number dependent transitional behaviours in the near-field were investigated, and direct stability analysis was conducted to study the lapping flow and stem instabilities. Experiments using a shadowgraph technique and an in-house, two-dimensional, two-component particle image velocimetry, with water as the working fluid, provided validations for the near-field unsteady behaviours of thermal plumes. A ventilated filling box flow with a transitional planar plume was also investigated by direct numerical simulation. A mapping of transitional flow behaviours was obtained, and the parametric dependencies of turbulence statistics and mean flow characteristics were investigated. The three-dimensionality was shown to have only minor effects on the transitional ventilated filling box flows being considered.

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Zakrzewski, Sam Mechanical &amp 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.

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A comprehensive understanding of high-speed liquid jets is required for their introduction into engine and combustion applications. Their transient nature, short lifetime, unique characteristics and the inability to take many experimental readings, has inhibited this need. This study investigates the outflow of a high-speed liquid jet into quiescent atmospheric air. The key characteristics present are, a bow shock wave preceding the jet head, an enhanced mixing layer and the transient deformation of the liquid jet core. The outflow regime is studied in an experimental and numerical manner. In the experimental investigation, a high-speed liquid water jet is generated using the momentum exchange by impact method. The jet velocity is supersonic with respect to the impinged gaseous medium. The resulting jet speed is Mach 1.8. The jet is visualised with the use of shadowgraph apparatus. Visualisation takes place over a variety of time steps in the liquid jet???s life span and illustrates the four major development stages. The stages progress from initial rapid core jet expansion to jet stabilisation and characteristic uniform gradient formation. The visualisation shows that at all stages of the jet???s life it is axi-symmetric. One dimensional nozzle analysis and a clean bow shock wave indicate that the pulsing jet phenomenon can be ignored. In the numerical investigation, a time marching finite volume scheme is employed. The bow shock wave characteristics are studied with the use of a blunt body analogy. The jet at a specific time frame is considered a solid body. The jet shape is found to have an important influence on the shock position and shape. Analysis of the results indicates a shock stand-off similar to that seen in experimental observations and the prediction of shock data. The jet life span is modelled using a species dependent density model. The transient calculations reproduce the key jet shape characteristics shown in experimental visualisation. The mushrooming effect and large mixing layer are shown to develop. These effects are strongest when the shock wave transience has yet to stabilise. Quantitative analysis of the mixing layer at varying time steps is presented.

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Robertson, 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.

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Circulation control involves tangentially blowing air around a rounded trailing edge in order to augment the lift of a wing. The advantages of this technique over conventional mechanical controls are reduced maintenance and lower observability. Despite the technology first being proposed in the 1960s and well-studied since, circulation control is not in widespread use today. This is largely due to the high mass flow requirements. Increasing the jet velocity increases both the efficiency (in terms of mass flow) and effectiveness. However, as the jet velocity exceeds the speed of sound, shock structures form which cause the jet to separate. Recent developments in the field of fluidic thrust vectoring (FTV) have shown that an asymmetrical convergent-divergent nozzle capable of producing an irrotational vortex (IV) has the potential to prevent separation through eliminating stream-wise pressure gradients. In this study, the feasibility of preventing separation at arbitrarily high jet velocities through the use of asymmetrical nozzle geometries designed to maintain irrotational (and stream-wise pressure gradient free) flow is explored. Furthermore, the usefulness of an adaptive nozzle geometry for the purpose of extending circulation control device efficiency and effectiveness is defined. Through a series of experiments, the flow physics of supersonic curved wall jets is characterised across a range of nozzle geometries. IV and equivalent area ratio symmetrical convergent-divergent nozzles are compared across three slot height to radius ratios (H/R): H/R = 0.1, H/R = 0.15, H/R = 0.2. The conclusion of this study is that at low H/R (0.1 and 0.15), there is no significant difference in behaviour between IV and symmetrical nozzles, whilst at high H/R (0.2), the IV nozzles begin separating whilst correctly expanded due to the propagation of pressure upstream from the edge of the reaction surface via the boundary layer. Consequently, it is shown that symmetrical nozzles of equivalent mass flow at high H/R have a higher separation NPR compared to IV nozzles. Specifically, the elimination of favourable, in addition to adverse stream-wise pressure gradients contradicts the expected behaviour of IV nozzles. The separation NPR for nozzles tested in this study, in addition to past studies is subsequently plotted against the throat height to radius ratios (A*/R). This shows that in fact, no previous experiments have shown a higher separation NPR for IV nozzles compared to symmetrical nozzles of equivalent mass flow. The overall outcome is that neither fixed geometry IV, nor adaptive nozzles are justified to maintain attachment, or to improve efficiency. This is because fixed nozzle geometries designed for higher separation NPR do not show any performance deficit when operating at lower NPRs. However, the throat height could be varied to maximise effectiveness (at the expense of mass flow). The contributions to new knowledge made by this study are as follows: the development of a new method of combining shadowgraph and schlieren images to simplify and enhance visualisation of supersonic flows; the use of pressure sensitive paint (PSP) to study the structure of the supersonic curved wall jet before and after separation; the identification of a clear mechanism for the separation of supersonic curved wall jets, valid over a broad range of nozzle geometries (including a clarification of previously unexplained behaviour witnessed in prior studies); the explanation that reattachment hysteresis occurs due to the upstream movement of the point of local separation at full separation (specifically, this explains why certain geometries such as backward-facing steps prevent reattachment hysteresis).

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Donzelli, 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.

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Knight, 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.

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Younis, 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.

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NUMERICAL AND EXPERIMENTAL STUDY OF TRANSIENT LAMINAR NATURAL CONVECTION OF HIGH PRANDTL NUMBER FLUIDS IN A CUBICAL CAVITY
Obai 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.

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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.

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Tadrous, 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.

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In this study, thermocapillary-driven convection around a gas bubble under a horizontal heated wall is experimentally investigated under gravitational conditions. The thermocapillary convective flow under conditions beyond the laminar steady state towards turbulent flow is explored in detail. Generally, Marangoni convection is more critical and important under microgravity conditions rather than on earth. Under low gravity, this surface tension induced flow can dictate both heat and mass transfer processes. Thus, thermocapillary convection should be considered by manufacturers during material production processes in space. Moreover, temperature gradients can be purposefully used to eliminate or move bubbles or drops suspended in liquid materials. In addition to that, thermocapillary convective flow appears in many other applications like manufacturing of single-walled carbon nanotubes and mono crystal production, to mention only few examples. Researchers have always seen Marangoni convection as an interesting topic for both numerical and experimental studies. Regarding the configuration of the injected gas bubble under a horizontal heated wall, this physical problem is mainly characterized by a dimensionless number that represents the ratio of convective heat flow induced by capillary convection to the heat transfer due to conduction which is termed Marangoni number (Mg). The past decade has seen different approaches to describe the flow behaviour at high Marangoni numbers. The thermocapillary flow has been mainly investigated and categorized regarding a stable laminar behaviour and a non-laminar one, which is characterized by periodic or non-periodic oscillations. Through previous studies, the point of the transition of the thermocapillary flow from the periodic oscillatory zone to the non-periodic one has been well investigated. However, there is a lack of information about this non-periodic behaviour at very high temperature gradients. Therefore, in the current study, our experimental investigations focus mainly on exploring different factors affecting the non-periodicity of the Marangoni convection and on explaining how this flow behaves under conditions above the transitional Marangoni number (Mg tran ). The experimental work was launched using a PIV technique and shadowgraphy. In addition to that, temperature measurements at different locations in the matrix fluid around the air bubble were conducted to determine the undisturbed temperature gradients at different boundary conditions. The transient observation of both velocity and temperature measurements at locations near the bubble allowed deeper insight in the behaviour of the thermocapillary bubbleconvection. Moreover, through shadowgraphy, a qualitative evaluation of the fluid flow periodicity around the gas bubble was achieved. The implementation of experiments inside a pressure chamber under gauge pressure conditions formed a novel methodology to enable us conducting experiments under higher temperature gradients in order to reach high Marangoni numbers. The thermocapillary bubble convection was categorized into laminar, periodic oscillatory, and non-periodic oscillatory flow. The periodic fluid flow oscillations were categorized in symmetric and asymmetric ones depending on the different applied boundary conditions. The non-periodic fluid flow oscillations around the gas bubble were also achieved at high temperature gradients for different bubble aspect ratios. We proved that for every bubble size, the non-periodic oscillatory state of the fluid flow around the gas bubble undergoes four different modes (A-D). The last one (phase D) is a developed turbulent state starting at Mg- numbers of 75000 for the smallest bubble aspect ratio of 1.2 up to the maximal measured Mg- number of 140000 for a bubble aspect ratio of 2.3. Hence, turbulent thermocapillary bubble convection was realized and studied in our experimental configuration. Moreover, the thermocapillary flow driving velocities at the bubble periphery were measured at different boundary conditions. This study clearly demonstrates that it is the high magnitude of the driving velocity that initiates the interactions between thermocapillary flow vortices leading finally to a highly developed oscillation mode (turbulent state) and that buoyancy plays a secondary role in the described flow configuration.:1 INTRODUCTION 2 LITERATURE REVIEW 3 EXPERIMENTAL SETUP AND METHODOLOGY 4 RESULTS AND DISCUSSION 5 CONCLUSIONS AND RECOMMENDATIONS
In 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

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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.

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Thesis (M.S. in Aeronauticl Engineering)--Naval Postgraduate School, June 2003.
Thesis advisor(s): Garth V. Hobson, Raymond P. Shreeve. Includes bibliographical references (p. 67). Also available online.

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Libri sul tema "Shadowgraph"

Settles, G. S. Schlieren and Shadowgraph Techniques. Berlin, Heidelberg: Springer Berlin Heidelberg, 2001. http://dx.doi.org/10.1007/978-3-642-56640-0.

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United States. National Aeronautics and Space Administration., a cura di. Interferograms, schlieren, and shadowgraphs constructed from real- and ideal-gas, two- and three-dimensional computed flowfields. [Washington, DC: National Aeronautics and Space Administration, 1992.

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Schlieren and shadowgraph techniques: Visualizing phenomena in transparent media. Berlin: Springer, 2001.

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United States. National Aeronautics and Space Administration., a cura di. Images constructed from computed flow fields. [Washington, DC: National Aeronautics and Space Administration, 1992.

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Snow, Walter L. Improvement in the quality of flow visualization in the Langley 0.3-meter Transonic Cryogenic Tunnel. Hampton, Va: Langley Research Center, 1986.

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Krishnamurthy, Muralidhar, e SpringerLink (Online service), a cura di. Schlieren and Shadowgraph Methods in Heat and Mass Transfer. New York, NY: Springer New York, 2012.

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Panigrahi, Pradipta Kumar, e Krishnamurthy Muralidhar. Schlieren and Shadowgraph Methods in Heat and Mass Transfer. New York, NY: Springer New York, 2012. http://dx.doi.org/10.1007/978-1-4614-4535-7.

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Settles, G. S. Schlieren and Shadowgraph Techniques: Visualizing Phenomena in Transparent Media. Berlin, Heidelberg: Springer Berlin Heidelberg, 2001.

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Springer, Anthony M. A shadowgraph study of space transportation system (STS): the space shuttle launch vehicle (SSLV). Huntsville, Ala: George C. Marshall Space Flight Center, 1994.

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Springer, Anthony M. A shadowgraph study of two proposed Shuttle-C launch vehicle configurations. Huntsville, Ala: George C. Marshall Space Flight Center, 1993.

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Capitoli di libri sul tema "Shadowgraph"

Settles, G. S. "Shadowgraph Techniques". In Schlieren and Shadowgraph Techniques, 143–63. Berlin, Heidelberg: Springer Berlin Heidelberg, 2001. http://dx.doi.org/10.1007/978-3-642-56640-0_6.

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Panigrahi, Pradipta Kumar, e Krishnamurthy Muralidhar. "Laser Schlieren and Shadowgraph". In Schlieren and Shadowgraph Methods in Heat and Mass Transfer, 23–46. New York, NY: Springer New York, 2012. http://dx.doi.org/10.1007/978-1-4614-4535-7_2.

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Settles, G. S. "Historical Background". In Schlieren and Shadowgraph Techniques, 1–24. Berlin, Heidelberg: Springer Berlin Heidelberg, 2001. http://dx.doi.org/10.1007/978-3-642-56640-0_1.

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Settles, G. S. "Quantitative Evaluation". In Schlieren and Shadowgraph Techniques, 263–78. Berlin, Heidelberg: Springer Berlin Heidelberg, 2001. http://dx.doi.org/10.1007/978-3-642-56640-0_10.

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Settles, G. S. "Summary and Outlook". In Schlieren and Shadowgraph Techniques, 279–89. Berlin, Heidelberg: Springer Berlin Heidelberg, 2001. http://dx.doi.org/10.1007/978-3-642-56640-0_11.

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Settles, G. S. "Basic Concepts". In Schlieren and Shadowgraph Techniques, 25–38. Berlin, Heidelberg: Springer Berlin Heidelberg, 2001. http://dx.doi.org/10.1007/978-3-642-56640-0_2.

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Settles, G. S. "Toepler’s Schlieren Technique". In Schlieren and Shadowgraph Techniques, 39–75. Berlin, Heidelberg: Springer Berlin Heidelberg, 2001. http://dx.doi.org/10.1007/978-3-642-56640-0_3.

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Settles, G. S. "Large-Field and Focusing Schlieren Methods". In Schlieren and Shadowgraph Techniques, 77–110. Berlin, Heidelberg: Springer Berlin Heidelberg, 2001. http://dx.doi.org/10.1007/978-3-642-56640-0_4.

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Settles, G. S. "Specialized Schlieren Techniques". In Schlieren and Shadowgraph Techniques, 111–41. Berlin, Heidelberg: Springer Berlin Heidelberg, 2001. http://dx.doi.org/10.1007/978-3-642-56640-0_5.

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Settles, G. S. "Practical Issues". In Schlieren and Shadowgraph Techniques, 165–99. Berlin, Heidelberg: Springer Berlin Heidelberg, 2001. http://dx.doi.org/10.1007/978-3-642-56640-0_7.

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Atti di convegni sul tema "Shadowgraph"

Doman, Michael J., Edward J. McCrea e Randy A. Rohde. "X-ray shadowgraph camera design". In Electronic Imaging '99, a cura di Alan M. Frank e James S. Walton. SPIE, 1999. http://dx.doi.org/10.1117/12.348416.

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Rodrigues, Joao, Barry Uscinski e Arthur Kaletzky. "Acoustic Shadowgraph Mapping of Convective Activity". In OCEANS 2006 - Asia Pacific. IEEE, 2006. http://dx.doi.org/10.1109/oceansap.2006.4393904.

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Kleine, Harald, e Kazuyoshi Takayama. "Holographic interferometry with additional shadowgraph visualization". In Optical Engineering for Sensing and Nanotechnology (ICOSN '01), a cura di Koichi Iwata. SPIE, 2001. http://dx.doi.org/10.1117/12.427057.

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Sun, Mingyu. "Computer modeling of shadowgraph optical setup". In 27th International congress on High-Speed Photography and Photonics, a cura di Xun Hou, Wei Zhao e Baoli Yao. SPIE, 2007. http://dx.doi.org/10.1117/12.725100.

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"CFI-shadowgraph/schlieren photography for aerodynamic applications". In 25th Plasmadynamics and Lasers Conference. Reston, Virigina: American Institute of Aeronautics and Astronautics, 1994. http://dx.doi.org/10.2514/6.1994-2616.

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HOLT, D., e G. WINCHENBACH. "An electronic shadowgraph station and control system". In 15th Aerodynamic Testing Conference. Reston, Virigina: American Institute of Aeronautics and Astronautics, 1988. http://dx.doi.org/10.2514/6.1988-2061.

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Galeote, Brian. "Ice Crystal Particle Measurement Using Shadowgraph Imaging Techniques". In AIAA Atmospheric and Space Environments Conference. Reston, Virigina: American Institute of Aeronautics and Astronautics, 2010. http://dx.doi.org/10.2514/6.2010-7531.

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Shakerin, Said. "Poster: Immiscible Fluids in Thin Enclosure and Shadowgraph". In 72th Annual Meeting of the APS Division of Fluid Dynamics. American Physical Society, 2019. http://dx.doi.org/10.1103/aps.dfd.2019.gfm.p0006.

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Lake, Don. "Four-million pixel camera for ballistic shadowgraph applications". In San Diego '92, a cura di Donald R. Snyder. SPIE, 1993. http://dx.doi.org/10.1117/12.139132.

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Matlo, Matyas, Farzan Parsinejad e Hameed Metghalchi. "Schlieren and Shadowgraph Images of Transient Expanding Spherical Thin Flames". In ASME 2002 International Mechanical Engineering Congress and Exposition. ASMEDC, 2002. http://dx.doi.org/10.1115/imece2002-39318.

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Experimental facilities have been built to visualize transient expanding spherical flames. Facilities include a cylindrical chamber with two end glasses for optical observation. Shadowgraph and Schlieren pictures of flame propagation have been taken using a high speed Charged Coupled Device (CCD) camera. In this paper the optical behavior of spherical flames has been investigated using both Schlieren and Shadowgraph methods. A mathematical model has been developed to predict the intensity of refracted light beams interacting with a transient expanding thin flame. Experimental results are in very good agreement with theoretical model. Schlieren and Shadowgraph techniques have also been used to view smooth, cracked and cellular flames, which are useful in determining the stability of propagating flame.

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Rapporti di organizzazioni sul tema "Shadowgraph"

Malone, R. M., R. L. Flurer, B. C. Frogget, D. S. Sorenson, V. H. Holmes e A. W. Obst. Shadowgraph illumination techniques for framing cameras. Office of Scientific and Technical Information (OSTI), dicembre 1997. http://dx.doi.org/10.2172/663173.

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Heath, John J. Procedure for Surveying a Station in the U.S. Army Research Laboratory Transonic Experimental Facility Spark Shadowgraph Range. Fort Belvoir, VA: Defense Technical Information Center, giugno 2014. http://dx.doi.org/10.21236/ada606473.

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