Obtaining geometrical and physical information of industrially manufactured products or manually created artifacts has increased dramatically in the past few years. These data are usually generated by means of specific devices which are called 3D scanners. 3D scanners generate virtual 3D models of objects which in different fields can be used for various applications such as reverse engineering and quality control in manufacturing industry or data archiving of valuable unique objects of cultural heritage. There are basically two types of 3D scanning depending on whether contact or non-contact techniques are used. Non-contact scanners have been developed to overcome the problems of contacts. Optical methods are the most developed and major category of non-contact scanning techniques. Remarkable progress in computer science has been the key element of optical 3D scanning development. Apart from this improvement, optical scanners are affected by surface characteristics of the target object, such as transparency and reflectivity, since optical scanners work based on reflected light from the object surface. For solving this problem, in most cases the object is sprayed with an aerosol spray to change its characteristics temporarily, e.g. from shiny to dull or transparent to opaque. It is important to apply coating of minimum possible thickness to keep the object geometry unchanged. To study this issue, an atomization-based spray coating system was developed in this thesis research and used in sets of experiments to evaluate the effects of thin layer coating on 3D scanning results. In this thesis, firstly the spray coating system structure and coating specifications will be offered. Then, for appraising the efficiency of atomization-based spray coating in 3D scanning process, some examples are presented. These examples are based on some actual parts from different industries which were used as target objects to be coated and scanned. / Graduate / 0548 / behzadv@uvic.ca

Thesis (Ph.D.)--Virginia Commonwealth University, 2008. / Title from title-page of electronic thesis. Prepared for: Dept. of Mechanical Engineering. Bibliography: leaves 212-233.

Thesis (Ph. D.)--Virginia Commonwealth University, 2008. / Prepared for: Dept. of Mechanical Engineering. Includes bibliographical references (leaves 212-233). Also available online via the Internet.

Thesis (Ph. D.)--University of California, Riverside, 2010. / Includes abstract. Available via ProQuest Digital Dissertations. Title from first page of PDF file (viewed May 18, 2010). Includes bibliographical references. Also issued in print.

L’atomisation assistée d’une phase liquide lente par un co-courant gazeux rapide est un sujet largement étudié dans la littérature, et des avancées notables sont intervenues notamment sur les mécanismes de brisure, la structure du jet atomisé ainsi que sur les caractéristiques des gouttes formées. En revanche, peu d’études traitent d’une configuration où la phase lente consiste en un jet diphasique gaz-liquide. Cette situation se rencontre par exemple lors du transitoire d’allumage des moteurs cryotechniques de fusée durant lequel la fraction volumique de gaz passe continument de 1 (jet interne purement gazeux) à 0 (jet interne purement liquide), de sorte que pratiquement tous les régimes d’écoulements diphasiques, allant du régime à bulles jusqu’aux écoulements annulaires, peuvent être observés.L’objectif est donc de comprendre comment la fraction volumique de gaz et/ou le régime d’écoulement diphasique du jet interne impactent les modes d’atomisation et in fine les caractéristiques du spray.Pour répondre à ces questions, des expérimentations ont été menées avec comme fluides de substitution de l’air et de l’eau en conditions ambiantes et sous gravité terrestre. Les trois paramètres de contrôle principaux sont la vitesse superficielle du liquide qui a été variée de 0,17 m/s à 2 m/s, la vitesse superficielle du gaz dans le jet interne qui a été fixée de telle sorte que la fraction de débit gaz balaye la plage 0 à 0,99 et enfin la vitesse du gaz externe qui a évolué entre de 20 à 200 m/s. Trois géométries d’injecteurs axisymétriques ont été utilisées pour d’une part accéder à tous les régimes d’écoulements diphasiques souhaités excepté l’écoulement à brouillard, et d’autre part pour varier le diamètre du jet central d’un facteur d’environ deux. Deux types de campagnes expérimentales ont été réalisées : une campagne à rapport des pressions dynamiques gaz-liquide fixé à 16 pour des fractions de débit volumique gaz variables, ainsi que des campagnes à fractions de débit volumique gaz fixe et M variable .Les caractéristiques structurelles du spray, sa longueur de brisure et l’angle du spray formé ont été mesurés par imagerie rapide alors que les caractéristiques de la phase dispersée, c’est-à-dire tailles, vitesses et flux de gouttes ont été mesurés par sonde optique.Les cartographies des régimes d’écoulements dans l’injecteur et des structures du jet diphasique avec et sans assistance par le gaz externe que nous avons établies ont permis de démontrer que ces structures étaient étroitement liées au régime d’écoulement du jet central. Trois modes d’atomisation principaux ont été identifiés et leur frontières établies. A faible fraction de débit gaz, l’atomisation de jets liquides chargés en petites bulles est sujet à l’épluchage de surface et aux battements latéraux à grande échelle comme sur un jet monophasique liquide. A très grande fraction de débit gaz, l’écoulement annulaire donne lieu à l’atomisation d’une nappe annulaire. Pour des valeurs intermédiaires, de nouvelles structures de type "parapluie" se forment à l’arrivée des bouchons de gaz caractérisées par une grande amplitude et un développement orthogonal au jet. L’atomisation des écoulements à régimes « churn » et annulaire donne lieu à des sprays à caractère intermittent du fait de passage de blocs liquides issus de l’écoulement interne.La longueur de brisure est réduite par l’ajout de gaz interne jusqu’à devenir très petite pour les fractions de débit gaz élevées. Le comportement de l’angle du spray est différent selon le diamètre du jet atomisé et le régime d’écoulement interne : il peut augmenter ou réduire selon la configuration.Les pdf centrées sur la taille goutte moyenne sont peu sensibles à la fraction de débit gaz. En revanche les tailles de gouttes moyennes et le flux volumique montrent des évolutions marquées : ils peuvent selon la fraction de débit gaz et donc selon la structure du jet atomisé réduire ou augmenter. / Assisted atomization of a liquid phase slow by a rapid gas co-current is a topic widely studied in the literature, and significant advances have occurred especially on the breakup mechanisms, the structure of the atomized jet as well as the characteristics of formed drops. However, few studies deal with a configuration where the slow phase consists of a two-phase liquid-gas jet. This situation occurs for example during the transitional ignition of cryogenic rocket engines during which the volumic gas fraction decreases continuously from 1 (purely gas) to 0 (purely liquid), so that almost all two-phases flow regimes, from bubbly flow to annular flow can be observed.The goal is to understand how the volumic gas fraction and/or two-phase flow regime of internal jet impact the atomization modes and the characteristics of the spray.To answer these questions, experiments were conducted with as fluid of substitution air and water under ambient conditions and under gravity. The three main control parameters are the superficial velocity of the liquid which was varied from 0.17 m/s to 2 m/s, the superficial gas velocity in the internal jet that has been set so that the gas flow rate fraction sweeps the range 0 to 0.99 and finally the external gas velocity that has evolved between 20 to 200 m/s. Three geometries of axisymmetric injectors were used to firstly access any desired phase flow regimes except mist flow, and also to vary the diameter of the central jet by a factor of about two. Two types of experimental campaigns were carried out: a campaign where the gas-liquid dynamic pressure ratio was set at 16 for varied gas flow rate fraction, as well as campaigns with fixed gas flow rate fraction and variable M.The structural characteristics of the spray, its breakup length and the angle of spray were measured by high speed imaging while the characteristics of the dispersed phase, that is to say, sizes, velocities and flows of the drops were measured by optical probe.Mapping of flow regimes in the injector and two-phase jet structures with and without assistance by external gas that we have established have shown that these structures were closely related to the flow regime of the central jet. Three main atomization modes were identified and its borders established. For small gas flow rate fraction, the atomization of liquid jets laden bubbles is subject to surface peeling and large-scale lateral beats like a single phase liquid jet. For very large gas flow rate fraction, the annular flow results in the atomization of an annular liquid sheet. For intermediate values, new structures type of umbrella form at the arrival of gas slugs characterized by high amplitude and orthogonal development with respect to the jet. Atomization of “churn" flow and annular flow gives rise to intermittent sprays because of passage of "liquid blocks" from the internal flow.The breakup length is reduced by the addition of internal gas and become very small for the high gas flow rate fractions. The behavior of the angle of the spray is different depending on the diameter of the atomized jet and the internal flow regime. It may therefore increase or decrease depending on configuration.Centred pdf on mean drop size are not much sensitive to the gas flow rate fraction. However mean drop sizes and volumic fluxes show marked evolution: they can according to the gas flow rate fraction and therefore the atomized jet structure decrease or increase.

Les incendies font partie des risques les plus redoutables en aéronautique, en raison des difficultés à les combattre, comme par exemple dans les espaces confinés où la propagation peut être très rapide. Le Halon1301 est utilisé depuis plus de 50 ans comme agent extincteur pour les moteurs d'avions, l'APU (Auxiliary Power Unit) et les applications de protection feux cargo. Le Halon1301 possède des propriétés spécifiques pour les systèmes de protection feux des moteurs. Il possède un point d'ébullition bas et une pression vapeur élevée, ce qui facilite le mélange de l'agent avec l'air de la ventilation dans les zones feux. De plus, son point d'ébullition à -57,8°C et sa capacité à se vaporiser à chaque point de décharge sont des propriétés physiques désirables. Suite à des changements de la réglementation environnementale, il est nécessaire de remplacer le Halon1301, l'agent extincteur actuellement présent sur les systèmes de protection feux des moteurs d'avions. L'utilisation de cet agent a été bannie dans l'industrie par le protocole de Montréal (1994) et de Kyoto (1998) qui vise à réduire les substances qui appauvrissent la couche d'ozone ainsi que les gaz à effet de serre. Des dérogations établies par la Commission Environnementale Européenne existent et sont appliquées au domaine de l'aéronautique à cause du manque de solutions alternatives. Depuis plusieurs années, Airbus travaille sur le projet de remplacement du Halon1301, appliqué notamment aux systèmes de protection feux des zones moteurs et APU. Depuis 2003, plusieurs agents alternatifs au Halon1301 ont été identifiés. Dans notre cas, on s'intéresse à un candidat qui apparait comme une alternative intéressante respectueuse de l'environnement : le \novec. La différence la plus importante entre le Halon1301 et le Novec1230 est leur phase physique. En effet, le Halon1301 est un gaz, alors que le Novec1230 est liquide en conditions ambiantes (il est liquide en dessous de +49,2°C). Que ce soit à la température de ventilation froide (température négative) ou à l'ambiant (+25°C), l'agent sera liquide. Les caractéristiques d'évaporation (courbe de saturation) indiquent que pour ces applications, nous sommes dans un état diphasique avec la présence de gouttes et de gaz : plus le mélange sera froid et plus l'équilibre sera déplacé vers la phase liquide. En phase gazeuse, le transport de l'agent dans chaque recoin du moteur ne pose pas de problème car il sera transporté par l'écoulement d'air de la ventilation. Or, en phase liquide, le transport efficace de l'agent sous forme de gouttes est plus complexe : si les gouttes sont trop grosses, elles tendront à avoir une trajectoire balistique et n'atteindront pas toutes les zones feux du moteur. Par conséquent, l'optimisation de l'atomisation de l'agent devient un paramètre central pour la conception du système de protection des incendies. Dans le contexte du projet, on étudie une technologie appelée atomisation effervescente. Le principe est de venir dissoudre un gaz (dans notre cas du dioxyde de carbone, CO2), dans l'agent liquide Novec1230. Plusieurs adaptations de cette technologie sont requises pour améliorer les performances de l'agent tel que son atomisation et son transport. Le processus d'atomisation effervescente est une technique d'atomisation diphasique prometteuse qui offre des améliorations potentielles en termes de qualité d'atomisation du fluide et de réduction de pression d'utilisation. L'objectif de ce projet est de conduire des recherches expérimentales sur le processus d'atomisation effervescente afin de prédire quels sont les paramètres clés qui influencent l'atomisation. / Fires are one of the most formidable risks in aviation because of the difficulties to fight them once airbone, as for example in confined spaces where the spread can be very fast. Halon1301 has been used for more than 50 years as extinguishing agent for aircraft engines, APU (Auxiliary Power Unit) and cargo fire protection. Halon1301 has specific properties for systems of fires engines protection. It has a low boiling point and high vapor pressure, which facilitates the mixture of the agent with the ventilation air in fire areas. In addition, its boiling point at -57,8°C and its ability to vaporize throughout the discharge are desirable physical properties. Because of changes in environmental regulation, it is necessary to replace Halon1301, the extinguishing agent currently present on aircraft engines fire protection systems. The use of this fluid has been banned by the Montreal (1994) and Kyoto (1998) protocols in industry, with the intent to reduce substances that deplete the ozone layer as well as greenhouse gases. Exemptions established by the European environmental Commission exist and are applied to the aeronautics field due to the lack of alternatives. For several years, Airbus has been working on the replacement of Halon1301 for engines and APU fire protection systems. Since 2003, several alternative agents to the Halon1301 have been identified. This study is dedicated to a fluid that appears as an environmentally friendly alternative: Novec1230. The most important difference between Halon1301 and Novec1230 is their physical phase. Indeed, Halon1301 is in gaseous state at all relevant conditions, while Novec1230 is a liquid below +49,2°C. At the cold temperature ventilation (negative temperature) or at ambient (+25°C), the agent will be liquid. The characteristics of evaporation (saturation curve) show that for these applications, we are in a two-phase flow with the presence of drops and gas. Gas-phase transport agent in every engine area is not a problem because it will be transported by the ventilation air flow. However, in the liquid phase, the efficient transport of the agent in the form of drops is more complex: If the drops are too large, they will tend to have a ballistic trajectory and will not reach all areas the engine. Therefore, the optimization of atomization of the agent becomes a central parameter for the design of the fire protection system. In the context of this project, a technology called effervescent atomization was considered. The principle is to dissolve a gas (in our case carbon dioxide, CO2), in the liquid agent Novec1230. Many adaptations of this technology are required to improve the performance of the atomization and subsequently the transport of the fire-extinguishing agent. The effervescent atomization process is a promising technology that offers potential improvements in terms of quality of atomization of the fluid and reduction of operating pressure. The goal of this project is to conduct theoretical and experimental research on the effervescent atomization process to identify the key parameters that influence the atomization.

Made available in DSpace on 2014-06-11T19:35:40Z (GMT). No. of bitstreams: 0 Previous issue date: 2013-07-05Bitstream added on 2014-06-13T19:25:03Z : No. of bitstreams: 1 gonzales_caq_dr_guara.pdf: 2226172 bytes, checksum: 7864c5078943183c9af88b6bafe9c341 (MD5) / A combustão é um processo que pode consumir consome grandes quantidades de glicerol bruto sem requerer purificação nenhuma. No entanto, a queima do glicerol bruto não é fácil, devido, entre outras razões, à sua alta viscosidade, que dificulta o processo de atomização. O objetivo deste trabalho é realizar um estudo teórico-experimental de dois tipos de injetores para a atomização de líquidos viscosos, como o caso da mistura de glicerina + etanol. Foram projetados e construídos dois protótipos de injetor para a realização de testes comparativos: um injetor tipo Y e um injetor efervescente. Água, óleo diesel e mistura de glicerina + etanol foram usados como líquidos de teste, enquanto que ar e hélio são utilizados como gases de atomização. Para os dois atomizadores foram determinados os coeficientes de descarga, os ângulos de cone do spray e diâmetro representativo das gotas do spray. Também foram estudados os efeitos da pressão de operação e das vazões mássicas do líquido e gás de atomização sobre o desempenho do injetor. Para o injetor tipo Y, foi realizada uma análise teórica do efeito da pressão na câmara de mistura e da substituição do gás de atomização no diâmetro médio das gotas. É avaliada a equação de Wigg para determinar o diâmetro médio das gotas. Para o injetor efervescente, são avaliadas a influência da geometria e a localização dos orifícios de aeração, assim como o diâmetro do orifício de descarga sob as diferentes condições de operação / Combustion is a process which can consumes large amounts of crude glycerol without requiring any purification. However, the burning of crude glycerol is not easy due, among other reasons, to the high viscosity, which hinders of the atomization process. The objective of this work is to perform a theoretical and experimental study of two type nozzles to atomize viscous liquids, such as the case of glycerin + ethanol mixture. Two prototype injectors were designed and built for comparative testing: Y-jet nozzle and effervescent atomizer. Water, diesel and a glycerin + ethanol mixture were used as testing liquids; whereas air and helium were used as atomization gases. For two atomizers were determined the discharge coefficients, spray cone angles and the average droplet diameters of the produced sprays. Also were studied the effects of operating pressure and mass flow rates of liquid and gas on the injector performance. For the Y-jet nozzle, was performed a theoretical analysis the pressure effect in the mixing chamber, as well as substitution of the atomization gas on the average droplet diameter. The Wigg`s equation is evaluated to determine the average droplet diameter. For the effervescent nozzle, were evaluated the influence of the geometry and localization of the aeration holes, as well as the diameter of the final discharge orifice, under different operating conditions

Orientador: João Andrade de Carvalho Júnior / Coorientador: Fernando de Souza Costa / Banca: Luiz Ropberto Carrocci / Banca: Celso Eduardo Tuna / Banca: Pedro Teixeira Lacava / Banca: Marcio Teixeira Mendonça / Resumo: A combustão é um processo que pode consumir consome grandes quantidades de glicerol bruto sem requerer purificação nenhuma. No entanto, a queima do glicerol bruto não é fácil, devido, entre outras razões, à sua alta viscosidade, que dificulta o processo de atomização. O objetivo deste trabalho é realizar um estudo teórico-experimental de dois tipos de injetores para a atomização de líquidos viscosos, como o caso da mistura de glicerina + etanol. Foram projetados e construídos dois protótipos de injetor para a realização de testes comparativos: um injetor tipo Y e um injetor efervescente. Água, óleo diesel e mistura de glicerina + etanol foram usados como líquidos de teste, enquanto que ar e hélio são utilizados como gases de atomização. Para os dois atomizadores foram determinados os coeficientes de descarga, os ângulos de cone do spray e diâmetro representativo das gotas do spray. Também foram estudados os efeitos da pressão de operação e das vazões mássicas do líquido e gás de atomização sobre o desempenho do injetor. Para o injetor tipo Y, foi realizada uma análise teórica do efeito da pressão na câmara de mistura e da substituição do gás de atomização no diâmetro médio das gotas. É avaliada a equação de Wigg para determinar o diâmetro médio das gotas. Para o injetor efervescente, são avaliadas a influência da geometria e a localização dos orifícios de aeração, assim como o diâmetro do orifício de descarga sob as diferentes condições de operação / Abstract: Combustion is a process which can consumes large amounts of crude glycerol without requiring any purification. However, the burning of crude glycerol is not easy due, among other reasons, to the high viscosity, which hinders of the atomization process. The objective of this work is to perform a theoretical and experimental study of two type nozzles to atomize viscous liquids, such as the case of glycerin + ethanol mixture. Two prototype injectors were designed and built for comparative testing: Y-jet nozzle and effervescent atomizer. Water, diesel and a glycerin + ethanol mixture were used as testing liquids; whereas air and helium were used as atomization gases. For two atomizers were determined the discharge coefficients, spray cone angles and the average droplet diameters of the produced sprays. Also were studied the effects of operating pressure and mass flow rates of liquid and gas on the injector performance. For the Y-jet nozzle, was performed a theoretical analysis the pressure effect in the mixing chamber, as well as substitution of the atomization gas on the average droplet diameter. The Wigg's equation is evaluated to determine the average droplet diameter. For the effervescent nozzle, were evaluated the influence of the geometry and localization of the aeration holes, as well as the diameter of the final discharge orifice, under different operating conditions / Doutor

Orientador: Flavio Luis Schmidt / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-26T09:05:26Z (GMT). No. of bitstreams: 1 Faria_CarolyneBitencourt_D.pdf: 4465395 bytes, checksum: f14b25e18870fa1f58207127c61810f1 (MD5) Previous issue date: 2014 / Resumo: Este trabalho teve como objetivo a avaliação da adição da farinha da casca de maracujá (FCM), em substituição parcial da maltodextrina utilizada como coadjuvante de secagem na atomização da polpa de maracujá. Foi realizado o estudo das características físico-químicas, tecnológicas e estruturais da farinha obtida da casca do maracujá amarelo. Esta apresentou alta porosidade, boa solubilidade em meio líquido e alta temperatura de transição vítrea (Tg), mostrando-se um produto com promissoras características tecnológicas. Para avaliar a quantidade de FCM adicionada em substituição a maltodextrina, foi realizado um estudo do seu comportamento reológico. Os parâmetros reológicos foram determinados a 25, 40, 60 e 80°C, por meio de um viscosímetro de cilindros coaxiais, com variação da taxa de deformação de 6,60 a 198,0 s-1. No ajuste dos dados foram utilizados os modelos matemáticos: Leis da Potência e Herschel-Bulkley. Para otimizar a quantidade máxima de FCM adicionada na polpa para se obter sua secagem por atomização, foi realizado um planejamento estatístico central rotacional 23, com 3 pontos centrais, totalizando 17 ensaios, onde as variáveis independentes foram a temperatura do ar de entrada (163 a 197°C), a vazão mássica de alimentação (340 a 540 mL/h) e a concentração de agente carreador (0/100% a 15/85% - FCM/maltodextrina p/p). As respostas analisadas foram densidade aparente, umidade do pó, teor de ácido ascórbico, rendimento do processo, tempo de dissolução e higroscopicidade do pó. A adição da FCM reduziu a umidade, aumentou o rendimento e a conservação do ácido ascórbico no produto final. Assim as melhores condições de secagem estabelecidas foram: 190°C, 500 ml/h e 11,6/88,4% de FCM/maltodextrina. O pó produzido no ponto ótimo apresentou boa aceitação sensorial, quando preparado na forma de néctar, com apenas redução do aroma. Foi avaliada sua higroscopicidade através de isotermas de adsorção. Observou-se que o pó permaneceu estável a baixas umidades e mostrou o mesmo comportamento dos pós contendo apenas maltodextrina. Os resultados obtidos neste trabalho mostraram a viabilidade da adição da FCM na secagem por atomização da polpa de maracujá, melhorando as características do pó e seu valor nutricional / Abstract: This work aimed to evaluate the addition of passion fruit peel flour (PFPF), as a substitute for part of maltodextrin used as an adjuvant in the spray drying of passion fruit pulp. The study of the physic-chemical, technological and structural characteristics of the flour obtained from the peel of yellow passion fruit was held. This having high porosity, good solubility in liquid medium and high glass transition temperature (Tg), being a product with promising technological characteristics. To assess the amount of PFPF added to replace maltodextrin, a study of the rheological behavior was performed. The rheological parameters were determined at 25, 40, 60 and 80°C via a coaxial cylinder viscometer, with variation of the strain rate from 6,60 at 198 s-1. In data fitting mathematical models of the: Laws of Power and Herschel-Bulkley. To optimize the maximum amount of PFPF was performed a rotational central statistical design 23, with 3 central points, totaling 17 tests, where the independent variables were the temperature of the incoming air (163 at 197°C), the mass flow rate (340 at 540 mL/h) and the concentration of maltodextrin (0/100% at 15/85% PFPF/maltodextrin w/w). The responses analyzed were bulk density, moisture powder, ascorbic acid content, process yield, dissolution time and hygroscopic powder. The addition of PFPF reduced moisture, increased yield and conservation of ascorbic acid in the final product. So the best drying conditions established were: 190°C, 500 mL/h and 11.6/88.4% PFPF/maltodextrin. The produced at optimum powder showed good acceptability, when prepared in the form of nectar, with only reduction of flavor. Its hygroscopicity was evaluated adsorption isotherms. It was observed that the powder was stable at low humidity and showed the same behavior of powders containing only maltodextrin. The results of this study show the viability of the addition of PFPF in spray drying of passion fruit pulp, improving the characteristics of the powder and its nutritional value / Doutorado / Tecnologia de Alimentos / Doutora em Tecnologia de Alimentos

<p>The sizes and velocities of fragments resulting from the aerodynamic breakup of charged drops are reported here. Measurements were made using digital inline holography (DIH). Highly and moderate conductive liquid droplets are used. Uncertainty of parameters is discussed. Finally, a discussion on the applied potential used for possible fragment charge-to-mass ratio charge is presented.</p>