Thesis (Ph. D.)--University of Wisconsin--Madison, 1975. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliography.

Abstract The interrelationship between variables involved in focusing schlieren systems is fairly well understood, however how changing the variables affects the resultant images is not. In addition, modified grids and arrangements, such as two dimensional, colour and retroreflective systems have never been directly compared to a standard system. The existing theory is developed from first principles to its current state. An apparatus was specifically designed to test grid and arrangement issues while keeping the system geometry, optical components and the test object identical. Source grid line spacing and clear line width to dark line width ratio were varied to investigate the limits of diffraction and banding and to find an optimum grid for this apparatus. Two dimensional, colour, retroreflective and a novel projected arrangement were then compared to this optimum case. In conclusion, the diffraction limit is accurately modelled by the mathematical equations. The banding limit is slightly less well modelled as additional factors seem to affect the final image. Inherent problems with the two dimensional and colour systems indicate that while they can be useful, they are not worth developing further though chromatism in the system meant that colour systems were not fully investigated. The retroreflective and projected systems have the most potential for large scale use and should be developed further.

Dissertação (mestrado)—Universidade de Brasília, Instituto de Química, Programa de Pós-Graduação em Química, 2015. / Submitted by Albânia Cézar de Melo (albania@bce.unb.br) on 2016-02-15T11:46:31Z No. of bitstreams: 1 2015_LaizOliveiraMagalhaes.pdf: 3662735 bytes, checksum: aa0ab1f8c6445e875927f84003af42c2 (MD5) / Approved for entry into archive by Raquel Viana(raquelviana@bce.unb.br) on 2016-02-15T16:31:12Z (GMT) No. of bitstreams: 1 2015_LaizOliveiraMagalhaes.pdf: 3662735 bytes, checksum: aa0ab1f8c6445e875927f84003af42c2 (MD5) / Made available in DSpace on 2016-02-15T16:31:12Z (GMT). No. of bitstreams: 1 2015_LaizOliveiraMagalhaes.pdf: 3662735 bytes, checksum: aa0ab1f8c6445e875927f84003af42c2 (MD5) / Este trabalho descreve o desenvolvimento de microssistemas fluídicos de uretano-acrilato integrados com coluna empacotada para a extração em fase sólida com trocador aniônico e detecção fotométrica com correção do efeito Schlieren. Um diodo emissor de luz (LED) emitindo sequencialmente em diferentes comprimentos de onda (470, 530 e 625 nm) foi utilizado para adquirir o sinal referente apenas ao efeito Schlieren e outro sinal referente ao efeito e também ao analito, permitindo a correção pela subtração dos sinais. Foi demonstrado que o referido efeito é eliminado ou minimizado mesmo quando soluções de trabalho com elevadas diferenças de concentração são gerenciadas no interior do dispositivo, permitindo a determinação de íons NO2- em meios com elevada concentração de eletrólitos, Cr (VI) em meios com elevada acidez e Fe (II) em amostras de medicamentos com elevado teor de sacarose, propiciando, neste último caso, erros relativos menores que 10% por meio da comparação com o método de referência. Um dispositivo com microesferas de resina aniônica Dowex 1X8 foi construído empacotando-se manualmente o material sólido em um reservatório com dimensões de 25 × 2,0 × 1,0 mm, previamente ao procedimento de selagem. O microssistema proposto não apresentou entupimentos ou vazamentos na região da coluna e a sua aplicação à determinação de íons NO2- em águas superficiais do lago Paranoá (Brasília-DF) proporcionou um fator de pré-concentração de aproximadamente quatro vezes a partir de um volume de apenas 3,80 mL da solução da amostra, permitindo a detecção do analito na faixa de 0,05 a 0,20 mg L-1 com limite de detecção de 0,04 mg L-1 (0,01 mg L-1 N), o qual é cerca de 100 vezes inferior ao limite máximo estabelecido pela legislação brasileira (CONAMA 357). A repetibilidade para quatro injeções do padrão de 0,10 mg L-1 foi estimada em 5,35%. Adicionalmente, recuperações na faixa de 96 a 101% foram estimadas para o analito em todas as amostras avaliadas, demonstrando a possível aplicação do dispositivo para este tipo de análise a partir de um procedimento com baixo consumo de reagentes e pequena geração de resíduos. ______________________________________________________________________________________________ ABSTRACT / This work describes the development of urethane-acrylate fluidic microsystems integrated with packed column for solid phase extraction based on anionic exchanger and photometric detection with Schlieren effect correction. A lighting emitting diode (LED) that sequentially emits on different wavelengths (470, 530 e 625 nm) was used to acquire a signal referent to the schlieren effect only and other signal for the sum of the effect with the analyte response, providing the correction of the effect by subtraction of the two signals. It was demonstrated that the effect is eliminated or quite reduced even when working solutions with elevated differences on concentrations are managed inside the microfluidic devices, allowing the determination of NO2- in a medium with high electrolyte concentrations, Cr (VI) in solutions with high acidity and Fe (II) in solutions with great concentration of saccharose, allowing, in this last case, relative errors lower than 10% by the comparison with the reference method. A microfluidic device, containing micro-spheres of the anionic exchanger Dowex 1X8, was constructed by manually packing the solid phase on a photolithographed reservoir with dimensions of 25 × 2.0 × 1.0 mm prior the sealing of the structures. The proposed microsystem presents no clogging or leaking in the region of the packed column and its application for the determination of NO2- in surface waters of Paranoá Lake (Brasília-DF) provided a pre-concentration factor of approximately four fold, using only 3.80 mL of sample solution, permitting the detection of analyte in the concentration range of 0.05 a 0.20 mg L-1 with a limit of detection of 0.04 mg L-1 (0.01 mg L-1 N), which is approximately 100 times lower than the maximum concentration permited by Brazilian regulations (CONAMA 357). The repetibility for four injections of the 0.10 mg L-1 standart was estimated in 5,35%. In addition, recoveries in the range of 96 to 101% were estimated for the analyzed samples, demonstrating the possible application of the proposed device for nitrite analysis using a procedure with low consumption of reagents and reduced generation of residues.

This thesis is concerned with the design and construction of an electromagnetic acoustic transducer (EMAT) and the characterisation of its acoustic field both conventionally, using a hydrophone and with high resolution laser illuminated schlieren techniques. During the early 80s the introduction of the EMA T along with the other types of shock wave source used for lithotripsy, revolutionised the treatment of stone disease. The process of shock wave induced destruction of calculi and the use of shock waves in other areas of medicine will be discussed, along with the causes and effects of stone disease in man. For the first time high temporal and spatial resolution schlierenimages of the shock waves and there interaction with simulation kidney stones have been recorded. The technique provides a clearer picture of the fragmentation process and may assist research into the suitability of shock wave treatment in other areas of medicine currently under investigation. Schlieren studies of the acoustic field have shown the complex structure of not only the EMA T shock wave, but also that associated with cavitation in the field. The primary source of cavitation is due to the rupture and subsequent collapse of bubbles generated in the water by the strong rarefaction phase of the shock wave. The images give evidence for the interaction of these 'primary' cavitation shocks with bubbles in the field, the collapse of some of these bubbles giving rise to additional or 'secondary' cavitation shocks. An optical lensing effect introduced by the shock has also been investigated. Objects seen through or immersed in the field of an EMAT shock wave such as cavitation, appear highly distorted, due to the strong positive and negative lensing effects associated with the changing refractive index of the compression and rarefaction cycles of the shock wave.

The schlieren technique describes an optical analysis method designed to enhance light distortions caused by air movement. The ability to visualize gas flows has significant implications for analyzing underground mine ventilation systems. Currently, the widely utilized traditional schlieren methods are impractical underground due to complex equipment and design requirements. Background oriented schlieren (BOS) provides a solution to this problem. BOS requires two primary components, a professional quality digital camera and a schlieren background. A schlieren background is composed of a varying contrast repetitive pattern, such as black and white stripes or dots. This background allows the camera's sensor to capture the minor light diffractions that are caused by transparent inhomogeneous gases through image correlation. This paper investigates a possible means of mitigating some of the major problems associated with surveying underground mine ventilation systems with the BOS method. BOS is an imaging technique first introduced in 1999 that allows the visualization of flowing inhomogeneous transparent media. In ventilation surveys, BOS can be used to attain qualitative data about airflows in complex areas and methane emissions from coal. The acquisition of such data would not only enhance the understanding of mine ventilation but also improve the accuracy of ventilation surveys. As an example, surveys can benefit from small scale BOS investigations around fans, regulators, overcasts, and critical junctions to identify effective data gathering positions. Regular inspections of controls and methane monitoring points could also be improved by the systematic nature of BOS. Computer programs could process images of each location identically regardless of quantity. BOS can then serve as a check to identify items that were overlooked during the routine inspection. Despite the potential of BOS for ventilation analysis, several limitations still exist. These issues are sensitivity threshold and quantification of flow data. This paper specifically examines the qualitative potential of the BOS technique for imaging various underground ventilation flows and outlines initial experimental efforts used for the evaluation. Three primary experiments were conducted to evaluate BOS as a potential qualitative analysis technique for underground mine ventilation. The first experiment used BOS to image of flow induced by an axial vane fan and an axial flow fan using an artificial background and an imitation rock background. This experiment showed that the BOS system was unable to image isothermal airflow from either fan. Heated airflow could be visualized with both fans using the artificial striped background but not with the imitation rock background. The BOS system lacked the sensitivity necessary to image isothermal airflow from the two fans. The focus of the overall BOS study was changed to explore higher pressure airflows through a regulator. The second experiment used BOS to image flow through a regulator induced by an axial flow fan using an artificial striped background. The BOS images were compared to ones produced by a traditional schlieren single mirror systems for validation of the BOS experimental design. This experiment was unable to image isothermal airflow through the regulator from either system. However, heated airflow could be visualized by both systems. The BOS and traditional schlieren systems used in this experiment lacked the sensitivity necessary to image isothermal airflow through a regulator. However, the BOS procedures were successfully validated by the ability of both the BOS and traditional schlieren systems to image heated airflows. The focus of the study was changed to explore methane gas emissions. Numerous mining industry techniques already exist to quantify methane content. However, methane content is different from the actual methane emission rate of exposed coal. Emission rates have been modeled using numerical simulation techniques, but the complexity of the methane migration mechanism still requires physical data to achieve higher accuracy. The third experiment investigated the feasibility of using the BOS technique for imaging methane flow by imaging methane emission from a porous medium. Laboratory grade methane was directly injected into a Brea sandstone core sample using a flexible tube. The BOS system was successfully able to image methane desorption in this study. A repeating pattern consisting of alternating black and white stripes served as the schlieren background for the Nikon D700 camera. The ability to image methane emission even at low injection pressures (i.e. 20 psi) demonstrates that actual methane desorption from coal can potentially be imaged. This result can only be conjectured because of a lack of research in the area of methane emission. Despite this issue, the experimental results suggest that BOS can be feasibly utilized to image methane emissions from coal in an underground mine. The results of the three experiment demonstrated that the potential for large scale implementation of BOS in underground mines does exist. Qualitative BOS information has the potential in the practical sense to optimize the procedures of ventilation surveys and design of ventilation monitoring equipment. For example, images of methane flow in active mining areas can be used to optimize the positioning of auxiliary ventilation equipment to dilute known areas of high methane concentration. BOS images could also be used to re-evaluate the placement of methane monitors on mining equipment to better facilitate the detection of dangerous methane concentrations in active mining areas. For these reasons, further investigation into the BOS technique for use in imaging underground airflows with differential temperatures and methane emissions in underground coal mines is suggested as an addendum to this study. / Master of Science

The next generation air breathing engine that would enable an alternative to conventional air travel or suborbital flight is the supersonic ramjet engine (SCRAM) which requires a highly accelerated rate of fuel mixing and combustion. For this type of engine, one of the improvement opportunities lies in the injection of the fuel into the supersonic flow inside the combustor. In order to determine the flow field that develops when a sonic jet of secondary gas is injected into a supersonic free stream, a dedicated test section was developed which was attached to the existing supersonic wind tunnel at the University of Central Florida. A Schlieren system was developed to visualize the associated flow fields and to provide a tool for future high-speed aerodynamic research. Mixing of a cross flow jet with a supersonic free stream is a topic of interest in the field of hypersonic air travel. In addition to a description and analysis of the resultant data, this thesis also serves as a reference for future research and work done with the UCF supersonic wind tunnel and the Schlieren system. The results agree with the literature, and the Schlieren images obtained show the associated shock and flow structures that are expected with a jet in cross flow.

Este trabalho experimental tem por objetivo apresentar os estudos experimentais realizados com jatos de líquidos evaporativos (\"flash boiling\") de iso-octano. Nos estudos, o jato emergia de um diminuto bocal que descarrega em uma grande câmara de baixa pressão. O líquido ao passar pelo bocal sofria uma expansão interna alcançando elevados graus de superaquecimento ou de metaestabilidade, já que se mantinha na fase líquida. Nos experimentos, eram controladas as condições de pressão e temperatura de injeção durante um período de alguns poucos segundos suficientes para que as condições de regime permanente fossem estabelecidas. Um dos métodos para a visualização do escoamento do jato evaporativo foi o \"Schlieren\", o qual permitia visualizar elevados gradientes de densidade como normalmente ocorrem com ondas de choque, presentes nesta investigação. Também foi empregada a técnica de visualização de \"iluminação por detrás\" para que fossem comparadas as imagens obtidas por este método com o do \"Schlieren\", bem como mostrar detalhes do fenômeno em estudo. Com isso, foi possível estudar a estrutura do processo evaporativo do jato e, com o auxílio de ferramentas de filtragem matemática e manipulação das imagens obtidas, os fenômenos compressíveis envolvidos. Os perfis dos jatos observados foram: (1) filete contínuo de líquido sem evaporação, (2) jato com fragmentações ou atomizado e (3) abrupta evaporação seguida por expansão com formação de ondas de choque. Neste último caso, a inspeção das fotografias indicou que a evaporação do líquido se dava externamente ao bocal, a partir de um núcleo metaestável de líquido, o qual apresentava o formato aproximado de um cone. Também foi aplicada a teoria de ondas oblíquas de evaporação para estudar o comportamento deste cone líquido. Os ensaios foram conduzidos com três bocais cônico-convergentes de dimensões e materiais diferentes, quais sejam: bocal de aço com diâmetro de saída de 0,3 mm, bocal de aço com 0,8 mm e bocal de vidro com 0,35 mm. / The main goal of this thesis is to present results of experiments with flashing liquid jets of iso-octane. The experiments were carried out with a liquid jet issuing from a small nozzle into a low-pressure chamber. High degrees of metastability were obtained as the liquid jet expanded within the nozzle. Injection pressure and temperature were controlled to the desired testing values for a few seconds, which were found long enough to reach and keep the steady state regime. The photographic documentation of the phenomenon was obtained from a \"Schlieren\" set up using CCD camera. The \"back-lightening\" visualization technique was also used in order to compare both image techniques and to unveil some flashing phenomenon details. Analyses of these images with the help of mathematical filters as well as other image manipulating techniques enabled a qualitative visualization of the flashing liquid jet structure and geometry leaving the nozzle. Three liquid jet regimes were observed: (1) continuous liquid jet (2) partially atomized, and (3) evaporation with the presence of shock waves. In this latter case, we speculate that the evaporation took part on the liquid jet surface, which had the approximate shape of a cone. Also it was employed the oblique evaporation wave theory to explain some of the behavior of the overall evaporation process. The tests were carried out using three conical-converging nozzles made of different materials: a 0.3 mm exit diameter steel nozzle, a 0.8 mm exit diameter steel nozzle, and a 0.35 mm exit diameter glass nozzle.

Este trabalho experimental tem por objetivo apresentar os estudos experimentais realizados com jatos de líquidos evaporativos (\"flash boiling\") de iso-octano. Nos estudos, o jato emergia de um diminuto bocal que descarrega em uma grande câmara de baixa pressão. O líquido ao passar pelo bocal sofria uma expansão interna alcançando elevados graus de superaquecimento ou de metaestabilidade, já que se mantinha na fase líquida. Nos experimentos, eram controladas as condições de pressão e temperatura de injeção durante um período de alguns poucos segundos suficientes para que as condições de regime permanente fossem estabelecidas. Um dos métodos para a visualização do escoamento do jato evaporativo foi o \"Schlieren\", o qual permitia visualizar elevados gradientes de densidade como normalmente ocorrem com ondas de choque, presentes nesta investigação. Também foi empregada a técnica de visualização de \"iluminação por detrás\" para que fossem comparadas as imagens obtidas por este método com o do \"Schlieren\", bem como mostrar detalhes do fenômeno em estudo. Com isso, foi possível estudar a estrutura do processo evaporativo do jato e, com o auxílio de ferramentas de filtragem matemática e manipulação das imagens obtidas, os fenômenos compressíveis envolvidos. Os perfis dos jatos observados foram: (1) filete contínuo de líquido sem evaporação, (2) jato com fragmentações ou atomizado e (3) abrupta evaporação seguida por expansão com formação de ondas de choque. Neste último caso, a inspeção das fotografias indicou que a evaporação do líquido se dava externamente ao bocal, a partir de um núcleo metaestável de líquido, o qual apresentava o formato aproximado de um cone. Também foi aplicada a teoria de ondas oblíquas de evaporação para estudar o comportamento deste cone líquido. Os ensaios foram conduzidos com três bocais cônico-convergentes de dimensões e materiais diferentes, quais sejam: bocal de aço com diâmetro de saída de 0,3 mm, bocal de aço com 0,8 mm e bocal de vidro com 0,35 mm. / The main goal of this thesis is to present results of experiments with flashing liquid jets of iso-octane. The experiments were carried out with a liquid jet issuing from a small nozzle into a low-pressure chamber. High degrees of metastability were obtained as the liquid jet expanded within the nozzle. Injection pressure and temperature were controlled to the desired testing values for a few seconds, which were found long enough to reach and keep the steady state regime. The photographic documentation of the phenomenon was obtained from a \"Schlieren\" set up using CCD camera. The \"back-lightening\" visualization technique was also used in order to compare both image techniques and to unveil some flashing phenomenon details. Analyses of these images with the help of mathematical filters as well as other image manipulating techniques enabled a qualitative visualization of the flashing liquid jet structure and geometry leaving the nozzle. Three liquid jet regimes were observed: (1) continuous liquid jet (2) partially atomized, and (3) evaporation with the presence of shock waves. In this latter case, we speculate that the evaporation took part on the liquid jet surface, which had the approximate shape of a cone. Also it was employed the oblique evaporation wave theory to explain some of the behavior of the overall evaporation process. The tests were carried out using three conical-converging nozzles made of different materials: a 0.3 mm exit diameter steel nozzle, a 0.8 mm exit diameter steel nozzle, and a 0.35 mm exit diameter glass nozzle.

<p>In this report, microrockets from the company NanoSpace were studied using schlieren imaging techniques. The rocket chips are manufactured using MEMS technology, which requires compromises regarding the shape of the nozzle. The rocket chips are 22x22x0.85 mm, manufactured from laminated silicon. The nozzles are approximately 20 µm wide at the throat, and 350 µm wide at the exit. A semi in-line schlieren apparatus was designed, set up, and aligned. A small vacuum chamber was constructed, and a series of tests was conducted in order to qualitatively evaluate the consequences of these compromises, and other performance issues. It was found that the existing 1 kW quartz-tungsten-halogen lamp was sufficient as a light source, standard photographic equipment served well as an imaging device, and a 400 mm, f/7.9 achromatic doublet as schlieren lens, resolved enough detail in the exhaust gas to perform the studies. At maximum magnification, the viewing area was 7 by 4.5 mm, captured at 14 Mpixel, or about 1.5 µm/pixel. Several different rocket chips were studied, with helium, nitrogen and xenon as propellant gases. Feed pressure ranged from 0.5 bar to 3.5 bar, and the rockets were studied at atmospheric pressure and in vacuum, and with and without heaters activated. Through these studies, verification and visualization of the basic functionality of the rockets were possible. At atmospheric pressure, slipping of the exhaust was observed, due to the severe overexpansion of the nozzle. In vacuum, the nozzle was underexpanded, and the flow was seen to be supersonic. There was a measurable change in the exhaust with the heaters activated. It was also shown that the method can be used to detect leaks, which makes it a valuable aid in quality control of the components.</p>

In this report, microrockets from the company NanoSpace were studied using schlieren imaging techniques. The rocket chips are manufactured using MEMS technology, which requires compromises regarding the shape of the nozzle. The rocket chips are 22x22x0.85 mm, manufactured from laminated silicon. The nozzles are approximately 20 µm wide at the throat, and 350 µm wide at the exit. A semi in-line schlieren apparatus was designed, set up, and aligned. A small vacuum chamber was constructed, and a series of tests was conducted in order to qualitatively evaluate the consequences of these compromises, and other performance issues. It was found that the existing 1 kW quartz-tungsten-halogen lamp was sufficient as a light source, standard photographic equipment served well as an imaging device, and a 400 mm, f/7.9 achromatic doublet as schlieren lens, resolved enough detail in the exhaust gas to perform the studies. At maximum magnification, the viewing area was 7 by 4.5 mm, captured at 14 Mpixel, or about 1.5 µm/pixel. Several different rocket chips were studied, with helium, nitrogen and xenon as propellant gases. Feed pressure ranged from 0.5 bar to 3.5 bar, and the rockets were studied at atmospheric pressure and in vacuum, and with and without heaters activated. Through these studies, verification and visualization of the basic functionality of the rockets were possible. At atmospheric pressure, slipping of the exhaust was observed, due to the severe overexpansion of the nozzle. In vacuum, the nozzle was underexpanded, and the flow was seen to be supersonic. There was a measurable change in the exhaust with the heaters activated. It was also shown that the method can be used to detect leaks, which makes it a valuable aid in quality control of the components.