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Estudo sobre a viabilidade da tomografia eletromagnética na medição do perfil de velocidades de escoamentos monofásicos em dutos / Study on viability of the electromagnetic tomography in the velocity profile measurements on monophase flow in pipeFigueroa, Teodora Pinheiro 09 September 2005 (has links)
Este trabalho apresenta um estudo prospectivo referente ao desenvolvimento de um medidor eletromagnético inteligente de vazão, cuja finalidade é determinar a vazão de escoamento a partir da reconstrução do perfil de velocidade utilizando técnicas tomográficas. Em conseqüência disso, o medidor de vazão será capaz de corrigir a vazão dada, através da integração do perfil de velocidade correto reconstruído por tomografia. A técnica de reconstrução tomográfica utilizada é baseada na construção de um funcional de erro, gerado a partir da diferença entre voltagens simuladas numericamente para uma condição experimental, conhecidos os parâmetros determinantes da velocidade no interior da tubulação, e voltagens aproximadas simuladas numericamente para aproximações destes parâmetros. Neste trabalho, o modelo físico do medidor eletromagnético de vazão é baseado em um número de eletrodos colocados sobre as paredes do tubo sob uma estratégia de excitação específica, sem injeção de corrente, considerando o campo magnético uniforme. A partir da expansão do funcional de erro, sobre um conjunto de funções conhecidas, uma superfície de erro é gerada. As características da patologia desta superfície requerem outros tipos de técnicas de otimização. Técnicas tradicionais de otimização não são viáveis, pois o processo de busca pára no primeiro mínimo local encontrado. Essa convergência para mínimos locais é justificada devido à presença de regiões planas e vales apresentando vários mínimos locais circundando o ponto de mínimo global (ou ponto referente aos parâmetros ótimos da velocidade). Em vista da ocorrência deste fato, técnicas baseadas em algoritmos evolucionários são testadas e apresentadas para uma série de casos demonstrando a praticidade de nossa pesquisa. / This work presents a prospective study on the development of an intelligent electromagnetic flow meter intended to determine output based on the reconstruction of velocity profile using tomographic techniques. As a result, the flow meter will be able to correct the output measure through the integration of the right velocity profile produced by tomography. The tomographic reconstruction technique utilized is based on the definition of an error functional generated from the difference between voltages simulated numerically for a experimental condition, being known the parameters which define the velocity within the pipe and approximate voltages simulated numerically for approaches of these parameters. In this work the physical model of the electromagnetic flow meter is based on a number of electrodes flush mounted on pipe walls and under a specific strategy of excitement, without electrical current input and considering the magnetic field uniform. From the expansion of the error functional over a set of known functions an error surface is generated. The characteristics of the pathology of this surface require other types of optimization techniques. Traditional optimization techniques are not viable since the search stops at the first local minimum. This convergence to local minimums is justified due to the presence of flat regions and valleys presenting several local minimums around the global minimum point (or point relative to the optimum parameters of velocity). Due to this fact techniques based on evolutionary algorithms are tested and presented for a series of cases demonstrating the usefulness of our research.
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Modelling of a Variable Venturi in a Heavy Duty Diesel Engine / Modellering av variabel venturi i en dieselmotor för tung lastbilTorbjörnsson, Carl-Adam January 2002 (has links)
The objectives in this thesis are to present a model of a variable venturi in an exhaust gas recirculation (EGR) system located in a heavy duty diesel engine. A new legislation called EURO~4 will come into force in 2005 which affects truck development and it will require an On-Board Diagnostic system in the truck. If model based diagnostic systems are to be used, one of the advantages is that the system performance will increase if a model of a variable venturi is used. Three models with different complexity are compared in ten different experiments. The experiments are performed in a steady flow rig at different percentage of EGR gases and venturi areas. The model predicts the mass flow through the venturi. The results show that the first model with fewer simplifications performs better and has fewer errors than the other two models. The simplifications that differ between the models are initial velocity before the venturi and the assumption of incompressible flow. The model that shows the best result is not proposed by known literature in this area of knowledge and technology. This thesis shows that further studies and work on this model, the model with fewer simplifications, can be advantageous.
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Modelling of a Variable Venturi in a Heavy Duty Diesel Engine / Modellering av variabel venturi i en dieselmotor för tung lastbilTorbjörnsson, Carl-Adam January 2002 (has links)
<p>The objectives in this thesis are to present a model of a variable venturi in an exhaust gas recirculation (EGR) system located in a heavy duty diesel engine. A new legislation called EURO~4 will come into force in 2005 which affects truck development and it will require an On-Board Diagnostic system in the truck. If model based diagnostic systems are to be used, one of the advantages is that the system performance will increase if a model of a variable venturi is used. </p><p>Three models with different complexity are compared in ten different experiments. The experiments are performed in a steady flow rig at different percentage of EGR gases and venturi areas. The model predicts the mass flow through the venturi. The results show that the first model with fewer simplifications performs better and has fewer errors than the other two models. The simplifications that differ between the models are initial velocity before the venturi and the assumption of incompressible flow. </p><p>The model that shows the best result is not proposed by known literature in this area of knowledge and technology. This thesis shows that further studies and work on this model, the model with fewer simplifications, can be advantageous.</p>
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Estudo sobre a viabilidade da tomografia eletromagnética na medição do perfil de velocidades de escoamentos monofásicos em dutos / Study on viability of the electromagnetic tomography in the velocity profile measurements on monophase flow in pipeTeodora Pinheiro Figueroa 09 September 2005 (has links)
Este trabalho apresenta um estudo prospectivo referente ao desenvolvimento de um medidor eletromagnético inteligente de vazão, cuja finalidade é determinar a vazão de escoamento a partir da reconstrução do perfil de velocidade utilizando técnicas tomográficas. Em conseqüência disso, o medidor de vazão será capaz de corrigir a vazão dada, através da integração do perfil de velocidade correto reconstruído por tomografia. A técnica de reconstrução tomográfica utilizada é baseada na construção de um funcional de erro, gerado a partir da diferença entre voltagens simuladas numericamente para uma condição experimental, conhecidos os parâmetros determinantes da velocidade no interior da tubulação, e voltagens aproximadas simuladas numericamente para aproximações destes parâmetros. Neste trabalho, o modelo físico do medidor eletromagnético de vazão é baseado em um número de eletrodos colocados sobre as paredes do tubo sob uma estratégia de excitação específica, sem injeção de corrente, considerando o campo magnético uniforme. A partir da expansão do funcional de erro, sobre um conjunto de funções conhecidas, uma superfície de erro é gerada. As características da patologia desta superfície requerem outros tipos de técnicas de otimização. Técnicas tradicionais de otimização não são viáveis, pois o processo de busca pára no primeiro mínimo local encontrado. Essa convergência para mínimos locais é justificada devido à presença de regiões planas e vales apresentando vários mínimos locais circundando o ponto de mínimo global (ou ponto referente aos parâmetros ótimos da velocidade). Em vista da ocorrência deste fato, técnicas baseadas em algoritmos evolucionários são testadas e apresentadas para uma série de casos demonstrando a praticidade de nossa pesquisa. / This work presents a prospective study on the development of an intelligent electromagnetic flow meter intended to determine output based on the reconstruction of velocity profile using tomographic techniques. As a result, the flow meter will be able to correct the output measure through the integration of the right velocity profile produced by tomography. The tomographic reconstruction technique utilized is based on the definition of an error functional generated from the difference between voltages simulated numerically for a experimental condition, being known the parameters which define the velocity within the pipe and approximate voltages simulated numerically for approaches of these parameters. In this work the physical model of the electromagnetic flow meter is based on a number of electrodes flush mounted on pipe walls and under a specific strategy of excitement, without electrical current input and considering the magnetic field uniform. From the expansion of the error functional over a set of known functions an error surface is generated. The characteristics of the pathology of this surface require other types of optimization techniques. Traditional optimization techniques are not viable since the search stops at the first local minimum. This convergence to local minimums is justified due to the presence of flat regions and valleys presenting several local minimums around the global minimum point (or point relative to the optimum parameters of velocity). Due to this fact techniques based on evolutionary algorithms are tested and presented for a series of cases demonstrating the usefulness of our research.
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Ultrasonic Flow Measurement for Pipe Installations with Non-Ideal ConditionsStoker, Devin M. 01 December 2011 (has links)
In the arid west, water is among the most valuable of resources. Typically, in order to successfully and accurately measure a flow rate using most types of flow meters, it is recommended that a straight section of pipe be installed immediately upstream from the flow meter to avoid distorted flow patterns and extreme turbulence at the metering location. In many field piping situations, however, such flow conditions are impossible to achieve.
The performance of ultrasonic flow meters in non-ideal piping scenarios was studied using laboratory experiments and numerical Computational Fluid Dynamics models. A Fuji PortaflowX clamp-on transit-time ultrasonic flow meter was calibrated in the laboratory and performed well within the manufacturer’s stated level of accuracy of ±1% for straight pipe. The ultrasonic flow meter was also used downstream of a single 12-inch long-radius elbow and the error in flow measurement resulting from the flow disturbance was measured. These tests were performed at four locations downstream of the elbow, at three orientations on the circumference of the pipe, and for three flow rates with Reynolds numbers ranging from 250,000 to 750,000. Using the same physical conditions, numerical models were built that utilized the realizable k-ε eddy viscosity model for turbulent flows. The resulting downstream velocity profiles from the numerical models were used to integrate the velocity of the flow across the ultrasonic signal path. The resulting velocity profiles were compared to similar profiles for fully developed flow to determine the error in flow measurement. The ultrasonic flow meter measurement errors downstream of the elbow were always negative, and were found to be as great as -16%. In general, the ultrasonic flow meter performed less accurately closer to the elbow due to the turbulent fluctuations and flow separation created by the elbow.
A correction curve was applied to the results of this study, which provided a method to correct the ultrasonic flow measurement. By applying the correction equation to the laboratory ultrasonic flow meter measurements downstream of the elbow, the measurement error was reduced by nearly 90%. Computational Fluid Dynamics appears to be a viable tool for studying flow disturbances and making appropriate corrections for ultrasonic flow measurement in pipes.
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Adenoidní vegetace a adenotomie z pohledu respirační fyzioterapie / Adenoid hypertrophy and adenodectomy from the viewpoint of the respirotory physiotherapySvětlíková, Adéla January 2014 (has links)
The aim of the thesis is the examination of respiratory and postural changes on examined group of children after adenoidectomy and evaluation, whether it is recommended in post- operative phase to indicate respiratory physiotherapy for the examined children. The theoretical part of the thesis deals with the anatomy, etiology and symptomatology, which accompanies adenoid hypertrophy. Furthermore, there is a description of the kinesiology examination and complete methodology of respiratory physiotherapy and more. In the practical part of the thesis there is a statistic analysis of the examination of 20 children after adenoidectomy and control group investigation. Examination content is the thoracic respiratory excursion (breathing amplitude) and orientational examination of lungs function (PEF, FEV 0,5, FEV 0,75 and FEV1) using digital Peak Flow Meter. The part of the thesis i also kinesiology analysis and questionnaire filled up before adenoidectomy and 3 weeks after operation.
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Simulaçõeses numéricas de efeitos de acidentes de linha causados por curvas à montante de medidores de vazão por ultrassom de um canal por tempo de trânsito para gás de flare / Numerical simulations of installation effects caused by upstream elbows on single-path transit-time ultrasonic flare flow metersMartins, Ramon Silva 23 May 2012 (has links)
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Previous issue date: 2012-05-23 / Oil and gas industry requires accurate flow measurements since they are stated by law. Nevertheless, curves and other obstacles are commonly found in such industry field, which may affect the quality of flow measurement due to flow disturbances, such as swirl and velocity profile asymmetries. Single-path ultrasonic flow meters are often used in flare gas installations, despite being sensitive to such disturbances. The present work use commercial CFD codes to obtain disturbed flow fields downstream from single and double elbow pipe installations, aiming to investigate both magnitude and behaviour of such effects on ultrasonic flow measurement. Numerical integration is applied for several acoustic path arrangements, simulating single-path ultrasonic flow meters in different situations in order to evaluate its correction factor deviation under disturbed conditions. Reynolds numbers from 1X10 4 to 2 X10 6 are considered. Transducers mounting angles from 0° to 180° are tested and axial positions up to 80D downstream from the curve are evaluated. Results indicate that single-path ultrasonic flow meters are sensitive to installation effects. Correction factor deviations usually showed to be significantly higher than 2% for axial positions shorter than 20D, as recommended by several manufacturers or regulations. Nevertheless, deviations may reach 0.01% in some specific configurations, which suggests that ultrasonic flow measurement might be improved by rearranging flow meter device in favourable angular position and mainly by implementation of specific functions for correction factors under disturbed conditions / A indústria de petróleo e gás requer medições de vazão de baixa incerteza, uma vez que são estabelecidas por lei. Contudo, curvas e outros obstáculos são comumente encontrados nesse cenário e podem afetar a qualidade da medição de vazão em função de perturbações no escoamento, tais como swirl e assimetrias no perfil de velocidades. Medidores de vazão por ultrassom de um canal são frequentemente utilizados em instalações de gás de queimadores, apesar de serem sensíveis a tais perturbações. O presente trabalho usa códigos comerciais de CFD para obter o escoamento à jusante de instalações com uma curva e duas curvas, visando a investigar a magnitude e o comportamento de tais efeitos na medição de vazão. Integração
numérica é utilizada para diversos arranjos de caminho acústico, simulando medidores de vazão por ultrassom de um canal em várias condições para avaliar o desvio do fator de correção em escoamentos perturbados. Números de Reynolds de 1×10 4 a 2×10 6 são considerados. Ângulos de montagem dos transdutores de 0° a 180° são testados e posições axiais até 80D à jusante do obstáculo são avaliadas. Os resultados indicam que medidores de vazão por ultrassom são sensíveis aos efeitos de acidente de linha. O desvio do fator de correção mostra-se, em geral, consideravelmente maior que 2% em distâncias menores que 20D, conforme recomendado por alguns fabricantes e por leis. Não obstante, tais desvios podem atingir 0,01% em algumas configurações específicas, o que sugere que a medição de vazão por ultrassom pode
ser melhorada pelo rearranjo do aparato em posição angular favorável e, principalmente, pela implementação de funções específicas para fatores de correção em condições perturbadas
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Numerical Modeling of Flow in Parshall Flume Using Various Turbulence ModelsHeyrani, Mehdi 29 August 2022 (has links)
Studying the behavior of hydraulic structures under various extreme conditions is far beyond the reach of traditional build-test experimental methods. Following the typical method, it is necessary to provide the downscaled model to be used in the laboratory and determine various structural parameters against unforeseen scenarios, which should be mimicked in the laboratory. Usually, human and instrument errors as well as scale effects are some of the causes of inaccurate results; therefore, substitute methods have always been sought to determine the stability and efficiency of various hydraulic devices. The implementation of computer models, also referred to as numerical simulation, is one of the most efficient ways to reduce time and cost, and at the same time, add to the degree of confidence in the design process. Improvements in computational power of supercomputers in recent decades have led researchers and engineers to become familiar with these numerical models and implement them in various studies. One of the basic hydraulic structures that is widely used to measure the flow for open channels is the Parshall flume. Although the Parshall flume is simple to use, the application of various rating equations for different sizes highly affects the output value, which is the flowrate. To avoid this, appropriate rating equation must be developed for various sizes that are not listed in the standard Parshall flume size chart. With the help of the Computational Fluid Dynamic (CFD) techniques, numerous turbulence models i.e., standard k-ε, RNG k-ε, realizable k-ε, k-ω, k-ω SST, k-ω SST DES, Smagorinsky and Dynamic k equation, have been used to simulate different geometric setups for different sizes of Parshall flumes. The result from various families of turbulence models, i.e., Reynold Average Navier-Stokes (RANS), Large Eddy Simulation (LES) and Detached Eddy Simulation (DES), used in this study, provide promising values with acceptable margins of error, which were found to be less than 3% in all cases except one. The application of numerical modeling to simulate the flow in Parshall flumes is used to verify the reliability of applying OpenFOAM as the open-source CFD used for all the simulations in this study. The data obtained from the numerical simulations are considered a reliable source to adjust the rating equation for any future non-standard Parshall flume. Overall, it should be pointed out that the quality of non-linear turbulence models, i.e., Shih-Q, LC, and v²-f, were considerably higher than those obtained using linear turbulence models.
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Exploring Spatial Optimization Techniques for the Placement of Flow Monitors Utilized in RDII StudiesSkehan, Christopher A. 31 August 2010 (has links)
Indiana University-Purdue University Indianapolis (IUPUI) / The aging infrastructure of a wastewater collection system can leak, capture ground water, and capture precipitation runoff. These are some of the most common problems in many of today’s US collection systems and are often collectively referred to as Rain Derived Inflow and Infiltration (RDII or I/I). The goal of this study is to investigate such optimized methods and their potential to improve flow monitor placement, especially for RDII studies, and to improve upon Stevens (2005) methodology. This project adopts a methodology from the “facility location problem”, a branch of operations research and graph theory. Solutions to a facility location problem will be adapted and utilized within a transportation GIS application to determine optimal placement.
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Utveckling av automatiserad urinflödesmätare / Development of an Automated Urine Flow MeterMohamed, Abdirahman January 2021 (has links)
Detta kandidatexamensarbete som utförts på uppdrag av ST-läkare i urologi Per Nordlund hade målet att bygga en urinflödesmätare. Eftersökta mätvärden att registrera var tidpunkt för miktionstillfället, mängden urin per tidsenhet (ml/s), flödesmönster, total mikterad volym (ml) samt miktionstid (sek). Urinflödesmätaren syftar till att förbättra initial bedömning samt uppföljning av personer med vattenkastningssvårigheter, en vanlig orsak till sjukvårdskontakt hos svenska män. För utvärdering av patienters vattenkastning ombeds patienten idag själv registrera och mäta urinvolym, en metod som ofta innebär besvär för patienten och kan innehålla inkomplett och felaktig data. Vid urologmottagningar ges möjligheten att elektroniskt mäta urinflöde och volym. Då en stor variation över dygn och miktionstillfälle föreligger kan en felaktig bild över symtom presenteras. Detta har gett upphov till idén att skapa en urinflödesmätare vars uppgift är att automatisera mätningsprocessen i hemmet. Arbetet utfördes genom att programmera en Arduino mikrokontroller samt användning av en flödessensor. Flödessensorns konstruktion bestod av en magnet, halleffektsensor samt en turbin. Halleffektsensorns uppgift var att mäta det elektriska fältet som uppstår då magneten som sitter på flödessensorns turbin roterar. Genom att utnyttja turbinrotationen kan bland annat volym beräknas. Arbetet har även inneburit användning av Python med syftet att spara det mätvärde från mikrokontrollern i en CSV fil som kan öppnas av en vårdgivare med applikationer som Excel. / This bachelor's degree project which was carried out on behalf of Per Nordlund, urology resident, had the goal of building a urine flow meter. The sought-after values to register each time of the micturition; the amount of urine per unit time (ml/ s), flow pattern, total micturized volume (ml) and micturition time (sec). The urine flow meter aims to improve initial assessment and follow-up of people with urination difficulties, a common cause of medical contact in Swedish men. Today, when evaluating patients urination, the patient is asked to register and measure urine volume themselves, a method that often causes problems for the patient and may contain incomplete and incorrect data. At urology clinics, individuals are given the opportunity to electronically measure urine flow and volume. When there is a large variation over day and occasion of micturition, an incorrect picture of symptoms can be presented. This has given rise to the idea of creating a urine flow meter whose task is to automate the measurement process in the home. The work was performed by programming an Arduino microcontroller and using a flow sensor. The design of the flow sensor consisted of a magnet, a hall-effect sensor and a turbine. The task of the hall-effect sensor was to measure the electric field that arises when the magnet attached on the flow sensor's turbine rotates. By utilizing the turbine rotation, volume can be calculated. The work has also involved the use of Python with the aim of saving the output values from the microcontroller in a CSV file that can be opened by a healthcare provider with applications such as Excel.
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