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Thesis (Ph.D.)--University of Adelaide, Dept. of Mechanical Engineering, 1998? / Title from screen page; viewed 7 Feb 2005. Includes bibliographical references. Also available in a print form.

Thesis (Ph. D.)--University of Washington, 1987. / Vita. Bibliography: leaves [197]-202.

A thrust anemometer was designed to measure the three components of wind velocity fluctuations in the atmospheric boundary layer over the surface of the sea, and hence to evaluate directly the Reynolds stress of the wind on the sea. The anemometer was shown to be suitable for its intended purpose first by wind tunnel tests and then by comparisons with spectra from measurements in the field by cup and hot-wire anemometers. Spectra and cospectra of wind velocity fluctuations were calculated by analog analysis for thirty-two runs of 32 minutes' duration each at the Spanish Banks experimental site and for one run at another site. The spectra of downwind and of vertical velocity fluctuations were each found to be grouped closely when plotted in normalized form, and an empirical formula was given for the low-frequency end of the vertical velocity spectrum. The correlation of the downwind and vertical velocity fluctuations was found to be -0.5 at low frequencies and to approach zero at higher frequencies. The average value of the drag coefficient of the surface of the sea for the thirty-three runs was .0010 and no significant variation with wind speed was observed over the range 3 to 13 m/sec. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

The dynamic characteristics of the K-Gill anemometer were evaluated by comparing the anemometer with a hot wire system in a field test, after the static characteristics of the anemometer had been evaluated in a wind tunnel test. The wind tunnel test showed a non-linear and a non-cosine behavior, as shown in previous studies (Ataktürk, 1988; Pond et al., 1979). The turbulence energy spectra from the field test revealed that the propeller anemometer behaves like a single-pole low-pass RC filter, as suggested in previous studies (Ataktürk, 1988; Pond et al., 1979; MacCready and Jex, 1964). The test results showed that mean wind velocity components can be measured with an error of 2%. To determine the Reynolds stress values, uw covariance and friction velocity from different methods were compared. When the stability conditions were unknown, the resulting Reynolds stress estimations have 15% relative differences between different methods. / Master of Science

SpinChem AB's rotating bed reactor (RBR) is a small cylindrical centrifuge that allowsfor eective convective reactions between chemical substances. The aim of my master'sdissertation was to develop a measurement system that could estimate the uid velocity insidethe RBR. This report covers a quick pre-study of dierent uid measurement methods,details how we designed and constructed the system using integrated circuits and other electroniccomponents, and illustrates calibration results and nal velocity measurements. Thesystem design was based on the architecture of hot-wire constant temperature anemometry(CTA), a technique that measures the uid velocity over a heated metal wire. The resultsof this project is the measurement system itself, and the calibration and velocity measurementsgathered from experimentation. Two issues we encountered was that the calibrationprocess resulted in an overestimation of the velocity in the order of 4000 cm/s, and thatthe response to changes in velocity rates was quite slow. However, a slight tuning of thetwo calibration constants A0 & B0 smoothed the velocity estimation out to 40 cm/s, whichis more what we would expect. This illustrated how sensitive the results were to errors inthe calibration. Further investigation of the slow response, and a more stringently executedcalibration setup, could make the CTA a potential candidate for estimating the uid velocityinside the RBR.

M.Phil. / The aim of this research is to study the underhood airflow thermal behaviour of the extra low profile (XLP) dozer due to the excessive heat dissipated and observed during testing sessions executed at ground level, using computational fluid dynamics (CFD). The motivation of this project is to identify the reasons of poor cooling performance of this equipment, to develop and to demonstrate the capabilities of CFD in thermal research by validating the CFD result with experiments using a scaled model, prior to analyzing the full-scale dozer ...

Este trabalho apresenta um estudo experimental a respeito do fenômeno da biestabilidade em cilindros finitos com média razão de aspecto. Na biestabilidade, há uma esteira estreita a jusante de um dos cilindros e uma esteira larga a jusante do outro. Pode estar presente em muitas situações práticas da engenharia dependendo da distância entre os cilindros. Em cilindros finitos ainda é pouco compreendida e explorada. Para compreender o mecanismo do desprendimento de vórtices, são estudados o escoamento em torno de um único cilindro finito, com cilindros de diâmetros entre 25 e 60 mm e razão de aspecto entre 1 e 4 e após, o escoamento em torno de dois cilindros finitos dispostos lado a lado, com cilindros de diâmetros entre 25 e 32 mm e razão de aspecto entre 3 e 4. A técnica experimental aplicada consiste na medição das flutuações de velocidade em canal aerodinâmico, utilizando a técnica de anemometria de fio quente e na visualização do escoamento no mesmo canal, mantendo os parâmetros, utilizando gelo seco e laser. Além disso, foi realizada a visualização do escoamento em canal hidráulico com as mesmas dimensões do canal aerodinâmico, utilizando injeção de tinta através de agulhas. Para o estudo foram utilizados Re=2,00×104 para um cilindro finito e 3,86×103 ≤ Re ≤ 4,81×104 para cilindros finitos dispostos lado a lado. Os dados medidos em canal aerodinâmico são tratados através de ferramentas estatísticas, espectrais e de ondaletas, e os resultados das visualizações do escoamento são apresentados por meio de imagens obtidas das filmagens realizadas com uma câmera digital. Além disso, os vídeos são tratados com softwares de edição de vídeo e com ferramentas estatísticas. Os resultados confirmam a existência do fenômeno da biestabilidade para dois cilindros finitos dispostos lado a lado, que é um dos objetivos do estudo, nas três posições estudadas. A técnica de visualização de escoamento reforça a interpretação dos resultados obtidos através da técnica de anemometria de fio quente. Neste trabalho é considerada a existência de três escoamentos concomitantes: o escoamento ascendente, caracterizado pela estrutura de vórtices na base; o escoamento descendente, caracterizado pela estrutura de vórtices no topo; e o aqui chamado escoamento principal, caracterizado pelo desprendimento de vórtices a meia altura dos cilindros. / This work presents an experimental study on the bistability phenomenon in finite cylinders with a mid-aspect ratio. In the bistability phenomenon the flow to form two wakes behind the cylinders, a large wake behind a cylinder and a narrow wake after another. It can be present in many practical engineering situations depending on the distance between the cylinders. In finite cylinders, it is still poorly understood and explored. To understand the vortex shedding mechanism are studied the flow in a single finite cylinder with diameters between 25 and 60 mm and aspect ratio between 1 and 4 is studied. After that, the flow of two finite cylinders placed side by side with cylinders of diameters between 25 and 32 mm and aspect ratio between 3 and 4 was studied. The experimental technique of hot wire anemometry in aerodynamic channel is applied in the measurement of velocity fluctuations of the flow. The flow visualization was performed on the same aerodynamic channel, keeping the parameters, through using dry ice and laser. In addition, flow visualization is performed on the hydraulic channel with the same dimensions of the aerodynamic channel using ink injection through needles. All images are captured with a camera digital. For the study, Re=2.00×104 for a finite cylinder and 3.86×103 ≤ Re ≤ 4.81×104 for finite cylinders arranged side by side were used. The data measured in aerodynamic channel are treated through statistics, spectral and wavelet tools and the videos are treated through video editing software and with statistical tools. The results show the existence of two different levels of mean velocity in time series, corresponding to two flow modes confirming the phenomenon of bistability for two finite cylinders placed side by side, which is one of the objectives of the study. The flow visualization technique strengthens the interpretation of the results obtained through the hot wire anemometer technique. In this work the existence of three concomitant flows is considered: the upwash flow, characterized by the vortex structure in the base; the downwash flow, characterized by the vortex structure at the top; and the so-called main flow, characterized by the vortex shedding at half height of the cylinders.

Ultrasonic anemometer (UA) is a core application in natural environment measurement. As well known, mechanical anemometer works well in good weather but it is not suitable to be applied in bad environment such as polar region and upper air. On the other hand, ultrasonic anemometer works well in most situations. Moreover, ultrasonic anemometer has wider detectable wind speed range. It can be said that ultrasonic anemometer is a more advanced instrument to measure wind velocity. In this paper, the theory of ultrasonic anemometer is first discussed. Using the theory, a test bed is then designed and constructed to measure one-dimensional wind speed. Active Butterworth filter is introduced into the circuit in order to increase the stability and accuracy. Furthermore, we test the one-dimensional ultrasonic anemometer and compare the measured wind speed with theoretical wind speed measured by a thermal anemometer device. Error is also discussed and improvement has also made during the experiment.

Este trabalho apresenta um estudo experimental a respeito do fenômeno da biestabilidade em cilindros finitos com média razão de aspecto. Na biestabilidade, há uma esteira estreita a jusante de um dos cilindros e uma esteira larga a jusante do outro. Pode estar presente em muitas situações práticas da engenharia dependendo da distância entre os cilindros. Em cilindros finitos ainda é pouco compreendida e explorada. Para compreender o mecanismo do desprendimento de vórtices, são estudados o escoamento em torno de um único cilindro finito, com cilindros de diâmetros entre 25 e 60 mm e razão de aspecto entre 1 e 4 e após, o escoamento em torno de dois cilindros finitos dispostos lado a lado, com cilindros de diâmetros entre 25 e 32 mm e razão de aspecto entre 3 e 4. A técnica experimental aplicada consiste na medição das flutuações de velocidade em canal aerodinâmico, utilizando a técnica de anemometria de fio quente e na visualização do escoamento no mesmo canal, mantendo os parâmetros, utilizando gelo seco e laser. Além disso, foi realizada a visualização do escoamento em canal hidráulico com as mesmas dimensões do canal aerodinâmico, utilizando injeção de tinta através de agulhas. Para o estudo foram utilizados Re=2,00×104 para um cilindro finito e 3,86×103 ≤ Re ≤ 4,81×104 para cilindros finitos dispostos lado a lado. Os dados medidos em canal aerodinâmico são tratados através de ferramentas estatísticas, espectrais e de ondaletas, e os resultados das visualizações do escoamento são apresentados por meio de imagens obtidas das filmagens realizadas com uma câmera digital. Além disso, os vídeos são tratados com softwares de edição de vídeo e com ferramentas estatísticas. Os resultados confirmam a existência do fenômeno da biestabilidade para dois cilindros finitos dispostos lado a lado, que é um dos objetivos do estudo, nas três posições estudadas. A técnica de visualização de escoamento reforça a interpretação dos resultados obtidos através da técnica de anemometria de fio quente. Neste trabalho é considerada a existência de três escoamentos concomitantes: o escoamento ascendente, caracterizado pela estrutura de vórtices na base; o escoamento descendente, caracterizado pela estrutura de vórtices no topo; e o aqui chamado escoamento principal, caracterizado pelo desprendimento de vórtices a meia altura dos cilindros. / This work presents an experimental study on the bistability phenomenon in finite cylinders with a mid-aspect ratio. In the bistability phenomenon the flow to form two wakes behind the cylinders, a large wake behind a cylinder and a narrow wake after another. It can be present in many practical engineering situations depending on the distance between the cylinders. In finite cylinders, it is still poorly understood and explored. To understand the vortex shedding mechanism are studied the flow in a single finite cylinder with diameters between 25 and 60 mm and aspect ratio between 1 and 4 is studied. After that, the flow of two finite cylinders placed side by side with cylinders of diameters between 25 and 32 mm and aspect ratio between 3 and 4 was studied. The experimental technique of hot wire anemometry in aerodynamic channel is applied in the measurement of velocity fluctuations of the flow. The flow visualization was performed on the same aerodynamic channel, keeping the parameters, through using dry ice and laser. In addition, flow visualization is performed on the hydraulic channel with the same dimensions of the aerodynamic channel using ink injection through needles. All images are captured with a camera digital. For the study, Re=2.00×104 for a finite cylinder and 3.86×103 ≤ Re ≤ 4.81×104 for finite cylinders arranged side by side were used. The data measured in aerodynamic channel are treated through statistics, spectral and wavelet tools and the videos are treated through video editing software and with statistical tools. The results show the existence of two different levels of mean velocity in time series, corresponding to two flow modes confirming the phenomenon of bistability for two finite cylinders placed side by side, which is one of the objectives of the study. The flow visualization technique strengthens the interpretation of the results obtained through the hot wire anemometer technique. In this work the existence of three concomitant flows is considered: the upwash flow, characterized by the vortex structure in the base; the downwash flow, characterized by the vortex structure at the top; and the so-called main flow, characterized by the vortex shedding at half height of the cylinders.