No description available.

Ji and Wang (2010) propose that the dominant source of sound from a forward facing step is the stream wise dipole on the face of the step and that sources acting normal to the flow are negligible. Sound radiation normal to flow of forward facing steps has been measured in wind tunnel experiments previously by Farabee and Casarella (1986, 1991) and Catlett (2010). A method for evaluating sound radiation from surface roughness proposed in Glegg and Devenport (2009) has been adapted and applied to flow over a forward facing step which addresses the sound normal to the flow that was previously unaccounted for. Far-field radiation predictions based on this method have been compared with wind tunnel measurements and show good agreement. A second method which evaluates the forcing from a vortex convected past surface roughness using RANS calculations and potential flow information is also evaluated. / by Benjamin Skyler Bryan. / Thesis (M.S.C.S.)--Florida Atlantic University, 2012. / Includes bibliography. / Mode of access: World Wide Web. / System requirements: Adobe Reader.

This dissertation will consider the sound radiation from forward-facing steps and a three dimensional cylindrical embossment of very low aspect ratio mounted on a plate. Glegg et al (2014) outlined a theory for predicting the sound radiation from separated flows and applied the method to predicting the sound from forward-facing steps. In order to validate this theory it has been applied to the results of Catlett et al (2014) and Ji and Wang (2010). This validation study revealed that the original theory could be adjusted to include a mixed scaling which gives a better prediction. RANS simulations have been performed and used to support the similarities between the forward-facing step and the cylindrical embossment. The simulations revealed that the cylindrical embossment exhibits a separation zone similar to that of the forward-facing step. This separation zone has been shown to be the dominant source of noise on the forward-facing step in previous works and therefore was expected to be the major source of sound from the cylindrical embossment. The sensitivity of this separation zone to the different parameters of the flow has been investigated by performing several simulations with different conditions and geometries. The separation zone was seen to be independent of Reynolds number based on boundary layer thickness but was directly dependent on the height of the cylinder. The theory outlined in Glegg et al (2014) was then reformulated for use with a cylindrical embossment and the predictions have been compared with wind tunnel measurements. The final predictions show good agreement with the wind tunnel measurements and the far-field sound shows a clearly defined directionality that is similar to an axial dipole at low frequencies. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2015. / FAU Electronic Theses and Dissertations Collection

Este trabalho tem como proposta desenvolver um difusor aerodinâmico compacto para uma turbina eólica de pequena escala, objetivando alcançar um melhor start rotacional (menor torque de partida para rotacionar) em baixas velocidades de vento. Um difusor é uma estrutura em forma de aro envolta ao rotor da turbina eólica, sua função é amplificar a captação e aceleração do vento, explorando os efeitos aerodinâmicos das zonas de vórtices de baixa pressão na saída do difusor. O estudo concentrar-se-á na manipulação da geometria dos difusores, analisando como seu design impacta no seu comportamento aerodinâmico impacta na capacidade do difusor equacionar as zonas de alta e baixa pressão ao longo de sua estrutura, essa relação é determinante para o efeito aerodinâmico que acelera o escoamento de ar, resultando em um start rotacional em baixas velocidade de vento. O ponto de partida para este trabalho são os estudos desenvolvidos por Ohya et al. (2010) sobre difusores compactos-flangeados (compact-type brimmed diffuser) para turbinas eólicas, denominado Wind-lens Technology. Para alcançar os objetivos, esta pesquisa vai utilizar simulações por CFD com software de túnel de vento virtual e ensaios experimentais em túnel de vento físico para avaliar o comportamento dinâmico (turbina + difusor). Foram desenvolvidas dezenove geometrias a partir de uma área construtiva padronizada para o design de difusores. Desenvolveu-se também, a partir dos resultados encontrados, um MFI (microseparador de fluxo interno), que consiste em uma estrutura adicional com função de potencializar as zonas de vórtices (baixa pressão) no plano de saída do escoamento de ar dos difusores. Os resultados mostraram que a manipulação da geometria do difusor produziu resultados promissores em comparação com o modelo de referência, alcançando em algumas geometrias de difusores um melhor start rotacional. O MFI mostrou-se eficaz para potencializar as zonas de baixa pressão e melhorou o start rotacional. Ao final, definiu-se dois modelos de difusores e suas respectivas versões com MFI como as melhores opções para o start rotacional. / This work aims to develop a compact wind turbine for a turbine and a small scale, aiming at a better rotational start at low wind speeds (lower starting torque to rotate). A diffuser is a rim-shaped structure wrapped around the wind turbine rotor, its function is to amplify the wind uptake and acceleration, exploiting the aerodynamic effects of the low-pressure vortex zones at the diffuser outlet. The study will focus on the manipulation of the diffuser geometry, analyzing how its design impacts on its aerodynamic behavior, especially on the diffuser's ability to equate the high and low pressure zones along its structure, this relation is decisive for the aerodynamic effect that accelerates the air flow, resulting in a rotational start at low wind speeds. The basis for this work are studies developed by Ohya et al. (2010) on compact-flanged diffusers for wind turbines, called Wind-lens Technology. To achieve the objectives, this research will use CFD simulations with virtual wind tunnel software and experimental tests in physical wind tunnel to evaluate the dynamic behavior (turbine + diffuser). Nineteen geometries were developed from a standardized design area for the design of diffusers. An MFI (internal flow microseparator) has also been developed, which is an additional structure whose function is to potentiate the low pressure zones of the diffusers. The results showed that the manipulation of the diffuser geometry produced promising results in comparison to the reference model, reaching in some conditions superior results in RPM and initial start. The MFI proved to be effective in boosting the low pressure zones and improved the initial start. At the end, two models of diffusers and their respective versions with MFI were defined as the best options for the initial start.

La déformation de torsion que subit un profil aérodynamique a une importance capitale car elle a une influence directe sur la valeur des incidences locales et donc sur la valeur locale des densités de portance et de traînée. L'amélioration des performances aérodynamiques passe donc par la connaissance et la maîtrise de ce vrillage. Cette thèse se propose d'y contribuer. Une des méthodes développées actuellement par de nombreux auteurs consiste à munir le profil d'actionneurs permettant de le déformer en torsion de manière à compenser tout ou partie, voire même contrer, la déformation « naturelle » de la structure. Cette méthode, dite de contrôle actif, est certes très efficace, mais elle présente des limitations car elle nécessite l'introduction d'une quantité d'énergie qui peut être importante. La méthode que nous proposons ici pour maîtriser le vrillage du profil consiste à modifier ses conditions d'équilibre interne. En solidarisant ou en désolidarisant des cloisons à l'intérieur du profil, il est possible de déplacer le centre de torsion des sections du profil sans modifier sa forme extérieure. Ces modifications internes induisent donc une modulation du moment de torsion et donc une modulation du vrillage. Ce processus ne demande que très peu d'énergie. A partir d'un profil simple, des simulations ont permis de montrer le potentiel théorique du système proposé. Trois démonstrateurs, de complexité croissante, ont également été réalisés pour évaluer les capacités du contrôle « réactif » de la torsion. La technique a été validée par la deuxième démonstration. Malheureusement, le troisième démonstrateur, beaucoup plus complexe, n'a pas permis, à l’heure actuelle, d'obtenir la validation finale. / The torsional deformation of aerodynamic profiles has to be considered with care because it induces a change in the angle of attack and therefore changes in the local densities of lift and drag forces. The improvement of the aerodynamic performances does require a good knowledge and control of the twist of the airfoil. A method currently developed by a lot of authors consists in inserting in the airfoil some actuators whose action tends to increase or reduce the ‘natural’ deformation of the structure. This method, named active control, is very effective but it has some limitations because it needs a level of energy which can be high. The method we propose to control the twist of the airfoil consists in modifying the internal elastic equilibrium of the structure. By joining or disjoining some walls inside the profile, it is possible to shift the shear center of the profile without any change of its external shape. So, these internal modifications induce variations of the torsional moment and therefore a variation of the twist angle. The process is no energy consuming. By means of a simple profile, simulations have been performed to show the theoretical potential of the proposed system. Three demonstrators have also been designed with increasing complexity to evaluate the feasibility of the ‘reactive’ control of the twist. The technique has been validated by the second demonstrator. Unfortunately, the third demonstrator, much more complex, has not shown the final demonstration.

Os estudos de caracterização acústica das vogais nasais são vastoa. Porém, há poucos estudos sobre a ditongação nasal. Este é um fenômeno que emerge da costelacao articulatória dos gestos. Isso pode ser notado a partir dos parâmetros acústicoaerodinâmicos. O objetivo desta é analisar o resultado da configuração gestual entre o movimento da língua e o gesto de abertura e fechamento do véu palatino, durante a produção dos ditongos nasais do Português Brasileiro. Mostraremos os efeitos da coarticulação no output sonoro e como ela se configura, a partir da gravação de dados acústicos e aerodinâmicos. O material foi gravado com o aparelho EVA Portátil 2. Esse permitiu que o output acústico e os dados aerodinâmicos fossem gravados concomitantes. O corpus do experimento é composto por vinte ditongos divididos em orais e nasais (dez posteriores e dez anteriores) todos dicionarizados: [p@w, s@w, m@w, k@w, t@w,p@)w), s@)w), m@)w), k@)w), t@)w), dej, sej, frej, hej, lej, te)j ), se)j ,) be)j ), a.mej), a.le)j\\) . As palavras foram inseridas na frase-veículo: Digo _____ cada dia. Essa foi repetida três vezes por seis informantes (três homens e três mulheres) falantes do dialeto Paulistano ( ). Para o controle de população foi utilizada outra frase-veículo: Digo ____ todo dia, essa foi repetida por 1.3 dos sujeitos, um de cada grupo ( ). Na inspeção visual utilizou-se o software Signal Explorer e Phonédit. Os parâmetros aerodinâmicos analisados foram: a configuração do fluxo de ar oral e nasal; a taxa máxima de nasalização e a duração do fluxo de ar nasal. Os parâmetros acústicos foram: a movimentação dos formantes; a extração de F0, F1, F2 e F3 de todos os segmentos e a duração do ditongo nasal: a vogal, o glide e o apêndice nasal. A Média, o Desvio Padrão e o teste ANOVA foram feitos no Excel. Os gráficos de dispersão dos formantes foram feito no Formant Explorer. Assim, notou-se uma variação nos valores da taxa de nasalização, p > 0,5, entre a variante sexo. Nas mulheres as frequências dos formantes são mais elevadas e a dispersão dos valores do glide nasal é mais evidenciada do que nos homens. As alterações remetem as diferenças fisiológicas entre os grupos. A taxa máxima de ar nasal variou significativamente, p > 0,5, se comparado os ditongos nasais: anteriores > posteriores. Acusticamente, a transição dos formantes é dependente do contexto silábico. O mesmo não acontece com o traçado do fluxo de ar nasal, que mantém o padrão de contorno, independente da articulação silábica. Concluí-se que há um padrão aerodinâmico relativo à sincronia do movimento do véu e da língua, gerando três fases acústicas distintas: vogal nasal, glide nasal e apêndice nasal. O contorno da trajetória padrão do fluxo de ar nasal, em 87% dos casos, apresentou três fases distintas: a primeira plana; a segunda, um pico acentuado; e a terceira, uma queda abrupta. Assim, concluímos que os ditongos nasais têm uma dinâmica articulatória, acústica e aerodinâmica diferente dos não-nasalizados e que a adequação do controle das variáveis do sistema fonético-fonológico e do o conjunto de articulações, que geram uma única percepção. / There are several studies that characterize the nasal vowels. However, there are few studies about the nasal diphthongation. This phenomenon emerges from the articulatory gestures constellation. This can be noted by analyzing of the acousticaerodynamics parameters. The aim of this work is study the gesture configuration between the thong movement and the velum aperture during the nasal diphthongs production of the Brazilian Portuguese. We will show the effects of the coarticulation in the output and how it sets up in the acoustic and aerodynamic data. The data was recorded by the device EVA Portable 2. Thus, the airflow and the acoustic output were collected concomitantly. The corpus of this experiment was covered by ten oral and ten nasal diphthongs, between ten back and ten front:[p@w, s@w, m@w, k@w, t@w,p@)w), s@)w), m@)w), k@)w), t@)w), dej, sej, frej, hej, lej, te)j ), se)j ,) be)j ), a.mej), a. le)j)\\. These words are dictionaries. They were inserted in the carry-sentence [dZi.gU__ ka.d5 dZi5] and were repeated three times, by six subjects (three men and three women); all of them are Paulistano Dialects speakers. This resulted in 360 tokens (3 × 6 × 20). The carry-sentence of the populational control was [dZi.gU__ to.dT dZi5]. This was repeated by 1/3 of the subjects. This resulted in 120 tokens (3 × 2 × 20 ). The diphthong was analyzed by Signal Explorer and Phonédit. The aerodynamic parameters studied were: the nasal and oral airflow shape; the peak of nasalization and the duration of nasal airflow. The acoustic parameters analyzed were: the movement and the configuration of the formants; the values of F0, F1, F2 and F3 were extracted of all segments; the nasal diphthongs duration in the vowel, the glide and the nasal appendix. The Average, Pattern Deviation and ANOVA were done by Excel. The dispersion graphics were made by Formant Explorer. As a result we noticed that the formants movements dependent on syllabic context. The womens formants had different values of males. The degree of the dispersion of hers was higher than him. This was showed more evident in the nasal glides. This reflects the physiological differences between the groups. The nasal airflow peak variation was p> 0,5 among the sex variant. The rate of nasal airflow of the back has more volume than front, dp > 0,5. The same does not happen with the nasal airflow shape. The shape pattern is independent of syllabic articulation, but the rate of nasalization depends of the articulation. We concluded that there is an aerodynamic pattern that is resulted of the thong movement and velum aperture. This product three distinct acoustic phases: vowel nasalization, glide nasal and the nasal appendix. By the aerodynamic view, in 87% of cases, the pattern shape of the nasal airflow represents three distinct phases: the first is sharp; the second is a peak; and last part is a drop line. Thus, we concluded that the nasal diphthongs have articulatory, acoustic and aerodynamic patters different from the non-nasalized segment. These reflect the adequacy of the control of variables of phonetic-phonological system and the set of these characteristics creates a single perception.

The skyline of many 'world cities' are defined and punctuated by tall buildings. The drivers for such dominant skylines range from land scarcity and social needs; high real estate values; commercial opportunity and corporate demand, through to metropolitan signposting. This fascination with tall buildings started with the patrician families who created the 11th Century skyline of San Gimignano by building seventy tower-houses (some up to 50m tall) as symbols of their wealth and power. This was most famously followed in the late 19th Century with the Manhattan skyline, then Dubai building the world's highest building, then China building some eighty tall buildings completed in the last 5 years, then UK building Europe's highest tower, the Shard and finally back to Dubai, planning a kilometre tall tower, potentially realising Ludwig Mies van der Rohe's 'Impossible Dream' of the 1920's and Frank Lloyd Wright's 1956 'Mile High Illinois'. This ambition to build higher and higher continues to challenge the Architects, Engineers and Builders of tall buildings and is expected to continue into the future. The tall building format is clearly here to stay.

Os estudos de caracterização acústica das vogais nasais são vastoa. Porém, há poucos estudos sobre a ditongação nasal. Este é um fenômeno que emerge da costelacao articulatória dos gestos. Isso pode ser notado a partir dos parâmetros acústicoaerodinâmicos. O objetivo desta é analisar o resultado da configuração gestual entre o movimento da língua e o gesto de abertura e fechamento do véu palatino, durante a produção dos ditongos nasais do Português Brasileiro. Mostraremos os efeitos da coarticulação no output sonoro e como ela se configura, a partir da gravação de dados acústicos e aerodinâmicos. O material foi gravado com o aparelho EVA Portátil 2. Esse permitiu que o output acústico e os dados aerodinâmicos fossem gravados concomitantes. O corpus do experimento é composto por vinte ditongos divididos em orais e nasais (dez posteriores e dez anteriores) todos dicionarizados: [p@w, s@w, m@w, k@w, t@w,p@)w), s@)w), m@)w), k@)w), t@)w), dej, sej, frej, hej, lej, te)j ), se)j ,) be)j ), a.mej), a.le)j\\) . As palavras foram inseridas na frase-veículo: Digo _____ cada dia. Essa foi repetida três vezes por seis informantes (três homens e três mulheres) falantes do dialeto Paulistano ( ). Para o controle de população foi utilizada outra frase-veículo: Digo ____ todo dia, essa foi repetida por 1.3 dos sujeitos, um de cada grupo ( ). Na inspeção visual utilizou-se o software Signal Explorer e Phonédit. Os parâmetros aerodinâmicos analisados foram: a configuração do fluxo de ar oral e nasal; a taxa máxima de nasalização e a duração do fluxo de ar nasal. Os parâmetros acústicos foram: a movimentação dos formantes; a extração de F0, F1, F2 e F3 de todos os segmentos e a duração do ditongo nasal: a vogal, o glide e o apêndice nasal. A Média, o Desvio Padrão e o teste ANOVA foram feitos no Excel. Os gráficos de dispersão dos formantes foram feito no Formant Explorer. Assim, notou-se uma variação nos valores da taxa de nasalização, p > 0,5, entre a variante sexo. Nas mulheres as frequências dos formantes são mais elevadas e a dispersão dos valores do glide nasal é mais evidenciada do que nos homens. As alterações remetem as diferenças fisiológicas entre os grupos. A taxa máxima de ar nasal variou significativamente, p > 0,5, se comparado os ditongos nasais: anteriores > posteriores. Acusticamente, a transição dos formantes é dependente do contexto silábico. O mesmo não acontece com o traçado do fluxo de ar nasal, que mantém o padrão de contorno, independente da articulação silábica. Concluí-se que há um padrão aerodinâmico relativo à sincronia do movimento do véu e da língua, gerando três fases acústicas distintas: vogal nasal, glide nasal e apêndice nasal. O contorno da trajetória padrão do fluxo de ar nasal, em 87% dos casos, apresentou três fases distintas: a primeira plana; a segunda, um pico acentuado; e a terceira, uma queda abrupta. Assim, concluímos que os ditongos nasais têm uma dinâmica articulatória, acústica e aerodinâmica diferente dos não-nasalizados e que a adequação do controle das variáveis do sistema fonético-fonológico e do o conjunto de articulações, que geram uma única percepção. / There are several studies that characterize the nasal vowels. However, there are few studies about the nasal diphthongation. This phenomenon emerges from the articulatory gestures constellation. This can be noted by analyzing of the acousticaerodynamics parameters. The aim of this work is study the gesture configuration between the thong movement and the velum aperture during the nasal diphthongs production of the Brazilian Portuguese. We will show the effects of the coarticulation in the output and how it sets up in the acoustic and aerodynamic data. The data was recorded by the device EVA Portable 2. Thus, the airflow and the acoustic output were collected concomitantly. The corpus of this experiment was covered by ten oral and ten nasal diphthongs, between ten back and ten front:[p@w, s@w, m@w, k@w, t@w,p@)w), s@)w), m@)w), k@)w), t@)w), dej, sej, frej, hej, lej, te)j ), se)j ,) be)j ), a.mej), a. le)j)\\. These words are dictionaries. They were inserted in the carry-sentence [dZi.gU__ ka.d5 dZi5] and were repeated three times, by six subjects (three men and three women); all of them are Paulistano Dialects speakers. This resulted in 360 tokens (3 × 6 × 20). The carry-sentence of the populational control was [dZi.gU__ to.dT dZi5]. This was repeated by 1/3 of the subjects. This resulted in 120 tokens (3 × 2 × 20 ). The diphthong was analyzed by Signal Explorer and Phonédit. The aerodynamic parameters studied were: the nasal and oral airflow shape; the peak of nasalization and the duration of nasal airflow. The acoustic parameters analyzed were: the movement and the configuration of the formants; the values of F0, F1, F2 and F3 were extracted of all segments; the nasal diphthongs duration in the vowel, the glide and the nasal appendix. The Average, Pattern Deviation and ANOVA were done by Excel. The dispersion graphics were made by Formant Explorer. As a result we noticed that the formants movements dependent on syllabic context. The womens formants had different values of males. The degree of the dispersion of hers was higher than him. This was showed more evident in the nasal glides. This reflects the physiological differences between the groups. The nasal airflow peak variation was p> 0,5 among the sex variant. The rate of nasal airflow of the back has more volume than front, dp > 0,5. The same does not happen with the nasal airflow shape. The shape pattern is independent of syllabic articulation, but the rate of nasalization depends of the articulation. We concluded that there is an aerodynamic pattern that is resulted of the thong movement and velum aperture. This product three distinct acoustic phases: vowel nasalization, glide nasal and the nasal appendix. By the aerodynamic view, in 87% of cases, the pattern shape of the nasal airflow represents three distinct phases: the first is sharp; the second is a peak; and last part is a drop line. Thus, we concluded that the nasal diphthongs have articulatory, acoustic and aerodynamic patters different from the non-nasalized segment. These reflect the adequacy of the control of variables of phonetic-phonological system and the set of these characteristics creates a single perception.

A hybrid design optimization method combining the stochastic method based on simultaneous perturbation stochastic approximation (SPSA) and the deterministic method of Broydon-Fletcher-Goldfarb-Shanno (BFGS) is developed in order to take advantage of the high efficiency of the gradient based methods and the global search capabilities of SPSA for applications in the optimal aerodynamic shape design of a three dimensional elliptic nozzle. The performance of this hybrid method is compared with that of SPSA, simulated annealing (SA) and gradient based BFGS method. The objective functions which are minimized are estimated by numerically solving the 3D Euler and Navier-Stokes equations using a TVD approach and a LU implicit scheme. Computed results show that the hybrid optimization method proposed in this study shows a promise of high computational efficiency and global search capabilities. / Singapore-MIT Alliance (SMA)

La thèse de Jean-François Simon est consacrée au développement d'un outil de simulation numérique de l'écoulement dans les turbomachines axiales. La démarche proposée a pour but de réduire l'empirisme présent dans les outils de calcul méridien en turbomachines. Cet objectif est atteint en deux étapes, l'une consistant à traiter de manière cohérente les effets dus à la viscosité du fluide dans le plan méridien, l'autre à injecter dans le calcul méridien les tensions déterministes et circonférentielles ainsi que les forces d'aubes. Les équations de Navier-Stokes sont moyennées azimutalement et sont résolues par une approche volumes-finis. La capture des effets dus à la viscosité du fluide le long des parois de carter et de moyeu permet d'éviter l'introduction d'un coefficient de blocage, ou le recours à un calcul couche-limite séparé. Jean-François Simon prolonge en outre l'approche d'Adamczyk par un opérateur de moyenne circonférentielle. Différents termes additionnels apparaissent alors dans les équations du modèle et traduisent entre autres linfluence des phénomènes non axisymétriques. L'importance relative de ces différentes contributions est analysée. Les méthodologies développées sont appliquées à plusieurs cas-tests (rotor simple, étages de compresseur ou de turbine, compresseur multi- étagé), qui permettent d'illustrer l'intérêt de la démarche proposée.