Thesis (M.S. in civil engineering)--Washington State University, December 2007. / Includes bibliographical references (p. 45-48).

Thesis (Ph.D.)--University of Adelaide, School of Mathematical Sciences, Discipline of Applied Mathematics, 2004. / "January 14, 2004" Includes bibliographical references (leaves 201-213). Also available online.

An impermeable weir constructed across a stream prevents the longitudinal movement of aquatic life and transportation of physical and chemical substances in water, eventually having a negative impact on river environment. However, a rubble mound weir is considered environmentally friendly, since its permeability allows the streamwise migration of aquatic life. This thesis investigates the performance of this type of weir as a water use facility. The particular objective of the investigation is to study the flow mechanism in terms of water surface profile and discharge through the weir. In the study, flow through the rubble mound weir is considered non-Darcian, steady, and one-dimensional. In the analysis, gradually varied open channel flow algorithm is applied to porous medium flow through the rubble mound weir in which laminar and turbulent components of flow are taken into consideration. Unlike previous studies where Stephenson and Wilkins relations were used, in this thesis Forchheimer equation is used. To verify the validity of numerical solution of governing equation based on Forchheimer relation, an experimental investigation is conducted in the laboratory. The experimentally obtained water surface profiles are compared with the numerical results. It is observed that there is a satisfactory agreement between numerical and experimental results. The water surface profiles obtained by numerical solution are further compared with those based on Stephenson and Wilkins relations. It is concluded that the proposed numerical solution technique for the Forchheimer based governing equation may be used in the analysis of flow through, and design of rockfill weirs.

Since the discovery of the drag reduction effects of even small amount of macromolecules in solutions in turbulent pipe flows, there have been many experimental and theoretical studies in order to understand mechanisms behind this phenomenon. Theories have been proposed based on the observations on the change in the characteristics of the turbulent flow near the pipe wall where friction of the momentum transfer between the flow and the conduit takes place. In this study drag reduction in fully developed turbulent pipe flow with four concentrations (200 to 500 wppm) of low molecular weight Sodium Carboxymethylcellulose (CMC) in aqueous solutions was investigated experimentally. Drag reduction was determined by pressure drop measurements. In order to observe the impact of the presence of CMC on the flow, Ultrasound Doppler Velocimetry (UDV) was employed to monitor the instantaneous velocity distributions. UDV is a non-invasive technique allowing one to obtain quick velocity profiles. Experimental measurements were used to calculate Fanning friction factor and radial distributions of the axial time-averaged velocity, velocity fluctuation (turbulent intensity) and eddy viscosity. The drag reduction level was determined through the Fanning friction factor versus Reynolds number data. Velocity data could be obtained as close as 3 mm to the wall by UDV. Two impacts of increasing CMC concentration on the flow field, hence pressure drop, were observed. The first effect was the decrease of the mean velocity gradient especially near the wall with increasing polymer amount which in turn gave rise to lower friction factor or pressure drop. In addition smaller eddy viscosities were obtained in the flow. The second impact of the polymer addition was on the velocity fluctuation or turbulent intensity variation along the radial distribution. An increasing trend in turbulence intensity in the turbulent core with polymer addition was observed. This was in agreement with the earlier studies in which similar turbulence behavior was observed in addition to the suppression of the turbulent intensities near the wall

Thesis (M.S.)--University of Montana, 2008. / Title from title screen. Description based on contents viewed Aug. 27, 2008. Includes bibliographical references (p. 90-94).

Cette thèse s'inscrit dans le cadre des énergies renouvelables au sein du programme HARVEST centré sur le développement d'un concept d'hydrolienne dérivé des turbines Darrieus et Gorlov. L'ajout d'un dispositif appelé carénage à la turbine permet à celle-ci d'extraire une portion de l'énergie cinétique du courant plus grande. Toutefois ce dernier peut favoriser la cavitation qui nuit à la turbine. Parmi les différents axes du programme, les travaux de thèse se situent dans cette problématique. En régime subcavitant et cavitant, l'analyse de l'hydrolienne a été menée suivant une approche numérique et expérimentale. Pour ce faire deux outils ont été mis en place. Du coté expérimental, le tunnel hydrodynamique du LEGI a été équipé d'une balance qui donne la mesure instantanée des forces et du couple qui s'exercent sur la turbine. Du coté numérique, les efforts ont été orientés sur l'amélioration et le développement du code de calcul universitaire, CAVKA. L'utilisation intensive de ces deux moyens, couplée à des modèles théoriques, a permis de mettre en évidence d'une part le fonctionnement de la turbine libre ou carénée et, d'autre part, les limites de fonctionnement vis-à-vis de la cavitation. / The general context of the present thesis is renewable energies within the HARVEST project, which consists in a water current turbine (WCT) development, inspired from the Darrieus and Gorlov geometries. The main advantage of the HARVEST WCT is the introduction of a channelling device, which allows extracting a bigger amount of the kinetic energy contained in the flowstream. However, the shrouding device can eventually increase cavitating risks, which generally damage the WCT itself and its performance. The main topic of this work is cavitation. The hydrodynamic behavior of the WCT is analyzed both numerically and experimentally, in non cavitating and cavitating conditions. For this analysis, two devices have been developed. On the one hand, the LEGI hydrodynamic channel is equipped with a measurement platform which provides the instantaneous and average measurements of two dimensional thrusts as well as the hydrodynamic torque. On the other hand, in the numerical domain, the work has been oriented to the improvement and the development of a CFD code, named Cavka. The intensive utilisation of these two devices, coupled to theoretical models, allow highlighting the functioning of the bare and shrouded WCTs and their limits in cavitating conditions.

Le but de cette thèse est le développement et l'optimisation de la chaine électrique d'une hydrolienne fluviale. L'approche est d'abord traitée en simulation pour ensuite finir par la conception et la mise au point d'un prototype. La partie simulation concerne la modélisation des ensembles turbines, génératrices et électronique de puissance mais aussi le développement des diverses lois de commandes. Ces commandes peuvent intervenir à différents niveaux du contrôle jusqu'à la supervision complète du système, permettant de gérer des défauts, des algorithmes de MPPT (extraction maximale de puissance), des synchronisations entre colonne, ... Le prototype d'hydrolienne fluviale sera ensuite présenté, de la mise au point des parties mécaniques jusqu'aux résultats expérimentaux. Les travaux nombreux autour de ce prototype ont permis d'obtenir des résultats satisfaisants et encourageants qui corroborent la théorie. / The purpose of this thesis is the development and optimization of the electrical system of a fluvial cross-flow current turbine. The approach is first treated in simulation and then eventually with the design and development of a prototype. The simulation section deals with the modeling of turbines groups, generators and power electronics, as well as the development of various control laws. These controls may have an influence at different levels of the control strategies up to the complete system supervision for fault management, MPPT (maximum power extraction) algorithms, turbine columns synchronization... The fluvial cross-flow current turbine prototype will then be presented, from the development of the mechanical parts to the experimental results. The various works involving the prototype have yielded satisfactory and encouraging results that corroborate the theory.

Orientador: Evaldo Miranda Coiado / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo / Made available in DSpace on 2018-08-12T09:09:22Z (GMT). No. of bitstreams: 1 Paiva_LuizEvaristoDiasde_D.pdf: 35394414 bytes, checksum: 213e131fa220c1a9965c1c327156d87f (MD5) Previous issue date: 2007 / Resumo: Nesta tese apresenta-se uma alternativa à definição do diâmetro de cículo a ser usado nas equações de estimativa da descarga de sedimentos na camada do leito, em escoamento com superfície livre. Foram empregadas quatorze equações de estimativa da descarga de sedimentos, a partir das quais foram determinados os diâmetros que poderiam ser empregados em substituição áqueles definidos pelos respectivos autores das equações. Para o desenvolvimento deste trabalho, foram empregados dados coletados no Rio Atibaia em Sousas, no município de Campinas (SP). No decorrer dos estudos, verificou-se que a vazão e a declividade da linha de água foram as variáveis mais significativas na definição do diâmetro. Para validar a alternativa à definição do diâmetro de círculo a ser usado nas equações de estimativa da descarga de sedimentos na camada do leito, foram utilizados dados de dois outros rios, de porte menor e maior que o rio Atibaia. Para os dois rios, a aplicação da metodologia produziu resultados mais satisfatários, se comparados àqueles obtidos pelos métodos na sua forma original. A aplicaçã da metodologia proposta nesta tese apresenta; além de ter demonstrado reduções nas diferenças percentuais relativas entre os valores das descargas calculadas e medidas, a vantagem de poder ser empregada para cursos de água com granulometria uniforme ou não e dispensa o levantamento de dados granulométricos. / Abstract: This thesis presents an alternative proposal to evaluate the sediment size to be used in the methods to estimate its discharge from bedload when occurring under open flow water. Fourteen different equations were employed in this work. From this equations different diameters were obtained that could replace respectively those suggested for each equation. Also, in order to undetake this work, data were collected from Atibaia River, Campinas-SP. Analises of these data showed that the discharge and slope of free surface of water were the most important variable to define de sediment dimension. To validate the alternative proposal to the calculated diameter, dates were used of the two other rivers one smaller and the other larger than Atibaia. Metodology apllied to those data produced sactisfactory results compared with the original methodology. The proposed methodology applied during this studies, besides having demonstrated decreased relative differences between calculated discharges and the measured ones also showed that it can be used in rivers whit uniform or non uniform grain sizes eliminating the necessity of collecting granulometric data. / Doutorado / Recursos Hidricos / Doutor em Engenharia Civil

Goal 6 of the United Nations Development Program’s new Sustainable Development Goals aims to ensure availability of clean water and sustainable management practices to all by the year 2030. Peace Corps Panama partners with communities in order to help provide sustainable water solutions to communities in need. Water, Sanitation, and Hygiene (WASH) Volunteers spend at least two years living in a community to identify and implement solutions to water problems and train local water committees on how to maintain their improved systems. A common solution for unequal distribution of flow in the distribution network of a gravity flow water system is through the installation of flow reducers before each faucet. These can be sized with the help of NeatWork, a free, downloadable compute software. In Panama, flow reducers (also referred to as orifices) are manufactured to create a perforated plastic diaphragm fitting placed in the distribution pipe or union section upstream of a faucet. They help ensure longevity of the aqueduct by balancing the flows between houses, thus, enabling continuous water flow for all users. An important characteristic of flow reducers is that while they can be installed in new water sys-tems, they can also be installed in existing systems to fix inequalities from inadequate original designs or extensions to the systems. However, little guidance exists for volunteers or commu-nities to ensure the sustainability of these projects. Accordingly, the object of this thesis was to investigate how adding houses to existing aqueducts would affect its serviceability and how to determine a way for communities to size the flow reducers for future houses. The existing gravity flow water system in Santa Cruz, Panamá was surveyed including all the potential houses which were then analyzed using NeatWork. The results demonstrate that while it is better to include all potential locations during the initial survey, if it expands at an average growth rate, additional houses may decrease serviceability, but in a negligible way that will not affect the overall reliability of the distribution system. Utilizing NeatWork, this research showed it is able to determine ideal sizes of flow reducers for additional houses that could be added. Patterns were identified and used to simplify flow reducer sizing so that community members could do it themselves. While most of the time, the ideal flow reducer size for a new house will be the same size as the flow reducer size that is installed in the closest house that is already connected to the aqueduct, sometimes this is not the case. This typically occurs towards the end of branches and in areas where not all flow reducer sizes are present. These areas are clearly identified to the water committee on a map of the distribution system that was provided to various water committee members. With this map and simple instructions, the Santa Cruz water committee can continue correctly adding flow reducers to new houses. Through the research of this thesis, fabricating and installing flow reducers in the Santa Cruz water distribution system, and working alongside community members many lessons were learned about flow reducers and best practices. This knowledge has been converted into a guide about sustainable flow reducer projects. It has been left with current volunteers and the director of training for the WASH sector of Peace Corps Panama so that the volunteers can adapt the developed tools in their own communities.

Tyrolean type water-intake structures are widely used on mountain rivers to provide water to hydropower stations. The main concern encountered in these kinds of structures is the amount of water diverted from the main channel and sediment carried by this flow. The diverted flow should not be less than the design discharge of the hydropower station and the amount of the sediment entering the hydraulic system should be minimum. In this study a physical model of a Tyrolean weir was constructed at the Hydromechanics Laboratory and by varying the dimensions of the various components of this system / the length, the inclination angle of the rack and the distance between the rack bars, the amount of water and sediment entering the system were measured for a wide range of discharges. The experiments were conducted in two stages. In the first stage the tests were made with only water, and in the second stage, water and sediment having different gradation were used. Applying dimensional analysis to the related parameters of the system dimensionless terms were defined for water capture efficiency and discharge coefficient of the system, and their variations with the relevant parameters were plotted. Using these diagrams one can determine the amount of water to be diverted by a Tyrolean weir of known geometry and main channel flow.