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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
81

Velocity field measurement of a scroll vortex intake flow

Guo, Jiuhao., 郭九昊. January 2012 (has links)
A scroll vortex intake is a hydraulic structure that transfers water stably from one elevation to a lower one by generating a swirling vortex flow down a vertical drop- shaft. Scroll vortex intakes are applied widely in water supply, stormwater drainage and sewerage systems. For a good engineering design, a sufficiently large and stable air core needs to be maintained within the dropshaft. Although a number of the- oretical and experimental investigations have been conducted, the understanding and predictions of the vortex flow is still far from complete due to a lack of de- tailed velocity field and air core measurements. This study aims to achieve a better understanding of the scroll vortex intake flow. The hydraulic theory of scroll vortex intake is revisited and detailed measurements of air core and velocity field of the vortex flow is conducted. A 1:15 physical model of a scroll vortex intake has been designed according to dynamic Froude similitude and constructed. Experiments have been conducted to measure the head-discharge relation. Piezometric head and air core size are measured at the throat of the vortex flow. Velocity fields are measured using Laser Doppler Anemometry (LDA). The measurements show that the vortex flow in the chamber resembles a free vortex and the circulation is approximately equal to that at the inlet to chamber. The chamber flow is not affected by the bottom boundary effect at bottom above a depth of the order of the dropshaft diameter. The throat section of the vor- tex flow is located slightly below the chamber bottom and within the bellmouth at the entrance to dropshaft. For the vortex flow in and downstream of the bell- mouth, the tangential velocity distribution can be described by a Rankine vortex (combination of forced and free vortex); the transition from forced to free vortex occurs at around the middle of the vortex flow layer. The pressure is positive for all locations and all discharges. Due to viscous effect, the maximum circulation is found to be lower than the inlet circulation. Consistent with the free vortex theory, the vertical velocity in the dropshaft is approximately constant. By accounting for the loss of circulation between chamber inlet and the dropshaft, a new 1D theory is proposed. Unlike previous models, the new theory gives good predictions of head-discharge relation and minimum air core size without the need of physically unrealistic assumptions. This study has revealed the structure of a scroll vortex intake flow for the first time. Characteristic flow features of the scroll vortex intake have been elucidated. The findings have helped to explain and resolve the long-standing discrepancies between the theoretical predictions of three representative 1D hydraulic theories. The vortex flow measurements also provide a basis for the development of a new theory and the validation of 3D numerical models. / published_or_final_version / Civil Engineering / Master / Master of Philosophy
82

Theory and simulation of sheared flows and drift waves in the large plasma device and the helimak

Perez, Jean Carlos 28 August 2008 (has links)
Not available / text
83

Numerical study of an isolated vortex and the lower critical field of a type-II superconductor in the presence of a twin plane

郭明遠, Kwok, Ming-yuen, Edward. January 1996 (has links)
published_or_final_version / Physics / Master / Master of Philosophy
84

Three-dimensional simulation of N₂O transport and antarctic vortex evolution

Lou, Guang Ping 12 1900 (has links)
No description available.
85

A smoke study of the motion of the vortices shed from the tips of a two-bladed model helicopter rotor in hovering flight

Swavely, Craig Eugene 12 1900 (has links)
No description available.
86

An experimental determination of the motion of a vortex sheet in the wake of an isolated two-bladed hovering model helicopter rotor

Scott, James Irvin 12 1900 (has links)
No description available.
87

Formation and evolution of tip vortices of an isolated rotor in forward flight

Wong, Oliver D. 12 1900 (has links)
No description available.
88

An experimental study of skin friction on a stationary flat surface in contact with vortex flow

Huntley, James Richard 08 1900 (has links)
No description available.
89

3D vortex flows in micro capillary tubes with patterned surface charges /

Zhang, Peng. January 2007 (has links)
Thesis (Ph.D.)--Hong Kong University of Science and Technology, 2007. / Includes bibliographical references (leaves 137-145). Also available in electronic version.
90

A study of the angular velocity in a liquid induced by a vortex in an emptying container

Hartman, James Paul, January 1963 (has links) (PDF)
Thesis (M.S.)--University of Missouri, School of Mines and Metallurgy, 1963. / Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed July 1, 2008) Includes bibliographical references (p. 32).

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