| Summary: | 碩士 === 國立臺灣海洋大學 === 機械與機電工程學系 === 102 === This paper explores the different arrangement modes of side-by-side and Tandem of single and multiple wind turbine tower under the low Reynolds number, to study the influences of wake flow field behaviors, speed characteristics, vortex street and different horizontal and longitudinal spacing ratio (g*﹐L*) on the wake flow field. The first part goes into the single wind turbine tower flow field characteristics and aerodynamic force performance at different heights; in open-type wind tunnel, the flow field can be visualized by streak line to observe the flow behaviors of single wind turbine tower at different heights, involving 4 sections-the blade at the tower top, bluff body of blade and generator, cylinder of turbine tower and junction part at the bottom to observe the structure characteristics of the rear flow field. It shows that the top flow field is only affected by the blade wing-tip and thus generates the blade wind-tip vortex street, the flow field structure of hub bluff body effect owing to the interaction between turbine blade and generator, cylinder vortex street of wind turbine tower body and junction flow at the junction between the tower bottom and the ground. Then, with the hot-wire anemometer to measure the vortex street frequency and flow field speed characteristics at different height along the tower, it can obtain the turbulence intensity.
In the second part, it focuses on the arrangement modes of side-by-side and Tandem for wind turbine tower and the streak line visualization of flow field, and then observes the structure characteristics of flow field at different heights. As the spacing ratio changes, the characteristics modes of flow field can be concluded by observing the different heights of the tower. The characteristic mode of side-by-side double turbines can be divided into single mode, anti-phase vortex mode and in-phase vortex mode, while that for tandem double turbines falls into single mode, reattach mode and bi-vortex mode. When the spacing ratio is rather small, the double wind turbine towers can be treated as one, and its wake flow mode resembles a single tower in the flow field characteristics, which is called single mode. With the spacing ratio increasing, the flow fields around the towers interference with each other, the side-by-side towers may generate two streams of wake flow which are in a symmetrical pattern, making the flow field an anti-phase vortex mode; while the front wake flow of the tandem turbines is connected to the rear one, which seems like that the front one is closely attached to the rear one and then generates the rear wake flow, so it is called reattach mode. When the spacing ratio achieves to a certain degree, each turbine of the side-by-side mode equals to a single turbine respectively, which generate two streams of wake flow with the same patterns, showing that the flow fields aren’t affect each other, hence its name is in-phase vortex mode. In addition, two vortex structures are formed in the tandem mode turbines, in which the front vortex may cover the turbine behind as well as its flow field state, indicating that the front turbine is capable of driving the rear turbine and affecting the rear flow field, which is called Bi-vortex mode. Among all six modes, the anti-phase vortex mode of side-by-side and Bi-vortex mode of tandem arrangement are the best group turbine arrangement.
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