|Abstract: ||本研究探討低雷諾數下單一及多隻風力發電機塔(Wind turbine tower)以並列(Side-by-side)與縱列(Tandem)方式排列的方式，研究尾流流場行為、速度特性和尾流渦旋逸放等，以及在不同橫向與縱向間距比(g*、L*)對流場所造成的影響。第一部分為單一風力發電機塔在不同高度的流場特性以及氣動力性能；利用開放式風洞，以煙線流場可視化觀察單一風力發電機塔在不同高度位置的流場行為，分別為風力發電機塔最頂端葉片、葉片與發電機之鈍體、風機塔之圓柱以及底部連接處等四部分觀察其後方流場結構特性，其中最頂端流場僅受到葉片翼尖影響下產生於葉片後方的葉片翼尖渦漩流逸(Blade wing-tip vortex street)、風機葉片以及發電機其二者交互做用之鈍體效應(Hub bluff body effect)的流場結構、風機塔柱體之圓柱渦漩流逸(Cylinder vortex street)以及風機塔底部與地面連接處流場結構(Juction flow)，再使用熱線風速儀量測風力發電機塔各高度位置後方的渦漩逸放之頻率與流場速度特性，進而得其紊流強度。 第二部分為風力發電機塔以並列與縱列方式排列並透過煙線流場可視化，觀察其不同高度位置的流場結構特性。隨著間距比的改變，觀察風力發電機塔不同高度位置，可歸納出其流場特徵模態。並列雙風機的特徵模態可分為單一模態(Single Mode)、反相渦漩模態(Anti-phase vortex mode)與同相渦漩模態(In-phase vortex mode)，而縱列雙風機的特徵模態可分為單一模態(Single Mode)、再貼附模態(Reattach mode)與雙渦漩模態(Bi-vortex mode)。當風機間距比甚小時，可以將兩隻風力發電機塔視為是一個個體，而其尾流模態近似於單一風力發電機塔的流場特徵，此流場模態稱為單一模態(Single Mode)。隨著間距比增加風力發電機塔之間的流場開始互相干擾，並列雙風機後方會產生兩組尾流並呈現形狀恰好對稱的形狀，此區流場為反相渦漩模態(Anti-phase vortex mode)，縱列雙風機中位於前方風機的尾流會剛好連接到後方風機宛如前者貼著後者再產生後方尾流，此流場模態稱為再貼附模態(Reattach mode)。當間距比再增加並達到一特定值後，並列雙風機中各風機等同於單一風機的狀態，產生兩個尾流並且其二者形狀相同，表示其流場已不互相影響，稱此流場模態為同相渦漩模態(In-phase vortex mode)；縱列雙風機分別在前方後方的風機產生兩個渦漩結構，前方的風機渦漩包覆後方風機與其流場的狀態，表示前方風機有一定程度上帶動後方風機轉動並且影響到後方流場，此區流場模態稱為雙渦漩模態(Bi-vortex mode)。其中以並列方式排列的風力發電機塔之反相渦漩模態(Anti-phase vortex mode)為最佳的群組風機並列模態，而以縱列方式排列的風力發電機塔則是雙渦漩模態(Bi-vortex mode)為最佳的群組風機縱列模態。|
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.