本文以螺槳之尾跡流為主要研究之對象,使用邊界積分法計算尋找螺槳推進時螺葉所產生之尾跡流位置。本文假設流場內之流體滿足勢流,並以邊界積分法描繪物體邊界幾何,以及使用高斯積分法對離散後的邊界積分方程式進行積分,以求解此螺槳葉片上之速度勢分布與葉片尾端之環流量,而後將葉片上之速度勢與環流量帶入邊界積分方程式,即可找到流場中各點之速度勢。本文之目標為找到螺槳之正確尾跡流位置,而所使用的方式為藉由迭代改變螺槳尾跡流曲面形狀,並且計算其法向速度,由於理論上尾跡流曲面之法向速度應為零,因此將迭代調整後的尾跡流所計算出的法向速度做平均方均跟誤差,透過迭代調整尾跡流曲面形狀將誤差值最小化,以找到最佳的尾跡流曲面位置。本文將以NDSRDC N4118螺槳為例,尋找出此螺槳所產生之尾跡流位置。
The objective of this thesis is to locate the wake position of propellers in steady flow. The flow field is assumed to satisfy on the potential theory. In addition, the Boundary Integral Equation is applied to solve the velocity potential on the boundary of the propeller’s blades. Once the strength of the velocity potential is solved, it can be substituted back into the Boundary Integral Equation to find the flow field velocity potential at all the positions. In the final, by adjusting the shape of propeller’s wake, and minimizing the normal velocity on the surface of the wake, the ultimate goal is to select an optimal position of propeller’s wake. The NDSRDC propeller N4118 are used as the test case.