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Development of a Design Method for Propellers in the Unsteady Inflow
|Contributors: ||NTOU:Department of Systems Engineering and Naval Architecture|
|Issue Date: ||2012-04-13T01:21:15Z
|Abstract: ||目前進行螺槳設計時的入流設定，大多是採用周向平均值，本 計畫希望提出一螺槳設計方法，能考量非定常流入流變化的效應。 所提的計畫將以兩年的時間完成，第一年將著重於理論與方法的建 立，並將以邊界元素法為計算方法；第二年將應用黏性流計算方法 作為設計的計算方法，並將探討設計應用於實際螺槳設計的效益。 本計畫在最佳化方法上，將結合拉格朗日法與伴隨法，以給定 扭力，設計最大推力為設計目標，並將使螺槳於不同周向位置時的 壓力變化受到控制。我們將嘗試兩種機制，第一種是將壓力變化設 為限制條件，第二種則是將壓力變化設為設計條件，後者並將使得 設計問題成為多目標的設計問題。此設計方法的設計參數除了幾何 的螺距與拱高外，並將環流分佈的變化也設為參數，這是因為考量 非定常流時，最佳環流分佈可能與定常流中的設計不同。我們也將 應用黏性流的計算方法於此設計方法，由於黏性流計算方法計算時 間冗長，必須發展較有效率的計算方法與設計策略，包括應用“類定 常流”的計算，應用“資料庫方法”進行梯度計算等。此次所提出的計 畫，探討非定常流中入流變化對於螺槳設計可能的影響，將可使得 螺槳設計進入一新的領域，並可能由於新的設計，對於節能減碳帶 來一定的績效。|
Most of the propeller design methods, the inflow is assumed to be the circumferential mean value. In the proposed project, a propeller design method will be developed based on the unsteady inflow. This is a two-year project, and we will focus on the theory and algorithm developments in the first year, and the design method will also be established based on the potential flow boundary element method in the first year. In the second year, the viscous flow RANS method will be used as the computational method, and practical designs will be carried out using the developed methods. The Lagrange-Multiplier method along with the adjoint method will be used to solve the design problem. The objective function of this design problem is to maximize the thrust, and the torque is given as a constraint. When considering the unsteady inflow, the variations of the pressure on the blade surface at different angular positions are designed to be minimized. Two different design algorithms will be developed, and the first one is to set the variations of the pressure as a constraint, and the second one is to set the variations of the pressure as an objective function. The design problem thus becomes a multi-objective optimization problem for the second algorithm. The design parameters will be the pitch and camber distributions, and the circulation distribution will also be used as the design parameter. This is because that the optimum circulation distribution considering the unsteady inflow may be different from that obtained from the steady inflow. The viscous flow method will be used as the computational method in the second year, and efficient computational procedures and design strategies will be used and evaluated since the viscous flow computational method is time-consuming. For example, the quasi-steady flow will be used as the inflow instead of the unsteady inflow, and the database will be established for the computations of the gradients. The proposed project will investigate the influence of the unsteady inflow to the propeller designs, and this may bring the propeller design to a new era. The assistance of the proposed method to the propeller designs may also benefit the energy-saving issues.
|Appears in Collections:||[系統工程暨造船學系] 研究計畫|
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