特殊葉尖幾何對螺槳葉尖流場影響之探討

The Effect of an Unconventional Tip Geometry on Propeller Tip Flow Phenomena

本文將探討如何建立一套結合數值計算與模型試驗之方法以評估一種新型的「葉尖圓角（Tip-fillet）」螺槳對於抑制葉尖渦流空化發生之效用。本文首先將描述葉尖圓角螺槳之設計方法，並展示數種不同葉尖圓角設計螺槳，再以勢流邊界元素方法及黏性流平均雷諾數（RANS）方法分析比較數種不同葉尖圓角設計對葉尖渦流空化發生之影響。勢流與黏性流程式之計算結果將仔細比對以確保數值計算結果之可靠性，對於如何從計算結果判別較佳設計之方法亦將在文中詳加討論。由計算結果顯示，葉尖圓角設計的確可以改變葉尖渦流現象，其效果將因不同之葉尖圓角設計而有所不同。最後，葉尖圓角設計螺槳並與傳統螺槳進行空蝕試驗比較以驗證數值分析結果之可靠性。 In this paper, a methodology which consists of numerical analysis and experimental tests will be established and used to investigate the effects of one special kind of propeller tip geometry, namely, the ”tip fillet”, on tip flow phenomena. The design process of this unconventional propeller tip geometry is first described, and several different designs are then demonstrated in the paper. Both the potential flow boundary element method and the viscous flow RANS method are used to compute the forces and flow field of these propellers with different tip geometries. In order to be confident about the computations, computational results from both potential flow and viscous flow methods are compared to each other and carefully verified, The criteria of determining which tip geometry is better to the formation of tip vortex are then discussed in the paper. It comes to the conclusion that the unconventional propeller tip geometry presented in this paper is more effective in controlling tip vortex formation than conventional tip geometry, and the effects are different for different designs. Finally, experimental results of designed tip geometries are investigated and compared to that of conventional tip geometry to confirm the computational results.