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Experimental investigation on the endplate propeller for high-speed craft
|Authors: ||Sheng-Te Hsu|
|Contributors: ||NTOU:Department of Systems Engineering and Naval Architecture|
Cavitation;EAR;Endplate propeller;Inclined shaft
|Issue Date: ||2013-10-07T02:47:03Z
|Abstract: || 文旨在探討不同面積比、不同端板攻角與葉尖負載對高速端板螺槳(Endplate Propeller, ENDP)的性能影響，測試的兩組螺槳皆為新翼型且四葉的端板螺槳，第一組，面積比0.80，端板攻角負1.0度，第二組為面積比0.95，端板攻角負1.3度，於中型空蝕水槽測試於不同空化係數下以及斜軸8度與10度時之螺槳性能。 由實驗結果顯示，面積比0.8的端板螺槳於低空化係數下，無論在抗推力突降以及效率表現皆優於面積比1.0的新翼形螺槳。第二組螺槳於低空化係數背面空化明顯有效消除，但於270度時外圍半徑發生正面空化，顯示其螺距比太小與拱高過大所致，加上面積比較大而提高摩擦阻力，導致效率偏低，但不容易發生推力突降。由端板空化的狀況研判，最佳的端板設計角度應為負1.0度。最後倘若要用端板螺槳控制葉尖渦空泡與外圍片狀空泡，葉尖的拱高與螺距的設計必須審慎進行。|
The influence on the performance of high-speed endplate propeller (ENDP) with different expanded area ratios, angles of attack on the endplate and tip loadings was investigated in this paper. Two 4-bladed ENDP propellers were thus designed, one with an EAR of 0.78 and another with 0.80. Each propeller also includes geometrical variation with a negative angle of attack, at -1.0° and -1.3° respectively on the endplate, followed by pitch ratio, camber ratio, and span width of the endplate. Two propellers were tested at the National Taiwan Ocean University’s (NTOU) medium-sized cavitation tunnel covering a wide range of cavitation numbers (atm, 1.0, 0.75, 0.6, 0.5) and shaft inclination angles (0°, 8°and 10°). Finally, cavitation was photographed and compared between these propellers. From the experimental results it is shown that the efficiency and cavitation performance for the ENDP propeller with an EAR of 0.80 are better than those of the propeller adopting new foil sections with an EAR of 1.0. For the ENDP propeller with an EAR of 0.95, the back cavitation at low cavitation numbers can be eliminated effectively. However, face cavitation on the outer radii of the propeller occurred due to a decrease in pitch when blade rotating at 270°. Furthermore, the propeller efficiency is decreased significantly due to the increased EAR. As can be seen from the local sheet cavitation on the endplate, the optimal angle of attack on the endplate remains at -1.0°.
|Appears in Collections:||[系統工程暨造船學系] 博碩士論文|
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