四葉面積比0.75彎殿緣螺槳於斜軸10度狀況下之性能探討

On the Performance of Cupped Propellers with Four Blades EAR0.75 at Inclined Shaft Condition

本文主要目的是找出適合操作於35節以上之高性能彎殿緣母型螺槳，以確保該等螺槳操作於斜軸狀況下能維持較佳之效率並可以避免螺槳葉片浸蝕之發生。本文將先設計一組四葉面積比為0.75之KCA改良翼形彎殿緣螺槳P4016A，該螺槳於0.7半徑處之拱高比為18%，而彎殿緣量為該處最大厚度之24%，並與一組拱高比及負載相當之新翼形彎殿綠螺槳P4013A作陸能比較以選出一組優良之翼形作為母型該組螺槳於0.7半徑處之拱高比為1.9%，而彎殿緣量為該處殼大厚度之20%，最後再設計組新翼形螺槳P4018，其拱高於0.7半徑處降為1.66%，而其彎殿緣量增加為最大厚度之37%，以測試彎殿緣量增加對性能之影響。由實驗結果可知，操作於斜軸狀況下，新翼形P4018於低空化係數下較不容易產生推力突降比能明顯較好其次是新翼形螺槳P4013A，最差者是KCA螺槳因此增加足夠之彎殿緣可使螺槳於低空化係數時緩和推力突降與維持較高效率。另外彎殿緣螺槳確實能使泡狀空泡較穩定產生於螺槳葉片艉緣，而破裂於葉片之外。 In this paper, it is aimed at finding a perant cupped propeller, which has good efficiency and can avoid cavitation erosion on blade surface for operating speed above 35 knots and at inclined shaft conditions. Three propellers with 4-blades and area ratio 0.75 will be designed, and tested at cavitation tunnel at 10 degrees inclined shaft condition. These three propellers have almost same deign loading. The first one P4016A is a modified KCA propeller with 1.8% camber ratio at 0.7 radius, and the cup is 24% of the maximal thickness at this section. The last two P4013A and P4018 are with new-foil section. The camber ratio of P4013A propellers is 1.9% at 0.7 radius and its cup is 20% of the maximal thickness at this section. The camber ratio of P4018 is 1.66% and the cup is 37% of the maximal thickness at the same section. From the experimental results, it is shown that at low cavitation number, the thrust breakdown of P4018 is not serious and thus with best efficiency, and then P4013A. The worse one is P4016A. Therefore, enough amount of cup is important for high-speed propeller operating at inclined shaft condition. In addition, the cavitation bubbles are generated relatively stable on the surface near the trailing edge, and collapse outside the trailing edge for all three propellers.