Development of Front Wheel to Improve Propulsive Performance of Ship

点击翻译按钮获取中文摘要

We aimed to develop a front wheel (F.W) which improves the propulsive performance of ship. Research results are as follows :(1) We made 22 F.Ws with different number of blades, diameters and pitches, and performed the interaction experiments among a propeller and F.Ws in a circulating water channel. From these tests, we understand that we can not improve the propulsive performance of the system with F.Ws rotating contrary to propeller rotation.(2) We measured the velocity field behind a working propeller, and confirmed that the flow behind a freely rotating propeller was retarded and it increased the thrust of a propeller set behind the front propeller.(3) We made 4F.Ws with 8 blades and 24cm diameter, i.e. two flat plate F.Ws (F60 and F65) and two constant pitch F.Ws (C60 and C65), and performed the interaction experiments among the propeller MP.261 (diameter 24.08cm) and F.Ws. Due to counter rotation of F.W against the propeller, the performance of the system was not improved.(4) In … More a cavitation tunnel, we did the interaction experiments among propellers (MP.105 and 261) and F65 and also between propeller MP.262 and C60. Then the counter rotating systems (F65 + MP.105 and F65 + MP.261) decreased the efficiency of the systems. On the contrary, the efficiency of the same rotation system (C60 + MP.262) was unchanged compared with the open water characteristics of MP.262. As to the cavitation, we confirmed that F.W could fairly decrease the cavitating area on the propeller blade in uniform flow.(5) We conducted the self-proptulsion test of a large ship model (length 6m) with C60 and MP.262, and analyzed the test results based on the open-water characteristics of the system (C60 + MP.262) and confirmed the improvement of propulsive performance due to F.W at two speeds.(6) By using small Wigley model (length 2.5m) and 6 flat plate F.Ws (diameter 10cm, 8 blades), we performed the load varying tests and analyzed the propulsive performance and confirmed the propulsive efficiency increased only in case of same rotation system.(7) After making a computer code to calculate the propulsive performance of ship with F.W, propeller and rudder, we made clear the mechanism of interactions among them. Less