大尺度自航模气层减阻试验研究

Experimental study of air layer drag reduction of self-propelled model

[目的]旨在研究气流量、航行倾角对船底凹槽内气层保持和节能效果的影响。[方法]以一艘肥大型散货船的较大尺度缩比模型为研究对象,通过设计气层减阻自航模系统和船底凹槽方案,开展开阔水域条件下自航模气层减阻试验,研究模型正浮状态下喷气减阻效果,以及模型一定纵倾角状态下对航速和轴功率的影响。[结果]结果表明:在主机转速一定时,喷气可以明显提高自航模的航速,停止喷气后,船底凹槽内的气体仍能维持较长时间;船体艉倾角为0°~0.25°时的气层减阻效果较好,较大艉倾角时气体从自航模艏部两侧溢出,气层无法对船底实现有效覆盖,减阻效果不佳。[结论]研究结果可对气层减阻技术在肥大型船舶上的工程应用提供一定参考。

[Objectives]This paper explores the effects of air flow rate and sailing angle on the air layer retention and energy efficiency of the bottom groove of a ship,focusing on a large scale model of a bulk carrier.[Methods]An air layer drag reduction self-propelled model system and hull cavity scheme are designed,and drag reduction experiments are conducted under open water conditions.The jet drag reduction effect on the model in a positive floating attitude of ship is examined,as well as the impact of a certain trim angle on the speed and shaft power of the model.[Results]The results indicate that,when the main engine speed is constant,air injection can significantly improve the speed of model;after stopping the jet,the air layer within the air cavity of the bottom groove can be maintained for a long time,with better drag reduction efficiency when the ship is in an upright state and the trimming is within 0.25 degrees.When the trimming angle is too large,the gas will overflow from both sides of the model head and the air layer will not effectively cover the bottom of the ship,decreasing the efficiency of drag reduction.[Conclusions]Several meaningful conclusions are obtained from the above experiments,providing useful references for the engineering application of air layer drag reduction technology on full-formed ships.