舵球推力鳍对最小推进功率的影响

Effect of Rudder Bulb and Thrust Fins on Minimal Power of Propulsion

针对安装有水动力节能装置的船舶,在最小推进功率的评估中,IMO临时导则的估算公式尚未涉及节能装置的影响.以数值模拟为主要手段,以大型散货船及其舵球推力鳍为研究对象,在验证了数值模拟方法的可靠性之后,重点对舵球推力鳍影响下的伴流分数、推力减额以及产生的节能效果进行了研究,为完善最小推进功率导则提供技术支撑.研究认为,临时导则第3.9条中静水阻力经验公式有良好的精度;舵球推力鳍对船舶静水阻力的影响很小,几乎可以忽略不计;数值计算结果显示,舵球推力鳍对推力减额、伴流分数有明显的影响,舵球推力鳍在超低航速时的节能效果远高于设计航速的节能效果,但是经验公式中并没有考虑节能装置在超低航速时对推进性能的影响.

Model tests and numerical simulation are carried out for a large bulk carrier together with the rudder bulb and thrust fins.Resistance and self-propulsion performance of the ship model at ultra-low speed is analyzed.It is proposed through the study that the empirical formula of hydrostatic resistance recommended in the term 3.9 of the Interim Guidelines has good accuracy,but influence of the rudder bulb and thrust fins on the hydrostatic resistance of the ship is so weak that can be neglected.Numerical calculation shows that effect of the rudder bulb and thrust fins on both the thrust deduction and wake fraction is significant.Energy saving effect of this device at ultra-low speed is much stronger than that at the design speed,which is not yet considered in the empirical formula.