大型船可调桨推进装置机动工况分析不容忽视

No Ignorance of Large Ship's CPP Mobil Operating Condition Analysis

论述主柴油机螺旋桨(FPP、CPP)推进特性的同时,结合螺旋桨推力系数(KP)、扭矩系数(Km)、随螺旋桨进程比,(λp)的变化情况,指出λp在大于某一定值后,螺旋桨将出现负推力和负转矩,这称为螺旋桨的水涡轮工况。此现象多发生在船舶机动作业的紧急换向工况中,对于CPP船若控制不慎,可能引发主机飞车或使船舶实际换向时间太长,两者都将延误船舶紧急避碰时机。现推荐一种"能耗法"的控制方法,可以有效地缩短船舶紧急换向实际时间,避免海难事故,保障航行安全。

The propulsive characteristics of main diesel engine propellers(FPP,CPP) is discussed,also it is pointed that propeller thrust and torque coefficients vary with advance ratio and propeller will have negative thrust and negative torque when the advance ratio is greater than a certain value.This so called propeller water turbine operating condition generally occurs in ship's reverse emergency operating conditions(ship mobile operations).For CPP ships,it may cause propeller racing without cautious control or longer reverse time,both of which will make ships delay collision avoidance.A kind of control method named 'Power Consuming Method' is recommended,which can shorten actual time for ship emergency reverse effectively as to avoid accidents and assure sailing safety.