风浪中船舶主机油耗预报方法

基于模型试验,采用1978年国际拖曳水池会议(International Towing Tank Conference,ITTC)推荐的实船功率、航速预报方法对船舶在静水中的主机功率和航速进行预报。采用ITTC推荐的阻力、推力一致法对船舶在风浪环境中的功率进行预报,其中,风阻采用经验公式计算,波浪增阻采用基于切片法的辐射能法和近似公式计算。在此基础上,结合主机的燃油特性,对船舶在风浪中的主机油耗进行预报。分析风速、波高和浪向对主机油耗的影响,结果表明:在艏斜浪范围内,浪向对油耗的影响不明显;随着波高的升高和风速的增大,相同转速下船舶的航速减小,单位里程的油耗增加。

Prediction of Fuel Consumption for a Ship in Wind and Waves

The speed-power relation for the ship in calm water is obtained from model tests.The power increases for wind and waves are computed with RTIM(Resistance Thrust Identical Method)recommended by ITTC(International Towing Tank Conference).The added resistance due to wind is calculated with the empirical formula,and that due to waves against the ship is calculated with radiated energy method together with STF strip method,meantime,the resistance corresponding to wave reflection is calculated by an approximate formula based on reflection law.The resultant fuel consumption is calculated according to the fuel characteristic of the main engine.The effects of wind speed,wave height,and wave direction on fuel consumption are examined.It shows that the fuel consumption goes up as wave height/wind speed increases,but almost does not change with wave direction.If engine rpm is kept constant,a lower ship speed signifys higher fuel consumption per mile.