最小推进功率第二层评估方法分析

Comparison of Level 2 Assessment Methods for Minimum Propulsion Power

将国际海事组织海上环境保护委员会第76次会议批准通过的《船舶在恶劣海况下维持最小推进功率导则修正案》(MEPC76导则)与2013年的临时导则相对比,重点对导则中最小推进功率第二层评估方法的差异进行分析。实船验算和对比结果表明:在MEPC76导则提供的3种波浪增阻计算方法中,经验公式的计算结果与试验结果较为接近,但在局部谱峰周期范围内,计算的波浪增阻值小于试验值,2种波谱分析方法的计算结果偏大,在工程实践中可采用经验公式计算;MEPC76导则对推力减额系数和伴流分数进行调整,更符合实际,虽然其海况条件更恶劣,总阻力计算结果较大,但其螺旋桨推力计算结果与2013年的临时导则相当。

The Revised Guidelines for Maintaining Minimum Propulsion Power of Ships in Adverse Sea Conditions(MEPC76 Guidelines)approved by the 76th Meeting of the Maritime Environmental Protection Committee of the International Maritime Organization is compared with the 2013 Interim Guidelines,with the focus on studying the differences in the Level 2 assessment methods for minimum propulsion power in the guidelines.The actual ship verification and comparison results show that the calculation results of the empirical formula are relatively close to the experimental results of the three wave resistance calculation methods provided by the MEPC76 guideline.However,the calculated wave resistance is smaller than the experimental value within the local range of the spectral peak period,while the calculation results of the two wave spectrum analysis methods are relatively large.Therefore,the empirical formula can be used for the engineering calculation.The MEPC76 guideline adjusts the thrust reduction coefficient and wake fraction to align better with the reality.Although the sea conditions are more severe and the total resistance calculation results are larger,the propeller thrust calculation results are comparable to the 2013 Interim Guidelines.