S-175集装箱船舶波浪载荷的船模试验与线性切片理论计算的比较

本文就日本S-175集装箱船舶的波浪载荷进行了船模试验与线性切片理论计算的比较,发现线性切片理论对于波浪载荷沿船长的纵向分布以及中拱与中垂的不同分量都与试验值存在着相当大的差异,仅纵向运动较为满意;揭示了对于在高浪级下快速舰船的波浪载荷,特别是砰击载荷应致力于开展非线性理论和试验研究。

MODEL TESTS OF S-175 CONTAINER SHIP ON WAVE LOADS AND COMPARISONS BETWEEN EXPERIMENTS AND CALCULATIONS OF LINEAR STRIP THEORY

According to the recommendations made by the Seakeeping Committee of the 15th ITTC that comparative study should be conducted on ship motions and wave loads of S-175 container ship, and in order to investigate the distribution of wave-induced moments along the hull of fast ship, an aluminum model of 1:55 scale was designed by employing the principle of similarity in hydrodynamics and structural dynamics. The hull was separated into six divisions and they were joined by a longitudinal circular steel beam through the whole length of the hull. At the seakeeping basin of CSSRC, measurements were made on moments, shearing forces and motions in regular and irregular waves. In head waves at Froude number equal to 0, 0.20 and 0.275 wave-induced bending moments(namely at stations 4 1/4, 7 1/4,12 3/4,153/4 and at the location of the centre of gravity), shearing forcesat the moddle section, heaving, pitching and wave heights were measured. In these experiments, the model was towed by a carrige and surge motion was restricted. Wave height measurement was made with an ultrasonic gage fixed to the carrige, and the height of regular wave and significant height of irregular wave were about L/42 and L/30 respectively.Experimental results were compared with those of theoretical calculations in which the computer programs of CSSRC and HSEI based on strip theory of S. T. F and K. K. J and SCORES were also used. From the results of comparison, it can be seen that at the section of the centre of gravity, bending moments calculated by using the programs of CSSRC and HSEI agree well with the experimental results both in amplitudes and trend. But, when SCORES was used, slight differences both in amplitudes and location of peak can be found. As to the other sections, the comparisons are satisfactory for the sections of afterbody, but for the sections of forebody, the calculated bending moments are obviously different from the experiments. However, for heaving and pitching, the results are fairly well for calculations made by using any strip theory.From the results of irregular wave experiment, it can be found that the components of the sagging moment are always larger than that of the hogging moment.The irregular wave experimental results were respectively shown in statistics of wave-induced moment ranges, sagging moment components, hogging moment components and magnitudes of slamming vibration double amplitudes. These results have provided useful data for comparative study of non-linear strip theory and for the theoretical research of slamming vibration moments.