Study on Hydroelasticity for Realization of Very Large Floating Structures

(1)提出了一种以矩形薄板固有模态叠加表示上部甲板弹性挠度的大型柱支撑浮式结构的计算方法，并正确考虑了大量支撑柱之间的水动力相互作用。(2)模型实验采用64个垂直圆柱，4排16列，等距布置。测量了一些单个圆柱体的水动力和沿结构中心线的波浪高度。实测结果与新建立的层次相互作用理论计算结果吻合较好。(3)提出了两种不同的计算方法来计算柱支撑的超大型浮体结构的波浪漂力和弯矩。一种是基于动量守恒原理的所谓“远场”法，另一种是基于直接压力积分的“近场”法。两种方法均能准确预测整个64缸的漂移力，验证了两种数值方法的有效性。测量了各圆柱上的局部定常力，结果与“近场”法计算结果吻合较好。(4)建立了飞机起降对浮桥式浮体结构瞬态弹性响应的时域计算方法。在数值精度和效率方面作出了特别的努力。将计算结果与船舶研究所的实测结果进行了比较，结果吻合较好，证实了所建数值格式的有效性。

(1) A new calculation method was developed for a column-supported very large floating structure, in which the elastic deflection of the upper deck was represented by a superposition of natural modes of a rectangular thin plate, and hydrodynamic interactions among a great number of supporting columns were correctly taken into account.(2) Model experiments have been conducted using 64 vertical circular cylinders arranged in 4 rows and 16 columns with equal separation distance. Measured were hydrodynamic forces on some of individual cylinders and the wave elevation along the center line of the structure. Measured results were in good agreement with the computed results by the newly-developed hierarchical interaction theory.(3) Two different calculation methods were developed for computing the wave drift force and moment on a column-supported very large floating structure. One is the so-called "far-field" method based on the momentum-conservation principle, and the other is the "near-field" method by the direct pressure integration.The drift force on the whole 64 cylinders was precisely predicted by both methods, confirming the validity of both numerical methods. The local steady forces on each cylinder were also measured and the results were in good agreement with computed results by the "near-field" method.(4) A time-domain calculation method was developed for evaluating transient elastic responses of a pontoon-type floating structure due to the take-off and landing of airplanes. Special efforts were devoted to the numerical accuracy and efficiency. Computed results were compared with measurements at the Ship Research Institute, which showed very good agreement confirming the validity of the developed numerical scheme.