升船机提升系统中船厢、水体和钢缆相互耦合作用分析

An Analysis of the Interaction of Ship Chamber,Water and Cables in Ship Lift System

本文在作者 [1 ] 先前采用水弹性理论建立的对整个提升系统的动力特性进行数值研究的理论模型的基础上 ,首先对船厢变形状态下的缆力表达式作了更为详细的推导 ,然后以中国船舶科学研究中心的 1∶ 3 0的缩比模型为对象 ,从整体角度 ,对其流固耦合问题 ,主要是提升过程中船厢内水体的晃荡、提升缆的受力和船厢动态响应 ,作了数值研究。在提升系统受到船厢内一非对称水波扰动的假定下 ,分别对船厢简化为刚性和考虑实际弹性的两种情况进行了计算、分析和对比 ,得出了一些有益的结论。计算结果表明 ,对升船机这样一个复杂系统 ,文献 [1 ]中所建立的理论模型及本文的数值计算方法是可行的。

The theory developed by authors in reference[1] for simulation of liquid sloshing and its interaction with flexible structure in time domain is applied to a very complicated dynamic system of a 1:30 scale reduced model of the ship lift for the dam of Three Gorges. Combing the sloshing problem with the structure of the ship chamber and the lifting cable as one entirety, the expressions of generalized cable forces are deduced and the characteristics of the ship lift system are analyzed. The procedures of solving the equations based on the Admas-Bashforth prediction-correction method and the time advancement technique are employed for solving the dynamic equations of the structure described in principal coordinates. The calculation is carried out under the assumption that the system is excited by an initial wave elevation. The non-linear dynamic behaviors of the fluid and the structures are numerically simulated and the responses including water wave elevation, motions of ship chamber and lifting cable force are obtained. Some results are compared with test ones of a 1:30 scale reduced model. The results show that in such an excitation:1) Even though the difference of the fluid field between two cases: the ship chamber is treated as rigid and flexible is not obvious, the change of cable force induced by the change of rigidity of ship chamber cannot be ignored. The more flexible structure is, the more uniform distribution of cable force is. 2) No matter the structure of ship chamber is rigid or not, a very low frequency can be seen in the history of water wave elevation and cable force. This phenomenon also was discovered in the structure strain curves by test. Conclusively, it is shown that the theory built in reference[1] and the numerical method adopted in this paper are useful to predict the dynamic response of complicated system such as ship lift.