EXPERIMENTAL STUDY ON A NEW KIND OF OPEN TYPE BREAKWATERS

A new kind of open type breakwaters was proposed based on the concept of wave energy conversion. The excellent feature of the structure is that it can absorb and utilize the wave energy to dissipate waves. The effects of some factors, such as the configuration insides, the geometrical parameters and the relative width (the ratio of the width to the wave length), on the performance of the breakwater were discussed based on a series of regular wave tests in the wave flume. The hydrodynamic characteristics of the new open type breakwater were analyzed in detail, and the structure was optimized to improve the performance of the breakwater to effectively dissipate the waves with long period. The variation of the coefficients of wave transmission and reflection along with attenuation with respect to relative width was examined. The results of the physical model tests indicate that the transmission coefficient significantly decreases by about twenty percent at the range of relative width from 0. 1 to 0.2, compared with the traditional open type breakwaters.     

数字波浪槽在防波堤预设计中的应用

传统的以物理模型进行的防波堤断面实验被以计算机进行的数字波浪槽代替,边界造波为Bretschneider/Mit-suyasu波浪谱,防波堤断面根据海港水文规范(简称“规范”)设计。以改进的Boussinesq波浪方程,通过引入波浪反射项以数值模拟实现了波浪在水槽中传播的全过程。通过数值水槽获得了波浪在本文防波堤断面前0.45的反射系数,将数值模拟的结果和规范中的反射系数进行了对比得出,数字波浪水槽有满意的精度以及在规范中使用了一定的安全系数,表明数字波浪槽在防波堤的预设计中有重要作用。     

斜坡式防波堤前海冰堆积数值模拟

本文将海冰在斜坡式防波堤前的堆积过程简化为二维的动力学问题，假定海冰为粘弹性体，在多边块体运动模拟系统基础上，采用离散元数值方法对冰排爬升堆积过程进行了实时仿真模拟。通过与二维理论断裂模型及物理模型试验结果对比，证明了此数值模型的合理性与可行性。     

Experimental study on wave-current structure around a pneumatic breakwater

A model of a pneumatic breakwater comprised of perforated pipes placed on a wave flume bottom and connected to a piston-type air compressor is installed in a wave flume. Ascending air bubbles form an aerial barrier which dissipates wave energy and reduces the height of transmitted waves. The model is exposed to regular waves with fixed parameters, and its properties are modified by changing the amount of air supplied to the pipes. Particle Image Velocimetry and Acoustic Doppler Velocimetry methods are employed to measure a wave-current velocity field in the close vicinity of a submerged aerial barrier used as a breakwater. The measurements are supported by free-surface elevation registration in order to evaluate the effectiveness of the pneumatic breakwater in damping waves and to identify processes responsible for wave energy dissipation. Basing on the measurements, the performance of the pneumatic breakwater in different wave conditions is analysed. The results indicate that the dissipation of energy inside a region of a turbulent flow induced by ascending air bubbles may be considered the main mechanism of wave energy attenuation by pneumatic breakwaters.     

Study on influence of different buried depth of steel cylindrical breakwater on seismic stability of structure

以位于高地震烈度区的某实际港口防护用的大直径薄壁钢圆筒-筒内改良土防波堤结构为研究对象,基于有限元数值模拟与室内振动台试验,探讨钢圆筒不同入土深度对该结构抗震稳定性的影响规律,得到在不同峰值加速度的地震波作用下,不同钢圆筒埋深比结构的位移与加速度时程反应曲线、地震作用前后地基土体的剪应力分布曲线。研究结果表明：钢圆筒埋深比、地震动峰值加速度、地基土压力是显著影响防波堤结构动力稳定性的重要参数,并且三者具有紧密的关联性。随着钢圆筒埋深比的增大,其地震位移响应与加速度响应呈现相反的变化趋势,并且地震前后的地基土压力变化幅度也相差较远。基于实际钢圆筒防波堤工程的场地条件与抗震等级,为保证钢圆筒防波堤结构的正常使用状态,提出了钢圆筒埋深比的合理取值范围。     

圆弧面防波堤的水力特性研究

指出圆弧面防波堤是在半圆形防波堤基础上开发的一种新型防波堤,利用数值波浪水槽对圆弧面防波堤的水力特性进行了初步研究,同时对波浪要素及防波堤断面设计进行了分析,得出一些有益的结论。     

弹簧刚度对嵌入式振荡水柱波能装置水动力性能的影响

提出嵌入方箱式防波堤的垂荡式振荡水柱（OWC）波能装置,利用开源计算流体动力学库OpenFOAM及工具箱waves2foam,对该波能装置的能量转换效率和水动力特性开展数值研究.采用流体体积法（VOF）捕捉气液界面,利用Rigid-Body Dynamic网格技术求解垂荡运动.在不同入射波频下,探究垂直线性弹簧约束（用无量纲弹簧刚度表示）对OWC波能装置的波能转换效率、反射系数、透射系数、能量耗散系数、相对压降、有效相对振荡幅度和相位差等的影响.结果表明,结构物适当的垂荡运动有利于提升OWC装置在特定频率条件下的波能转换效率;振荡水柱和结构物间的运动相位差是决定能量转换效率的关键因素;为了提升能量转换效率,调节结构物的垂荡运动来控制相位差的措施是可行的.     

罐车防波板受力分析和优化设计

罐车防波板是罐车在紧急制动时,减小罐体内介质剧烈运动,避免介质对罐体的撞击,保障罐车平稳运行的作用。然而由于防波板设计和制作过程不被重视,加上受力复杂,致使超过30％的罐车防波板在年度检验的时候发生不同程度的损坏,有的甚至脱落,开裂,所以为了减少防波板的损坏,就必须了解防波板各部位的受力状况,找出防波板的损坏原因,并根据分析结果有针对性地作出优化设计方案。为提高防波板的使用寿命,保障罐车安全运行,建议尽快修改《汽车罐车安全技术监察规程》中不合理的部分,使此《规程》能更好地指导罐车的设计和制造。     

离岸堤在海岩防护中的应用探讨

由于海岸侵蚀问题日益严重,海岸防护已成为海岸工程研究的重要内容.通过对目前常用的几种海岸防护形式的综述,提出离岸堤是一种有效且应用广泛的护岸结构物.根据国内外的研究成果,从水动力过程、泥沙运动机制以及岸滩响应等方面,阐述了出水离岸堤的防护机理,并总结归纳了堤后岸滩响应的预报经验公式和稳定岸线形态模型.最后,回顾了近年来离岸潜堤在海岸防护中的研究概况,对其防护机理进行了初步分析,并在此基础上就离岸潜堤防护的进一步研究提出了建议.