受扰欠驱动自主水下航行器的最优扰动抑制控制

针对近水面航行的欠驱动自主水下航行器(AUV),研究了其波浪力作用下的航向控制问题。首先,利用局部微分同胚将AUV非线性系统转换为Brunovsky标准型系统;其次,基于波浪力的Morison方程给出了波浪力干扰外系统模型;然后,根据最优控制理论,基于二次型性能指标设计欠驱动AUV系统的前馈反馈最优扰动抑制控制律,并通过求解Riccati方程和矩阵方程获得。最后,通过AUV系统仿真实例验证了该方法的有效性。     

小直径组合桩的波浪力实验分析

本文给出小直径孤立桩、两个桩和2×2个桩的波浪作用力实验结果。在波浪水槽中以0°,45°,90°三个波浪方向测量了各桩所受的纵向力和横向力,文中讨论了组合桩之间的干扰效应,给出了干扰系数随KC数和桩距的变化。     

港口波况恶化的观测和分析技术

首先分析了港口波况恶化的可能成因,确定观测和分析目标。根据港内波浪中船行波占相当份量的因素和测量作业不能干扰港务活动的要求,讨论了有关港内波浪观测仪器设备、测站布设、观测方法和质量控制的问题。根据波况恶化分析的要求和非平稳波动过程的特点,研究了波浪频谱和特征值的计算、波浪能量的方向分布、不规则波沿海墙的反射和风浪、涌浪及船行波计算的技术。最后作为实例对某港进行了波况恶化的观测和分析。     

波浪对阻抗型圆柱群的绕射

应用柱面上阻抗型边界条件分析单柱和圆柱群上波面高度和总波浪力的分布规律。随着阻抗值减小波面高度明显减小,柱上总的波浪力也随之减小。由于柱间干扰和阻抗影响,波浪力在一定的波数尺寸范围内出现急降区,阻抗型柱的变化平缓,而刚性光滑壁面柱降低显著,说明阻抗越小柱间波浪散射强度越小。     

透空式防波堤周围的非线性波浪传播的数值模拟

对非线形波浪在透空式防波堤周围的波浪变形进行了数值模拟,在Boussinesq波浪方程中加入与透空建筑物有关的新的耗散项,从而界定了透空建筑物引起的部分反射和透射,波浪折射衍射的传播过程通过控制方程求解。波浪控制方程通过有限差分方法求解。模型应用于模拟波浪经过具有部分反射的群桩式透空结构,结果表明透空式防波堤可以有效地衰减波浪,是重力式结构的一种替代形式。     

海洋平台沉垫的波浪载荷试验研究

本文通过对海洋平台沉垫的波浪载荷试验研究分析，着重研究了在规则波中平台沉垫总体波浪载荷和局部水动压力分布的情况，定性地考察了非线性影响、浅水影响的重要性，为今后波浪理论中粘性的引入，进而考虑粘性与波浪运动的非线性相互干扰提供实测依据     

闭环控制在波浪数值水槽中的应用

为了解决波浪数值水槽控制端与试验区波浪数据不一致的问题,需建立波浪数据的"控制—采集—反馈—再控制"闭环控制系统。采用FLUENT的UDF编程功能,实时采集试验区波浪数据作为造波控制系统的反馈信号,通过对试验区波浪数据进行谱分析,并与目标谱进行比较,进而修改控制系统的传递函数,实现了波浪数值水槽的闭环控制。大量的不规则造波实例表明,该闭环控制方法不仅可以修正波浪控制端与试验区的误差,且具有较好的稳定性。闭环控制的实现显著提高了系统的造波质量与品质,具有较好的应用前景。     

垂直园柱群波浪作用力的研究(英文)

在波浪槽中进行了三个园柱的单排桩群和4×4个园柱的桩群所受波浪作用力的实验研究。单排桩的波浪入射角为0°、45°和90°:4×4桩群的波浪入射角为0°和45°。通过研究给出了三个园柱的单排桩群和4×4桩群的总干扰系数以及各个组成桩的干扰系数随Keulegan-Carpenter数、相对桩距和波浪入射角的变化;找出了桩群中承受最大波浪作用力的组成桩;提出了遮蔽效应、整体效应、射流效应和抑制效应等四种效应以解释所得到的结果。     

波浪在可渗海床上传播时的衰减

在以往的波浪理论研究中,通常假定海床是不可渗的。但在浅水区,海床的可渗性对波浪的传播有一定影响,它能引起波高的衰减,同时波浪也能够引起海床的变形、滑动、甚至液化。当海床的弹性小,渗透性大时,波浪与可渗海床的这种相互作用更为明显。本文通过对波浪场控制方程－拉普拉斯方程和弹性海床的控制方程－比奥方程联合解析求解,给出了海床土体响应、孔隙水压变化规律,以及波高在传播过程中的衰减。     

双浮筒直驱式波浪发电系统的优化控制

针对双浮筒直驱式波浪发电系统的工作效率较低问题,提出了一种基于PID(Proportional Integral Derivative)控制的系统优化方法。首先根据波浪力学理论,计算出了双浮筒直驱式波浪发电系统的外浮筒(动浮筒)在自然条件下的运行特性,计算结果表明,受到波浪频率、垂直波浪速度和波浪周期固有特性的影响,外浮筒的垂直运动速度不能与波浪的垂直运动速度达到共振,进而也就导致波浪能转换成电能的工作效率较低。当采用基于PID控制算法对该波浪发电系统进行优化控制之后,波浪能转换成电能的效率有了很大的提高。详尽的算例分析和仿真结果表明本文提出的优化控制方法有效、可行。     

风浪波群中波高分布研究

在实验室风浪槽中观测风浪,发现波群连长是影响波群中波高分布的重要因素,随着波群连长增大,波群中波高分布信息熵增大。当以平均波高无因次化,连长较大时波群中波高累积概率明显大于连长较小时情形。波群中波高分布受谱宽度影响。当谱宽度增大,波群中波高累积概率降低。谱宽度和波群连长对波群中波高累积概率的影响相当。引进体现波群特性的1个无因次化波高参量研究波群中波高累积概率。     

Exploitable wave energy assessment based on ERA-Interim reanalysis data—A case study in the East China Sea and the South China Sea

Wave energy resources assessment is a very important process before the exploitation and utilization of the wave energy. At present, the existing wave energy assessment is focused on theoretical wave energy conditions for interesting areas. While the evaluation for exploitable wave energy conditions is scarcely ever performed.Generally speaking, the wave energy are non-exploitable under a high sea state and a lower sea state which must be ignored when assessing wave energy. Aiming at this situation, a case study of the East China Sea and the South China Sea is performed. First, a division basis between the theoretical wave energy and the exploitable wave energy is studied. Next, based on recent 20 a ERA-Interim wave field data, some indexes including the spatial and temporal distribution of wave power density, a wave energy exploitable ratio, a wave energy level, a wave energy stability, a total wave energy density, the seasonal variation of the total wave energy and a high sea condition frequency are calculated. And then the theoretical wave energy and the exploitable wave energy are compared each other; the distributions of the exploitable wave energy are assessed and a regional division for exploitable wave energy resources is carried out; the influence of the high sea state is evaluated. The results show that considering collapsing force of the high sea state and the utilization efficiency for wave energy, it is determined that the energy by wave with a significant wave height being not less 1 m or not greater than 4 m is the exploitable wave energy. Compared with the theoretical wave energy, the average wave power density, energy level, total wave energy density and total wave energy of the exploitable wave energy decrease obviously and the stability enhances somewhat. Pronounced differences between the theoretical wave energy and the exploitable wave energy are present. In the East China Sea and the South China Sea, the areas of an abundant and stable exploitable wave energy are primarily located in the north-central part of the South China Sea, the Luzon Strait,east of Taiwan, China and north of Ryukyu Islands; annual average exploitable wave power density values in these areas are approximately 10–15 k W/m; the exploitable coefficient of variation(COV) and seasonal variation(SV)values in these areas are less than 1.2 and 1, respectively. Some coastal areas of the Beibu Gulf, the Changjiang Estuary, the Hangzhou Bay and the Zhujiang Estuary are the poor areas of the wave energy. The areas of the high wave energy exploitable ratio is primarily in nearshore waters. The influence of the high sea state for the wave energy in nearshore waters is less than that in offshore waters. In the areas of the abundant wave energy, the influence of the high sea state for the wave energy is prominent and the utilization of wave energy is relatively difficult. The developed evaluation method may give some references for an exploitable wave energy assessment and is valuable for practical applications.     

Numerical Simulation of Wave Height and Wave Set-Up in Nearshore Regions

Based on the time dependent mild slope equation including the effect of wave energy dissipation, an expression for the energy dissipation factor is derived in conjunction with the wave energy balance equation, and then a practical method for the simulation of wave height and wave set-up in nearshore regions is presented. The variation of the complex wave amplitude is numerically simulated by use of the parabolic mild slope equation including the effect of wave energy dissipation due to wave breaking. The components of wave radiation stress are calculated subsequently by new expressions for them according to the obtained complex wave amplitude, and then the depth-averaged equation is applied to the calculation of wave set-up due to wave breaking. Numerical results are in good agreement with experimental data, showing that the expression for the energy dissipation factor is reasonable and that the new method is effective for the simulation of wave set-up due to wave breaking in nearshore regions.     

浙江近海波浪能资源的初步研究

以2000年为例,采用SWAN波浪数值模型对浙江近海海域的波浪进行了全年模拟计算,并计算获得年、月平均波功率密度分布。研究表明,浙江近岸海域年平均波功率密度约为2~6 kW·m^-1,往外海逐渐增大;同时季节变化明显,秋、冬季节波功率密度较大,春、夏季节较小。另外,通过对浙北、浙中和浙南3个近海海区的波浪出现频率和波功率密度随波高和周期变化的分析可知,浙北海域波功率密度比较高的波高及周期范围和波浪出现频率较高范围较为接近,而其对应平均波功率密度相对较低;浙南海域波功率密度比较高的范围所对应的平均波功率密度较高,而与波浪出现频率较高的范围则略有差异;浙中海域居两者之间。总体而言,浙江近海波浪能资源丰富,且全年中可开发与利用的波浪能出现频率较高。     

应用特征波预报公式进行台风浪计算的一个根本缺陷

Wilson方法和井岛方法均是移动风区上著名的波浪推算方法,被广泛应用于台风波浪的推算和预报上。本文通过分析指出:使用上述方法以海洋工程界所推行的风浪预报公式作台风浪推算时,所得特征波波陡将与台风浪实测波陡分布定性不符,并指出产生这种缺陷的原因。     

复杂地形下海浪数值模式的特征线计算格式

LAGFD-WAM海浪数值模式是一种第三代海浪数值模式，通过求解波数谱平衡方程，并考虑风输入、波浪破碎耗散、底摩擦耗散、波波非线性相互作用和波流相互作用等源函数，模拟波数空间下的海浪方向谱，并依此获得海浪的波高、周期和平均波向。该模式的一个显著特点是采用特征线嵌入格式求解海浪的传播。在进行浅水区域的海浪模拟时，特征线嵌入格式的数值计算方案是否合理对海浪数值模拟结果产生直接的影响。为此LAGFD-WAM海浪数值模式提出了一种新的特征线混合数值计算格式，并应用于浅水海浪数值模拟。结果表明，采用该计算方法，能够使数值模拟结果与实测结果很好符合。     

斜坡平台波浪破碎数值模拟

波浪在斜坡地形上破碎,破波后稳定波高多采用物理模型试验方法进行研究,利用近岸波浪传播变形的抛物型缓坡方程和波能流平衡方程,导出了适用于斜坡上波浪破碎的数值模拟方法。首先根据波能流平衡方程和缓坡方程基本型式分析波浪在破波带内的波能变化和衰减率,推导了波浪传播模型中波能衰减因子和破波能量流衰减因子之间的关系;其次,利用陡坡地形上的高阶抛物型缓坡方程建立了波浪传播和波浪破碎数学模型;最后,根据物理模型试验实测数据对数值模拟的效果进行验证。数值计算与试验资料比较表明,该模型可以较好地模拟斜坡地形的波浪传播波高变化。     

基于实测数据的台湾海峡中部波浪特征分析 *

利用台湾海峡中部2号大浮标2017年全年的实测波浪资料, 对海浪的基本波要素及其与风的相关性、波谱特性进行统计分析, 得出了重要特征波参数之间的回归关系和适合台湾海峡中部的海浪谱形式。研究结果显示: 1) 台湾海峡中部的常浪向是NE向, 强浪向是NNE向, 月均有效波高的变化范围为0.87~2.98m, 7月波高最小, 12月波高最大, 波周期与波高有着相似的月际变化趋势; 2) 主要波浪类型是以风浪为主的混合浪, 谱型上以单峰为主, 波高与风速整体上呈正相关关系, 大浪主要由台风和强劲的东北季风引起; 3) 波浪的平均周期与大部分特征波周期之间具有良好的线性相关性, NNE、NE方向的波浪有效波高和有效波周期线性相关性较强; 4) 相比于Jonswap谱, 规范谱一是更符合本区域的海浪谱模式, 给出了基于有效波高和谱峰周期拟合的规范谱一形式。这些研究成果可为海洋工程设计和波浪数值模拟提供参考。     

潮汐影响下海滩前滨波浪传播耗能过程分析

文章基于长乐海滩前滨剖面的实测波浪数据, 通过统计分析以及谱分析的方法, 探讨了潮汐过程中长乐海滩波浪参数及耗能过程的变化规律。结果表明, 观测期间内波浪以混合浪为主, 各测点谱型较宽, 存在多峰振荡现象。向岸传播过程中, 波能耗散的形式为窄频域向宽频域转变, 能量分布趋于分散, 高频波能减小, 低频波能反而有所上升, 波浪破碎后生成长重力波。破波带内的能量衰减与波浪传播距离具有良好的相关性, 破碎波能在破波带内大约衰减了98.3%。潮汐水位对波浪具有明显的调制作用。入射波能随潮汐水位的增加而有所增加, 且水位越高, 入射波能分布越分散。破波带内的有效波高和潮汐水位具有显著的正相关关系。潮汐过程中固定测点的波谱变化与波浪沿剖面的波谱变化具有明显的相似性。     

基于多星融合高度计数据的中国海波浪能资源评估

Wave energy resources are abundant in both offshore and nearshore areas of the China's seas. A reliable assessment of the wave energy resources must be performed before they can be exploited. First, for a water depth in offshore waters of China, a parameterized wave power density model that considers the effects of the water depth is introduced to improve the calculating accuracy of the wave power density. Second, wave heights and wind speeds on the surface of the China's seas are retrieved from an AVISO multi-satellite altimeter data set for the period from 2009 to 2013. Three mean wave period inversion models are developed and used to calculate the wave energy period. Third, a practical application value for developing the wave energy is analyzed based on buoy data. Finally, the wave power density is then calculated using the wave field data. Using the distribution of wave power density, the energy level frequency, the time variability indexes, the total wave energy and the distribution of total wave energy density according to a wave state, the offshore wave energy in the China's seas is assessed. The results show that the areas of abundant and stable wave energy are primarily located in the north-central part of the South China Sea, the Luzon Strait, southeast of Taiwan in the China's seas; the wave power density values in these areas are approximately 14.0–18.5 k W/m. The wave energy in the China's seas presents obvious seasonal variations and optimal seasons for a wave energy utilization are in winter and autumn. Except for very coastal waters, in other sea areas in the China's seas, the energy is primarily from the wave state with 0.5 m≤H s≤4 m, 4 s≤T e≤10 s where H s is a significant wave height and T e is an energy period; within this wave state, the wave energy accounts for 80% above of the total wave energy. This characteristic is advantageous to designing wave energy convertors(WECs). The practical application value of the wave energy is higher which can be as an effective supplement for an energy consumption in some areas. The above results are consistent with the wave model which indicates fully that this new microwave remote sensing method altimeter is effective and feasible for the wave energy assessment.