基于谱的海浪模拟与谱估计

针对掠海飞行器系统仿真的需要,研究了海浪仿真方法。选取P—M谱作为海浪谱,通过海况确定波谱参数,在波谱仿真带宽内采用频率等分法对其进行分割,根据Longuest—Higgins海浪模拟模型进行仿真,得出了海浪时域波形。并采用Welch法进行波谱估计,从波谱能量度量,仿真精确度达到了99．22％。     

海浪磁场谱在航海上的应用

同浪高一样,海浪的频率对航海影响非常大,文中通过分析海浪磁场谱与海浪谱的关系,提出利用海浪磁场谱对海浪谱进行描述,并对海浪磁场谱在航海上的应用做了说明。     

船舶动力定位海浪环境的实时仿真与海浪谱分析

提出一种根据随机海浪频谱来实时模拟随机海浪的方法，它可以用于研究动力定位船舶及其控制系统在不同海况时的性能，该方法可以采用多种海浪谱来进行海浪的仿真，仿真结构利用了快速傅立叶变换FFT（Fast Fourier Transform)进行频谱分析，仿真程序可用于实际的动力定位船舶系统。     

双峰谱海浪的数值模拟技术研究

海上的波浪观测资料统计表明，海上纯风浪和纯涌浪的出现机会比较少，大部分以混合浪形式出现，其频谱结构多为双峰甚至多峰。研究双峰谱波浪的模型表述和数值模拟技术，对三种典型的双峰谱海浪进行了数值模拟，仿真结果表明了双峰谱海浪数值模拟的有效性。     

由船舶摇荡时历反推海浪方向谱

针对现有获取海浪谱方面存在的不足,提出了一种根据现场较短时间的船舶横摇、纵摇和垂荡等时历数据,采取合适的谱分析技术,由船舶摇荡时历反推实际的海浪方向谱方法,以满足工程应用中对现场实际海浪谱的需求.     

基于 OpenGL 的实时三维海浪可视化仿真

海浪虚拟仿真技术是海上虚拟作战平台模型库构建的重要组成,直接影响到平台运行的逼真性和可行性。论文首先以重力波为例,分析了对规则海浪模型的仿真方法,然后采用线性波浪叠加法和海浪谱理论,探讨了不规则海浪模拟及其三维生成算法,通过建立海面规则网格,调用O penG L函数库,实现了对真实海浪进行模拟,为建立海上虚拟作战平台海浪模型提供了一种技术方案。     

船舶并靠中海浪模型算法的研究

首先从波能谱入手,在ITTC标准海浪谱的基础上,利用等能量划分法,构造船舶并靠中的海浪模型;然后分析在此海浪模型中并靠两船的相对运动情况,在研究中发现波浪会对船舶的横摇有影响。针对并靠船舶的横摇设计变阻尼波浪补偿器,对船舶的相对运动进行补偿,保证船舶在并靠过程中的安全。     

船载S波段雷达多普勒谱模型

根据海表面的散射机理和船舶在海中的运动规律,建立了3次谐波船舶运动模型,提出了船载S波段雷达回波多普勒谱的中心频率和谱宽的理论模型。本文采用仿真多普勒谱的方法,分析了船载S波段雷达多普勒谱的中心频率和谱宽大小与船速的关系,并讨论了船舶各种运动导致多普勒谱的变化情况,最后采用一段实测船载三坐标速度并仿真其多普勒谱,结果表明其中心频率的变化明显,谱展宽明显。文章的结论为船载S波段雷达海浪参数提取提供先验信息和理论模型,具有重要的价值。     

船舶动力定位海浪环境的实时仿真与海浪谱分析

提出一种根据随机海浪频谱来实时模拟随机海浪的方法，它可以用于研究动力定位船舶及其 控制系统在不同海况时的性能。该方法可以采用多种海浪谱来进行随机海浪的仿真。仿真结果利用了 快速傅立叶变换FFT(FastFourierTransform)进行频谱分析。仿真程序可用于实际的动力定位船舶系 统。     

海浪波动对电磁浮标姿态的影响研究

本文在前人对海浪理论研究的基础上,对我国浅水区海浪谱模型进行了仿真分析,初步研究了浅水区海浪波动对电磁浮标姿态变化的影响,建立了浮标姿态横滚角θ随海浪波动的变化模型,并通过对不同海况级下的θ变化规律进行了matlab仿真分析,说明了模型建立的正确性.     

Estimation of directional wave spectra and hull structural responses based on measured hull data on 14,000 TEU large container ships

To ensure hull structural strength of container ships in association with their increase in size, it is very important to grasp the hull stress histories all over the hull structure in actual sea state. However, ordinary hull stress monitoring systems are insufficient for this purpose because of the small number of stress sensors actually practicable. Therefore, in this paper, we discuss an approach to reproduce the hull stress responses which are not measured based on the estimated wave spectrum from the limited measurement data. To achieve this, we introduce a new model to estimate directional wave spectra based on measured ship stress responses and ship response functions, and further we estimate other ship responses using the model. To model an arbitrarily shaped directional wave distribution, the 360° direction is discretized into 36 directions of 10-degree intervals instead of using a directional distribution function, and in each direction, the wave spectrum is represented using the Ochi (3P) spectrum with three parameters (average wave period, significant wave height, and kurtosis). The authors discuss the evaluation results based on two stress response combinations, and a comparison is made between the sea state estimates made by the proposed method and the ocean wave hindcast database (JWA). Furthermore, by comparing the significant values and the spectra of the measured response of the ship with the estimated response based on both the estimated sea state by the proposed method and the hindcast sea state, the accuracies of the proposed method and the hindcast method are discussed in terms of ship stress estimation at non-instrumented locations.     

印尼ADIPALA海域较长周期波浪谱分析

波浪谱是进行海岸工程设计的重要基础,不同海区、不同周期的波浪谱特性不同,因此有必要对于实际海上观测波浪的谱特性进行分析研究。针对在印尼海岸观测的较长周期波浪数据进行了波浪谱分析,给出谱特征参数与海浪统计特征值之间的关系。并基于JONSWAP谱型,对实测波浪谱进行拟合,得出适用于该海域的波浪谱公式,研究成果可为实际工程设计提供重要的参考。     

大型集装箱船参数横摇模型试验和数值模拟研究

以4000TEU集装箱船为研究对象，通过系列自航模型试验，确定其在迎浪规则波中发生参数横摇的限界。试验结果显示：在迎浪规则波中，参数横摇通常发生在波浪遭遇周期为横摇固有周期一半的附近；对应不同遭遇频率时参数横摇的发生，存在一个临界波高；航速的增加和舭龙骨的安装将使参数横摇发生的临界波高增加；当有初始干扰时，参数横摇发生的临界波高较小。而且，数值模拟结果与模型试验结果比较吻合。     

沿海高速双体搜救艇水动力性能试验

为了满足沿海船只发生海损时,搜救船舶应能第一时间到达事故发生位置,并且完成勘察现场、事故人员救助的任务,设计了2种线型的双体搜救艇.通过船模阻力试验选出阻力性能较优的一种,对其进行耐波性分析,与某双体船试验数据进行对比,并用ITTC双参数谱预报了实船耐波性,验证了该船型能满足沿海海况和日常任务的需求.     

Model experiment reproducing an incident of fast ferry

A model scale experiment at a new basin reproduced a phenomenon occurring for a fast ferry; large roll motion and subsequent cargo shift in a quartering sea. Wave generators surrounding the whole periphery of the basin realized a designated directional sea. A carriage system tracked a free-running model ship and a movable weight simulated the cargo shift. Measuring the directional wave field in the basin confirmed the all-around wave generator successfully reproduced the intended wave field that was estimated for the location and the time of the incident. The encounter wave spectrum analyzed using measured data agree well with the theoretically predicted one. The reproduced ship motion, triggered by a small concentrating wave, tells how the ship responded in the successive large quartering waves and the validity of the procedure to reproduce the incident. Repeated measurements of the model ship’s extreme motion confirm a high repeatability of the experiment.     

基于船舶运动信息的航行海域海浪特性预报

以船舶自身为波浪测量仪,致力于采集方便而又尽可能少的船舶运动信号以提取航行海域实时海浪特性.由于估计中不依赖原始理论计算的传递函数,不需要附带波浪采集装置,而仅利用航行中船舶运动的观测序列完成海浪谱反演,故该海浪测量方法可适应船舶自身运动参数的变化.另一方面,由于反演估计的船舶运动频率响应特性,与事先计算或以其它实验方法得到的船舶运动频率响应特性得以比较,可以深化、修正对许多不易实时测量的海浪激励状态与船舶运动响应关系的认识,并积累船舶工程研究设计所必需的相关海域海浪谱信息.     

Difference in ship motion and wave load in long and short crested irregular waves北大核心CSCD

[Objective]To investigate ship motion and load responses in realistic 3D waves and overcome the limitations of the traditional 2D wave assumption, this paper develops a method for predicting ship motion and load responses in short-crested waves. [Method]The long- and short-term responses of ship motion and load in long- and short-crested waves are numerically predicted using the spectral analysis and statistical probability methods, respectively. The influence of directional function on ship response is also numerically analyzed. Moreover, tank model tests and a large-scale model sea trial are comparatively conducted to validate the difference between ship response and statistics in long- and short-crested irregular waves. [Results]The results show that when navigating against the waves in the same sea condition, the long-crested wave assumption overestimates the statistical mean value of ship load response, but underestimates extreme load in real seas. For long-crested waves, the ship motion and acceleration power spectrum is concentrated around a certain frequency band. [Conclusion]Ship motion and load responses in realistic 3D waves are significantly different from those in 2D long-crested waves. The directional function of short-crested waves also has a significant effect on ship motion and load responses. © 2023 The Author(s).     

Ocean wave spectrum estimation using measured vessel motions from an in-service container ship

This article is about the use of measured wave-induced vessel motions for estimation of ocean wave spectra by application of the wave buoy analogy. In the study, data from a larger, in-service container ship is considered. The estimation of wave spectra, equivalently sea state parameters, is based on measurements from, respectively, a gyro and two accelerometers leading to the simultaneous use of the pitching motion together with the horizontal and vertical accelerations in a position close to the forward perpendicular. The study of in-service data leads to contemplations about the vessel's advance speed, as the possible existence of sea current means that speed-over-ground (SOG) and speed-through-water (STW) will be different. The article discusses aspects related to advance speed in the context of the wave buoy analogy, and a smaller sensitivity study is conducted. Preceding to the sensitivity study, a comparison is made between sea state estimates by the wave buoy analogy and estimates obtained from a hindcast study. The article shows an acceptable agreement between the two sets of estimates. Following, the main conclusion from the sensitivity study on advance speed is that errors and uncertainties in the speed log have an effect on the estimates of the wave buoy analogy. In fact, the effect can be severe if reliable STW measurements are not available. In the final part, the article includes a few discussions about (non)stationary conditions in the context of the wave buoy analogy, and, although the effect on results is not necessarily detrimental, care must be shown when the wave buoy analogy is applied during in-service conditions.     

改进的海浪波包谱

结合实测波浪资料对描述波浪群性的主要特征参数进行了统计和相关性分析,结果表明波群的高度特征和长度特征之间相关性较弱。在此基础上根据渤海和珠江口两地的波浪观测数据,采用合理的无因次化方式,拟合得到一个适于风浪的波包谱经验公式。该公式同时考虑了群高与群长两方面的因素,只要给出波要素和波群的特征参数便可确定波包谱形,便于应用,根据对实测资料波群参数的分析结果,与俞聿修等人先前建议的波包谱公式相比,该公式中给出了更合理的参数取值原则。