基于等效电路的舰船轴频电流建模与实验分析

针对舰船轴频电场信号源的发生机理和应用研究的问题,以实验室轴电流模拟装置为平台, 建立了一种基于等效电路的舰船轴频电流的模型,研究了轴电流模拟装置的大轴振动情况,对大轴电流进行了建模仿真,得到了不同转速下大轴轴电流波形图及其频谱,使用轴电流模拟装置进行了轴电流实验。 通过仿真结果与轴电流实验数据对比,计算得到该建模方法轴电流平均误差在 8% 以内,验证了该建模方法在理论上的可行性。     

海底聚氨酯弹性体保温输油管道散热损失测试与总传热系数计算

聚氨酯弹性体保温管因具有铺管速度快、施工费用低、使用水深不受铺管船限制等优点,在深水管道保温中广泛应用。管道散热损失测试和总传热系数是输油管道的关键热力参数。测量模拟运行环境下的管道热损失和总传热系数对输油管道的保温层设计有着重要的意义。文章以聚氨酯弹性体保温管道作为研究对象,列出了管道散热损失与传热系数的计算公式,依据其运行环境及工况设计了可模拟深水压力、温度的管道散热损失测试装置。装置的研制有助于工程现场采用的保温管道产品保温效果的测试与评价,还可作为保温结构设计计算和材料选择的参考。文章通过具体实例给出了聚氨酯弹性保温管道散热损失的试验方法与在模拟工况环境下总传热系数的计算过程。     

内部转塔锚泊系统转塔装置的性能研究

为满足海上石油浮式生产系统发展的需要,本文研究了内部转塔锚泊系统转塔装置的性能。本文采用系统评价方法确定了适用于单点系泊的转塔最佳结构型式;通过相似模型的实验研究提供了一组不同工况下实测得到的力、力短、位移的数据;利用有限元法针对实验结构计算出转塔各部分的应力、变形值.研究表明:所选的转塔结构和所设置的转搭机械在技术上是完全可行的。     

基于VOF模型的浮式消波海流机性能优化

针对浮式消波海流机样机测试时出现的问题,对其吃水深度线和叶片安装角度进行优化。根据装置结构特点,用Gambit建立了装置横截面的二维网格模型。根据浮式消波海流机实际工作环境,利用Fluent流体仿真软件,使用VOF(volume of fluid)两相流模型,分配空气相与液态水相在流域中的不同比例,来确定不同的吃水深度线。并且结合k-epsilon紊流模型建立模拟仿真环境。先对3种水线进行仿真分析,然后进行实验验证。通过分析对比装置的3种不同吃水深度线的模拟与实验结果,得到装置的最优吃水深度线为1/3水线。基于最优吃水深度线,分别对叶片的4种安装角度在相同的仿真环境中进行模拟仿真。利用仿真得到的扭矩数据,计算扭矩系数、功率系数,分析对比仿真数据以及仿真过程中扭矩趋势图得出4种叶片安装角度的最优角度是90°。吃水深度线决定了装置的消波能力,并且为叶片获能提供条件,叶片安装角度直接影响着装置的获能效率,所以最优的吃水深度线和叶片安装角度对海流机的消波能力和获能效率具有重要意义。     

坠物撞击管道实验装置设计与实验研究

针对船舶抛锚或海洋平台坠物对海底管线的撞击会对管道造成一定的危害,本文设计了坠物撞击管道的实验装置,并对实验装置进行了优化分析,在此基础上提出了可行的实验方案。通过ANSYS有限元软件对该实验装置进行了静力分析,确定了最终的装置结构形式,并开展了坠物与管道的撞击实验。该装置在实验条件下最大变形不足1mm,可满足实验要求。实验证明,随着撞击能量的增加,管道的损伤程度明显增大。本次实验研究结果为分析坠物对管道的撞击作用提供了研究基础。     

新型海上无人平台登临装置研究

本文总结了国内外海上平台登临方式,并设计了一种新型海上无人平台登临装置。这一新装置具有结构简单、占用空间小、系统可靠等优点,本文详细描述了该装置的登临和离开工作流程及控制模式,并针对不同作业阶段设置了不同的控制模式,通过设计安全性仿真实验及实验参数,确保在6级风况下,装置臂展长度需大于1.42 m,以保障人员的安全。同时,本文探讨了该装置的关键技术,如人员姿态识别、船舶运动检测与预测等,这些技术的应用有望提高作业的安全性和效率。未来,新型海上无人平台登临装置的发展趋势将集中在人工智能技术的应用,以进一步提高作业人员的安全,并实现远程操控和设备维护。这一新型智能装备将具备识别、感知和实时监测功能,以应对不断变化的海上工作环境,同时注重信息反馈,以支持后勤维修工作。     

一种新型的现代海底热液环境模拟实验装置设计

已有的海底热液活动模拟实验装置主要通过控制流体的温度和压力实现热液活动环境下的水岩反应实验,随着近年来对海底热液活动研究程度的逐渐深入以及热液保真采样器等新技术的应用,有必要设计新型的海底热液活动模拟实验装置.为此,我们设计了一种可以模拟海底热液环境的实验装置,该装置主体由两个圆柱形钛合金舱体对接而成,利用加热装置、加...     

波浪能发电装置液压模拟测试技术研究

文中针对波浪能发电装置液压系统测试需要,介绍了液压系统测试平台的研制工作。该平台采用由电液伺服阀和比例压力阀组成的液压系统模拟波浪能发电装置在波浪作用下往复运动,实现测试液压系统工作性能。建立系统传递函数,分析了系统稳定性;通过计算仿真分析,其结果表明所设计的波浪能发电装置液压检测平台能够满足模拟波浪输入条件的要求。     

波浪能振荡浮子转换方式实验装置的研究与设计

针对阵列式振荡浮子波浪能转换设备,提出一种在实验室进行测试研究的实验装置。该实验装置由一组阵列柱形水槽组成,水槽液面在水动力系统的驱动下,按照计算机设定的函数做升降运动;对该装置模型——柱形阵列水槽的假设,依据波浪理论进行了论证;对装置的工作原理、结构设计、技术参数、控制电路和操作运行等做了较详细的说明;对实验装置实际运行和测试情况做了介绍。结果表明:该实验装置设计合理可行,模拟波浪高度,远高于现有的造波水池,构成了一种专用的模拟造波装置;该装置为不同形式振荡浮子式波浪能转换设备的研制提供了一种多功能、大振幅、高效灵活的实验平台。     

深海水下采油树结构及强度计算

针对不同水深、油气温度等操作条件对水下采油树结构的影响,采用ABAQUS软件对深水水下采油树在正常生产工况下的整体结构强度进行计算,总结出不同水深以及不同油气温度对水下采油树结构强度影响的规律.计算结果表明:在高油气温度、深水条件下,采油树的综合应力受其水下导向基座及H4连接器等固定边界的影响很大.凶此,在设计水下采油树时需特别考虑水下导向基座及H4连接器等的设计,尽量减小固定边界的边界效应对采油树的影响范围,避免这些边界效应与采油树所受外力产生的应力叠加.同时,为减小热应力值,应注意采油树的保温设计.     

钱塘江河口风暴潮经验预报

钱塘江河口的风暴潮预报工作可归结为澉浦或乍浦两个单站的预报,这使得经验预报成为可能。利用一种动力线性模型将动力学的线性问题转化为统计学的线性回归模型,通过合理选取预报量及预报因子,并采用正交筛选技术确定每个预报因子所对应的系数,建立经验预报方程。后报结果表明该方法可取得较好的效果。     

实验水槽常规流速模拟的缩尺方法

提出了一种实验室水槽中流速模拟的方法,该方法可根据需要提供合适的模型缩尺比,用来完成相关海洋工程的模型水动力性能实验,可以近似地模拟出实际设备在水中的工作状态,为在实验水槽中模拟水流动力参数提供有效的参考,方便水槽中的科学实验的开展。     

The Hawaii-2 Observatory

A permanent deep ocean scientific research facility-the Hawaii-2 Observatory (H2O)-was installed on the retired HAW-2 commercial submarine telephone cable in September 1998. H2O consists of a seafloor submarine cable termination and junction box in 5000 m of water located halfway between Hawaii and California. The H2O infrastructure was installed from a large research vessel using the Jason ROV and standard over-the-side gear. The junction box provides two-way digital communication at variable data rates of up to 80 kbit/s using the RS-422 protocol and a total of 400 W of power for both junction box systems and user equipment. Instruments may be connected by an ROV to the junction box at 8 wet-mateable connectors. The H2O junction box is a "smart" design, which incorporates redundancy to protect against failure and allows full control of instrument functionality from shore. Initial instrumentation at the H2O site includes broad-band seismometer and hydrophone packages     

An approximation to energy dissipation in time domain simulation of sloshing waves based on linear potential theory

This paper proposes a new approximation to energy dissipation in time domain simulation of sloshing waves by use of a linear potential theory.The boundary value problem is solved by the NURBS(non-uniform rational B-spline) higher-order panel method,in which a time-domain Green function is employed.The energy dissipation is modeled by changing the boundary condition on solid boundaries.Model experiments are carried out in a partially filled rectangular tank with forced horizontal motion.Sloshing-induced internal pressures and horizontal force obtained numerically and experimentally are compared with each other.It is observed that the present energy dissipation approximation can help produce a fair agreement between experimental forces and those of numerical simulations.     

Stratified convection with multiple states

A simplified box model of the cooling of a salt-stratified ocean is analyzed analytically and numerically. A large isothermal basin of salt water has a layer of fresh water at the surface. Beside this is a small basin, cooled from above and connected to the large basin by horizontal tubes at the top, middle and bottom. For small cooling rate, fresh water enters the small basin, is cooled and leaves through the middle tube. For greater cooling rate, the fresh water leaves the small basin through the middle and bottom tube. If the top tube is smaller than the deeper tubes and the fresh water layer is sufficiently shallow, flow in the middle tube reverses at a critical cooling rate. In this case, a mixture of salt and fresh water is cooled and leaves the bottom tube. Increased cooling produces much greater flow rate; consequentially temperature increases rather than decreases in the small basin. A relaxation heat flow condition results in multiple equilibria. One of the stable modes has fresh surface water descending in the small basin and flowing out through the middle and bottom tube. The other has a greater rate of flow of both fresh and salty water (through the middle tube) into the basin with the flow of mixed salty water out of the bottom tube. Implications for deep convection in the ocean are discussed.     

A comparative study of numerical simulations for fluid–structure interaction of liquid-filled tank during ship collision

Although International Maritime Organization (IMO) has taken many measures to minimize ship collisions, ships carrying liquid cargo sometimes do get struck by other vessels. The outflow of crude oil causes very serious consequences to the environment. In such cases it is necessary to analyze the response of structure of struck liquid cargo-filled tank to account for fluid–structure interaction accurately. In this paper, numerical simulation of collision between a container ship with double hull very large crude carrier (VLCC) is presented. Three different numerical simulation mothods were adopted to model fluid–structure interaction in liquid-filled cargo tank, namely arbitrary Lagrangian–Eulerian finite element method, Lagrangian finite element method and linear sloshing model. The numerical simulation results reveal that the fluid–structure interaction of liquid cargo-filled tank has a significant effect on the motion and structural response of the struck cargo tank. Compared with the calculation results of ALE FE method, the linear sloshing model underestimates the influence of fluid–structure interaction of liquid cargo tank while the Lagrangian–Eulerian finite element method may be considered as the practical method for engineering applications as it provided more reasonable results with a relatively low central processing unit (CPU) time.     

海面温度变化影响台风"海棠"强度的数值研究

通过对台风"海棠"5 d的数值模拟,研究海表温度(SST)变化对台风强度的影响。与NCEP月平均海表温度相对比,在中尺度大气模式中引入热带测雨卫星(TRMM)微波成像仪(TMI)/先进微波扫描辐射计(AMSR-E)来考察SST对台风"海棠"路径和强度的影响。研究结果表明,每天变化SST的试验模拟的台风强度和路径整体效果不错;模拟的台风路径不敏感于SST的变化,而台风强度的变化不仅取决于由于台风移动引发的SST冷却的幅度大小,而且取决于SST冷却区域的相对位置。在台风"海棠"强烈发展过程中,台风中心右侧冷却区对台风中心气压影响很小;台风强烈发展过后,SST冷却区开始影响台风强度,但造成台风中心气压下降幅度不大,6 h内台风中心气压减弱约3.9 hPa。海面热量通量和海面风速与SST的分布都有良好的相关性:在SST变化为正值的暖水区,感热通量和潜热通量都是一个正的通量分布的极值区,并有风速极大值区域存在;在台风右侧相应的冷却区,则存在着负的通量异常和风速极小值区域。     

Effect of desiccation of marine environment on beam structure

This paper presents the study on the effect of desiccation for different part of offshore structure corresponding to the water level.A coupled elastoplastic damage model is proposed to describe the mechanical behavior of cement-based materials under external loading and desiccation,in which both the plastic and damage behaviors under multi-axial stress are considered in composition with the desiccation effect.The comparison between numerical simulation and experimental data indicates that the proposed model can well predict the mechanical characteristics of cement-based materials with different saturations.In addition,a series of small beams subjected to desiccation are further analyzed to reveal the response of structure in the drying process.     

Cooling-Induced Current in the Upper Ocean of the Japan Sea

The most plausible scenarios for seasonal to interannual variabilities and their possible causes are investigated for the Tsushima Current system passing through the Japan Sea. The study is based on the north and south two-box model across the polar front in an idealized upper ocean of the Japan Sea. The boxes are connected by lateral diffusive heat transport and cooled by atmospheric forcing at the annual mean state. The south box, i.e. the Tsushima Current region, only interacts with the outside warmer box in the East China Sea and has an eastward thermal-driven current originating in the outside box. The magnitude of this current depends on the strength of the thermal gradient between the north and south boxes; the inflow of warm waters can therefore be maintained by net heat loss through the sea-surface. I call such a thermal-driven inflow process a "Cooling-Induced Current" system in the present study. Under periodical heat forcing, the perturbation response of the model to water temperature fields and inflow transport were examined. It is shown that the lateral diffusion time across the polar front (over a period of 10 years) is crucial to the interannual modeled response. An analysis of the seasonal heat budget suggests that the heat transported into the Japan Sea from the East China Sea in summer is stored mainly within the Tsushima Current region and contributes to heat loss by the sea-surface cooling in winter.     

水面薄层热结构变化诱发机制的模拟研究──空气冷/暖平流效应

利用ＨＤＧ－高灵敏度红外测温仪和常规测试仪器在低温实验室的水槽中,对气温可控条件下模拟形成空气冷／暖平流流经水面过程中的静态水面薄层热结构进行了分层同步测量。数据分析表明,在空气暖平流过程中的静态水面薄层热气温骤增２１．５℃,水面皮温商步增加达１．５７℃,温度响应系数为＋０．０７３,这种温度应系数在升温吕过程中,其平均值为０．０４６;而在冷平流（降温）过程中,则为－０．０２２,个别情况下,皮温降低