扁平潜器微速操纵性研究

针对扁平潜器的特点建立了其微速操纵性运动方程,提出了忽略攻角、漂角与旋转角速度耦合影响的水动力模型,由拖曳水池模型试验确定了攻角、漂角水动力,近似估算了旋转水动力.在主辅推进器的PD控制下,数值仿真计算了水平面航向保持与改变、垂直面潜浮的微速运动控制.     

浅海海底管线检测艇操纵性和运动仿真研究

研究了用于维护和检修中国渤海海域输油管道的浅海管道检测艇的操纵性和运动仿真,提出了浅海海底管道检测艇的水动力学方程。为了更好地了解在配置上与一般潜器不同的浅海海底管线检测艇的动力学性能,通过水动力系数分析,研究了浅海海底管线检测艇的操纵性。最后根据运动方程建立了仿真系统,并通过仿真试验结果验证了仿真试验平台的可行性和可靠性。     

AUV矢量推进水动力计算及水平回转操纵性试验

针对矢量推进模式下的 AUV 水动力性能和操纵性能,开展了 AUV 矢量推进水动力 CFD 计算, 对矢量推进水平回转操纵性进行了评估,加工了矢量推进样机,并进行湖上操纵性验证。理论计算和试验数据表明：矢量推进具备极高的低速操纵性,该研究为矢量推进在 AUV 上的应用提供了理论和技术基础。     

低速潜器水动力试验及操纵运动预报

本文用平面运动机构测定了作用在低速潜器上的水动力，并用富里埃级数来表达大攻角范围时的水动力。在此基础上，用计算机进行模拟计算，预报了低速潜器的部分操纵性能     

强迫摇荡运动三维球体水动力系数的CFD计算

采用计算流体力学(CFD)的雷诺平均法(RANS方法),并考虑了自由表面的影响(采用VOF方法模拟自由表面),来模拟三维球体的单自由度强迫摇荡运动,得到纵荡、升沉及横摇的附加质量与阻尼系数。该数值模拟结果与三维势流理论计算的结果进行比较,趋势基本一致,但CFD方法更能凸显粘性的作用。本文所应用方法能合理给出浮式结构物的水动力系数,更精确描述海洋浮式结构物周围的流场,可应用于船舶与海洋工程浮式结构物的水动力性能研究。     

基于CFD的水下实验平台升沉阻力研究

为了选择出合适的水下实验平台的无动力下潜方向和预计出下潜时间,用CFD方法对水下实验平台的无动力下潜工况进行了数值模拟。通过与常用的摩擦阻力系数公式计算结果对比,选用了一组较为合适的网格进行CFD分析,通过FLUENT计算结果拟合出阻力系数与速度的函数,使用Simulink对水下实验平台无动力下潜的过程进行了仿真。最终选出以正向下潜为海试时的下潜方向,并得到了下潜过程的时间,通过与海试结果对比,验证了CFD计算结果的准确性。     

船舶在随机波浪中操纵运动预报

将船舶操纵运动模型和船舶耐波性理论结合起来,建立了适用于求解船舶在随机波浪中运动的六自由度数学模型.该模型采用水平随船坐标系,与操纵运动有关的水动力采用经验公式估算;与耐波性相关的水动力除二阶力外采用从频域到时域的方法,其中一阶波浪力通过脉冲响应函数的卷积求取,记忆效应力由时延函数的卷积表示;对于二阶波浪力则只考虑其定常部分.最后,应用该模型对一艘集装箱船在静水、规则波、随机波下的回转运动进行了预报,并就波浪对回转运动的影响做了讨论.认为一阶力对船舶操纵运动影响不明显;在考察波浪对船舶操纵运动的影响,必须考虑二阶力的作用.     

利用双水舱减摇系统预防船舶参数横摇研究

在研究船舶参数横摇的产生原因和发生条件的基础上,结合减摇水舱对于船舶的作用效果研究,根据参数横摇的特点,提出利用由两个不同结构的被动式U型减摇水舱组成的双水舱系统来避免船舶参数横摇的发生。在所建立的船舶—双水舱系统模型的基础上,介绍双水舱系统的设计方法,并以一艘集装箱船为例,仿真研究在参数横摇发生条件下双水舱系统对参数横摇的影响。同时还对双水舱系统在船舶正常航行时的减摇效果进行仿真研究。     

水陆两栖机器人水下动力学建模及操纵性研究

针对多模态水陆两栖机器人作业环境复杂使得水下运动状态难以预报等难题,基于 CFD 方法求解的水动力系数,构建了机器人水下运动的五自由度动力学和运动学模型。基于机器人水下动力学模型,采用四阶经典龙格库塔法,开展了机器人直航运动及水平面回转运动数值仿真研究,并进行了水池试验验证。 试验结果数据与数值仿真结果误差均不超过 10%,验证了机器人水动力系数及五自由度动力学模型的准确性, 为水陆两栖机器人研制提供了理论与技术支撑。     

基于频域Rankine面元法的船舶耐波性计算和分析

在频域中分别使用Rankine面元法和去奇点Rankine面元法（desingularized-Rankine panel method，简称DRPM）快速求解有航速船舶耐波性问题。使用两种不同的线性化方式：叠模流线性化法（double-body flow，简称DB）和均匀流线性化方法（Neumann-Kelvin，简称NK）计算了Wigley I、Wigley III和S175在有航速时船舶的水动力系数、波浪激励力和运动响应。两种线性化方法的计算结果与试验结果进行了比较，研究表明：使用Rankine面元法和去奇点Rankine面元法计算的结果相差不大，且与NK法相比使用DB法计算的结果和试验值更吻合，尤其是非对角线上交叉耦合水动力系数A35,B35,A53,B53的计算结果。运动响应对于边界条件线性化方式比较敏感，尤其是垂荡运动，在船共振频率附近，运动受到的影响最明显。     

基于神经网络的船舶自动舵设计

依据人工操舵的基本原理 ,提出了一种能适应船舶航行环境变化和自动获取船舶操纵运动特性知识的神经网络控制器。仿真结果表明 ,此神经网络控制器不仅能对系统进行有效的控制 ,而且可达到无超调、无波动的控制效果。此外 ,其操舵规律与人工操作时的最佳操舵规律一致     

一种新概念潜浮平台操纵性仿真研究

新概念潜浮平台是一种全新的船型,在建造实船之前对其操纵性能进行全面评估非常重要.首先在模型操纵性试验和理论分析的基础上建立考虑波浪干扰力和力矩作用的平台操纵运动数学模型,并用Simulink建立图形化的动力学仿真程序.基于该程序对水面和水下各种操纵情况进行仿真和分析,并就平台在波浪中的操纵性进行研究.仿真结果表明该平台具有良好的操纵性能,从而验证了设计,并为今后运动控制系统的设计提供了一个验证平台.     

A Study on the Maneuvering Motion of a Low Speed Submersible

In this paper,the maneuvering characteristics of a low speed submersible are investigated.First,the captive model tests are carried out to obtain the hydrodynamic forces acting on the submersibleusing a Planar Motion Mechanism(PMM).For the hydrodynamic forces within a wide range of attack an-gles,the hydrodynamic coefficients which are usually used in the conventional maneuvering motion arequite difficult to be applied.In this case,a Fourier series is adopted to represent the hydrodynamic forcesand it fits the experimental data well.Then,based on the experimental results the simulation calculationsare made to predict some of the maneuvering performance of the low speed submersible.     

System-based investigation on 4-DOF ship maneuvering with hydrodynamic derivatives determined by RANS simulation of captive model tests

For the non-negligible roll-coupling effect on ship maneuvering motion, a system-based method is used to investigate 4-DOF ship maneuvering motion in calm water for the ONR tumblehome model. A 4-DOF MMG model is employed to describe ship maneuvering motion including surge, sway, roll, and yaw. Simulations of circular motion test, static drift and heel tests are performed by solving the Reynolds-averaged Navier-Stokes (RANS) equations, after a convergence study quantifying the necessary grid spacing and time step to resolve the flow field adequately. The local flow field is analyzed for the selected cases, and the global hydrodynamic forces acting on the ship model are compared with the available experiment data. Hydrodynamic derivatives relating to sway velocity, yaw rate, and heel angle are computed from the computed force/moment data using least square method, showing good agreement with those obtained from EFD data overall. In order to investigate further the validity of these derivatives, turning circle and zigzag tests are simulated by using the 4-DOF MMG model with these derivatives. The trajectories and the time histories of the kinematic variables show satisfactory agreement with the data of free-running model tests, indicating that the system-based method coupled with CFD simulation has promising capability to predict the 4-DOF ship maneuvering motion for the unconventional vessel.     

Investigation of a method for predicting AUV derivatives

The paper addresses the problem of autonomous underwater vehicle (AUV) modelling and parameter estimation as a means to predict the dynamic performance of underwater vehicles and thus provide solid guidelines during their design phase. The use of analytical and semi-empirical (ASE) methods to estimate the hydrodynamic derivatives of a popular class of AUVs is discussed. A comparison is done with the results obtained by using computational fluid dynamics to evaluate the bare hull lift force distribution around a fully submerged body. An application is made to the estimation of the hydrodynamic derivatives of the MAYA AUV, an autonomous underwater vehicle developed under a joint Indian-Portuguese project. The estimates obtained were used to predict the turning diameter of the vehicle during sea trials.     

深远海养殖工船最小推进功率研究

针对十万吨级深远海养殖工船在波浪中的阻力和运动响应开展了船模试验与模拟计算,并对其最小推进功率进行了校核。以试验流体力学（EFD）模型试验与模型尺度计算流体力学（CFD）模拟计算的结果进行对比作为方法验证,将实尺度CFD模拟计算的结果直接用于最小推进功率的校核。结果显示,EFD模型试验结果与模型尺度CFD计算结果误差在10%左右,计算精度满足工程要求。在规定的恶劣海况下该船型波浪增阻占总阻力的比例最高可达56.3%,螺旋桨转矩可达最大转矩的63.9%。等级2简化评估法得到的最小推进功率为等级1线评估法给出的最小功率线值的58.9%。研究表明实尺度CFD模拟计算可直接用于船舶最小推进功率的校核,此深远海养殖工船使用等级2简化评估方法进行校核更容易满足规范要求,其最小推进功率应不小于6 833 kW。     

涌浪作用下港内大型集装箱船运动特性数值研究

随着船舶大型化和港口建设深水化发展,外海不同周期波浪作用下大型系泊船泊稳问题与小型系泊船相比出现了新的特点。为此,利用数值模型方法研究了在不同入射角度和周期的涌浪作用下港内大型系泊船的水动力响应,针对系泊船的泊稳情况探讨了船舶的运动规律和运动特性。研究发现,在涌浪周期较大的情况下,限定波高的泊稳标准不足以用来确定系泊船的正常作业条件,港内泊船的水平运动（纵荡、横荡和艏摇）极易超出运动标准值并影响装卸作业效率,并且船舶的水平运动表现出主要由次重力波主导的低频运动特性,而垂直运动（垂荡、横摇和纵摇）表现出主要由短波主导的波频运动特性。     

A new CFAR ship target detection method in SAR imagery

Many ship target detection methods have been developed since it was verified that ship could be imaged with the space-based SAR systems. Most developed detection methods mostly emphasized ship detection rate but not computation time. By making use of the advantages of the K-distribution CFAR method and two-parameter CFAR method, a new CFAR ship target detection algorithm was proposed. In that new method, we use the K-distribution CFAR method to calculate a global threshold with a certain false-alarm rate. Then the threshold is applied to the whole SAR imagery to determine the possible ship target pixels, and a binary image is given as the preliminary result. Mathematical morphological filter are used to filter the binary image. After that step, we use the two-parameter CFAR method to detect the ship targets. In the step, the local sliding window only works in the possible ship target pixels of the SAR imagery. That step avoids the statistical calculation of the background pixels, so the method proposed can much improve the processing speed. In order to test the new method, two SAR imagery with different background were used, and the detection result shows that that method can work well in different background circumstances with high detection rate. Moreover, a synchronous ship detection experiment was carried out in Qingdao port in October 28, 2005 to verify the new method and one ENVISAT ASAR imagery was acquired to detect ship targets. It can be concluded from the experiment that the new method not only has high detection rate, but also is time-consuming, and is suitable for the operational ship detection system.