无人潜航器总体性能评估试验需求研究

为有效提高无人潜航器(UUV)水池总体性能评估试验能力,以国内三大UUV重点实验室试验水池尺度及设施配置情况为基础,结合UUV原理和结构组成,分析了UUV水池总体性能评估具体试验需求。通过分析UUV试验水池体量特点和水池设施配置需求,总结了9项UUV水池性能评估试验需求。为下一步水池规划建设和开展各项UUV水池试验提供借鉴和参考。     

整体式止屈器数值模拟方法与优化研究

海底管道是海洋石油主要的运输方式,但海底管道在外部静水压力作用下很可能发生局部屈曲压溃,造成灾难性后果。安装止屈器可有效阻止屈曲传播,保证管道安全,整体式止屈器在实际中应用最为广泛。整体式止屈器存在通过减小止屈器体积以节约成本进行优化的可能性,因此,在保证止屈器止屈效果的前提下,可通过减小止屈器的体积,以达到减轻重量、节约成本、减少安装难度等多种目的。研究过程中使用ABAQUS进行模型的仿真模拟,比较了广义弧长法的优缺点,决定选用更方便的静水流体单元法,计算得到不同止屈器的穿越压力以及相应的体积,对比各止屈器的穿越压力变化和体积变化,实现结构优化的目标。基于以上研究,可以得出减少止屈器体积的结构优化方案具有可行性的结论。     

Numerical simulation of micro-bubble drag reduction using population balance model

The phenomenon of drag reduction by the injection of micro-bubbles into turbulent boundary layer has been investigated using an Eulerian-Eulerian two-fluid model. Multiple-size group (MUSIG) based on population balance models, which resolve a wide range of bubble sizes taking into account the bubble break-up and coalescence have been used for this purpose. The simulated results are compared against the experimental findings of Madavan et al. [1984. Reduction of turbulent skin friction by micro-bubbles. Physics of Fluids 27, 356-363] and also other numerical studies explaining the sophisticated phenomena of drag reduction. For the two Reynolds number cases considered, the buoyancy with the plate on the bottom configuration is investigated, as from the experiments it is seen that buoyancy seem to play a role in the drag reduction. Numerical model employed in the investigation comprises of a micro-bubble laden flow wherein two independent sets of Reynolds averaged Navier-Stokes (RANS) transport equations were used to describe both the phases of the flow. The shear stress transport (SST) turbulence model is used as the turbulent closure for the primary phase and a zero equation turbulence model is used for the micro-bubbles. Change in the mean streamwise velocity profiles, void fraction, turbulence modification and other results are presented and discussed with corresponding change in the gas injection rates. The complex mechanism of drag reduction are scrutinised and explained in context to our numerical findings. Special attentions have been also devoted to divulge the effect of bubble coalescence and break-up caused by random collision and turbulent impact. Numerical results showed good agreement for the skin-friction coefficients against experimental data throughout various air injection rates. The MUSIG model was found to be one of the best candidates to resolve the bubble dynamics in micro-bubble-induced drag reduction problems.     

Model test of the surface and submerged vehicles with the micro-bubble drag reduction

This study is based on the effective experiment observation and measuring technology to discuss the interaction influence between liquid turbulent boundary layer and a crowded group micro-bubbles. It is in order to understand and quantify the micro-bubbles clouds inside the turbulent boundary layer to eliminate the capacity of skin friction drag. Whenever the micro-bubbles are over supplied, pile up effect happened which makes micro-bubbles to integrate to each other as a large-size air film. Although they still have the drag reduction effect, the efficiency of drag reduction slowed down at this transition period. In the experiment of vertical type circulating water tunnel, when 1 μm porous medium is at 7 m/s flow speed, the C_v value at 0.056 has the best drag reduction efficiency of 26%. While 10 μm porous medium is at the same flow speed, the drag reduction efficiency is only around 23%.     

仿鱼尾推进小型水下航行器设计与模型试验研究

以蓝鳍金枪鱼为蓝本,进行了仿鱼尾推进小型水下航行器方案设计与模型制作,包括设计主体外形、主体结构及安装形式、传动机构、尾鳍形状等。在水池中开展了自航实验,测定了尾鳍的摆幅、频率、形状及刚度对航速的影响,结果表明在相同条件下提高尾鳍摆动频率或增大尾鳍摆幅,能提高水下航行器的速度;当采用柔性尾鳍时,航行器的速度明显增加。     

潜水器控制系统层次故障诊断模型设计

在潜水器控制系统的基础上,按照结构、功能和组件的关系,为潜水器控制系统进行故障诊断建模。依据基于模型的层次故障诊断技术,建立了适用于潜水器控制系统故障诊断的具体诊断和推理策略,开发了故障诊断软件系统,描述了故障诊断具体过程,并利用数字仿真验证系统设计的有效性。     

Depth-trim mapping control of underwater vehicle with fins

Underwater vehicle plays an important role in ocean engineering.Depth control by fin is one of the difficulties for underwater vehicle in motion control.Depth control is indirect due to the freedom coupling between trim and axial motion.It includes the method of dynamic analysis and lift-resistance-coefficient experiment and theory algorithm.By considering the current speed and depth deviation,comprehensive interpretation is used in object-planning instruction.Expected depth is transformed into expected trim.Dynamic output fluctuation can be avoided,which is caused by linear mapping of deviation.It is steady and accurate for the motion of controlled underwater vehicles.The feasibility and efficiency of the control method are testified in the pool and natural area for experiments.     

浅海管线检测维修潜水器控制系统自航模试验

浅海海底管线检测维修潜水器是具有复杂动力特性和作业方式的特种载人潜水器，其作业需配备姿态及航行自动控制系统。为了保证其自动控制系统研制成功，研制了1：8缩尺的自航模作为平台，将实际控制系统方案遵循相似性准则改造为自航模控制系统，包括校正与补偿回路、指令分配器、姿态控制回路、航行控制回路。在海洋工程水池模拟风浪流等海洋环境，进行各种情况下的控制试验，对实现的控制律加以验证和改进，这些改进又按照相似性准则反映到实际控制系统方案的修正中。控制系统的设计方案由此得到全面验证和改善。     

水下机器人主动升沉补偿系统研究

介绍一种基于水下机器人常规液压收放绞车的主动升沉补偿系统,利用加速度传感器获得母船的升沉运动信号,控制绞车的运转来降低母船的升沉运动对水下机器人的影响。通过理论计算建立主动升沉补偿系统的数学模型,仿真分析绞车运动对水下机器人升沉运动的补偿效果,并利用主动升沉补偿系统实验台验证基于常规液压收放绞车的主动升沉补偿方案的可行性。     

Wave effects on ascending and descending motions of the autonomous underwater vehicle

In the paper, a hydrodynamic model including the characteristics of maneuvering and seakeeping is developed to simulate the six-degree of freedom motions of the underwater vehicle steering near the sea surface. The corresponding wave exciting forces on the underwater vehicle moving in waves are calculated by the strip theory, which is based on the source distribution method. With the hydrodynamic coefficients relevant to the maneuvering and seakeeping, the fourth-order Runge–Kutta numerical method is adopted to solve the equations of motions and six-degrees of freedom of the motions for the underwater vehicle steering near the free surface can be obtained. The wave effect on the corresponding motions of the underwater vehicle is investigated and some interesting phenomena with respect to different wave frequencies and headings are observed. The hydrodynamic numerical model developed here can be served as a valuable tool for analyzing the ascending and descending behaviors of the underwater vehicle near the sea surface.     

海底管线检修潜水器垂直面控制及自航模试验

论述了纵倾控制律设计及自航模试验。首先选择一系列深度,对同一深度采用频域校正法单独设计控制律,使之对不同的速度和漂角具有足够的稳态精度和抗干扰性,这些控制律被集成统一为纵倾控制器,并根据潜深变化进行切换,对于其它深度采用同样的方法设计。控制器首先通过计算机仿真,然后进行自航模试验验证。设计的纵倾控制系统同时在其他试验项目中(水下管线跟踪和动力定位)发挥了重要的作用。     

一种基于视觉的水下机器人动力定位方法

以7 000 m载人潜水器的工程需求为背景,以水下单目摄像机为视觉传感器,进行了水下机器人动力定位方法研究。该动力定位方法利用视觉系统测量得到水下机器人与被观察目标之间的三维位姿关系,通过路径规划、位置控制和姿态控制分解,逐步使机器人由初始位姿逼近期望位姿并最终定位于期望位姿,从而实现了机器人的4自由度动力定位。通过水池实验验证了提出的动力定位方法,并且机器人能够抵抗恒定水流干扰和人工位置扰动。同时,该动力定位方法还可以实现机器人对被观察目标的自动跟踪。