相关原理在船速测定中的应用

用相关原理进行船速测定是继声原理中用多普勒原理测定船速之后又一新的测速方法.它们的共同特点都能测量舰船对地的速度,而且测量精度高,这对于舰船导航,精确定位,提高武备系统的命中率等都有重要意义。用相关原理测定船速的仪器称为声相关计程仪,它垂直向海底发射声波束,因而回波信号要比多普勒计程仪大得多,波束也能做得相当宽,所以在换能器的体积尺寸相同的条件下,在海底跟踪的工作深度,要比多普勒计程仪大得多,同时在声暴露方面小得多,这对于在潜艇上使用是很可贵的。本文对相关的几何条件作了较详细的介绍,对混合相关法测速原理进行了论述,并导出了判别式,从而拟定了相关解算装置的实施方框图,并对其进行混合相关解算的可实现性进行了验证。文章对计程仪的误差作了粗略的分析,前后介绍了JX-1型声相关计程仪这个应用实例。该计程仪于1988年7月通过设计定型,测速和计程精度分别达到0.1kn和0.2％的设计指标,可测对地船速的工作深度达235m,并附有测深功能,在3个半月,航程约5000海里的实船试用中情况良好。该计程仪现已批量生产,陆续安装舰船。     

国内外多普勒计程仪发展现状和展望

声学多普勒测速计程仪（DVL）是利用多普勒效应研制的一种为水面、水下载体提供速度信息并计量航程的自主导航设备。对DVL的发展现状进行了分析,对美国Teledyne RDI公司目前在产的4款DVL系列化产品特征和性能进行了阐述。针对当前研究的关键技术难点,如大深度多普勒计程仪体积受限、水面航船空化造成能量衰减导致作用距离降低、航船姿态摇摆和安装误差、非典型海底地形等因素导致解算错误等问题进行了分析,从工程实用角度展望并分析了未来的研究发展趋势及面临的挑战,为高精度DVL产品的设计提供了有益参考。     

声学多普勒计程仪测速误差分析与补偿

主要分析了声学多普勒计程仪测速误差的主要来源,并针对载体的姿态误差提出有效的补偿方法,对多普勒计程仪的安装偏差、波束方向误差和电路设计误差等固定误差,通过标定试验给出多普勒计程仪的补偿系数,并验证其有效性.     

修正Kalman滤波技术在复杂环境DVL标定中的应用研究

声学多普勒计程仪的安装偏角误差和比例因子误差是影响水下自主导航精度的主要误差源,需要进行精确误差标定。然而任何声呐性能均与海洋环境密切相关,如何实现复杂环境精确标定是计程仪工程应用中面临的实际问题。为此,在分析真实测速数据统计分布基础上,提出了一种基于修正 Kalman 滤波预处理的误差校准方法,并与标准 Kalman 滤波预处理方法的校准性能进行了比对;试验结果验证了新方法的有效性,降低了对标定试验场地的要求,大幅提高了校准效率。     

计程仪测速创新方法研究

为了在非理想环境的测速场或者没有测速场进行相对计程仪的准确测速,在通用方法基础上,论述了两种切实可行有效的测速新方法,通过理论及实验证明,实用性较强,具有一定的推广价值。     

探索中的仿生潜艇

据外刊报道,为提高潜艇的水下机动性和隐蔽性,美国海军正在利用仿生技术加紧研制一种全新概念的潜艇——金枪鱼式潜艇。美国海军科学家认为,金枪鱼具有平滑的线条,极快的游动速度以及在水中的高度灵敏性,是设计下一代新型潜艇理想的生物模型。目前,一艘长近2.5米的仿金枪鱼式潜艇原型已经问世,正在马萨诸塞州德雷珀实验室接受     

基于可重置联邦滤波器的水下运载体导航定位方法

单一导航系统无法满足水下运载体高精度、高可靠性的导航需求,文中根据常用水下导航系统的特点,提出基于可重置联邦滤波器的水下运载体导航定位方案,设计了以惯导系统(INS)为主参考系统,声学定位系统/深度计、多普勒计程仪(DVL)、罗经为子参考系统的联邦滤波器,并进行了仿真研究。结果表明文中设计的滤波器能有效融合各个传感器的导航信息,实现水下运载体高精度导航定位,并具有一定容错性。     

深海自治式水下航行器组合导航/定位误差分析与建模

在深海海洋油气资源勘探开发中,导航定位数据是各个测量参数的基准信息,测量载体的定位精度在一定程度上决定了其搭载的传感器探测精度。以COSL Explorer型深水自治式水下航行器为研究对象,分析其组合导航/定位系统的特点,得出包含超短基线水下定位、多普勒计程仪与惯性系统组合导航、海水中声速影响的深水自治式水下航行器导航/定位误差模型,并对该模型参数进行等误差剖面分析,得到该载体导航/定位误差分布趋势。并针对不同航速、不同定位斜距、不同时间间隔下的组合导航定位误差进行预报,为自主航行器在大海深、大范围工程勘察测量时参数设置提供理论依据。     

海军舰艇世界之最

最早的运输潜艇——美国“海狮”号潜艇第二次世界大战期间,鉴于盟军运输舰艇在大洋上被德军潜艇屡屡击沉,美国海军决定用潜艇从水下运送兵力和物资,于1944年将一艘老式作战潜艇改装成水下运输潜艇,取名为“海狮”号,这便是世界上最早的运输潜艇。该艇排水量为     

无人航行器对抗敌反潜装备作战使用技术研究

美国及其盟友为限制中国前出第一岛链进入西太平洋和北印度洋,采用天基卫星监测、水面舰船监听、水下潜艇区域探测、水下无人航行器及在海峡布设海底监听阵等方式在源头、航路及峡口等多个区域对我潜艇实施监视和跟踪.通过对潜艇不同探测装备分析,提出了一种具备水面、水下诱骗和打击能力的无人潜航器,敌反潜机诱骗、反潜直升机诱骗打击和潜艇...     

海底管线表面压力分布的理论分析

为了获取海底管线表面压力变化特征,基于固体边界层基本方程,利用摄动方法推导了管线表面压力分布解析式,并利用物理模型试验数据对理论公式进行了检验。经对公式系数做出适当调整,压力系数的计算公式能反映出边界层分离点前后的分布规律。     

Submarine slope stability analysis during natural gas hydrate dissociation: Discussion

Abstract

Volume change during natural gas hydrate dissociation is important for calculation of excess pore pressure and corresponding submarine slope stability. A short discussion is presented here to the paper of Wang et al. including some notes about the standard condition and parameters used in their model. This discussion calls attention to the wrong use of standard temperature and pressure during calculation of volume change, excess pore pressure, and submarine slope stability.     

考虑阻尼海底悬跨段管道的动力特性及允许悬空长度

以海底悬跨段输液管道为研究对象,考虑管道结构阻尼、流体附加阻尼、管内流体流动及管道轴向力和压强的作用,对其进行受力分析,导出管道振动微分方程,进而得到管道动力特性方程。用Hermit插值函数对管道的动力特性方程进行离散得到有限元表达式,采用复模态分析法,求得管道的自振频率。为防止管道发生横向涡激振动,用约化速度作为控制条件,确定管道允许悬空长度。结果表明,管道允许悬空长度随着内流流速、轴向压力和管内压强的增加而减小,随着轴向拉力的增加而加大。     

Mechanism of local scour around submarine pipelines based on numerical simulation of turbulence model

1 IntroductionSubmarine pipelines are important ocean engi-neeringequipm ents, especiallyfortheoiland gasin-dustries. M anyresearchershavebeendedicatedtotheproblem of local scour around the submarinepipelines, butmostoftheirwork arelaboratory testsand foc…     

曹妃甸海底深槽斜坡稳定性分析与评价

海底斜坡稳定性受风暴潮、海底地震等诸多不确定因素影响,易发生失稳破坏,产生较大的海洋地质灾害。简要介绍海底斜坡稳定性分析方法,建立曹妃甸深槽典型斜坡计算模型,确定了模型计算的海底地形参数、地层结构参数、土体物理力学参数等指标,利用GEO-SLOPE斜坡分析软件进行海底斜坡稳定性定量计算,分析了工程建设前自然状态下以及在大规模工程建设后海底斜坡稳定性,并模拟分析了在大风浪和地震等极端条件下斜坡的稳定性,确定了海底斜坡失稳空间特征。首次采用数值计算对曹妃甸海底斜坡稳定性进行定量分析评价,可以为类似近海建设工程提供重要的参考作用。     

Characteristics of Vibrational Wave Propagation and Attenuation in Submarine Fluid-Filled Pipelines

As an important part of lifeline engineering in the development and utilization of marine resources, the submarine fluid-filled pipeline is a complex coupling system which is subjected to both internal and external flow fields. By utilizing Kennard’s shell equations and combining with Helmholtz equations of flow field, the coupling equations of submarine fluid-filled pipeline for n=0 axisymmetrical wave motion are set up. Analytical expressions of wave speed are obtained for both s=1 and s=2 waves, which correspond to a fluid-dominated wave and an axial shell wave, respectively. The numerical results for wave speed and wave attenuation are obtained and discussed subsequently. It shows that the frequency depends on phase velocity, and the attenuation of this mode depends strongly on material parameters of the pipe and the internal and the external fluid fields. The characteristics of PVC pipe are studied for a comparison. The effects of shell thickness/radius ratio and density of the contained fluid on the model are also discussed. The study provides a theoretical basis and helps to accurately predict the situation of submarine pipelines, which also has practical application prospect in the field of pipeline leakage detection.     

海底水平管线回流区水流特性研究

针对管线绕流剪切层区的水流特征,利用射流分析的类似方法,通过简化控制方程,从理论上探讨了剪切层区的时均速度分布规律。物理试验中采用ADV测速仪对回流区流场进行了测量,对各流区流速和紊动强度变化趋势进行了讨论,并将试验结果与理论推导进行对比,二者基本吻合,为进一步研究海底管线防护措施提供了理论依据。     

An Analytical Solution for the Run-Out of Submarine Debris Flows

Submarine debris flows have a significant impact on offshore and coastal facilities. The unique characteristics of submarine debris flows involve large mass movements and long travel distances over very gentle slopes. To improve our insight and knowledge of the basic mechanism behind submarine debris flows, an analytical model was derived for the mobility of submarine debris flows. This model takes into account the mass change of debris flows induced by deposition, stagnation pressure, and the topography of the depositional area. One case study on the Palos Verdes debris flow proves its ability to predict the run-out distance of a submarine debris flow to a reasonable level of accuracy. On the gentle slopes, the submarine debris flow progressively loses mass due to deposition, which in turn influences the flow velocity. In addition, the results show that the slope angle and spreading angle of the debris depositional zone play important roles in the sliding process.     

The influence of scale,slope and channel geometry on the flow dynamics of submarine channels

Submarine channels are major morphological features of the sea floor and are important in the transport of sediment to the deep ocean. Although much is known concerning the large-scale distribution of sediment within and surrounding submarine channels, there is little understanding of the fluid dynamic processes that control this sedimentation. Direct measurement of flow velocities and concentrations has proved to be extremely difficult within submarine channels, with the resultant paucity of direct observations making physical laboratory modelling a critical technique for examining the processes that operate in, and control, submarine channel development.Recent experimental and numerical studies have proposed a new model of secondary circulation within submarine channel bends, characterised by a reversal in the orientation of the secondary circulation cell relative to that found in meandering rivers. This new paradigm for submarine channels thus predicts basal flow from the inside to the outside of the bend at a bend apex, with an upper return flow directed towards the inner bend. The reversal in orientation of the secondary flow cell has been linked to the vertical distribution of downstream velocity and associated changes in centrifugal and pressure gradient forces. However, previous work has additionally proposed that shearing of the within-channel flow by overbank flow may also generate secondary flow reversal.This study assesses the applicability of the proposed submarine bend flow model against a range of key channel parameters. We demonstrate that the sense of secondary circulation is the same for all experimental conditions, strongly supporting the new model of secondary flow in submarine channels. Furthermore, investigation of overbank shear induced secondary circulation confirms for the first time that this mechanism can occur, and identifies the channel styles most likely to exhibit this effect. Such shear-induced circulation is, however, shown to be a secondary mechanism, with the vertical distribution of downstream velocity the principal mechanism. In certain channel configurations, the two mechanisms may act to augment one another.     

海底边坡稳定性分析中波浪力的求解

针对浅水区波浪的非线性特性,提出了在海底边坡稳定性分析中应用椭圆余弦波理论来研究波浪力的问题,利用非线性弥散关系建立了新的适用于整个水深范围的椭圆余弦波的近似求解方法.结合工程实例,确立了海底边坡波浪力的计算步骤,并编制了计算程序.