Multi‑Crack Interaction and Influence on the Spherical Pressure Hull for a Deep‑Sea Manned Submersible

This study investigates the interaction and influence of surface cracks on the spherical pressure hull of a deep-sea manned submersible.The finite element model of the spherical hull is established,and a semi-elliptical surface crack is inserted in the welding toe of the spherical hull as the main crack.Considering the combined effect of external uniform pressure and welding residual stress at the weld toe,the stress intensity factor(SIF)is obtained based on the M-integral method.Inserting disturbing cracks at different positions on the spherical hull surface,the interaction and influence between multi-cracks are revealed by numerical calculation.The results show that the existence of the disturbing crack has a great influence on the stress intensity factor of the main crack,and the influence is different with the different location of disturbing crack.The study of the interaction of multiple cracks under different interference factors and the influence of disturbing cracks on the main crack can provide some reference for future engineering applications.

A Numerical and Experimental Study on the Hull-Propeller Interaction of A Long Range Autonomous Underwater Vehicle

Range is an important factor to the design of autonomous underwater vehicles (AUVs), while drag reduction efforts are pursued, the investigation of body-propeller interaction is another vital consideration. We present a numerical and experimental study of the hull-propeller interaction for deeply submerged underwater vehicles, using a proportional-integral- derivative (PID) controller method to estimate self-propulsion point in CFD environment. The hydrodynamic performance of hull and propeller at the balance state when the AUV sails at a fixed depth is investigated, using steady RANS solver of Star-CCM+. The proposed steady RANS solver takes only hours to reach a reasonable solution. It is more time efficient than unsteady simulations which takes days or weeks, as well as huge consumption of computing resources. Explorer 1000, a long range AUV developed by Shenyang Institute of Automation, Chinese Academy of Sciences, was studied as an object, and self-propulsion point, thrust deduction, wake fraction and hull efficiency were analyzed by using the proposed RANS method. Behind-hull performance of the selected propeller MAU4-40, as well as the hull-propeller interaction, was obtained from the computed hydrodynamic forces. The numerical results are in good qualitative and quantitative agreement with the experimental results obtained in the Qiandao Lake of Zhejiang province, China.

Numerical Study on Flow Around Modern Ship Hulls with Rudder-Propeller Interactions

Reducing the fuel consumption of ships presents both economic and environmental gains. Although in the past decades,extensive studies were carried out on the flow around ship hull, it is still difficult to calculate the flow around the hull while considering propeller interaction. In this paper, the viscous flow around modern ship hulls is computed considering propeller action. In this analysis, the numerical investigation of flow around the ship is combined with propeller theory to simulate the hull-propeller interaction. Various longitudinal positions of the rudder are also analyzed to determine the effect of rudder position on propeller efficiency. First, a numerical study was performed around a bare hull using Shipflow computational fluid dynamics(CFD) code to determine free-surface wave elevation and resistance components.A zonal approach was applied to successively incorporate Bpotential flow solver^ in the region outside the boundary layer and wake, Bboundary layer solver^ in the thin boundary layer region near the ship hull, and BNavier-Stokes solver^in the wake region. Propeller open water characteristics were determined using an open-source MATLAB code Open Prop, which is based on the lifting line theory, for the moderately loaded propeller. The obtained open water test results were specified in the flow module of Shipflow for self-propulsion tests. The velocity field behind the ship was recalculated into an effective wake and given to the propeller code that calculates the propeller load. Once the load was known, it was transferred to the Reynolds-averaged Navier-Stokes(RANS) solver to simulate the propeller action. The interaction between the hull and propeller with different rudder positions was then predicted to improve the propulsive efficiency.

Analysis of structural behavior during collision event accounting for bow and side structure interaction

The main goal of this study was to investigate the effects of selected ship collision parameter values on the characteristics of the absorbed energy in several ship collision scenarios. Non-linear simulations were performed using a finite element method （FEM） to obtain virtual experiment data. In the present research, the size of the side damage from a collision phenomenon were measured and used to verify the numerical configuration together with the calculation results using an empirical equation. Parameters in the external dynamics of a ship collision such as the location of the contact point and velocity of the striking ship were taken into consideration. The internal energy and deformation size on the side structure were discussed further in a comparative study. The effects of the selected parameters on several structural behaviors, namely energy, force, and damage extent were also observed and evaluated in this section. Stiffener on side hull was found to contribute significantly into resistance capability of the target ship against penetration of the striking bow. Remarkable force during penetration was observed to occur when inner shell was crushed as certain velocity was applied in the striking bow.

Numerical simulation of hull/propeller interaction of submarine in submergence and near surface conditions

Hull/propeller interaction is of great importance for powering performance prediction. The features of hull/propeller interaction of a submarine model with a high-skew five blade propeller in submergence and near surface conditions are numerically simulated. The effect of propeller rotation is simulated by the sliding mesh technique. Free surface is captured by the volume of fluid （VOF） method. Computed results including resistance, thrust, torque and self-propulsion factor are compared with experimental data. It shows fairly good agreement. The resistance and wave pattern of the model at different depths of submergence are computed. And the thrust, torque and self-propulsion factor of the model in submergence and near surface condition are compared to analyze the effect of free surface on self-propulsion performance. The results indicate that free surface has more influence on resistance than that on self-propulsion factors.

环肋布局对钛合金圆柱耐压壳内爆过程的影响研究

环肋圆柱壳是深潜器耐压结构的主要形式,但由于极限承载能力和振动特性的需求,存在不同的环肋布局形式。为探究环肋布局对钛合金圆柱耐压壳内爆的影响,基于任意拉格朗日欧拉方法开展数值研究。首先对比试验结果验证液-固-气三相流固耦合数值模型的准确性。然后分析3种环肋布局下圆柱耐压壳水下内爆过程中的结构动态响应、冲击波传播以及能量演化等特征。结果表明,环肋均布时,内爆中心由筒体中部向一端移动。而中部和端部加强时,内爆中心由环肋稀疏位置向密集位置移动,结构动能均存在显著的二次波峰现象。此外,中部加强能有效降低最大冲击波峰值。通过对环肋圆柱壳内爆响应特性的分析,对深海耐压结构的设计具有重要的工程意义。

Hydrodynamic interaction among hull,rudder and bank for a ship sailing along a bank in restricted waters

By applying a CFD tool to solve the RANS equations, the viscous flow around a model of hull-rudder system towed along a bank in shallow water is numerically simulated. Hydrodynamic forces and moments acting on the ship are calculated for different ship-bank distances and rudder angles. A container ship, KCS, is taken as an example for the numerical study. Under the assumption of low ship speed, the influences of free surface elevation and ship squat are assumed to be negligible. Based on the calculation results, the hydrodynamic interaction among the hull, rudder and bank is analyzed.

Numerical estimation of bank-propeller-hull interaction effect on ship manoeu-vring using CFD method

This paper presents a numerical investigation of ship manoeuvring under the combined effect of bank and propeller. The incompressible turbulent flow with free surface around the self-propelled hull form is simulated using a commercial CFD software （ANSYS-FLUENT）. In order to estimate the influence of the bank-propeller effect on the hydrodynamic forces acting on the ship, volume forces representing the propeller are added to Navier-Stokes equations. The numerical simulations are carried out using the equivalent of experiment conditions. The validation of the CFD model is performed by comparing the numerical results to the availa- ble experimental data. For this investigation, the impact of Ship-Bank distance and ship speed on the bank effect are tested with and without propeller. An additional parameter concerning the advance ratio of the propeller is also tested.

三体船船型分析及兴波干扰的模型试验研究

以本文设计的高速三体船型线为研究对象,分析了三体船船型的特点。应用均匀设计法进行了三体船兴波干扰的模型试验研究,依据试验结果分析了片体位置对三体船兴波干扰的影响,比较了同用途三体船与单体船的阻力性能,并讨论了多体船快速性试验结果的换算问题。

船后桨的布局对螺旋桨水动力性能的影响

为了研究大型水面船舶船桨干扰作用对螺旋桨的水动力性能的影响,探讨船后螺旋桨的布置设计原则,以某大型四桨水面船舶为研究对象,基于RANS(Reynolds-averaged Navier-Stokes)方法,建立了船桨整体计算模型,重点研究了螺旋桨的相对纵向和横向布置位置的变化对螺旋桨水动力性能的影响.数值计算结果表明:对于四桨船舶,船后螺旋桨的水动力性能对螺旋桨的纵向位置移动不是很敏感,而对螺旋桨横向位置移动则比较敏感,应当尽量避免使同侧两螺旋桨的盘面中心横向距离小于1倍螺旋桨直径.

螺旋桨/船体粘性流场的整体数值求解

螺旋桨和船体是相互作用的,孤立地对螺旋桨或船体流场进行数值模拟均无法有效地对它们的相互影响进行研究。本文采用周向平均的混合面处理方法,实现了螺旋桨/船体流场的整体计算,计算结果和试验数据进行了比较,表明该方法能很好地模拟螺旋桨和船体之间的相互影响,从而揭示了真实螺旋桨和船体之间相互干扰的内在规律。本文研究结果为研究螺旋桨和船体相互影响提供了更加精确和实用的研究手段。

冰区航行船舶操纵性研究综述

极地资源的开发和北方航道的通航对冰区船舶操纵运动性能提出了更高的要求和挑战。论文梳理了冰区航行船舶遭遇不同冰况时的操纵性特点,分析了冰区船舶操纵问题的本质,对国内外冰区船舶的全尺度和模型的操纵性试验、冰-船相互作用下的操纵性数值预报研究进展进行了介绍。冰区船舶操纵性的研究主要应用基于经验公式的半数值计算方法,仍是一个较新的领域。

实效伴流雷诺数影响的数值模拟

本文用数值计算的方法模拟三维船舶尾流与螺旋桨之间的相互作用，计算在四个不同量级雷诺数情况下（包括实船雷诺数１．６７×１０９和模型雷诺数１．６７×１０６）的水动力性能。船桨干扰采用三维不可压ＲＡＮＳ方程、ｋ－湍流模型和升力面理论作为基本研究工具进行相互干扰和迭代来预报此复杂流场及其螺旋桨的水动力性能。比较四个不同量级雷诺数情况下实效伴流分布及实效伴流分数的计算值，初步探索实效伴流的雷诺数影响。

过载保载对金属材料疲劳裂纹扩展速率影响研究

文章基于载荷次序效应产生影响的原因和相关预报模型,提出了考虑单峰过载和保载共同作用下疲劳裂纹扩展速率预报模型。在文中提出的考虑载荷次序效应的疲劳裂纹扩展速率预报模型的基础上,对几种金属材料在单峰过载、多峰过载、过载与保载共同作用下疲劳裂纹扩展速率进行了预报研究,并将预报结果与相应试验结果进行了比较,对考虑载荷次序效应的疲劳裂纹扩展速率预报模型的适用性进行了验证。

吊舱推进器与船体间相互影响研究进展

吊舱推进器是近年来发展起来的一种新型船舶推进装置。针对吊舱推进器与船体之间影响的成因、干扰形式和研究方法进行了阐述,总结了吊舱推进器与船体之间相互影响的理论研究和模型试验方面取得的成果。最后提出该领域的主要研究方向,作为进一步研究的参考。

GPU并行计算加速的实时可视外壳三维重建及其虚实交互

针对现有的基于图像的三维重建方法难以实现真实物体的快速三维重建,无法满足虚实交互等应用需求的问题,提出一种基于GPU并行计算的实时三维重建及其虚实交互方法.首先把物体所在空间剖分成具有数据独立性的体素集合,结合可视外壳重建算法和精确行进立方体算法并行遍历每个体素得到体素状态序列;然后并行压缩体素状态序列得到非空体素集合,对非空体素进行并行三角形网格化,并利用图形硬件的多重纹理映射和可编程功能进行基于像素的纹理映射;最后假定虚拟物体的粒子为运动受限的拉格朗日流体粒子,重建物体网格顶点为流体边界,通过流体动力学方程的并行光滑粒子动力学方法求解来计算虚实交互.实验结果表明,该方法在GPU上进行完全并行求解,在32×32×32的空间剖分精度下,实现了实时三维重建和20帧/s左右的虚实交互计算,适用于计算机图形学和虚拟现实等领域中的虚实交互应用.

潜水器螺旋桨和舵翼布局的优化

对潜水器螺旋桨和舵翼的布置方式进行了研究。根据双桨在敞水中的相互干扰情况确定双桨的安装位置,而后将螺旋桨、艇体和舵翼作为一个整体来分析,采用数值模拟的方法计算四种不同的桨舵布置方式中螺旋桨的水动力性能、舵翼的舵效和艇体的阻力随着舵角不同的变化情况。结合实际要求,选择最好的桨舵布置方式。

顶浪规则波中小水线面双体船纵向运动特性数值分析

基于RANS方程和VOF模型求解船体粘性兴波流场,采用Overset技术处理船体运动,开展了小水线面双体船(Small Waterplane Area Twin Hulls,SWATH)迎浪规则波中运动响应特性及其产生机理的研究。通过数值计算结果与模型试验结果的对比分析,验证了本文方法的有效性;在此基础上,分析了船体运动响应曲线中各峰值产生的原因及片体间相互干扰对SWATH船在波浪中运动响应的影响,发现其中一个峰值出现的原因为遭遇频率接近船体运动固有频率,由此发生共振;另一个峰值的出现则可能与SWATH特殊的船型及附体配置有关。由于SWATH船片体间的水动力干扰效应,SWATH船在波浪中运动响应峰值较单个片体响应峰值明显减小,且出现的位置向低频方向移动。

船桨整体及螺旋桨诱导的船体表面脉动压力计算

为了形成一套满足工程使用要求的船桨整体计算规程,对现有各种螺旋桨CFD计算方法进行了综合研究.定常计算主要进行了多参考系方法(MRF)和混合面方法(M IX)的研究.非定常计算采用移动网格方法,主要是探讨了时间步长和内迭代次数以及网格对计算结果的影响.结果表明:与其他混合面方法相比,MRF是最容易收敛的,混合面方法中3个面都混合不易收敛;MRF的推力和扭矩计算精度最高,其次是前后2个面混合的方法;由于非定常计算本身而非真实的物理现象引起的高频振荡成分,通过细化网格和增加内迭代次数,可以得到解决.

腐蚀、疲劳损伤下船体结构可靠性研究现状与展望

对考虑腐蚀、疲劳损伤影响下船体结构可靠性分析层面的研究现状进行梳理和概述。通过综述发现:近年来,船体结构可靠性分析的对象已由拟建船体向现役船体结构方向扩展,且研究重心开始由腐蚀、疲劳损伤单一影响下的可靠性分析向两者交互作用影响下的可靠性分析方向发展。未来开展腐蚀、疲劳损伤下船体结构可靠性研究工作的重点将主要体现在以下4个方面:1)点蚀损伤船体结构破坏机理及对应的评估方法研究;2)腐蚀、疲劳损伤交互作用下的船体结构破坏机理研究;3)基于有限的实船损伤勘验数据,开展合理、可行的可靠性评估方法研究,进行船体结构全寿命周期内综合损伤下的可靠性分析;4)建立不同服役环境、服役期限的实船腐蚀、疲劳损伤数据库。