RANSE Simulation of High-speed Planning Craft in Regular Waves

This paper presents a study on the numerical simulation of planing crafts sailing in regular waves. This allows an accurate estimate of the seas keeping performance of the high speed craft. The simulation set in six-degree of freedom motions is based on the Reynolds averaged Navier Stokes equations volume of fluid （RANSE VOF） solver. The trimming mesh technique and integral dynamic mesh method are used to guarantee the good accuracy of the hydrodynamic force and high efficiency of the numerical simulation. Incident head waves, oblique waves and beam waves are generated in the simulation with three different velocities （Fn =1.0, 1.5, 2.0）. The motions and sea keeping performance of the planing craft with waves coming from different directions are indicated in the flow solver. The ship designer placed an emphasis on the effects of waves on sailing amplitude and pressure distribution of planing craft in the configuration of building high speed crafts.

Fuel Saving and Emissions Cut Through Shore-Side Power Concept for High-speed Crafts at the Red Sea in Egypt

The progress of economic globalization,the rapid growth of international trade,and the maritime transportation has played an increasingly significant role in the international supply chain.As a result,worldwide seaports have suffered from a central problem,which appears in the form of massive amounts of fuel consumed and exhaust gas fumes emitted from the ships while berthed.Many ports have taken the necessary precautions to overcome this problem,while others still suffer due to the presence of technical and financial constraints.In this paper,the barriers,interconnection standards,rules,regulations,power sources,and economic and environmental analysis related to ships,shore-side power were studied in efforts to find a solution to overcome his problem.As a case study,this paper investigates the practicability,costs and benefits of switching from onboard ship auxiliary engines to shore-side power connection for high-speed crafts called Alkahera while berthed at the port of Safaga,Egypt.The results provide the national electricity grid concept as the best economical selection with 49.03 percent of annual cost saving.Moreover,environmentally,it could achieve an annual reduction in exhaust gas emissions of CO2,CO,NOx,P.M,and SO2by 276,2.32,18.87,0.825 and 3.84 tons,respectively.

Developments and Prospects of Long-Span High-Speed Railway Bridge Technologies in China

With the rapid developments of the high-speed railway in China, a great number of long-span bridges have been constructed in order to cross rivers and gorges. At present, the longest main span of a constructed high-speed railway bridge is only 630 m. The main span of Hutong Yangtze River Bridge and of Wufengshan Yangtze River Bridge, which are under construction, will be much longer, at 1092 m each. In order to overcome the technical issues that originate from the extremely large dead loading and the relatively small structural stiffness of long-span high-speed railway bridges, many new technologies in bridge construction, design, materials, and so forth have been developed. This paper carefully reviews progress in the construction technologies of multi-function combined bridges in China, including com- bined highway and railway bridges and multi-track railway bridges. Innovations and practices regarding new types of bridge and composite bridge structures, such as bridges with three cable planes and three main trusses, inclined main trusses, slab-truss composite sections, and steel-concrete composite sections, are introduced. In addition, investigations into high-performance materials and integral fabrication and erection techniques for long-span railway bridges are summarized. At the end of the paper, prospects for the future development of long-span high-speed railwav bridges are provided.

Hydrodynamic Performance Prediction of Stepped Planing Craft Using CFD and ANNs

In the present paper,the hydrodynamic performance of stepped planing craft is investigated by computational fluid dynamics(CFD)analysis.For this purpose,the hydrodynamic resistances of without step,one-step,and two-step hulls of Cougar planing craft are evaluated under different distances of the second step and LCG from aft,weight loadings,and Froude numbers(Fr).Our CFD results are appropriately validated against our conducted experimental test in National Iranians Marine Laboratory(NIMALA),Tehran,Iran.Then,the hydrodynamic resistance of intended planing crafts under various geometrical and physical conditions is predicted using artificial neural networks(ANNs).CFD analysis shows two different trends in the growth rate of resistance to weight ratio.So that,using steps for planing craft increases the resistance to weight ratio at lower Fr and decreases it at higher Fr.Additionally,by the increase of the distance between two steps,the resistance to weight ratio is decreased and the porpoising phenomenon is delayed.Furthermore,we obtained the maximum mean square error of ANNs output in the prediction of resistance to weight ratio equal to 0.0027.Finally,the predictive equation is suggested for the resistance to weight ratio of stepped planing craft according to weights and bias of designed ANNs.

Prediction of Planing Craft Motion Based on Grey System Theory

In order to minimize the harm caused by the instability of a planing craft, a motion prediction model is essential. This paper analyzed the feasibility of using an MGM（1,N） model in grey system theory to predict planing craft motion and carried out the numerical simulation experiment. According to the characteristics of planing craft motion, a recurrence formula was proposed of the parameter matrix of an MGMfl,N） model. Using this formula, data can be updated in real-time without increasing computational complexity significantly. The results of numerical simulation show that using an MGM（1,N） model to predict planing motion is feasible and useful for prediction. So the method proposed in this study can reflect the planing craft motion mechanism successfully, and has rational and effective functions of forecasting and analyzing trends.

On Prediction of Longitudinal Attitude of Planing Craft Based on Controllable Hydrofoils

The purpose of this research study was to examine the attitude response of a planing craft under the controllable hydrofoils.Firstly,a non-linear longitudinal attitude model was established.In the mathematical model,effects of wind loads were considered.Both the wetted length and windward area varied in different navigation conditions.Secondly,control strategies for hydrofoils were specified.Using the above strategies,the heave and trim of the planing craft was adjusted by controllable hydrofoils.Finally,a simulation program was developed to predict the longitudinal attitudes of the planing craft with wind loads.A series of simulations were performed and effects of control strategies on longitudinal attitudes were analyzed.The results show that under effects of wind loads,heave of fixed hydrofoils planing craft decreased by 6.3%,and pitch increased by 8.6% when the main engine power was constant.Heave decreased by less than 1% and trim angle decreased by 1.7% as a result of using variable attack angle hydrofoils;however,amplitude changes of heave and pitch were less than 1% under the control of changeable attack angle hydrofoils and longitudinal attitude.

Brief Introduction to a Bionic Lizard Flywheel Planing Craft

Based on the research, simulation and experimental investigation of Basilisk Lizard running on the water surface, and similar experimental investigation of the craft models and practical crafts running on the water surface for about 30 years. The Bionic Lizard Flying Wheel Planing Craft was created and invented. This paper describes the evolution, experimental investigation, test results, design features, advantages, applications, and prospect of the innovation, which denotes the craft with excellent speed performance （high speed, extra STOL （short take-off and landing distance） and VTOL（vertical take-off and landing） characteristics, good transverse and longitudinal stability, super shallow water draft, high propulsion efficiency at high speed without cavitations obstacle, low external field noise, small dimension, simple configuration and structure, good economy, nice transportation efficiency, and possibly is first of these kinds in the HPMV （High Performance Marine Vessels） family around the world.

A CFD Study of the Resistance Behavior of a Planing Hull in Restricted Waterways

The demand for high-speed boats that operating near to shoreline is increasing nowadays.Understanding the behavior and attitude of high-speed boats when moving in different waterways is very important for boat designer.This research uses a CFD(Computational Fluid Dynamics)analysis to investigate the shallow water effects on prismatic planing hull.The turbulence fl ow around the hull was described by Reynolds Navier Stokes equations RANSE using the k-ɛturbulence model.The free surface was modelled by the volume of fl uid(VOF)method.The analysis is steady for all the ranges of speeds except those close to the critical speed range Fh=0.84 to 1.27 due to the propagation of the planing hull solitary waves at this range.In this study,the planing hull lift force,total resistance,and wave pattern for the range of subcritical speeds,critical speeds,and supercritical speeds have been calculated using CFD.The numerical results have been compared with experimental results.The dynamic pressure distribution on the planing hull and its wave pattern at critical speed in shallow water were compared with those in deep water.The numerical results give a good agreement with the experimental results whereas total average error equals 7%for numerical lift force,and 8%for numerical total resistance.The worst effect on the planing hull in shallow channels occurs at the critical speed range,where solitary wave formulates.

滑行艇穿浪艏型线智能优化设计

[目的]针对滑行艇艏部型线对耐波性的影响,对其进行智能优化设计。[方法]基于某型穿浪艏滑行艇,以艏柱角度、二次曲线形因子、折角线艏部控制点坐标值为参数驱动艏部型线变形,对艇首进行参数化建模;基于模型试验结果验证数值计算方法,根据数值计算结果建立代理模型;优化体积弗劳德数F r?=2.7工况下的静水阻力及在规则波中的运动响应幅值,探究设计航速下兼顾阻力与耐波性的艇首型线优化设计。[结果]结果显示,以静水阻力与波浪平均阻力增幅不超过12%为约束,优化后新艇型的加速度幅值、垂荡幅值、纵摇幅值和升沉值均减小了20%。[结论]通过优化艇首型线,在保证滑行艇低阻力的同时能改善其在规则波中的运动响应,可为滑行艇型线优化提供智能优化设计方法。

高速滑行艇阻力和运动响应数值分析

为了研究自主设计的滑行艇在高速行驶状态下,船体航行状态以及运动响应对滑行艇的运动性、阻力性和耐波性的影响。试验运用建模软件Solidworks完成滑行艇的三维建模;基于RANS方程的粘流理论,利用CFD软件FINE/MARINE耦合求解六自由度运动方程。计算分析发现,该艇在航速24~32 kn之间阻力上升相对较缓,并且在重心位置后移0.2 m后,该艇在航速24~32 kn之间阻力上升总阻力依然趋于平缓;在航速30 kn以上时,纵摇与升沉的运动响应趋于相对较好的状态;当滑行艇在16倍船长的波长附近时,滑行艇的运动响应最为剧烈。本研究为该滑行艇的航速设计和航行安全策略提供了参考。

Hull forms of small high-speed wave-piercing monohull crafts and hydrodynamics study

Wave-piercing design is a revolution in hull design for small high-speed boats to operate in adverse sea conditions. To study hydrodynamics of the small high speed wave piercing monohull craft systematically, four typical small high-speed wave-piercing monohull crafts were developed, and validated CFD methods were adopted to calculate hull resistances and motions. The resistances and hull motions of these high-speed wave piercing monohull crafts in calm water and waves were obtained and compared. Obvious operating differences can be observed. High-speed wave piercing monohull crafts with slender and twisted planing hulls have smaller resistance at high speed, but the dynamic effects increase as sea conditions worsen. The high-speed wave-piercing monohull craft with a slim multi-chine hull maintains in waves for softer hull motions but suffers the disadvantages of larger resistance. The high-speed wave piercing monohull craft with a triangular hull shows no obvious advantages compared with the other types.

滑行艇波浪中纵向运动理论预报的新方法

分析了现有滑行艇纵向运动理论预报方法的不足;根据滑行艇的艇型特点以及模型静水阻力试验和规则波、不规则波的试验结果,提出了滑行艇纵向运动的基本假设;建立了计及浮性和滑行力、滑行力矩影响的滑行艇纵向运动基本方程,提出了预报滑行艇纵向运动的实用计算方法(滑航法)并编制了理论预报程序;比较了忽略浮态变化的全排水量法、只考虑浮态变化的浮航法、同时考虑浮态变化和滑行力、滑行力矩影响的滑航法的计算值和实验值的差别,指出在预报滑行艇纵向运动时,低速宜采用全排水量法或浮航法,中高速时宜采用滑航法。

深V型滑行艇横摇阻尼的实验确定

对深V型滑行艇模型进行了静水横摇衰减实验和零速正横浪规则波中横摇运动实验,讨论了在处理试验数据时所面临的一些问题;采用分段最小二乘拟合法对静水横摇衰减实验曲线进行光顺,用峰值处理法计算不同横摇角时的横摇阻尼,并进行多项式回归得到深V型滑行艇横摇阻尼公式.

高速滑行艇约束模式下的喷溅阻力特性研究

为了研究高速滑行艇瞬态喷溅流体动力特性,基于计算流体软件Fluent及自编写后处理程序,对体积傅汝德数、攻角分别为Fr▽=1.0、τ=10°,Fr▽=2.0、τ=8.0°,Fr▽=3.0、τ=5.0°,Fr▽=4.0、τ=2.5°这4种工况下,开展了高速滑行艇三维数值模拟.计算收敛后,从Fluent软件中导出艇体平均动压、对水相积分求出浸湿面积等相关参数、提出了关于计算喷溅阻力的4条假设和关于喷溅区的几何形状、特征雷诺数与喷溅阻力的计算方法.计算结果与试验值具有良好的一致性,摩擦阻力系数Cf通过Davidson经验公式和ITTC公式的反推验证,误差分别为2.58%和3.36%,表明采用此种方法研究高速滑行艇静水航行喷溅阻力是可行的.

断阶滑行艇喷气减阻机理研究(英文)

本文通过艇底流态显示、艇体运动姿态及阻力测量 ,研究了滑行艇艇底喷气对流场、阻力等的影响规律。断阶稍前处喷气引起总阻力和浸湿面积的大幅减少 ,喷气所减少的阻力成分为摩擦阻力 。

滑行艇阻力研究进展

本文分析了滑行艇阻力预报中常用的十余种方法 ,指出了各种方法中参数的变化范围、适用的艇型及存在的问题 ;讨论了理论求解的困难和减阻措施 ;说明了在滑行艇阻力预报中常被忽视的艇形概念及其重要作用。

深V型滑行艇静水阻力性能影响因素研究

基于深V型滑行艇的系列模型阻力试验数据,比较系统地分析了深V型滑行艇静水阻力的影响因素,研究了阻力、浸湿面积、浸湿长度以及航行纵倾角随折角线长宽比、重心纵向位置、负荷系数、艇底斜升角等因素的变化规律,指出在舯部斜升角保持24.6°不变的前提下,艇底艉部横向斜升角为10°左右时滑行艇静水中的阻力性能较优,进一步增加增升角度对静水阻力性能不利。

棱柱型滑行艇在规则波中迎浪运动响应的频域解

滑行艇在高速滑行时因其艇重基本由水动升力支撑,用较常规的排水型船运动预报方法计算并不准确.针对这一问题提出了一种计及水动升力影响的预报方法,用于计算棱柱型滑行艇在静水中的滑行姿态和波浪中的运动响应.在半经验公式的基础上,讨论了水动升力对各水动力系数的影响,并建立了棱柱型滑行艇在规则波中迎浪运动响应的频域解模型.将计算值和试验值进行了比较,结果吻合较好.

滑行艇喷溅阻力特性模型试验研究

通过开展棱柱型滑行艇喷溅阻力的模型试验研究，提出了一种滑行艇喷溅阻力的计算分析方法.试验选取4组不同初始纵倾角τ=1.5°，2.2°，3.0°，5.0°，每个纵倾角对应2个吃水，分别为：τ=1.5°时吃水dA =37.3，27.3 mm；τ=2.2°时dA =58.0，38.0 mm；τ=3.0°时dA =58.0，48.0 mm；τ=5.0°时dA =73.0，53.0 mm.每个吃水下的航速分别为1，2，3，4，5 m/s共计40种工况.通过在艇底布置压力传感器测量航行过程中受到的水动压力，同时采用高速摄像机拍摄的视频捕捉航行过程中的喷溅区域和滑行面，开展滑行面压力传感器数据的处理分析，确定了滑行艇滑行面的阻力特性，在此基础上采用间接法完成了滑行艇喷溅阻力的分析计算.结果表明：高速滑行状态下，滑行艇的喷溅阻力约占总阻力的22%-35%.

气幕减阻研究进展

本文从试验研究、理论探讨及实船开发三个方面，简要地介绍了气幕减阻技术的研究状况，指出这项技术值得大力研究开发，并提出了有待深化研究的问题。