数值波浪水池与排水型高速船波浪增阻计算方法研究

基于CFD技术对三维数值波浪水池以及排水型高速船波浪增阻进行计算研究。采用在水池入口处模拟波浪速度的方法造波。水池尾部采用人工阻尼结合稀疏网格消波,自由面采用VOF方法处理,采用动网格技术结合运动控制程序模拟船舶的纵摇与升沉运动。对规则波中迎浪前进的Wigley III船模和Model 5b船模纵摇与升沉运动以及波浪增阻进行计算并与试验值进行比较、分析,为排水型高速船波浪增阻的计算提供参考。     

基于重叠网格方法的船舶迎浪增阻与运动数值预报

基于粘性流CFD软件建立了三维数值波浪水池,并对带舵的KCS船模在静水和5个不同波长的规则波中航行进行数值模拟。文中采用入口处模拟波速的方法造波,消波方法运用强迫消波技术(Wave Forcing),并利用VOF方法追踪自由波面的变化,在数值水池中成功模拟了波浪的生成与传播;最后结合重叠网格方法对KCS船模迎浪增阻与运动响应进行数值计算,并将计算结果与试验数据进行对比分析,吻合良好,为今后准确预报舰船在波浪中的增阻和运动响应提供参考。     

大排水量长度系数中高速船阻力计算方法

船型设计的关键技术之一是其水动力性能的预报,而静水阻力预报则是其水动力性能预报的重要内容。针对某大排水量长度系数中高速船,在运用传统的阻力近似估算方法、船舶计算流体动力学(CFD)技术进行计算模拟的基础上,进行船模试验,并将其总阻力和有效功率计算结果与船模试验结果进行比较分析,从而说明适合大排水量长度系数中高速船的阻力计算方法。     

船舶运动状态下舵附推力鳍水动力性能分析

采用基于RANSE的数值波浪水池技术和数值拖曳水池技术,针对75 000 t船模型开展带有纵摇和横摇运动的自航CFD模拟研究。首先进行静水中的船模阻力和自航CFD模拟,通过与模型试验结果比较,初步验证了文中的CFD模拟方法 ;随后开展不同运动状态下是否带有舵附推力鳍的船模自航CFD模拟,并对该种状态下的船模阻力、运动响应以及船后螺旋桨的推力和扭矩等进行分析,获得相关变化特性。该项研究对于运动中船舶快速性研究和预报等,具有较好的指导意义和参考价值。     

船舶纵摇对内外桨水动力性能的影响分析

本文采用基于RANS方程的数值波浪水池和数值拖曳水池技术,针对四桨两舵船模,开展了带有纵摇运动的自航CFD模拟研究.首先开展了静水中的船模阻力和自航CFD模拟,并通过与模型试验结果的比较,初步验证了本文的CFD模拟方法;随后开展了不同运动周期的耦合运动响应的船模自航CFD模拟,对该种状态下船模的阻力、运动响应和船后螺旋桨的推力、扭矩等进行了分析,获得了有关变化特性.本文的研究工作,包括对于运动中舰船的快速性研究和预报等,具有一定的指导意义和参考价值.     

基于STAR-CCM+的双体风电运维船静水阻力仿真

船舶阻力是影响船舶快速性的重要因素.对于风电运维船来说,优异的快速性能是维持运维效率的保障.为提高该双体运维船的静水阻力性能,基于CFD进行数值仿真,运用STAR-CCM+建立数值水池,进行静水阻力计算并研究不同片体间距对双体船阻力的影响.根据数值仿真结果设计船模拖曳试验与其对比,结果表明,采用STAR-CCM+对双体...     

基于多种组合算法的船附体结构设计优化

为了减少船舶的阻力,提升船舶快速性和耐波性,本文将添加球鼻首的DDG1000驱逐舰作为原始船型,研究增加尾压浪板、鳍和水翼对船体性能的影响.首先,将原始模型添加尾压浪板,并且caeses软件平台下进行全参建模,基于组合优化算法策略进行优化.设置2套组合优化方案,经对比发现,sobol算法和NSGA-Ⅱ组合优化方案得到的模型更为优越.添加尾压浪板优化后的模型,在2.02 m/s和1.77 m/s航速下,优化后模型阻力都减少2.5％,证明尾压浪板有减阻特性.将添加尾压浪板优化后的船体后作为初始模型,添加鳍和水翼,并基于组合算法策略,进行多维参数优化.经数值计算,发现鳍和水翼并不能起到减阻效果,但是在一定航速下,鳍与水翼可以抑制兴波,进而减少剩余阻力.最终,在规则波条件下,进行数值模拟,发现安装尾压浪板、鳍与水翼附体后,波浪增阻增大,当λ/L超过0.9时,波浪增阻小于优化后,安装附体后船体,升沉与纵摇以及耐波性均得到不同程度的改善.     

14000 kW救助船恶劣海况下失速系数数值研究

为研究救助船舶在恶劣海况条件下的失速性能,保证救助船舶的航行安全性,选取非线性势流计算方法和黏流CFD方法,计算KCS船在静水和规则波中的波浪增阻及船舶运动.将计算结果与船模试验数据进行对比可得:2种数值模拟计算方法在计算波浪增阻时,误差均在3.6％以内,但非线性势流理论方法相较于黏流CFD方法能够大量节约时间.因此,选定非线性势流理论计算方法为救助船数值试验计算方法,将救助船非线性势流理论计算结果与静水船模试验结果对比,在设计航速17.5 kn时,阻力误差绝对值为2.22％,选取方法有效.根据ITTC 2014年提出的失速系数计算方法进行目标船型失速预报,在设计航速17.5 kn条件下,5级海况时失速系数最大,为0.93,7级海况时失速系数最小,为0.66.     

典型油船船模静水阻力CFD计算策略探讨

选取多艘航运市场常用的典型油船系列船型为研究对象,采用商业软件对其船模静水阻力性能进行数值计算研究,探索针对肥大型船阻力性能数值计算方法.研究中,对全局网格尺度、首尾网格尺度、时间步长和边界层网格高度等参数进行变化调整,确定船舶阻力数值计算中对计算结果影响较大的关键因素,得到计算结果与关键参数之间的变化关系,将计算结果与模型试验结果进行对比分析,总结出相应参数的最佳取值范围,形成针对油船的船舶静水阻力数值计算方法,为今后解决油船船舶阻力数值预报问题做有益探索.     

基于CFD方法的舰船顶浪运动响应幅值算子计算

基于计算流体力学(CFD)方法,给出了舰船在波浪中运动的数值模拟方法,采用边界造波法生成了精确的三维规则波浪,实现了DTMB 5512船模在2种不同波高规则波中顶浪运动时的垂荡及纵摇耦合运动数值模拟,求取了垂荡及纵摇运动的响应幅值算子,通过船模水池实验数据及势流理论方法验证了数值模拟方法的精确性.     

4000t级单体深V复合船型阻力及耐波性能

单体复合船型是基于减纵向运动组合附体技术研发的高耐波性船型。基于性能优良的圆舭船型进行深V船型线型设计,再应用减纵摇组合附体技术,生成深V单体复合船型,使其耐波性得到大幅提高的同时对静水阻力影响较小。本文基于某四千吨级圆舭船型,经过深V改造生成深V主船体,并设计匹配的首部组合附体和尾板,生成四千吨级单体深V复合船型。通过合理的主船体和附体构型设计和水动力布局,有效降低深V船型兴波阻力。经模型试验验证表明该单体深V复合船型对静水阻力影响不大,耐波性得到大幅提升。     

Fundamental research on resistance reduction of surface combatants due to stern flaps

It is well known that a decrease in ship resistance may be achieved due to the installation of a stern flap. Therefore, so far, a considerable amount of research on stern flaps has been conducted. Previous research has demonstrated that the primary mechanism by which a stern appendage reduces resistance is a change in the pressure distribution over the aft body of the hull, and secondly through effects on the running attitude, near and far field wave generation, and local transom flow among other phenomena. However, the change in pressure distribution is influenced by the other components. Hence, there is still room for argument about the relative contribution of each component to the pressure distribution. Therefore, as the first step of the research, by conducting the model experiment in towing tank and CFD (Computational Fluid Dynamics) analysis, we examined the effect of running attitudes and wave making at the after portion of the hull on resistance reduction. As a result, it is concluded that a flap affects a change in the wave generated at the transom part and it could lead to a decrease in wave-making resistance.     

排水型舰船加装尾板实船试验研究

尾板是一种加工和安装简单的节能装置,为了验证尾板节能的效果,在某舰上进行了未装尾板和加装尾板的实船对比试验,试验结果表明,加装尾板对某舰的快速性能有较大的改善,在相同主机功率时,巡航速度和高航速时分别比未装尾板时提高了0.97kns和0.78kns,在相同巡航速度和高航速时节能分别为16.7%和12.7%.加装尾板对操纵性和尾部振动没有影响或略有改善.此外,加装尾板后,每年可节约140吨燃油,节约40万元的燃油费用,估计在一年内就可回收尾板加工和安装的投资.     

基于RANS法和边界层理论预报三维船体阻力

基于船体阻力成因和分类,应用二因次RANS法并结合EFD技术为研究手段,研究了船体各阻力成分和兴波波形,考虑边界层第一层网格高度对数值计算结果的影响,通过数值模拟计算和兴波波形比较,分析表明第一层网格无量纲高度y+值充分影响数值结果精度,总阻力在高傅汝德数下其数值误差有增大趋势,同一航速下摩擦阻力值随y+增加略微增大,剩余阻力值却明显减少,且自由面兴波随傅汝德数增大首部波高愈发明显,船中及尾部区域兴波向外扩散,船首尾肩部开尔文波系明显且波峰后移,其趋势与EFD波形一致,具有实用性。     

波浪中螺旋桨非定常水动力性能研究（英文）

The speed of a ship sailing in waves always slows down due to the decrease in efficiency of the propeller. So it is necessary and essential to analyze the unsteady hydrodynamic performance of propeller in waves. This paper is based on the numerical simulation and experimental research of hydrodynamics performance when the propeller is under wave conditions. Open-water propeller performance in calm water is calculated by commercial codes and the results are compared to experimental values to evaluate the accuracy of the numerical simulation method. The first-order Volume of Fluid(VOF) wave method in STAR CCM+ is utilized to simulate the three-dimensional numerical wave. According to the above prerequisite, the numerical calculation of hydrodynamic performance of the propeller under wave conditions is conducted, and the results reveal that both thrust and torque of the propeller under wave conditions reveal intense unsteady behavior. With the periodic variation of waves, ventilation, and even an effluent phenomenon appears on the propeller. Calculation results indicate, when ventilation or effluent appears, the numerical calculation model can capture the dynamic characteristics of the propeller accurately, thus providing a significant theory foundation forfurther studying the hydrodynamic performance of a propeller in waves.     

方艉舰船及加装尾板的兴波阻力计算

本文给出方艉舰船兴波流场和阻力的实用计算方法，并用于加装尾板的情况，可以计算方艉舰船在加装尾板后的兴波阻力、尾流场，以及尾板长度、反角等因素变化导致流场及阻力上的差异，从而对尾板的设计方案从数值计算的角度作出比较。     

首升力体、首鳍/尾板与船体水动力相互干扰与匹配研究

升力体技术已被CFD、缩比模型试验和实船试验证实,在零航速与有航速情况下均可减小船舶在波浪中的运动响应,提高船舶耐波性。该文以数值计算为主要技术手段,结合模型试验验证,开展了首升力体、首鳍/尾板与船体水动力相互干扰与匹配研究。首先,采用自由船模拖曳的数值模拟方法,开展了基于快速性的首升力体与船体位置匹配研究,获得了首升力体在船体上的较佳位置;其次,对首升力体加装首鳍,分析了首升力体、首鳍组合与船体水动力相互干扰,获得了复合初步船型方案;再次,对复合初步船型方案加装尾板,讨论了首升力体、首鳍、尾板组合与船体水动力相互干扰,获得了复合优化船型方案;最后,对复合优化船型方案在规则波中的运动响应进行数值预报与对比分析,并预报不规则波中的减摇效果。文中的研究成果可为后续首升力体在单体船上的应用提供技术支撑。     

EFD and CFD for KCS heaving and pitching in regular head waves

The KCS container ship was investigated in calm water and regular head seas by means of EFD and CFD. The experimental study was conducted in FORCE Technology’s towing tank in Denmark, and the CFD study was conducted using the URANS codes CFDSHIP-IOWA and Star-CCM+ plus the potential theory code AEGIR. Three speeds were covered and the wave conditions were chosen in order to study the ship’s response in waves under resonance and maximum exciting conditions. In the experiment, the heave and pitch motions and the resistance were measured together with wave elevation of the incoming wave. The model test was designed and conducted in order to enable UA assessment of the measured data. The results show that the ship responds strongly when the resonance and maximum exciting conditions are met. With respect to experimental uncertainty, the level for calm water is comparable to PMM uncertainties for maneuvering testing while the level is higher in waves. Concerning the CFD results, the computation shows a very complex and time-varying flow pattern. For the integral quantities, a comparison between EFD and CFD shows that the computed motions and resistance in calm water is in fair agreement with the measurement. In waves, the motions are still in fair agreement with measured data, but larger differences are observed for the resistance. The mean resistance is reasonable, but the first order amplitude of the resistance time history is underpredicted by CFD. Finally, it seems that the URANS codes are in closer agreement with the measurements compared to the potential theory.     

Experimental study of drillship resistance performance in open and closed state of moonpool北大核心CSCD

[Objective] This paper carries out an experimental study of a multi-function dirllship model with moonpool structure in towing tank, aiming at analyzing the effects of the moonpool structure on the ship resistance in open and closure condition.[Methods]Taking a dirllship as the research object, the ship motion response in regular and irregular waves is investigated. The resistance of the ship in hydrostatic water and waves is measured with tension sensors, and the acceleration characteristics of the bow, midship and stern are analyzed by acceleration sensors.[Results]The results indicate that hull resistance under light load conditions is greater when open moonpool, while hydrostatic water resistance with closed moonpool is greater under design load conditions. The closed moonpool in regular waves reduces stern acceleration by 58.2%, bow resistance by 46.7% and heave response by 41.8%. The peak of resistance at the bow in irregular waves is about ten times higher than that at the stern, and the peak of resistance occurs more often when the moonpool is open at the same time.[Conclusions]The experimental study shows that the difference in load conditions changes the waterplane area and affects the hull resistance in hyrostatic water. In contrast, the closure of the moonpool not only reduces acceleration and resistance, but also improves surge and heave. As such, this paper can provide references for the structural design of drillships with moonpools. © 2023 Journal of Nanjing Agricultural University. All rights reserved.     

高速排水型舰船加装尾板的节能机理

尾板是加装在高速排水型船尾封板端板处沿船体向后延伸的一块短板,是一种方便和简单的节能措施,本文主要研究其节能的原因.通过大量的模型试验结果分析和对某舰有无尾板的CFD理论计算,并与高速水面快艇加装尾板减阻机理的比较发现:排水型船的节能机理有所不同,尾部压力分布的变化是高速排水型船加装尾板节能的主要原因.