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《船舶与海洋工程学报》2016,(3)
Currently, second generation intact stability criteria are being developed and evaluated by the International Maritime Organization(IMO). In this paper, we briefly present levels 1 and 2 assessment methods for the criteria of pure loss of stability and parametric roll failure modes. Subsequently, we show the KG_(max) curves associated with these criteria. We compute these curves for five different types of ships and compare them with the curves embodied in the current regulations. The results show that the safety margin ensured by the first level-1 method of calculation for both pure loss of stability and parametric roll seems to be excessive in many cases. They also show that the KG_(max) given by the second level-1 method and by the level-2 method may be very similar. In some cases, the level-2 method can be more conservative than the second level-1 method, which is unanticipated by the future regulation. The KG_(max) curves associated with parametric roll confirm that the C11 container ship is vulnerable to this failure mode. The computation of the second check coefficient of parametric roll level 2(C2) for all possible values of KG reveals the existence of both authorized and restricted areas on the surface formed by both the draft and KG, which may replace the classical KG_(max) curves. In consequence, it is not sufficient to check that C2 is lower than the maximum authorized value(R_(PR0)) for a fixed ship's loading condition. 相似文献
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国际海事组织(IMO)正致力于第二代完整稳性规范的制定,而参数横摇一直是船舶动态完整稳性研究的热点。文章采用考虑船舶操纵性和耐波性运动耦合的统一模型对迎浪规则波下的船舶参数横摇运动进行了时域数值模拟。在时域模型中,六自由度耐波性运动辐射绕射力采用切片理论计算,并由脉冲响应函数法转化到时域。非线性回复力和入射波力采用瞬时湿表面压力积分方法计算。操纵性运动基于MMG模型,依据统一理论将操纵性与耐波性运动进行耦合计算。文中先应用简化三自由度模型对三艘集装箱船进行了参数横摇样船计算,并进行了初步的模型实验验证,依据结果对比分析了横摇惯性矩、初稳性高和方形系数对参数横摇的影响。基于统一模型分析了操纵性运动对参数横摇的影响,并进行了参数横摇舵减摇研究。 相似文献
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IMO第二代完整稳性衡准对现有万箱船设计的影响 总被引:1,自引:1,他引:0
国际海事组织(IMO)正在制定基于水动力学的第二代完整稳性衡准,新衡准的实施必然对现有船舶的设计带来巨大影响。集装箱船大型化是航运界的发展趋势,万箱船船型订单近年也大幅上升。已有的事故发现大型集装箱船对参数横摇、过度加速度等衡准相对敏感,但现有船舶的设计对此类事故模式考虑较少,因此有必要开展相关研究。本文选取了某万箱集装箱船,对其大量装载工况进行四种稳性失效模式的计算分析,研究了第二代完整稳性的实施对大型集装箱船的稳性影响,并对其装载、设计等提出一定的建议。 相似文献
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Monte Carlo analyses are generally considered the standard for uncertainty analysis. While accurate, these analyses can be expensive computationally. Recently, polynomial chaos has been proposed as an alternative approach to the estimation of uncertainty distributions (Hosder et al. A non-intrusive polynomial chaos method for uncertainty propagation in CFD simulations. In: 44th AIAA aerospace sciences meeting and exhibit, Reno, Nevada, 2006; Wu et al. Uncertainty analysis for parametric roll using non-intrusive polynomial chaos. In: Proceedings of the 12th international ship stability workshop, Washington, DC, USA, 2011). This approach works by representing the function as a series of orthogonal polynomials; the weights for which can be calculated via several methods. Previous studies have demonstrated the usefulness of this technique for comparatively simple systems such as parametric roll modeled by the Mathieu equation with normally distributed parameter values (Wu et al. Uncertainty analysis for parametric roll using non-intrusive polynomial chaos. In: Proceedings of the 12th international ship stability workshop, Washington, DC, USA, 2011). In the present work, a polynomial chaos method is applied to a nonlinear computational ship dynamics model with normally distributed input parameters. Test cases were selected where parametric roll was expected to potentially occur. The resulting probability distributions are compared to the results of a Monte Carlo analysis. In general, these results demonstrate good agreement between Monte Carlo simulation and polynomial chaos in the absence of capsize with significant computation gains found with polynomial chaos. Overall, we conclude that polynomial chaos is an effective tool for reducing simulation time costs when studying parametric roll, and potentially other ship dynamics phenomena, particularly in the absence of capsize-like bifurcations. 相似文献
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针对国际海事组织(IMO)正在制定的船舶第二代完整稳性衡准中的纯稳性丧失直接评估衡准,本文提出了纵荡-横荡-横摇-首摇4自由度运动耦合的标准数学模型,进行了纯稳性丧失直接评估.该方法首先基于MMG操纵性标准方法,构建纵荡-横荡-横摇-首摇4自由度运动方程,同时考虑了舵控制方程,其次在纵荡、横荡、横摇、首摇方程右边考虑时域波浪力/力矩,且横摇方程右边进一步考虑了粘性横摇阻尼力矩和波浪中复原力臂变化.最后采用ONR内倾船进行了尾斜浪中纯稳性丧失直接数值计算,为纯稳性丧失直接稳性评估衡准的应用奠定了基础. 相似文献
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纵浪上船舶的动稳性研究 总被引:6,自引:2,他引:4
在纵浪上航行的船舶,当升沉(或纵摇)固有频率约为横摇固有频率的2倍时将发生参数激励主共振。本文考虑升沉对横摇的耦合作用,建立了非线性参数激励横摇运动方程。用多尺度方法对方程进行求解,用Floquet理论和分岔理论对定常解进行稳性分析,获得了参数激励主共振下的不稳定域和可以导致船舶倾覆的多数区域,为船舶的动稳性研究提供了一种新的方法。与数值结果的比较验证了本文的结论。 相似文献
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Jasna Prpić-Oršić Roberto Vettor Odd Magnus Faltinsen Carlos Guedes Soares 《Journal of Marine Science and Technology》2016,21(3):434-457
The influence of various parameters, such as ship initial speed (full ahead and lower engine loads), loading condition, heading angle and weather conditions on ship fuel consumption and CO2 emission is presented. A reliable methodology for estimating the attainable ship speed, fuel consumption and CO2 emission in different sea states is described. The speed loss is calculated by taking into account the engine and propeller performance in actual seas as well as the mass inertia of the ship. The attainable ship speed is obtained as time series. Correlation of speed loss with sea states allows predictions of propulsive performance in actual seas. If the computation is used for weather routing purposes, values for various ship initial speed, loading conditions and heading angles for each realistic sea‐state must be provided. The voluntary speed loss is taken into account. The influence of the ship speed loss on various parameters such as fuel consumption and CO2 emissions is presented. To illustrate the presented concept, the ship speed and CO2 emissions in various routes of the Atlantic Ocean are calculated using representative environmental design data for the track of the routes where the ship will sail. 相似文献
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我国有数量庞大的渔业船舶,其稳性对船舶安全生产、船型设计开发等方面产生重要影响。本文整理现行渔业船舶稳性衡准要求;分析稳性衡准数的数理实质;进而应用国内外普遍认可的总体设计软件NAPA进行渔业船舶稳性衡准数核算方法研究开发。有助于提高对渔业船舶稳性的认知水平和校核能力,亦可为具备类似衡准要求的其他船型设计研发及稳性校核工具开发提供借鉴。 相似文献
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This paper examines the influence of stability characteristics on roll motion in the main parametric resonance region. For this purpose, parametrically exited roll motion was modeled as a single degree of freedom system considering heave and pitch effects by means of time varying restoring moment. In addition, restoring moment variations in waves with respect to time and instantaneous roll angle was modeled analytically using the restoring moment curves for the wave crest and wave trough conditions. Roll responses were evaluated in frequency domain by solving the model with an averaging method. Notable correlation between the stability of roll responses and moment curves were observed. The results revealed that, the ratio of metacentric height (GM)between the wave trough and wave crest affects the stability of the trivial solution. Furthermore, the shape of the restoring moment curves in wave trough and wave crest conditions affects the stability of the non-trivial solution or, in other words, the pitchfork bifurcations. 相似文献
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《船舶与海洋工程学报》2018,(3)
Since the research of flare slamming prediction is seldom when parametric rolling happens, we present an efficient approximation method for flare slamming analysis of large container ships in parametric rolling conditions. We adopt a 6-DOF weakly nonlinear time domain model to predict the ship motions of parametric rolling conditions. Unlike previous flare slamming analysis, our proposed method takes roll motion into account to calculate the impact angle and relative vertical velocity between ship sections on the bow flare and wave surface. We use the Wagner model to analyze the slamming impact forces and the slamming occurrence probability. Through numerical simulations, we investigate the maximum flare slamming pressures of a container ship for different speeds and wave conditions. To further clarify the mechanism of flare slamming phenomena in parametric rolling conditions, we also conduct real-time simulations to determine the relationship between slamming pressure and 3-DOF motions, namely roll, pitch, and heave. 相似文献
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参数横摇是船舶因复原特性改变而引起的典型非线性现象。文章采用三维时域方法预报规则迎浪中船舶的参数横摇运动。该方法引入匹配面将流域分为内域和外域,内域中采用Rankine源来满足物面条件和线性自由面条件,而外域中应用时域格林函数来满足线性自由面条件和远场辐射条件。数值方法中,Froude-Krylov力和恢复力是通过对船舶瞬时湿表面积积分获得,同时考虑了横摇、垂荡和纵摇三自由度之间的耦合作用,以及非线性横摇阻尼的影响。数值结果与试验结果吻合很好,说明该方法可以有效地预报参数横摇。 相似文献
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当采用弹性理论对舰船结构进行稳定性计算时,其欧拉应力超过了材料的比例极限,可应用临界应力与欧拉应力关系曲线得到计算构件的临界应力。因此,稳定性的临界应力与欧拉应力关系曲线将影响到舰船结构的稳定性设计,乃至总纵极限强度的校核。通过对相关资料进行综合分析,就“舰船通用规范”中的稳定性临界应力与欧拉应力关系曲线问题提出了看法。 相似文献
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Naoya Umeda Satoshi Usada Kentaro Mizumoto Akihiko Matsuda 《Journal of Marine Science and Technology》2016,21(1):23-37
To avoid stability failure due to the broaching associated with surf riding, the International Maritime Organization (IMO) has begun to develop multilayered intact stability criteria. A theoretical model using deterministic ship dynamics and stochastic wave theory is a candidate for the highest layer of this scheme. To complete the project, experimental validation of the theoretical method for estimating broaching probability in irregular waves is indispensable. We therefore conducted free-running model experiments using a typical twin-propeller and twin-rudder ship in irregular waves. A simulation model of coupled surge–sway–yaw–roll motion was simultaneously refined. The broaching probability calculated by the theoretical method was within the 95 % confidence interval of that obtained from the experimental data. This could be an example of experimental validation of the theoretical method for estimating the broaching probability when a ship meets a wave. 相似文献