月池共振对超深水钻井船运动性能的影响

为了研究月池内流体共振对船体运动的影响,以一艘超深水钻井船为研究对象,采用三维势流理论计算钻井船月池内自由液面和船体的运动,通过月池内自由液面的运动信息,得到月池各种模态下的共振频率,并以此来检验相关理论和经验公式对月池共振频率预报的准确性。月池底部打开和关闭2种状态下钻井船的运动特性显示,月池的活塞共振运动会显著增加船体的垂荡运动,而月池的晃荡共振运动对船体运动的影响较小。     

深水钻井船运动性能分析

采用数值计算与模型试验相结合的方式研究深水钻井船的运动性能。对某钻井船的垂荡、横摇和纵摇运动进行短期预报,并衡量钻井船在特定海况下的钻井作业能力;同时,针对钻井船具有较大月池开口这一特点,分析研究了月池开口对钻井船运动性能的影响。     

波浪作用下钻井船月池内流体水动力性能研究

为了规避钻井船月池内发生共振情况带来的危险,本文采用势流理论和CFD数值模型相结合的方式,对钻井船的水动力性能和月池内流体运动进行研究。在入射波为月池共振周期的情况下,将船体有无耦合运动时月池内流体的不同运动进行比较研究,得出船体运动会增大月池内流体运动的结论。     

双月池对某援潜救生船运动性能及波面升高的影响

介绍某援潜救生船配设双月池的船型特点,规划双月池和不带月池2种方案来评估双月池开口对援潜救生船船体运动性能的影响。采用三维势流理论对2个方案的运动性能进行计算,得到船体运动响应函数,对船舶运动性能进行短期预报,研究总结双月池效应对援潜救生船运动的影响规律。对比双月池内水面和舷外波面升高的情况,比较两个位置处波面升高的差异性,总结双月池波面升高对潜水钟收放的影响。     

带月池超深水钻井船的水动力特性

基于三维势流理论,开展钻井船水动力性能数值计算,完成月池、黏性阻尼对钻井船水动力和运动性能的影响分析,研究带月池钻井船水动力和运动性能特性,以期指导钻井船及其月池的设计。     

不同月池形状对钻井船附加阻力的影响

针对钻井船月池附加阻力,开展月池形状对钻井船附加阻力性能的影响研究。通过对不同形状月池内非定常流动特性的研究和钻井船附加阻力的对比分析,探讨月池形状对附加阻力的影响。经CFD分析可知,航行中的钻井船月池内的流体阻塞效应及漩涡运动导致附加阻力增加,优化月池形状和结构可有效降低月池内的波高和漩涡强度,改善航行性能。     

波浪作用下月池开口对钻井船水动力的影响

结合模型试验与频域数值计算结果,分析月池对船体水动力性能的影响,并对模型试验与数值计算的RAO、月池敞开和封闭的RAO、运动统计结果和附加质量系数进行对比。分析结果显示:月池开口会增大横摇和垂荡运动幅值,并且减小船体的横摇固有周期;当外部激励使月池发生共振时,月池内流体产生的附加质量会发生剧烈变化。因此,月池开口对船体水动力性能会产生一定负面影响,作业时,应当避免发生共振现象。     

耗散系数修正对波浪载荷预报的影响研究

在参考模型试验结果选取适当月池自由面耗散系数的基础上,对目标船进行波浪载荷预报。选取合理的月池自由面耗散系数,以准确模拟月池围壁压力;进而准确计算月池开孔对船体梁波浪载荷的影响,形成一套数值计算与模型试验相结合的带月池船体梁波浪载荷预报方法。研究成果为船舶波浪载荷预报提供参考。     

月池对钻井船阻力性能影响研究

针对钻井船海上航行工程背景,考虑浮态变化对钻井船阻力的影响,采用粘性流体力学算法,对某艘有详细实验数据的钻井船在静水中的阻力性能进行计算与分析。通过研究网格划分形式与网格数量等因素对计算结果的影响,确定合理的网格划分方法,提高计算的准确性。之后,对一艘3 000 m深水钻井船进行计算,分析月池形状与航速等方面对钻井船阻力的影响,有较好的实际应用前景。     

航行状态下钻井船月池内流场特性

以某钻井船"凸"字型月池为研究对象,基于黏流理论,运用FINE MARINE软件对某钻井船的月池附加阻力及流场特性进行研究.研究发现,开敞式的月池使得钻井船航行阻力增加,最大占船舶总阻力的19.34％,月池附加剩余阻力是月池附加阻力增加的主导因素."凸"字型月池内流体的流场完整地呈现了月池内流体的漩涡运动以及对月池后壁砰击运动的全过程.在高航速下,"凸"字型月池内流体运动主要是以晃荡运动为主导的,晃荡与活塞混合的运动模式;月池内流体的周期性漩涡运动主要形成于月池中后缘,流体对月池后壁的砰击作用增大了月池受力,并随航速的增加而愈加剧烈;月池的受力谱峰频率分别为0.820Hz和1.046Hz,与月池波面变化的谱峰频率相同.通过探究月池流场运动形式和月池附加阻力机理,可对钻井船"凸"字型月池设计提供一定的借鉴和参考.     

基于CFD的钻井船月池流场及附加阻力研究

研究了基于CFD方法的钻井船月池流场及阻力性能。针对某阶梯型月池的钻井船,采用定常方法分析其阻力性能,并与模型试验结果进行比较,分析钻井船月池阻力数值计算方法的可靠性;采用非定常方法模拟月池内流体的非定常流动,分析月池附加阻力产生的原因。计算方法及所得出的结论可为具有月池的船舶阻力性能研究提供参考。     

CFD simulation of the vertical motion characteristics of the moonpool fluid for the truss spar

The research purpose of this paper is to estimate theimpacts of the parameters of the guide plate on the vertical motioncharacteristics of the moonpool fluid. With the volume of fluid（VOF） method, three-dimensional models of the moonpool fluidmotions of the truss spar platform are established. Simulationresults are then presented for the moonpool forced oscillation byemploying the dynamic mesh method and user-defined functions inFLUENT. The motions of the moonpool fluid and the loads on theguide plates are obtained for both cases of square-ring andcrisscross. The results show that the shape and area of the guideplate at the bottom of the moonpool have a significant impact onthe physical parameters of the moonpool, including the load on themoonpool guide plate, motion form of the moonpool fluid and themass flow rate.     

月池对FDPSO水动力性能的影响分析

采用数值模拟的方法,分析了不同尺寸、位置、吃水的月池对FDPSO船体附加质量和阻尼系数的影响。建立FDPSO三维水动力模型,采用水动力计算软件AQWA,研究了月池在不同尺寸、位置、吃水情况下对FDPSO横荡、垂荡、横摇附加质量和阻尼力的影响。结果表明：月池内流体的“活塞”振荡会增大船体的垂荡运动;FDPSO船体附加质量和阻尼力在频域范围内存在极值,垂向附加质量和阻尼力极值对应的波浪频率位置与月池尺寸、吃水有关,与位置无关。     

浮式钻井生产储卸装置运动性能分析

首先介绍了浮式钻井生产储卸装置(FDPSO)设有月池开口的船型特点,为评估月池开口对FDPSO船体运动性能的影响,设计了不同月池尺寸的方案。采用三维势流理论对不同月池尺寸方案水动力性能进行计算,得到FDPSO船体运动传递函数,总结FDPSO船体横摇和垂荡运动响应随月池尺寸变化的规律,并确定合理的目标FDPSO方案。最后对目标FDPSO方案进行运动性能实例分析,评估目标FDPSO方案的耐波性。     

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.     

Experimental study on piston- and sloshing- mode moonpool resonances

An experimental study was performed on the piston- and sloshing-mode moonpool resonances of offshore structures. Two different geometries were considered to investigate the flow characteristics in a plain moonpool and a moonpool with a cofferdam. To examine the efficiency of a cofferdam for reducing the flow in a moonpool, three cofferdam geometries were tested. The plain moonpool presented violent flows as a result of the piston- and sloshing-mode resonances. However, the moonpool with the cofferdam introduced violent sloshing waves instead of the ascent and descent of the water column in the piston-mode moonpool resonance. Among three different cofferdam geometries, the model with a right triangle facing to the left on the top of the cofferdam was most effective in reducing the flow in the moonpool when compared with the other models.