共查询到18条相似文献，搜索用时 345 毫秒
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以浮式半潜平台为研究对象,针对影响气隙结果的波浪非线性效应进行研究分析。通过分析平台气隙响应特性,确保平台在极端海况下的安全性。首先通过数值计算与模型试验,对一座浮式半潜平台在极端海况下的气隙响应进行计算与测量;进一步对平台附近18个典型位置的波面升高响应进行统计分析与概率分布拟合处理;最终求得反映各处波浪非线性强度的非线性因子∂值,并与OTG-13规范中的建议值对比讨论。结果发现∂的计算值与建议值并不完全一致,由于波浪受平台运动及平台结构扰动影响,平台下浮体附近处波浪非线性效应较强,计算值较建议值大,需要重点考虑分析。相应地,距离平台结构较远位置处的计算结果与建议值一致。 相似文献
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采用理论分析和模型试验相结合的方法,对一U型半潜式起重铺管平台进行了运动性能与气隙分析,为该平台的主尺度确定和作业能力评估提供了参考依据。同时,对半潜式起重铺管平台水动力分析的方法和流程进行了归纳与总结。 相似文献
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半潜式平台气隙量数值预报方法研究 总被引：2，自引：1，他引：1
以半潜式平台为研究对象,基于势流理论开展了有义波高Hs=10 m,谱峰周期Tp=15.4、14.1、12.8、11.8及10.6 s,有义波高Hs=8 m,谱峰周期Tp=10.1及9.6 s,浪向角β=0°、30°、45°、60°及90°,共计35个工况下半潜式平台气隙量的数值预报技术研究,计算结果表明:波浪的有义波高、特征周期及浪向角对半潜式平台气隙量的影响较大,半潜式平台甲板边缘易出现负气隙,同时平台垂向固有周期应避免与波浪的统计周期相同或接近。 相似文献
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针对半潜式平台的立柱群和沉箱群,设计了两套独立的载荷测量系统,利用大型重力式密度分层水槽,在不同来波方向下对孤立波中半潜式平台载荷进行了系列模型试验。研究表明,对平台立柱部分,其内孤立波载荷可以用Morison公式进行计算,基于试验结果建立了Morison公式中其拖曳力系数以及惯性力系数的经验公式;对于半潜式平台的沉箱部分,当来波方向与其中纵剖面不平行时,其水平内孤立波载荷同样可以使用Morison公式进行计算,并建立了Morison公式中其拖曳力系数以及惯性力系数的经验公式;当来波方向与半潜式平台中纵剖面平行时,沉箱群的水平内孤立波载荷可以采用Froude-Krylov公式进行计算;同时,在不同来波方向下沉箱群的垂向载荷同样可以采用Froude-Krylov公式进行计算。 相似文献
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在深海油气田开发中,干式采油树比湿式采油树具有更多优势。为减小半潜平台的垂荡运动,使其能够采用干式采油树,对一种深吃水且具有大面积下浮箱的新型半潜平台的运动性能进行了探究。基于势流理论,采用频域和时域相结合的分析方法,计算了平台在多种海况下的运动响应,为新型平台的运动分析和设计提供指导。同时,开展了水池模型试验,将计算结果与试验结果相比较,验证了数值模拟结果的准确性。为进一步探究新型平台的运动性能,研究了下浮箱放置深度对平台运动性能的影响,并进行相应的模型试验。研究表明:下浮箱的存在可大幅改善新型干树半潜平台的垂荡运动性能。综合考虑平台运动性能和工程实际应用条件,确定了最合适的下浮箱放置深度值。 相似文献
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Sensitivity Analysis of Air Gap Motion with Respect to Wind Load and Mooring System for Semi-Submersible Platform Design 总被引：1，自引：1，他引：0
A design of semi-submersible platform is mainly based on the extreme response analysis due to the forces experienced by the components during lifetime. The external loads can induce the extreme air gap response and potential deck impact to the semi-submersible platform. It is important to predict air gap response of platforms accurately in order to check the strength of local structures which withstand the wave slamming due to negative air gap. The wind load cannot be simulated easily by model test in towing tank whereas it can be simulated accurately in wind tunnel test. Furthermore, full scale simulation of the mooring system in model test is still a tuff work especially the stiffness of the mooring system. Owing to the above mentioned problem, the model test results are not accurate enough for air gap evaluation. The aim of this paper is to present sensitivity analysis results of air gap motion with respect to the mooring system and wind load for the design of semi-submersible platform. Though the model test results are not suitable for the direct evaluation of air gap, they can be used as a good basis for tuning the radiation damping and viscous drag in numerical simulation. In the presented design example, a numerical model is tuned and validated by ANSYS AQWA based on the model test results with a simple 4 line symmetrical horizontal soft mooring system. According to the tuned numerical model, sensitivity analysis studies of air gap motion with respect to the mooring system and wind load are performed in time domain. Three mooring systems and five simulation cases about the presented platform are simulated based on the results of wind tunnel tests and sea-keeping tests. The sensitivity analysis results are valuable for the floating platform design. 相似文献
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Impact Analysis of Air Gap Motion with Respect to Parameters of Mooring System for Floating Platform
In this paper, the impact analysis of air gap concerning the parameters of mooring system for the semi-submersible platform is conducted. It is challenging to simulate the wave, current and wind loads of a platform based on a model test simultaneously. Furthermore, the dynamic equivalence between the truncated and full-depth mooring system is still a tuff work. However, the wind and current loads can be tested accurately in wind tunnel model. Furthermore, the wave can be simulated accurately in wave tank test. The full-scale mooring system and the all environment loads can be simulated accurately by using the numerical model based on the model tests simultaneously. In this paper, the air gap response of a floating platform is calculated based on the results of tunnel test and wave tank. Meanwhile, full-scale mooring system, the wind, wave and current load can be considered simultaneously. In addition, a numerical model of the platform is tuned and validated by ANSYS AQWA according to the model test results. With the support of the tuned numerical model, seventeen simulation cases about the presented platform are considered to study the wave, wind, and current loads simultaneously. Then, the impact analysis studies of air gap motion regarding the length, elasticity, and type of the mooring line are performed in the time domain under the beam wave, head wave, and oblique wave conditions. 相似文献
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基于气温的浮冰侧向融化速率参数化方案实验研究 总被引：3，自引：3，他引：0
为定量探究影响冰层侧向融化的主导因素,并简化冰层侧向融化速率参数化方案,在实验室模拟了无风、静水、无辐射、纯热力学条件下纯水冰的融化过程,测量了冰层的侧向融化量,并记录了融化期间实验室气温、冰面皮温、水温及冰温等要素。观测结果表明,无辐射纯热力学条件下冰层侧向融化整体较均匀,侧向上层和下层融化速率相对中间层较快;相关性分析结果表明,气温与水温、冰温、冰面皮温之间都有很好的线性相关;信息流结果表明,气温是影响冰层侧向融化的最主要因素;最后通过拟合建立了用气温表征冰层侧向融化速率的参数化方案,并与前人的方案进行了比较,结果显示本文参数化方案模拟效果较好,所得标准偏差最小,为0.08 mm/h,达到了简化参数的目的。 相似文献
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深海极端波浪环境为浮式海洋平台作业时最为关键的海洋动力环境之一。在其作用下,深海浮式平台的运动、气隙以及结构响应等均为近年来的研究热点。然而,在深海环境中,入射波浪环境往往通过X波段雷达进行测量,仅能获得波浪的短时统计值,极大限制了实海域浮动平台动力响应的研究。目前,尚无成熟的方法能够对海洋浮式平台所处海域的入射波时序进行实时测量。针对深远海半潜式平台的波浪时序随船测量问题,结合平台气隙响应与运动响应数据建立基于深层神经网络的波浪非线性解耦模型,准确估计辐射、绕射波浪以及其非线性成分对时序波浪场的影响。研究显示,基于深度神经网络的波浪时序测量技术可以实现从气隙响应到入射波信息的反推,利用该方法计算得到的波浪时序具有较高的精度。 相似文献
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A two-dimensional analytical solution is presented to study the reflection and transmission of linear water waves propagating past a submerged horizontal plate and through a vertical porous wall. The velocity potential in each fluid domain is formulated using three sets of orthogonal eigenfunctions and the unknown coefficients are determined from the matching conditions. Wave elevations and hydrodynamic forces acting on the porous wall are computed. Reflection and transmission coefficients are presented to examine the performance of the breakwater system. The present analytical solutions are found in fairly good agreement with the available laboratory data. The results indicate that the plate length, the porous-effect, the gap between plate and porous wall, and the submerged depth of the plate all show a significant influence on the reflected and transmitted wave fields. It is also interesting to note that the submerged plate plays an important role in reducing the transmitted wave height, especially for long incident waves. 相似文献
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According to observations, drops freely falling in the air under the action of gravity are deformed and oscillate in a wide range of frequencies and scales. A technique for calculating surface axisymmetric oscillations of a deformed droplet in the linear approximation under the assumption that the amplitude and wavelength are small when compared to the droplet diameter is proposed. The basic form of an axisymmetric droplet is chosen from observations. The calculation results for surface oscillations agree with recorded data on the varying shape of water droplets falling in the air. 相似文献
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Self-aeration in high-speed free surface flows occurs commonly and is of interest to ocean engineering, hydraulic engineering, and environmental engineering. For two-phase air–water flows, macroscopic air–water flow properties develop gradually, accompanied by the change of microscopic air–water structures. In this article, representational experimental studies on macroscopic and microscopic characteristics of self-aerated open-channel flows are summarized and compared. The isolated effect of the flow Reynolds number and air quantity on the differences in air count rate and chord size are analyzed and discussed. The results show that the characterized flow depth y50, affected by the turbulence transfer, is a specific criterion to distinguish the interior air–water structure development. Two distinct linear trends of self-aeration are found, depending on the y50/y90 variation with a breaking point at Cmean = 0.50. The air count rate and size scale in self-aerated flows are affected by the air quantity of self-aerated flows, even with identical flow Reynolds numbers. Thus, a specific parameter is proposed to assess the air–water structures and a series of self-similarity relationships in self-aeration properties are obtained. The link between macroscopic and microscopic air–water properties results in significant scale effect on air–water structures in self-aerated flows. 相似文献