共查询到19条相似文献，搜索用时 906 毫秒
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本文探讨了海底水力冲射开沟机械总体设计主要参数的计算方法及确定原则。基中包括作业水深，挖掘射水压力、流量，气举排泥风压、风量，水举排泥射冲射泵面积比，喷头的直径与数量，脐带软管直径，排泥角，主跨度，橇板尺度，开沟速度，牵引力和整机重量等。 相似文献
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大直径单桩风机基础冰荷载模型试验研究 总被引：1，自引：0，他引：1
针对渤海某海域以单桩结构为支撑的海上风电系统,对大直径直立桩风机基础进行了一系列静冰载荷模型试验研究。首先,针对目标海域海冰调研结果确定多个冰速工况,对3 MW及4 MW装机功率对应的两种不同直径的单桩基础开展静冰载荷模型试验;随后在试验现象及试验结果的分析中重点关注了冰排在大直径结构前的破坏模式及破坏特点;最终,通过对比模型试验冰力极值试验结果与多规范冰载荷计算结果,确定大直径直立桩静冰载荷计算规范的合理选择,并根据试验结果对直立桩静冰载荷计算方法进行了经验参数修正。得出的相关结论可为渤海海域大直径单桩式风机基础冰载荷的工程估算提供参考。 相似文献
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根据1993年1─2月“实验3”号考察船在霍尼亚拉港（瓜达尔卡纳尔岛）至关岛的断面观测的温、盐度资料，分析了该断面上的地转流结构，计算了南赤道流及北赤道逆流的地转流流速和流量。结果表明：在纬线方向上E向流与W向流呈带状分布，在垂向上也多为E向流与W向流交替出现。在南赤道流和北赤道逆流中都夹有与主流向相反的流动，它们的流量分别约占主流向流量的1／3和1／5。文章还将分析计算结果与手头掌握的文献报道的结果作了比较。 相似文献
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根据１９９３年１－２月“实验３号”号考察船在霍尼亚接港（瓜达尔卡纳尔岛）至关岛的断面观测的温、盐度资料，分析了该断面上的地转流结构，计算了南赤道流及北赤道逆流的地转流流速和流量。结果表明：在纬线方向上Ｅ向流与Ｗ向于带状分布，在垂 也多为 流一Ｗ向流交替出现。在南赤道流和北赤道逆流中都夹有与主流上反的流动，它们的流量分别占向流量的１／３和１／５。文章还将分析计算结果与手头掌握的文献报道的结果作了比较 相似文献
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本文根据有关单位提出研制大型波力发电灯浮标的使用要求,经计算,提出两个不同直径的浮体方案,每个方案具有浮体排水量、中心管长度、喷嘴比和气室高度等四个可变参数,共组成162个模型试验方案,在水池中进行规则波的优化试验。模型试验表明,排水量为8吨、浮体直径为3.6米、中心管长度为4米、喷嘴比为200和气室高度为2.5米的方案,具有超过设计要求的输出功率,且满足最佳频响在3秒左右的要求.同时,根据试验结果,也讨论分析了浮标各参数对中心管气室功率的影响,不同的 H/λ比值对浮标气室性能的影响,对今后设计大型波力发电灯浮标有参考作用. 相似文献
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地震作用下的导管架海洋平台结构动力优化设计研究 总被引：3，自引：1，他引：3
把导管架海洋平台看作钢框架结构，并把优化方法用于结构的抗震设计中；以结构的总重量最小为优化目标，导管的平均直径和壁厚作为设计变量，考虑强度、刚度和稳定等约束条件。通过渤海BZ28—1油田储油平台为例进行了计算，计算结果表明，此方法对海洋平台的设计具有一定的参考意义。 相似文献
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深海蕴藏着丰富的多金属结核资源,受海水深度等限制,结核采集目前仍存在巨大挑战。水力式采矿具有结构简单、可靠性高的优势,是目前最具发展前景的采集方式之一。水力式采矿通过水流动力进行结核采集,喷射形成的复杂流场结构直接影响海床上结核颗粒剥离、起动、采集效率和海洋环境扰动强度,采集器离地高度、喷嘴射流角度和速度等具有较大优化空间。基于计算流体力学数值模拟研究了集矿头附近三维水流结构,分析了喷嘴射流速度和结核粒径对局部流场、床面剪切力以及结核采集能效的影响。结果表明：集矿头周围流场存在典型分区结构,包括淹没射流区、冲击区、壁面射流区、汇合区和上升区;随着喷射流速增大,最大床面剪切力近似线性增长,结核有效起动面积指数增长;随着结核粒径增大,有效起动面积减小,结核采集能效降低;综合考虑结核采集强度和采集能效,建议采集器喷射流速取8～9 m/s。 相似文献
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Trenching depth calculation of traveling jet is a very important field in both pipeline burying and dredging engineering. The trenching ability of a noncontact control flow jet trencher was predicted by experimental method according to the geometry similarity. In the test, the jet pressure, the shear strength of clay, and the translational speed of nozzle were the same with the design parameters, while the nozzle was a reduced scale model. The trenching depth was found about seven to nine times of the nozzle’s diameter. The width of the trench was about four times of the nozzle’s diameter. Based on the test results the noncontact jet trencher was produced and succeeded in practical usage. 相似文献
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The spoiler is a kind of device to disturb current and promote burying.At present,all submarine pipeline spoilers at home and abroad are parallel spoilers,that is,the plane of the spoiler is parallel to the vertical plane of the pipeline axis.According to the results of indoor experiments,when the pipeline with the forward spoiler is installed perpendicular to the direction of water flow,the spoiler will accelerate the seabed erosion and cause the pipeline to endure downward pressure,which will eventually cause the pipeline self-buried to form a protection.However,when the pipeline direction is consistent with the flow direction,the self-buried behavior and protective effect is vanished.By aiming at the defect that the forward spoiler cannot be self-buried when the direction of the pipeline and the flow are basically parallel,the spoiler burying aid device perpendicular to the pipeline axis has been innovatively developed,and the hydrodynamic changes and sediment erosion characteristics near the pipeline after the installation of the device were studied based on the experiment.Results reveal that although the perpendicular spoiler cannot generate downforce,it can greatly increase the turbulent kinetic energy of the flow and the rate of sediment erosion.The larger the angle between the pipeline axis and the spoiler plane is,the larger the increase in turbulent energy will be.The increase in turbulent energy near the bed surface can reach up about 70%when the angle is 90°,while serious sediment erosion mainly occurs along both sides of the pipeline with a distance of about 2?4 times the pipe diameter.In the future,we can further explore the influence of the perpendicular spoiler size and installation position on the pipeline downforce and the effect of burying promotion.At the same time,field tests on the perpendicular spoiler burying aid device currently developed will conduct to observe the actual effect of perpendicular spoiler promoting pipeline scouring and burying,and improve submarine pipeline safety protection technology. 相似文献
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海底管道阻流板(Spoiler)自沉埋技术是一种新型管道自埋技术,为深入了解其作用机制及其效果,本文通过分析安装有阻流板的杭州湾海底管道历年检测资料,结合管道附近海域海床、潮流动力特性,深入探讨了阻流板装置在实际工程中的运行效果,分析了其作用机制及其适用条件。研究发现安装阻流板装置的杭州湾海底管道在往复潮流作用下逐渐埋入海床,其埋入段长度由2005年的50%增加到2013年的80%以上,而且平均埋入深度超过2.6 m,自埋效果较好;而在管道路由与海流平行段或管道敷设于抗冲刷强海床上时,阻流板作用不能有效发挥,管道仍然呈现裸露状态。 相似文献
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AbstractBlast response of submerged pipelines has been a research focus in recent years. In this article, a three-dimensional numerical model is established to investigate dynamic response of pipelines due to underwater explosion. The u–p approximation is integrated into finite element method (FEM) to simulate pore water effect in the seabed. Numerical continuity between hydraulic pressure in the flow field and pore pressure in the marine sediment is guaranteed to realize the blast response of submerged pipelines in ocean environment. Both fluid–structure interaction (FSI) and pipeline–seabed interaction (PSI) have been considered in the proposed model simultaneously. A comprehensive parametric study is carried out after validation of the present model with test data from underground explosion and underwater explosion, respectively. The effect of embedment depth, TNT equivalent, stand-off distance, pipeline diameter, and pipeline thickness to blast response of the submerged pipelines is investigated based on numerical results. Variation of deformation patterns and stress distribution of the pipeline with various installation and structure parameters has been illustrated and discussed to facilitate engineering practice. 相似文献
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近壁圆柱绕流问题在海底悬跨管道的研究中具有重要的意义。在绕流阻力、升力以及海底土壤的耦合作用下,海底管道所发生的移位、悬跨等现象对于海底管道的安全运行构成了很大的威胁。正确预测各种绕流条件下管流之间的作用力是保证油气管道安全的首要任务。海底管道在极端海洋环境条件下的管、流相互作用为高雷诺数绕流问题,处于高雷诺数下的绕流模拟比处于低雷诺数下的绕流模拟要复杂很多,它需要更精细的网格以及合适的湍流模型。此文对处于悬跨状态下的海底管道进行数值研究,给出不同间隙比下海流绕流海底管道的流场结构形态,分析了间隙比对绕流阻力和绕流升力的影响,为进一步研究海底悬跨管道的受力和变形提供载荷边界数据。 相似文献
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This paper describes a unique new physical testing facility for studying ocean-structure–seabed interactions, and in particular pipeline on-bottom stability on erodible seabed under hydrodynamic loading. The facility, named the O-tube due to its shape, is a fully enclosed flume in which ambient and storm-induced near-seabed flows are generated by a computer-controlled flow pump. Combined steady and oscillatory flow can be generated by alternating pump flow directions in a controlled manner, and computer control also allows irregular flow to be generated. The design of the O-tube combines the capabilities of a conventional open channel flume (which provides steady current) with a U-tube (which provides oscillatory flow). The facility is designed to physically model severe storm conditions, as well as ambient or tidal flows. When studying pipeline stability on erodible seabed under severe hydrodynamic loading conditions, tests can be performed at a relatively large scale (typically 1/5) for large diameter pipelines (e.g. 40 in. gas trunklines) and at full scale for small diameter pipelines (< 8 in.) to minimize potential scaling effects associated with movable bed model tests. The specifications of the O-tube, a model pipe and an actuator system that supports the model pipe are given in detail. Preliminary model testing results show that the facility has met its design expectations. 相似文献
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A numerical model is developed to predict the onset of local scour below offshore pipelines in steady currents and waves. The scour is assumed to start when the pressure gradient underneath the pipeline exceeds the floatation gradient of the sediments. In this model, the water flow field above the bed is determined by solving the two-dimensional (2-D) Reynolds-averaged Navier–Stokes equations with a k-ω turbulence closure. The seepage flow below the seabed is calculated by solving the Darcy's law (Laplace's equation) with known pressure distribution along the common boundaries of the flow domains-seabed. The numerical method used for both the turbulent flow around the pipeline and Darcy's flow in the seabed is a fractional finite element method. The average pressure gradient along the buried pipe surface is employed in the evaluation of onset condition with a calibration coefficient. The numerical model is validated against experimental data available in literature. A unified onset condition for steady currents and waves is proposed. Influences of flow parameters, including water depth, embedment depth, boundary layer thickness, Reynolds number (Re) and Keuleagan–Carpenter (KC) number, on the pressure drop coefficient over the pipeline are studied systematically. 相似文献
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AbstractThe mechanism of local scour under two vibrating pipelines is investigated numerically in this research. A sediment scour model is adopted to estimate the motion of sediment. The general moving objects model, which is dynamically coupled with fluid flow, is set up to simulate the vortex-induced vibration (VIV) of the pipeline. The sediment scour model and pipeline vibration model are verified with the previous experimental results and show good agreement. Then, the coupling effects between the pipeline vibration and the local scour are investigated numerically. The effects of G/D (the ratio of the distance between the two pipelines to the diameter of the pipelines) on the local scour and the VIV of the pipeline are examined. The results indicate that the maximum scour depth under the vibrating pipelines is much larger than the scour depth under the fixed pipelines. Due to the shadowing effect of the upstream pipeline, the maximum scour depth under the upstream pipeline is deeper than that under the downstream pipeline. The pipeline vibration magnitude is closely related to the strength of the vortex that sheds behind the pipeline. The effect of G/D on the shape and strength of the vortices that shed behind the pipelines is significant. 相似文献
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Physical modeling of untrenched submarine pipeline instability 总被引：1，自引：0，他引：1
Wave-induced instability of untrenched pipeline on sandy seabed is a ‘wave–soil–pipeline’ coupling dynamic problem. To explore the mechanism of the pipeline instability, the hydrodynamic loading with U-shaped oscillatory flow tunnel is adopted, which is quite different from the previous experiment system. Based on dimensional analysis, the critical conditions for pipeline instability are investigated by altering pipeline submerged weight, diameter, soil parameters, etc. Based on the experimental results, different linear relationships between Froude number (Fr) and non-dimensional pipeline weight (G) are obtained for two constraint conditions. Moreover, the effects of loading history on the pipeline stability are also studied. Unlike previous experiments, sand scouring during the process of pipe’s losing stability is detected in the present experiments. In addition, the experiment results are compared with the previous experiments, based on Wake II model for the calculation of wave-induced forces upon pipeline. It shows that the results of two kinds of experiments are comparable, but the present experiments provide better physical insight of the wave–soil–pipeline coupling effects. 相似文献