共查询到18条相似文献，搜索用时 93 毫秒
1.
基于物理模型试验,考虑畸形波参数、相对板宽、相对波高等影响因素,就畸形波对平顶双层水平板防波堤作用进行研究。首先对畸形波作用下双层水平板的波浪力分布特征进行了讨论,然后就最大波动压强、结构最大总垂向力与不规则波作用进行了对比分析。结果表明,畸形波作用下,双层水平板最大波动压力出现在前端迎浪区域附近,向尾端逐渐递减。双层水平板4个受力面的压力分布不同且有相位差,4个受力面的最大波动压力时间差约在0.1Tp~0.4Tp范围内变化。与不规则波作用比较,畸形波作用没有显著改变波压包络分布特征,但增大了波压包络强度值。试验范围内,就最大总力而言,两者最大总浮托力比值在1.06~2.45间变化;向下的最大总垂向力比值在1.22~2.07之间变化;就波动压力而言,其增大的幅度与畸形波参数α1相关性最强,随α1的增大而增大,在α1=2.04~3.1试验范围内,畸形波作用时的最大压强比不规则波作用时可约增大20%~80%。就最大波吸力而言,两者的比值与畸形波参数α4相关性最强,随α4的增大而减小。在α4=0.62~0.75试验范围内,最大波吸力强度的比值在1.61~0.87范围内变化。当α4≤0.72时,畸形波作用时的最大波吸力大于不规则波作用时的最大波吸力;当α4 > 0.72时则刚好相反。 相似文献
2.
畸形波作用下JIP Spar平台波浪力分析 总被引：2，自引：1，他引：1
利用时域高阶边界元法研究畸形波、系泊系统与浮式结构物耦合作用问题,运用四阶Runge-Kutta方法更新下一时间步的波面和速度势,采用非线性有限元法模拟系泊缆索的各种受力及缆索的弹性变形。以Longuet Hinggins模型为基础,调整组成波的初相位,在很短的波列中得到满足畸形波定义的波形。分析了聚焦位置、初始相位、谱峰周期、谱宽以及水流参数等对系泊JIP Spar平台缆绳力和波浪荷载的影响。将入射波浪的聚焦点分别设置在平台的迎浪侧和背浪侧,分析缆绳力和波浪荷载聚焦峰值,模拟结果发现其最大值产生在聚焦点为迎浪侧的情况。当聚焦点在迎浪侧时,缆绳力和波浪荷载聚焦峰值随着初相位的增加而减小,随着谱宽的增加而减小,而随着谱峰周期的增加而增加。 相似文献
3.
针对设计的新型双浮筒+Savinious型(S型)桨叶浮式防波堤的结构形式,基于势波理论和结构耦合水动力分析理论,利用面元积分和Newmark-β时间步进格式进行计算,研究其在线性规则波作用下的消波性能、运动响应和系泊张力响应,验证该结构的合理性。数值计算结果表明,阻尼修正后的防波堤纵摇运动响应合理,在波高H=1.5 m、波浪周期T=3 s下其消浪性能较为理想,透射系数达到0.65,同时系泊线张力呈周期响应并满足最大破断力的条件。此外,还研究了浮筒相对间距S1/L,浮筒—桨叶相对间距S2/L以及Savinious型桨叶高径比d/h三个无量纲关键几何参数对防波堤透射系数Ct和系泊线时域张力响应的影响。计算结果表明,浮筒间距S1越接近波长,防波堤消波性能越好,但迎浪侧张力响应幅值越大;随着浮筒—桨叶相对间距S2/L由0趋近于1,其透射系数随之减小,但迎浪侧张力响应幅值基本保持不变;减小桨叶的高径比d/h可以提高防波堤消波性能的稳定性,但张力响应幅值随之增大。 相似文献
4.
多点系泊下后弯管波力发电浮体模型试验研究 总被引：1，自引：5，他引：1
在大型造波水池中，对最佳后弯管浮体模型3－3，进行了多点系泊下浮体模型试验研究。测定了该模型在不同系泊条件下，气室平均输出气流功率随波周期的变化曲线NA－T，最大锚泊力与入射波高之比随波周期的变化曲线Fmax/Ho-T和最大纵荡距离与入射波高Ho之比随波周期变化曲线Xmax/Ho-T。选定L型链三点系泊为最佳系泊方案。进行了不同喷嘴比的性能试验和不类来波方向的试验，测定了浮体波能转换性能、最大锚泊力、最大纵荡距离随来波方向的变化。 相似文献
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随着船舶大型化和港口建设深水化发展，外海不同周期波浪作用下大型系泊船泊稳问题与小型系泊船相比出现了新的特点。为此，利用数值模型方法研究了在不同入射角度和周期的涌浪作用下港内大型系泊船的水动力响应，针对系泊船的泊稳情况探讨了船舶的运动规律和运动特性。研究发现，在涌浪周期较大的情况下，限定波高的泊稳标准不足以用来确定系泊船的正常作业条件，港内泊船的水平运动（纵荡、横荡和艏摇）极易超出运动标准值并影响装卸作业效率，并且船舶的水平运动表现出主要由次重力波主导的低频运动特性，而垂直运动（垂荡、横摇和纵摇）表现出主要由短波主导的波频运动特性。 相似文献
6.
波浪能是一种清洁、可再生的新型能源，波浪能发电装置在海上作业时会受到变化的风、浪、流载荷作用，需要系泊系统保证其稳性和安全性。以适用于中国南海500 m水深的振荡双浮体式波浪能发电装置为研究对象，运用频域计算与时域计算结合的方法对双浮体及其系泊系统的运动响应和动力载荷进行计算，获取极端海况与工作海况下浮体运动和系泊缆索张力的时历数据。参照BV船级社NR-493规定的海上浮式结构物系泊安全系数规范，对3种系泊方案进行安全校核和对比分析。选定其中一种系泊方案，通过改变系泊系统以及能量转换器（PTO）的参数，探究参数变化对双体波浪能装置运动响应以及系泊系统特性的影响，为类似应用于深水的双体波浪能装置系泊系统的设计提供参考。 相似文献
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波浪在传播过程中遇到岛屿就会发生绕射。本文使用混合元方法对修正型缓坡方程进行了数值求解,并与KUO et al的解析解进行了比较验证。在此基础上研究了工程尺度背景下,波浪在三维圆形岛地形上的绕射,计算了不同入射波浪周期、浅滩形状参数和岛屿尺寸情况下,沿波浪传播方向断面上和岛屿岸线上的相对波高大小。计算结果表明：随着入射波周期的减小、浅滩形状参数的增大和岛屿尺寸的减小,圆形岛迎浪侧的相对波高振荡幅度、圆形岛背浪侧的相对波高大小以及岛屿岸线上的相对波高振幅和大小均随之增大。不同情况下,岛屿岸线上的相对波高最大值大多数发生在迎浪点,个别发生在迎浪点两侧20°~25°处;最小值发生在背浪点两侧30°附近。 相似文献
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以三锚系浮标系统为研究对象，基于AQWA与OrcaFlex软件开展了三锚系大型浮标系统运动响应特性数值模拟研究。对直径10 m的浮标结构在波浪荷载下的水动力特性进行研究，校核了浮标的初稳性和大倾角稳性特征，计算分析了浮标的附加质量、辐射阻尼、运动响应幅值算子RAO等水动力参数，阐明了不同风、浪、流工况下三锚系浮标与辅助浮筒的运动响应特性，揭示了浮标三锚链导缆孔处锚泊张力随入射角度、波高和周期等的变化规律。研究结果表明：该浮标稳性和随波性能较好。与无浮筒三锚系浮标相比，带辅助浮筒的三锚系浮标系统的运动响应和锚泊张力减小，随着波高和周期增大，三锚系浮标系泊锚链的极端张力值逐渐增大，尤其是在极端海况下，迎浪向锚链极端张力急剧增大。 相似文献
9.
半潜浮式风机逐渐在深海风电开发中受到关注,建立风机、平台与系泊结构耦合数值计算模型,通过FAST与AQWA链接进行风机塔基荷载及平台运动响应相互耦合传递,基于随机波与极限波组合模型生成畸形波时程序列,进行半潜浮式风机系泊失效全过程时域模拟计算分析,得出系泊锚链张力、风机、塔筒和平台运动时程响应,探究系泊失效、风机停机和叶片变桨速率对浮式风机平台系泊结构动力响应的影响。结果表明：畸形波作用下浮式平台和系泊结构动力响应显著,系泊失效导致塔基剪力增加,平台纵荡和纵摇运动响应显著增大;风机停机会引起系泊锚链张力显著减小,转子推力、塔基剪力和叶尖挥舞位移响应逐渐衰减,平台纵荡、纵摇和横摇运动响应显著减小;随着叶片变桨速率增加,风机转子推力和塔基剪力波动幅值增大。 相似文献
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11.
Dynamic Analysis of Turret-Moored FPSO System in Freak Wave 总被引：1，自引：1，他引：0
Freak wave is the common wave which has significant wave height and irregular wave shape, and it is easy to damage offshore structure extremely. The FPSOs (Floating Production Storage and Offloading) suffer from the environment loads, including the freak wave. The freak waves were generated based on the improved phase modulation model, and the coupling model of FPSO-SPM (Single Point Mooring) was established by considering internal-turret FPSO and its mooring system. The dynamic response characteristics of both FPSO and SPM affected by the freak wave were analyzed in the time domain. According to the results, the freak waves generated by original phase modulation model mainly affect the 2nd-order wave loads. However, the freak waves which are generated by random frequencies phase modulation model affect both 1st-order and 2nd-order wave loads on FPSO. What is more, compared with the irregular waves, the dynamic responses of mooring system are larger in the freak waves, but its amplitude lags behind the peak of the freak wave. 相似文献
12.
系泊方柱在畸形波与波群伴生波浪作用下运动响应试验研究 总被引：1，自引：1，他引：0
畸形波与波群伴生波浪作用于系泊浮体,和常规随机波浪作用比较,运动响应时频域特征均将发生显著变化。基于物理模型试验,采用小波方法计算伴生波浪和常规随机波浪作用下系泊浮体运动响应的时频域特征变化及波群因子与浮体运动响应时频域特征的定量关系。结果表明:伴生波浪作用下浮体运动响应显著大于常规随机波浪的作用结果,且波群因子G A对浮体运动响应时频域特征有显著影响;伴生波浪作用下浮体纵荡运动的广义能量谱E(t)统计特征值E max(t)、E 1/10(t)、E 1/3(t)、E average(t)均明显大于相同波谱下常规随机波浪的结果,且随着波群因子G A增大显著增大;伴生波浪作用下各运动响应能量集中度δE显著大于常规随机波浪作用结果,且能量集中时域分布范围参数ΔT E以纵荡运动分量最为显著。 相似文献
13.
Based on the lumped-mass method and rigid-body kinematics theory, a mathematical model of a gravity cage system attacked by irregular waves is developed to simulate the hydrodynamic response of cage system, including the maximum tension of mooring lines and the motion of float collar. The normalized response amplitudes (response amplitude operators) are calculated for the cage motion response in heave and surge, and the mooring line tension response, in regular waves. In addition, a statistical approach is taken to determine the motion and tension transfer functions in irregular waves. In order to validate the numerical model of a gravity cage attacked by irregular waves, numerical predictions have been compared with the experimental observations in the time and frequency domain. The effect of wave incident angle on the float collar motion, mooring line tension and net volume reduction of the gravity cage system in irregular waves is also investigated. The results show that at high frequencies, the cage system has no significant heave motion. It tends to contour itself to longer waves. The variation amplitude of mooring line forces decreases as the wave frequency increases. With the increasing of wave incident angle, the horizontal displacement of the float collar increases. 相似文献
14.
为研究顺应式海洋平台慢漂运动的影响因素,以截断圆柱和漂浮方箱为例进行了不规则波作用下的慢漂运动模型试验。测量了不同系泊刚度条件下的漂浮方箱以及相同系泊刚度条件下的截断圆柱和漂浮方箱在静水中自由衰减运动和在不规则波中的运动响应,并将运动响应分解成一阶波频运动响应和二阶低频运动响应,分析了系泊刚度和浮体形状对浮体运动的影响。通过物理模型试验发现了系泊刚度及浮体形状对顺应式系泊浮体一阶运动标准差和二阶低频运动平均漂移值和标准差的关系。结果表明由于顺应式浮体的固有周期远离波浪谱峰周期时,系泊刚度以及浮体形状对慢漂运动的一阶运动响应影响不大;二阶低频运动相对偏离平衡位置的平均值和标准差均随系泊刚度增大而减小,浮体形状同样对慢漂运动的二阶低频纵荡运动响应影响较大。试验结果为实际海洋工程的外形选择和系泊刚度选择提供数据支持。 相似文献
15.
本文基于Longuet-Higgins随机波浪模型和JONSWAP谱,进行了大量深水随机波的模拟,获取了畸形波发生概率稳定的随机波列,并对随机波列中的畸形波进行了分析。结果表明,畸形波发生的概率小于基于Rayleigh分布预测结果,且随谱宽的减小而增大。在固定时间段内,畸形波发生的频次服从泊松分布,时间间隔服从指数分布,且随着谱宽的增大,畸形波的发生频次减小,相邻畸形波的发生时间间隔增加。通过小波变换方法分离随机波中的波群,研究了出现畸形波的波群特征,发现一个波群中最多会出现4个畸形波,但是在发生畸形波的波群中,单个畸形波的概率最大。随着谱宽减小,一个波群中包含多个畸形波的概率增加。另外,出现畸形波的波群时间长度服从广义极值分布,随着谱宽减小,畸形波波群的时间跨度增加。 相似文献
16.
Effect of mooring-line stiffness on the performance of a dual coaxial-cylinder Wave-Energy Converter
A point-absorber-type Wave-Energy Converter (WEC) consisting of a floating vertical inner cylinder and an annular outer cylinder that slides along the inner one is considered. The two cylinders heave differently under wave excitation, and wave energy can be harnessed from the relative heave motion between the two cylinders using a Permanent Magnet Linear Generator (PMLG) as the Power Take-Off unit. A mooring cable is attached to the bottom of the inner cylinder. This paper aims to examine the effect of the stiffness of the mooring cable on the performance of the coaxial-cylinder WEC system. The two limiting cases of no mooring cable (freely floating inner and outer cylinders) and an infinitely stiff mooring cable (fixed inner cylinder) were also considered. To perform the analysis, hydrodynamic and interference coefficients of the two heaving cylinders were computed semi-analytically using the method of matched eigenfunction expansions. Experimentally determined viscous corrections on damping were also included in the model in order to have more realistic predictions. The performance of the system in terms of motion responses and capture width were predicted and discussed for both regular and irregular waves. The results of the analysis indicate that both the freely floating design and the design with rigidly moored inner cylinder are viable. The two limiting cases show similar optimal performances, albeit with very different optimal generator damping. However, an ill-chosen mooring-cable stiffness may cause the inner and the outer cylinders to have the same resonance frequency, eliminating the relative heave motion and leading to almost no energy extraction. This situation needs to be avoided when designing the mooring system for a coaxial-cylinder WEC. 相似文献
17.
This paper investigates the intact and damage survivability of a floating–moored Oscillating Water Column (OWC) device using physical model experiments and Computational Fluid Dynamics (CFD) simulations. Different extreme wave conditions have been tested using irregular and regular wave conditions. The device was moored to the tank floor via four vertical taut lines and the effect of the mooring line pre–tension on the device response was studied. It was found that the instantaneous position of the floating device was a key factor in the survivability analysis such that a certain irregular wave train that might not include the largest wave could induce the maximum response. Reducing the pre–tension minimized the maximum surge, but significantly increased the maximum tension due to mooring slack events causing snatch loads. A design regular wave with a period equal to the peak period and a height of 1.9–2.0 times the significant wave height could reasonably predict the same maximum line tension as the irregular sea state, but a smaller wave height was required to achieve the maximum surge. A single failure in the mooring system increased the maximum tension by 1.55 times the intact tension. For a damaged mooring system, using the same design regular wave condition derived from the survivability analysis with an intact mooring system could result in overestimating the maximum tension by more than 20% in comparison to the tension from the irregular sea state, but a smaller regular wave height or a different regular wave condition representing another sea state could lead to the same maximum tension. This highlighted the importance of investigating survival conditions with a damaged mooring system instead of simply using the same conditions derived for the intact mooring system. 相似文献
18.
The experimental studies of the wave breaking effects on freak wave generation are presented within a finite-depth random wave train in a laboratory wave tank. The main attention is paid to the abnormal index,AI=Hmax/Hs,being used to characterize the freak waves,and the changes of the coefficient due to wave breaking. The results show that the occurrence probability of freak wave events in non-breaking waves is much larger than that in breaking waves and such occurrence in deep water is larger than that in ... 相似文献