共查询到19条相似文献,搜索用时 109 毫秒
1.
2.
3.
针对波浪作用下平台运动引起的立管疲劳损伤,进行完整的频域计算方法研究。首先采用势流理论对平台的运动响应进行分析,求得平台的运动频响函数;接着采用有限元法对立管的应力响应进行分析,求得立管的应力频响函数;最后,结合立管材料的S-N曲线,采用谱分析方法对四种不同海况下波致立管振动引起的疲劳损伤进行分析,获得损伤沿立管轴线方向的分布曲线。研究结果表明:波致立管振动疲劳损伤与有义波高密切相关,疲劳损伤值随着波高的增加成指数次方增长;立管的最大疲劳损伤值通常出现在立管的边界区域。 相似文献
4.
《舰船科学技术》2014,(8):27-32
讨论规则波下某张力腿平台的动力响应时域运动特性。着重分析入射波角度(15°,22.5°和45°),波高(6m,8m和10m)及波周期(10s,12s和14s)对张力腿平台各自由度运动、顶端张力的影响。探讨吃水高度、工作水深、不同张力腿数目对张力腿平台运动特性的影响。计算结果表明:由于张力腿平台各自由度对入射波角度、波高和波周期敏感度不同,张力腿平台在不同波浪参数下的运动特性(如位移幅值、平衡位置等)及顶端张力表现各异;不同吃水下的张力腿平台位移大小、平衡位置和运动方向等均不同。工作水深越大,各自由度运动越剧烈,这体现了工作环境对张力腿平台运动具有较大影响。张力腿数目越多,张力腿平台运动的位移、幅度等越小,随时间变化也越稳定。 相似文献
5.
6.
7.
小水线面双体船在波浪中的运动响应预报 总被引:4,自引:0,他引:4
用切片理论方法发展了SWATH船耐波性预报程序,提供了390t方案的油田小水线面交通船计算分析结果,包括规则波中纵向运动频率响应函数的计算及不规则波中各种海况下的运动有义值预报。 相似文献
8.
9.
三体船横摇模型试验及其特性分析 总被引:1,自引:0,他引:1
三体船在波浪中的横摇特性和优点是三体新船型研发的技术支撑,采用模型试验和理论分析相结合的方法,对三体船横摇运动特性进行探讨。开展三体船静水横摇、正横浪零速波浪横摇模型试验,得出三体船线性、非线性阻尼假设下的横摇阻尼、频率响应和周期。通过横摇响应曲线的分析和对比,得出三体船不同侧体位置下波浪中横摇附加惯量、阻尼和运动响应、周期特性,以及侧体位置对以上各横摇特性影响的规律。研究表明:三体船横摇阻尼远大于常规单体船,而横摇运动幅值响应远小于常规单体船;侧体的横位置对三体船横摇具有显著影响,侧体纵向位置对横摇影响很小。综合考虑运动响应和横摇周期,在不规则波中三体船的横摇比常规单体船缓和得多。 相似文献
10.
11.
基于MIKE 21 Mooring Analysis系泊分析软件,模拟研究在不同周期和入射角度的不规则波作用下系泊船舶运动的变化规律。结果表明,系泊船舶运动量随波浪入射角度和波浪周期的变化相互影响。在不同周期波浪作用下的系泊船横移、横摇和升沉运动量均随波浪入射角度的增大而增大,横摇运动的共振效果随着波浪入射角度远离90°方向逐渐减弱,升沉运动量在波浪入射角度靠近90°或0°方向时基本不变。当入射波浪周期较长时,纵移和回转运动量随着波浪入射角度的增大先增大后减小,一般在波浪60°入射时产生峰值。 相似文献
12.
系泊船舶运动响应周期试验研究 总被引:1,自引:0,他引:1
针对国内外系泊船舶物理模型试验中所给系泊船舶运动响应周期特征参数的不同,对横向波浪作用下一艘26.6×104 m3系泊LNG船舶的运动响应周期特性进行物理模型试验研究。结果表明,半载状态下,纵移运动存在着32 s的自振周期;横移运动为周期性间歇增长运动,横移运动周期与系泊船舶固有横摇周期的比值在1.11~1.23,大体上随波浪周期增大成倍数增长;横摇运动峰值随波浪周期增大而增大,横摇运动周期与系泊船舶固有横摇周期的比值在1.23~1.48,大体上随波浪周期增大成倍数增长;不同装载状态下回转运动均存在着较长的自振周期:半载状态为30 s,满载状态为32 s。 相似文献
13.
Hydrodynamic load and motion response are the first considerations in the structural design of a submerged floating tunnel (SFT). Currently, most of the relevant studies have been based on a two-dimensional model test with a fixed or fully free boundary condition, which inhibits a deep investigation of the hydrodynamic characteristics with an elastic constraint. As a result, a series of difficulties exist in the structural design and analysis of an SFT. In this study, an SFT model with a one-degree-of-freedom vertical elastically truncated boundary condition was established to investigate the motion response and hydrodynamic characteristics of the tube under the wave action. The effect of several typical hydrodynamic parameters, such as the buoyancy-weight ratio, γ, the relative frequency, f/fN, the Keulegan–Carpenter (KC) number, the reduced velocity, Ur, the Reynolds number, Re, and the generalized Ursells number, on the motion characteristics of the tube, were selectively analyzed, and the reverse feedback mechanism from the tube's motion response to the hydrodynamic loads was confirmed. Finally, the critical hydrodynamic parameters corresponding to the maximum motion response at different values of γ were obtained, and a formula for calculating the hydrodynamic load parameters of the SFT in the motion state was established. The main conclusions of this study are as follows: (i) Under the wave action, the motion of the SFT shows an apparent nonlinearity, which is mainly caused by the intensive interaction between the tube and its surrounding water particles, as well as the nonlinearity of the wave. (ii) The relative displacement of the tube first increases and then decreases with increasing values of f/fN, Ur, KC number, Re, and the generalized Ursells number. (iii) γ is inversely proportional to the maximum relative displacement of the tube and the wave force on the tube in its motion direction. (iv) Under the motion boundary condition (as opposed to the fixed boundary condition), the peak frequency of the wave force on the SFT in its motion direction decreases and approaches the natural vibration frequency of the tube, whereas the wave force perpendicular to the motion direction increases. When the incident wave frequency is close to the natural vibration frequency of the tube, the tube resonates easily, leading to an increased wave force in the motion direction. (v) If the velocity in the Morison equation is substituted by the water particle velocity measured when the tube is at its equilibrium position, the inertia coefficient in the motion direction of the tube is linearly related to its displacement, whereas that in the direction perpendicular to the motion direction is logarithmically related to its displacement. 相似文献
14.
为了探求风浪流成长全过程对应的单点系泊FPSO低频响应极值,应用三维势流理论及非线性时域耦合分析方法,研究了单点系泊FPSO低频运动响应与风浪流入射角度之间的关系,得出了给定风浪流大小前提下最危险的入射角度,计算了风浪流载荷在发展、顶峰、消亡各不同阶段对应的船体低频运动响应极值。结果表明:单点系泊FPSO低频响应与风浪流入射角度密切相关,且响应最大值可能并不出现在有义波高、风速、流速最大的顶峰时期,而可能出现在有义波高、风速、流速较小但风浪流入射角度呈强非线性的发展或消亡阶段。因此,在研究单点系泊FPSO的低频响应极值时,必须考虑风浪流成长过程中的发展和消亡阶段。文中考虑了易被忽略的风浪流成长过程中入射角度呈强非线性的发展和衰亡阶段,为单点系泊FPSO低频响应特性的分析提供了有益参考。 相似文献
15.
由丹丹;孙丽萍;曲治国;王涛 《船舶与海洋工程学报》2013,12(4):459-462
For a large floating vessel in waves,radiation damping is not an accurate prediction of the degree of roll unlike other degrees of freedom motion.Therefore,to get the knowledge of roll motion performance of deepwater pipelay crane vessels and to keep the vessel working safety,the paper presents the relationship between a series of dimensionless roll damping coefficients and the roll response amplitude operator(RAO).By using two kinds of empirical data,the roll damping is estimated in the calculation flow.After getting the roll damping coefficient from the model test,a prediction of roll motion in regular waves is evaluated.According to the wave condition in the working region,short term statistics of roll motion are presented under different wave parameters.Moreover,the relationship between the maximal roll response level to peak spectral wave period and the roll damping coefficient is investigated.Results may provide some reference to design and improve this kind of vessel. 相似文献
16.
In this study, we consider first- and second-order random wave loads and the effects of time-varying displacement volume and transient wave elevation to establish motion equations of the Spar platform’s coupled heave-pitch. We generated random wave loads based on frequency-domain wave load transfer functions and the Joint North Sea Wave Project (JONSWAP) wave spectrum, designed program codes to solve the motion equations, and then simulated the coupled heave-pitch motion responses of the platform in the time domain. We then calculated and compared the motion responses in different sea conditions and separately investigated the effects of second-order random wave loads and transient wave elevation. The results show that the coupled heave-pitch motion responses of the platform are primarily dominated by wave height and the characteristic wave period, the latter of which has a greater impact. Second-order mean wave loads mainly affect the average heave value. The platform’s pitch increases after the second-order low frequency wave loads are taken into account. The platform’s heave is underestimated if the transient wave elevation term in the motion equations is neglected. 相似文献
17.
A two-dimensional numerical Computational Fluid Dynamics(CFD) model is established on the basis of viscous CFD theory to investigate the motion response and power absorption performance of a bottom-hinged flap-type wave energy converter(WEC)under regular wave conditions. The convergence study of mesh size and time step is performed to ensure that wave height and motion response are sufficiently accurate. Wave height results reveal that the attenuation of wave height along the wave tank is less than 5% only if the suitable mesh size and time step are selected. The model proposed in this work is verified against published experimental and numerical models. The effects of mechanical damping, wave height, wave frequency, and water depth on the motion response, power generation, and energy conversion efficiency of the flap-type WEC are investigated. The selection of the appropriate mechanical damping of the WEC is crucial for the optimal extraction of wave power. The optimal mechanical damping can be readily predicted by using potential flow theory. It can then be verified by applying CFD numerical results. In addition, the motion response and the energy conversion efficiency of the WEC decrease as the incident wave height increases because the strengthened nonlinear effect of waves intensifies energy loss. Moreover, the energy conversion efficiency of the WEC decreases with increasing water depth and remains constant as the water depth reaches a critical value. Therefore, the selection of the optimal parameters during the design process is necessary to ensure that the WEC exhibits the maximum energy conversion efficiency. 相似文献
18.