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  

霍发力  聂焱  杨德庆  董刚  崔锦 《海洋工程》2016,(4):535-548

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   

定量模拟分析船体与空气枪间的安全距离          下载免费PDF全文

王立明  胡毅  许江  刘保华 《应用海洋学学报》2016,35(4):575-578

海洋地震勘探过程中,水中放置的空气枪与船体之间须保持一定安全距离,否则引起船载设施和仪器剧烈抖动,影响船舶设施和仪器的安全运行,甚至更严重情况下,有可能造成船体的损坏.利用海水压力脉冲与船体受到的冲击压力关系,结合建立的空气枪震源子波模型模拟近场震源子波,可计算出船体与空气枪间的安全距离.研究结果表明,根据震源子波模型模拟的近场子波主峰值,总容量150in3G枪、300 in3相干G枪及760 in3相干G枪的安全距离分别为3.90、6.57 m和9.13 m.由此可知,空气枪与船体间距离只有大于安全距离,才能避免船体大的振动或设备免遭损害,保证海洋地震勘探有效、安全的进行.  相似文献   

上海大气湿度的城、郊对比分析   总被引：5，自引：0，他引：5  

周淑贞 《海洋湖沼通报》1994,(2):13-25

本文通过对１９８４－１９９０年上海城区１１个气象站和近郊４个县气象站逐月平均水汽压及对１９８４年１、４、７、１０等４个月逐日０２、０８、１４、２０时等４个观测时刻气象观测资料的对比分析结合上海城市下垫面特征，阐明上海“城市”这个人为因子对大气湿度（水汽压ｅ）的影响，发现在年、月水汽压平均值上均是城区ｅｕ小于郊区ｅｒ，但在１、４、７、１０等月逐日４个观测时刻水汽压的城、郊水汽压差值△ｅｕ－ｒ上，却出  相似文献   

气浮结构物的沉降过程分析     

王传荣徐炯  沈国光 《海洋工程》2003,21(2):82-86

通过对空腔内气体的小孔出流和运动方程的分析，计算了气浮结构物在不同情况下的沉陷过程，讨论了其沉陷规律并对有关振荡和稳定性等问题进行了分析讨论。  相似文献   

一次冷空气强风的成因分析   总被引：7，自引：3，他引：7  

王雷 《海洋预报》2005,22(4):96-101

文章分析了2004年12月底的一次冷空气强风过程,揭示了冷空气南下与东海低压的发展造成的气压梯度、高低空较强的冷平流以及中低空辐合辐散差异引起的动力强迫下沉作用所造成的动量下传是造成本次猛烈强风的主要原因.最大强风发生区域和发生时间既与低层和中层700hPa分别转为辐散和辐合中心对应,又与中低层700hPa以下正好处于下沉速度中心附近对应.  相似文献   

印度洋海—气某些特征及其海温与北半球大气环流的联系     

蒋国荣  沙文钰 《海洋预报》1992,9(2):19-27

本文根据印度洋海-气热交换和海温信息区分布特征,得出阿拉伯海是印度洋海-气相互作用的一个重要区域。并讨论了阿拉伯海海温与北半球500hPa高度场和西太平洋副热带高压的一些联系。  相似文献   

Monthly Variation of Sea-Air Temperature Differences in the Korean Coast     

Hyo?ChoiEmail author  Yuan?Hang?Zhang 《Journal of Oceanography》2005,61(2):359-367

Monthly variations of sensible heat, latent heat and momentum fluxes and the modification of sea temperature to air temperature were examined at four coastal stations—Sokcho, Kangnung, Ulsan and Chungmu in the path of the East Korea Warm Current from the year of 1981 to 1990, which was one of main migration routes of Japanese common squid. The difference between monthly averaged sea surface and air temperatures at the 10 m height above the sea surface mainly became negative values from April through August, while they had positive ones from September through March. Monthly variability of the temperature differences is significant in both summer and winter, while it is generally small in spring and fall. Negative values of sensible heat fluxes, which indicated a heat gain by the sea through heat conduction across the air-sea interface were found at the four coastal stations from April to August. Minimum values of sensible heat fluxes at Sokcho, Kangnung and Chungmu were in June, except for Ulsan in August. To the contrary, positive sensible heat flux implying a heat loss from sea toward atmosphere occurred from October to February with a maximum in December. Latent heat fluxes due to condensation of moist air over sea surface had small magnitudes from April to August and those due to evaporation of water particles from the sea surface into the lower atmosphere had relatively large magnitudes from October to March. Minimum values of latent heat fluxes also occurred in June except for August in Ulsan. Momentum flux was small from June to August under weak wind in summer, but it was large from December to February under strong wind in winter. Regression equations between sea surface temperature and air temperature at the 10 m height above the sea surface had very high correlation coefficients from 0.92-0.98, except for 0.78-0.84 of Ulsan, which was partially affected by upwelling of cool water from the bottom into the sea surface. Similar to the sea surface, correlation coefficients were over 0.83-0.97 except for 0.70-0.79 for Ulsan at the 10 m depth of sea and were over 0.70-0.95 except for 0.59-0.82 for Ulsan at the 20 m depth.  相似文献   

由数字化气压场计算海面风场     

黄企洲  陈俊昌  李毓湘  李志伟 《热带海洋学报》1992,(1)

根据数字化仪给出的天气图等压线与经线或纬线交点的数组(Φ,λ,P),采用Kriging网格化方法得出计算区域中1°×1°经纬度网格上的气压值。然后根据地转风与气压梯度间的关系,并经地理纬度和高度等订正。算出1°×1°网格点上海面10m高的风速。经与东沙气象站的实测风速比较,两者符合良好。  相似文献   

地球生态系统的气温和水温补充机制   总被引：1，自引：0，他引：1  

杨东方  吴建平  曲延峰  胡均  周艳荣 《海洋科学进展》2007,25(1):117-122

首次提出了地球生态系统的气温和水温补充机制,并用框图模型说明了补充机制在运行过程中的每个流程,阐明了人类对生态环境的影响过程、生态环境变化对地球生态系统的影响过程以及地球生态系统对环境变化的响应过程,解释了气温和水温的补充起因。研究结果表明,人类是引起环境变化的起源以及其变化后的结果又作用于人类,即人类排放二氧化碳引起气温和水温的上升,地球生态系统又借助其补充机制使得气温和水温下降恢复到正常的动态平衡。尽管这个补充机制带来了沙尘暴、洪水和风暴潮,但由人类引起水温和气温上升造成的灾害要比自然界中这3种灾害要深重得多。自然界的这3种灾害是局部的、短期的,而人类引起水温和气温上升的灾害却是全球的、长期的。  相似文献   

广西沿海全新世以来气候变化   总被引：10，自引：1，他引：10  

黎广钊  方国祥 《海洋地质与第四纪地质》1996,16(3):49-60

本文根据孢粉分析，有孔虫氧同位素分析，历史记载及现代气温观测资料，综合资料广西沿海全新世以来的气候变化，经过研究，初步划分了本区全新世以来的７个气候期，在晚全新世内，进一步划分了７个气候亚期，早全新世，中全新的气候变化具有１５００－２０００ａ周期，晚全新世界的气候变化具有５００－１０００ａ周期，晚全新世中－晚期的气候变化具２００ａ周期，２００ａ来的气候变化呈冷，热交替出现，具有１０－２０ａ或３０－  相似文献