共查询到19条相似文献,搜索用时 218 毫秒
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建立了船舶破舱瞬时进水速度模型,通过比较、分析船舶破舱进水量速度与船舶排水设备能力的关系,确定船舶抗沉施救能力的可行性。并分析了当破口参数变化时,进水量速度的变化规律和对船舶浮态的影响。 相似文献
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枢纽下游泄水波传递及对船队航行影响研究 总被引:1,自引:1,他引:0
根据已建枢纽非均匀下泄水流的调度和实测资料,采用二维水流数学模型研究模式,结合水流对船舶的阻力计算,研究了泄水渡传递运动规律和对上行船舶的阻滞作用.研究表明:泄水波波锋处产生的附加水面比降和流速与泄水波产生前水面比降和流量以及枢纽下泄流量方式有关,泄水渡传递速度呈沿程递减、波峰逐渐坦化规律.通过对碍航河段采取工程措施减小水流流速以及减小枢纽泄流变化幅度、延长流量增加的调度时间等方法,可减小泄水波尺度,削弱水流对行船的阻滞作用,有效改善船舶上滩条件. 相似文献
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船舶前置导管流态的数值计算与分析 总被引:2,自引:1,他引:1
利用Fluent 6.0软件计算和分析了船舶螺旋桨前置导管的平面流流态.比较了安装前置导管前后船体艉部流态,发现安装后流态发生了改变,旋涡大幅减少,流速显著增加,伴流不均匀性减小.用数值方法再显了现有模型试验分析的结果. 相似文献
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本文针对无舱盖集装箱船这种全新概念的船舶,分别论述了如何用计算方法和实验方法来研究干舷大小与货舱进水量的关系,对无舱盖集装箱船的航行安全性设计提出了良好的依据。 相似文献
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破舱后船舶性能计算是有关船舶的最复杂的计算之一。在船舶设计阶段可以使用NAPA.Tribon.Damcargo等软件计算,而在航行过程中如果发生破损则需要航海人员能迅速估算出结果。以便及时采取适当有效的措施。曾有文章对此提出了一种快速计算船舶破舱进水量的方法,但文中没有解释这种计算方法的原理和适用范围。本文将就船舶发生第三类破损情形下,也就是破损位置在水面以下,舱柜上部开敞时。分析进水量的变化,以及如何进行快速合理的计算最终进水量提出一些浅显的看法。 相似文献
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A flow field around a streamlined body at an intermediate angle of incidence is dominated by cross-flow separation and vortical flow fields. The separated flow leads to a pair of vortices on the leeside of the body; therefore, it is essential to accurately determine this pair and estimate its size and location. This study utilizes the element-based finite volume method based on RANS equations to compute a 3D axisymmetric flow around a SUBOFF bare submarined hull. Cross-flow vortex structures are then numerically simulated and compared for a submarine with SUBOFF and DRDC STR bows. Computed results of pressure and shear stress distribution on the hull surface and the strength and locations of the vortex structures are presented at an intermediate incidence angle of 20°. A wind tunnel experiment is also conducted to experimentally visualize the vortex structures and measure their core locations. These experimental results are compared with the numerical data, and a good agreement is found. 相似文献
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Nobuaki Sakamoto Pablo M. Carrica Frederick Stern 《Journal of Marine Science and Technology》2012,17(4):446-468
Part 2 of this two-part paper presents the analysis and validation results of local flow characteristics for a surface combatant Model 5415 bare hull under static and dynamic planar motion mechanism simulations. Unsteady Reynolds averaged Navier–Stokes (URANS) computations are carried out by a general-purpose URANS/detached eddy simulation research code CFDShip-Iowa Ver. 4. The objective of this research is to investigate the capability of the code in relation to the computational fluid dynamics-based maneuvering prediction method. In the current study, the ship is subjected to static drift, steady turn, pure sway and pure yaw motions at Froude number 0.28. The free surface, three dimensional vortical structure and, the validation of two dimensional local flow quantities together with the available experimental data are of the interest in the current study. Part 1 provides the verification and validation results of forces and moment coefficients, hydrodynamic derivatives, and reconstructions of forces and moment coefficients from resultant hydrodynamic derivatives. 相似文献
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This article concerns thermal radiation hazards associated with unconfined liquefied natural gas (LNG) spills on water. Consequence
assessment methods were compared to clarify their model characteristics in large-scale LNG spills from an LNG carrier (LNGC).
The consequences of LNG release, pool spread, and pool fire hazards were estimated using the following practical methods:
the Federal Energy Regulatory Commission’s (FERC) method, the Sandia National Laboratories’ method, and the Fay method. The
sensitivity of consequence analysis results to the breach size of a tank was examined under the assumption that LNG is released
from a common type LNGC of 125000 m3 cargo capacity. Consequently, it was found that the FERC method is useful from the practical viewpoint of being applicable
to any breach size. Finally, thermal radiation hazards from pool fires involving spills from one of the latest and largest
LNGCs (250 000 m3 cargo capacity), which are currently considered for construction, were investigated using the recommended FERC method, and
the results are discussed in comparison with those for common type LNGCs. As a result, it was found that the maximum thermal
hazard distance is longer by only about 24% compared with the common type LNGC, whereas the spill volume is twice as much. 相似文献
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江苏如东人工岛工程对周边海域水动力的影响 总被引:2,自引:0,他引:2
利用MIKE21软件水动力模块建立和验证了西太阳沙二维潮流数学模型,并将该模型应用到工程项目中,分析了工程前后水动力条件的变化。应用结果表明:人工岛方案实施后整体流场基本不变,即使出现流速、流向的变化也仅局限在人工岛周围的局部区域,对烂沙洋深槽流场不会产生影响。因此,在现状纵横岸线边界条件下,实施人工岛工程后,要维持工程附近的滩槽稳定,潮流优势是关键,所以在实施任何建港或围垦工程时都必须以维持现状水流特征和动力环境为前提,应尽量消除不稳定因素,以保证烂沙洋海域滩槽的稳定。 相似文献
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大连新机场工程建设采用离岸填筑人工岛方案,深水围堰采用爆破挤淤填石法施工。有效确定炸药药量以及炸药埋深等相关施工参数是深水围堰处理过程中的重点与难点。针对深水围堰爆破参数的问题,以B27围堰中点为研究对象,进行爆破参数计算、施工工艺拟定,并进行施工效果分析。 相似文献
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Nobuaki Sakamoto Pablo M. Carrica Frederick Stern 《Journal of Marine Science and Technology》2012,17(4):422-445
Part 1 of this two-part paper presents the verification and validation results of forces and moment coefficients, hydrodynamic derivatives, and reconstructions of forces and moment coefficients from resultant hydrodynamic derivatives for a surface combatant Model 5415 bare hull under static and dynamic planar motion mechanism simulations. Unsteady Reynolds averaged Navier–Stokes (URANS) computations are carried out by a general purpose URANS/detached eddy simulation research code CFDShip-Iowa Ver. 4. The objective of this research is to investigate the capability of the code in regards to the computational fluid dynamics based maneuvering prediction method. In the current study, the ship is subjected to static drift, steady turn, pure sway, pure yaw, and combined yaw and drift motions at Froude number 0.28. The results are analyzed in view of: (1) the verification for iterative, grid, and time-step convergence along with assessment of overall numerical uncertainty; and (2) validations for forces and moment coefficients, hydrodynamic derivatives, and reconstruction of forces and moment coefficients from resultant hydrodynamic derivatives together with the available experimental data. Part 2 provides the validation for flow features with the experimental data as well as investigations for flow physics, e.g., flow separation, three dimensional vortical structure, and reconstructed local flows. 相似文献