外部气流影响下的船舶通风口烟气扩散试验

为预先确定船舶初步设计中的通风口系统在外部气流场作用下的排气效果，找出设计方案在通风口排气方面存在的问题，采用计算流体力学（Computational Fluid Dynamics，CFD）和风道试验的方法进行研究。以外部气流作用下的通风口烟气扩散试验为研究对象，建立含通风口边界条件的风道三维网格模型，求解不同气体流速下的黏性不可压缩定常流动。计算不同外部气流速度下和不同通风口布局下排气中的CO2分布扩散情况，结果表明来流速度增大会加快CO2体积分数沿流向的衰减速率，削弱CO2横向扩散程度。根据试验结果验证计算的准确性，证明应用CFD技术可评估通风口布局的优劣。     

Optimal base motion to compensate for the influence of sea currents during riser re-entry

One of the difficult operations, which consists in moving the riser and placing its end relatively close to a desired position, is the re-entry operation. Complex dynamic behavior of risers under different sea conditions requires efficient modelling methods. The model used in this paper applies a modification of the segment method using joint coordinates, in which it is possible to analyze only one selected deformation while neglecting the others. This enables a very high computational efficiency of the method to be achieved. The models developed take into account the impact of the environment in which the risers work. The model is validated by comparison of the authors' own results with those presented by other researchers and the simulations are concerned both with statics and dynamics of spatial risers. The numerical effectiveness of the method presented enables it to be applied in the solution of dynamic optimization problems, one of which is presented by the example of the re-entry process. The process of moving the riser is useful in emergency situations (evacuation) when it is necessary to disconnect the riser from the wellhead and move it together with the platform. This optimization task is a 3D problem due to the sea currents acting at different angles on the riser in relation to the direction defined by beginning and final positions of the bottom end of the riser. The calculations are carried out for a hang-off riser, and the optimal motion of the base for different conditions of the sea is defined. The influence of the LMRP (Lower Marine Riser Package) on this movement is also examined.     

LNG船液舱预冷中甲烷双液滴自然对流传热特性分析

针对液化天然气（Liquefied Natural Gas，LNG）船液舱喷雾预冷过程中上下垂直的双液滴在自然对流条件下同种蒸汽中液滴之间影响研究的欠缺，运用计算流体力学（Computational Fluid Dynamics，CFD）方法，基于气液界面能量守恒原理，对不同温差、粒径和相对距离条件下甲烷双液滴自然对流传热特性进行分析。研究结果表明：液滴表面热流密度、传热量和质量蒸发率随温差10～190 K的增大而线性增大；液滴表面热流密度随粒径0.1～2.5 mm的增加先快速减小后缓慢减小，传热量和质量蒸发率随粒径的增加而快速增加；上液滴表面热流密度、传热量和质量蒸发率随相对距离10～70的增加基本不变，下液滴表面热流密度、传热量和质量蒸发率随相对距离10～70的增加而缓慢增加。