波浪中船舶破损进水模拟研究

针对波浪中船舶破损之后舱室进水情况,介绍一种进水模拟方法。对波浪作简化后,以Bernoulli方程为基础,讨论了一维进水和二维进水情况,并在时间域内对其作了比较。     

周期性波动管流的压降研究

Experiments were conducted to study characteristics of flow when flow is fluctuating. The experimental results showed a phase difference between the flow rate and the pressure drop fluctuations. This phase difference between the fluctuating flow rate and pressure drop was analyzed for laminar flow. Analysis showed that the phase difference changes with the period of the flow fluctuation, the pipe radius, the density and the dynamic viscosity of the liquid. Fluctuating pipe flow was then numerically simulated. Results of the numerical simulation were compared with theoretical values and experimental results. It was shown that, when the flow rate fluctuates with time as a sine wave, the pressure drop fluctuates with the same periodicity, and there is a phase difference between them.     

砰击载荷作用下船底肋骨等效设计压力的确定

通过一个船体二维分段的自由落体试验,测量模型入水速度、砰击压力和结构响应,获得模型底部板架在砰击载荷作用下的响应特征;对结构模型在均布静压力作用下的应力响应进行有限元分析;比较试验和计算得到的应力响应,获得作用在模型肋骨上的砰击压力的折减系数,从而使该结构在设计时仍可按常规的静力计算方法进行强度校核。该折减系数与船体入水速度成线性关系,在已知船体设计入水速度和试验压力分布时,可以获得船体设计均布静压力。     

高压空气减压阀的动态性能仿真

高压空气减压阀是舰船气动系统中的重要元件,通过建立高压空气减压阀的动态数学模型,利用Matlab软件进行仿真计算,对其动态性能进行分析和预测。仿真结果表明采用合适的结构减小阀口过流面积有助于高压空气减压阀的性能稳定。     

Two Phase Pressure Drop Performance of Refrigerant in a Small Horizontal Smooth Tube with 2.5 mm inside Diameter

Two-phase flow pressure drop measurements were made during the phase change heat transfer process of R22 in a small horizontal smooth tube with 2.5 mm inside diameter. Conclusions can be drawn that the quality corresponding to the pressure gradient peak value of small tubes became higher than that of large tubes. The effect of quality to pressure drop becomes weak as the mass flux increases. The experiment data were compared with the predicated values of the state-of-the-art correlations from the open literature. The comparisons between the data and the predictions indicate that most of the state-of-the-art correlations fails to predict the experimental data.Chisholm model shows a relatively better predictive ability than the other empirical correlations although it has a mean deviation of 26.7%. But the predicated values of Chisholm model are lower by 50% than the experimental data when the quality becomes larger.     

开洞位置对无粘结预应力板挠度影响的实验分析

无粘结预应力混凝土楼面经常要进行开洞处理,洞口附近区域易产生应力集中现象,对楼板的整体性能有很大影响,会导致楼板的裂缝开展,挠度增大,抗弯承载能力急剧下降等。文章通过4块无粘结预应力混凝土开洞板的实验现象,着重对不同开洞位置无粘结预应力板的挠度情况进行研究分析。结果表明,楼板开洞对板造成的影响是复杂的,与洞口的位置、形状、周边的受力、楼板的受力、楼板的性质（单向板、双向板、连续板）等都密切相关。     

从实测数据判断箱筒型结构在风浪作用下的稳定性

箱筒型结构是一种新型的防波堤结构。通过土压力、孔隙水压力、振动、波浪、十字板等数据,对箱筒结构在大风浪作用下的稳定性进行了综合分析,得出在大风浪作用下箱筒稳定的结论。该结构适用于软土地基,工程费用低,建设速度快。     

某船用加压舱空调系统改进设计

本文介绍了某船加压舱空调系统制冷工况设计原理,给出了空调系统改造的相关计算以及选型设备主要性能指标。结果表明经调试检测,各项指标均达到设计要求。     

隧道稳定性分析与设计方法讲座之一：隧道围岩压力理论进展与破坏机制研究

本文作为一个讲座对以往研究成果做一个综述,回顾了围岩压力理论的发展过程与隧道破坏机制研究的进展,通过模型试验与弹塑性有限元强度折减法,得出浅埋拱形隧道的破坏在拱顶,深埋隧道的破坏在侧壁的破坏机制,并可求出隧道围岩破裂面位置与形态。分析了矩形隧洞与拱形隧道破坏机制随埋深增加而变,矩形隧道可划分为浅埋顶部破坏阶段、深埋压力拱破坏阶段和深埋两侧破坏阶段3个阶段,而拱形隧道不存在压力拱破坏阶段。     

弯道上的桥台侧墙开裂原因分析

根据实桥状况,对桥台侧墙开裂的原因进行分析.考虑了弯道行车产生离心力作用,同时对墙后主动土压力计算公式进行比选,通过土压力和离心力共同作用的计算模式,运用有限元进行计算,找出了侧墙开裂的原因.