Three-dimensional analysis of transient slosh within a partly-filled tank equipped with baffles

The directional dynamic analyses of partly-filled tank vehicles have been limited to quasi-static fluid motion due to computational complexities associated with dynamic fluid slosh analyses. The dynamic fluid slosh causes significantly higher magnitudes of slosh forces and moments in the transient state that cannot be characterized through quasi-static approach, which provides reasonably good estimates of the mean responses. In this study, a three-dimensional nonlinear model of a partly-filled cylindrical tank with and without baffles is developed to investigate the significance of resulting destabilizing forces and moments caused by the transient fluid slosh, and the effects of baffles. The baffles and the end caps are modeled with curved shapes. The analyses are performed under varying magnitudes of steady lateral, longitudinal and combinations of lateral and longitudinal accelerations of the tank, and two different fill volumes using the FLUENT software. The results of the study are presented in terms of mean and peak slosh forces and moments, and variations in the mass moments of inertia of the fluid cargo within a clean bore and a baffled tank, for two different fill volumes and different magnitudes of acceleration excitations. The ratios of transient responses to the mean responses, termed as amplification factors, are further described to emphasize the significance of dynamic fluid slosh on the forces and moments induced on the vehicle. The results in general suggest that the mean responses attained from dynamic fluid slosh analyses correlate well with those attained from the quasi-static analyses for a clean bore tank. The amplification ratios of the resulting forces and moments could approach as high as 2. The results clearly show that the presence of baffles helps to suppress the peak as well as mean slosh forces and moments significantly.     

武汉地铁徐家棚换乘站设计方案研究

研究目的:武汉市轨道交通7号线是武汉远景规划网络中衔接西部新城组群、南部新城组群的一条重要的市域线路,7号线一期工程共设站18座,其中换乘站9座。徐家棚站为7号线长江以南靠江第一个站,该站位于和平大道和团结路交叉路口处,在线网规划中7号线徐家棚站与5号线、8号线换乘,因此徐家棚站为三线换乘车站,如何处理好三线的换乘关系、做好换乘节点的对接规划预留以及处理好与市政工程之间的关系是本文研究的重点及难点。研究结论:本研究根据三条线路的大致规划走向,结合站址周边环境条件提出徐家棚站换乘方式为三线"工"字形换乘,并将过江公路隧道这一市政工程与地铁车站结合起来统筹考虑工期设计、同期实施,减少不必要的重复建设,本文对于正在或者即将进行的三线换乘车站与市政工程的结合设计有一定参考价值。     

基于实船观测的大型船舶回旋水域尺度研究

我国原规范主要采用较小吨级船舶调头数据分析得出回旋水域尺度。为了验证原规范的规定是否能够满足大型乃至超大型船舶调头需要,在我国多个典型港口,通过实船观测共获得了57艘船舶的回旋水域半径数据样本,并对这些实测数据进行统计分析,得出大型船舶回旋水域尺度规律性结论,为规范修订提供技术支持。     

石浦港区主航道一期工程航道尺度设计

以宁波-舟山港石浦港区主航道一期工程设计为例,分析了复杂自然条件下的航道设计不利因素。针对航道水深、通航宽度以及转弯半径等主要航道设计尺度,在按现行国内规范计算的基础上,参考了以《进港航道设计导则》为代表的国外主要航道设计规范,对计算结果进行对比分析,归纳比较了国内外规范在相关参数取值上的异同点,最终推荐航道设计尺度。通过操船模拟试验论证,相关结论可供航道工程设计参考。     

气垫船操纵性能理论分析

研讨了全垫升气垫船垫态航行时的操纵性.利用所建立的气垫船六自由度仿真系统和航向保持控制系统使气垫船进入稳定直航后,进行了操舵回转特性和螺距差回转特性仿真试验研究,并进行了验证气垫船直线稳定性的回舵试验和航向保持能力的Z形机动试验.最后,对仿真试验结果进行了详细分析,并对气垫船的操纵特点进行了论述.     

汽车转向管社总成标准的分析研究

通过比较我国现行汽车转向管柱总成标准与国外相关标准的差异，具体分析现行的国外汽车转向管柱总成标准的特点及优势，从而提出在保留行业标准OC/T649—2000《汽车转向传动轴总成性能要求及试验方法》、QC/T647—2000《汽车转向万向节性能要求及试验方法》中11项内容的基础上，可增加汽车转向管柱总成其他相应的试验要求。     

Simulation study of plane motion of air cushion vehicle

This research is on horizontal plane motion equations of Air Cushion Vehicle (ACV) and its simulation. To investigate this, a lot of simulation study including ACV‘s voyage and turning performance has been done. It was found that the voyage simulation results were accorded with ACV own characteristic and turning simulation results were accorded with USA ACV‘s movement characteristic basically.     

上建转圆处结构应力集中的工程预报方法研究

运用ANSYS软件,对上层建筑与主船体连接部位在外力作用下的应力场分布规律进行了分析,以转圆过渡半径R为研究变量,对不同R导致的过渡连接区应力分布的变化,进行了系列化的对比分析.通过对比不同转圆半径R下的上建转圆处结构应力水平以及应力集中度,重点对半径与应力分布状态的变化规律进行了定性分析,建立了设计变量R对转圆区结构应力变化的影响模型,提出了转圆区结构应力集中系数K关于转圆半径R的拟合公式.     

常规海运船型开发中舵面积的预选研究与验证

船舶操纵性是船舶的重要指标,然而各船级社近期相继删除了其规范中对舵面积的强制要求。本文基于对操纵性理论的分析和总结,对常规运输船舵面积的确定进行了方法上的探讨,为方便数值分析对吃水、舵面积比等进行了统一定义,根据系列船资料拟合出修长度与舵面积比的关系曲线,并根据操纵性试验结果对87000t散货船进行了舵面积和舵形优化讨论,在此基础上梳理出舵面积的开发思路,即舵面积比应与船体修长度在较小时成负相关关系,但当修长度大过某一数值时,需要相对较大的舵面积比。在进行货船初步开发设计时,可根据修长度数值分析结果,选用合适的舵形和舵面积。     

基于Ziegler—Nichols的PID控制系统仿真分析

介绍基于Ziegler-Niehols的PID参数整定方法和PID控制器设计,应用MATLAB／Simulink对所提出的PID参数整定方法进行仿真分析。仿真结果表明,此方法设计的PID控制器的各项性能指标良好。