桨毂形状对螺旋桨水动力影响仿真

采用全结构化网格对桨毂进行计算流体动力学(CFD)水动力仿真,验证仿真方法的有效性,研究3种典型桨毂形状对螺旋桨敞水特性、截面压力分布和空化的影响。通过对比分析发现:圆弧形桨毂阻力最小,效率最优,桨毂形状主要影响叶根区域的流动;圆柱形桨毂叶根的压力最小,空化面积最大;圆弧形桨毂的抗空化性能最优。     

浮式抗冰平台设计理念及水动力特性研究

钻探极地地区近海石油和天然气资源对移动式离岸钻井平台的水动力性能、抗冰性能和作业性能有着极大的要求。本文主要介绍了浮式抗冰平台的设计方案,并结合当今最新一款半潜式抗冰平台的设计理念,分别从频域和时域分析的角度与传统的半潜式平台作对比,分析得出其具有优越的水动力性能,垂荡、横摇、纵摇运动响应都优于传统的半潜平台,为下一步抗冰性能分析及其关键技术的研究做基础,同时也给半潜式平台带来新的设计理念,为浮式抗冰平台的设计建造提供合理思路。     

浅水塔架式单点系泊系统低频响应实验研究

浅水中,单点系泊系统可能存在显著的低频运动,低频大幅运动响应会给系泊系统设计带来严重影响,是系泊系统设计的控制因素之一,在水动力性能预报时必须仔细予以考虑。针对HYSY113FPSO单点系泊系统在浅水风浪流条件下的运动性能进行了物理模型试验研究和数值对比,定量分析了低频运动的运动量和产生的原因,所得结论可供今后浅水水域塔架式单点系泊系统设计参考。     

Maneuvering simulations of pusher-barge systems

Pusher-barge systems were studied in nine different configurations. Captive model tests were performed at the Hiroshima University Towing Tank and the hydrodynamic derivatives for the various configurations were obtained. At a service speed of 7 knots, pusher-barge systems with the same number of barges but arranged in a row (shorter length overall but with a larger breadth) require more power to operate than those that were arranged in a line. When the length overall increased, the tactical diameter, advance, and transfer distances also increased, mainly due to the significant increase in the moment of inertia when barges are arranged in a line, rather than in a row. All pusher-barge systems had small first and second overshoot angles. Pusher-barge systems with the same number of barges had a longer response time to the rudder angle of attack and required a longer stopping distance when arranged in a line, mainly due to the increased moment of inertia and reduced resistance when barges are arranged in this way.     

Investigation of model and parameter uncertainty in water quality models using a random walk method

A mathematical model to predict the effect of chemical spills in the Forth estuary in Scotland has been in use for many years. The model, based on the random walk method, predicts chemical concentrations in the estuary waters and estimates the elapsed time before the dilution is sufficient to render the spill harmless (making use of a toxicity measure such as the LC50 or a water quality standard). The model gives a deterministic result without any estimate of the uncertainty. Field studies using tracer dyes to measure the horizontal and vertical mixing rates in the estuary show that these rates vary over time. The literature on turbulent diffusion includes modelling applications using different parameterisations of the mixing process. This paper investigates the uncertainties in predicted concentrations due to model parameterisation of horizontal mixing and due to the variability in the measured mixing rates determined from surveys in the estuary. Estimates of the range of concentrations for a specific spill scenario are presented.The study shows that model formulation and parameter uncertainty are both important factors in estimating the uncertainty in model predictions. The uncertainty caused by the variations with time found in the measured mixing rates is found to be of similar magnitude to the differences in concentration resulting from using three different methods for modelling the horizontal mixing in the estuary. Uncertainties associated with model formulation could be reduced if a small number of longer timescale (e.g. 24 h) dispersion experiments were available. In addition, further data from short-term (3 h) dispersion experiments would give a better understanding of the distribution of mixing coefficients and how the mixing relates to other parameters such as tidal range and wind speed and direction.     

近水面航行二维水翼的水动力特性研究

利用有限体积方法和RNG k-ε湍流模型直接求解RANS方程计算近水面航行二维水翼(NACA 0012)的水动力特性,自由水面采用流体体积方法(VOF)描述,与试验结果的比较表明,本文的计算模型是合理的,结论是正确的,通过计算给出了不同浸深、攻角和傅氏数的升力系数、阻力系数等曲线。     

全方位推进器水动力性能理论预报

本文应用升力线理论建立了全方位推进器水动力性能计算的数学模型，对其在非定常情况下水动力性能计算进行了理论推导，分析了推进器各参数对水动力性能的影响。数值计算结果表明，本文的全方位推进器水动力性能理论预报方法计算值和实验值吻合良好。     

空港地面设备车辆静压和液力传动特点分析

空港地面设备行走车辆中广泛采用静压传动和液力传动技术。两者在空港地面设备行走车辆中相互渗透，相互影响，但两者的工作原理和结构却完全不同，用于主机传动系的匹配计算方法也完全不同。本文以飞机牵引车为例，分析两种传动的工作特点。通过对匹配原理的分析，为行走式空港地面设备的行走车辆开发、设计、选配提供了依据和方法。     

国外车辆液力传动研究现状及其展望

本文综合了国外近几年来车辆液力传动研究的进展和研究水平的现状，内容包括求解液力变矩器内部三维，粘性，湍流，不稳定流动的数值模拟，采用先进流动测量技术的流场测试，以及将液力传动元件为车辆传动系的子系统所进行的动态特性辨识。     

操纵运动船体水动力计算

提出一个适用于船舶初步设计阶段计算船舶操纵运动水动力的方法,给出了与船体表面局部线型相关的非线性力的估算方法。通过对方型系数Ｃｂ值为０．５７￣０．８３５艘船模的具体计算,结果表明与其相应的约束模试验结果吻合良好,本文方法可用于操纵运动数值模拟,也能作为港内低速大漂角航行船舶的运动模拟。