水下滑翔器整体外形设计及水动力性能分析

对水下滑翔器的整体外形设计与水动力性能进行研究。在Slocum等几种典型水下滑翔器样机的基础上,对滑翔器的主体和附体进行一体化设计,得到阻力最小的新型水下滑翔器构型设计。利用CFD方法对水下滑翔器进行模拟仿真,通过分析对比五种主体构型,得到了比较合理的主体线型,然后用正交设计方法和曲线拟合法对附体进行了优选工作,最后得到了性能更优的整体载体外形。模拟仿真实验表明,滑翔器在8°左右攻角航行时,具有最大的升阻比;和Slocum等经典样机相比,新的载体具有更好的水动力性能。通过上述研究工作,也可以缩短水下滑翔器研制周期,降低设计成本,并为水下滑翔器的更优设计提供了有力的技术指导和参考。     

扁平型水下滑翔器水动力特性及滑翔性能研究

续航力与水平速度均是水下滑翔器的重要性能指标。采用单位重量滑翔器、单位水平速度所耗功率作为滑翔效率的评价指标，以一新型扁平型水下滑翔器为研究对象，利用 CFD 计算结合模型试验验证的方法获取了所需的流体动力系数，然后进行了滑翔运动分析及垂直面滑翔运动仿真计算，得到了最优滑翔运动参数。 建立的滑翔性能计算方法对扁平型水下滑翔器水动力性能设计及滑翔运动参数优化有着重要的应用价值。     

新型无尾翼水下滑翔器升阻比性能的研究

采用标准k-ε两方程涡粘性模型,压力的隐式算子分割算法(PISO)求解时均Reynolds方程(RANS),对三种新型无尾翼水下滑翔器的升阻比性能进行研究。先对滑翔器摩擦阻力的CFD模拟结果与理论计算结果进行对比分析,验证CFD模拟结果的合理性与可靠性;再对不同迎流速度、不同速度攻角下的试验工况进行数值模拟,分析不同试验工况下滑翔器的粘压阻力与升力,得到不同试验工况下滑翔器的升阻比性能。研究结果表明,新型无尾翼水下滑翔器在5°~15°攻角区间内具有良好的升阻比,小攻角下圆碟型和飞碟型滑翔器的升阻比性能优于椭圆型滑翔器,而大攻角下椭圆型滑翔器相对其它两种具有更佳的升阻比性能,为新型无尾翼水下滑翔器升阻比性能的研究提供一定的思路。     

水下滑翔器定常直线滑翔运动稳定性分析

对水下滑翔器定常直线滑翔运动的稳定性问题进行研究.以定常直线滑翔运动时的纵倾角为考察对象,利用自由扰动运动方程特征根的方法对研制的滑翔器的运动稳定性进行了分析判断.在此基础上,考察了在小扰动作用下纵倾角扰动量的时间响应特性.研究结果表明,研制的水下滑翔器在做定常直线滑翔运动时,具有运动稳定性,而且具有方向稳定性.     

混合驱动自主潜航器续航能力分析

混合驱动自主潜航器融合了自主潜航器机动灵活和水下滑翔机续航能力强的优点,针对自身携带能源有限的问题,对在两种工作模式下如何实现最大航行距离进行了研究.从航行过程中的能源消耗入手,得出航行距离与速度、电子设备功率等的关系,通过理论分析和仿真手段得出最大续航能力的实现方法.在螺旋桨驱动模式下,当以经济航速航行时,可以达到最大航行距离;在浮力驱动模式下,当以最大滑翔效率航行时,水平方向上的滑翔距离最大,并且水平方向上的滑翔距离随着剖面深度的增大而增大,当剖面深度大到一定程度之后,最大滑翔距离趋于恒定.该研究方法可为类似水下航行器电源管理系统的能源分配提供参考,也可为航行器外形的设计和传感器的选型提供理论指导.     

水下滑翔器运动控制与自主导航策略

水下滑翔器嵌入式控制系统采用Philips公司的LPC2478为主控芯片,搭载多路高精度传感器以及伺服执行系统。通过对水下滑翔器的结构分析,构建出水下滑翔器的动力学模型,采用神经网络PID控制算法调节动力学模型中的俯仰角和横滚角,实现水下滑翔器在水下运行时的姿态调节与航迹控制。引入高斯大地线算法,分析处理经纬度坐标与航向角数据,计算得到水下滑翔器的航行距离与航向角偏差数据,从而控制伺服系统实现导航控制。同时,鉴于水面环境与水下环境的差异,为提高水下滑翔器的导航精度,引入水下航位推算算法,推算出水下滑翔器在水下的航向与姿态角,提高其在水下运行的精确度。     

温差能驱动的水下滑翔器设计与实验研究

论文设计开发了一种新型的温差能驱动的水下滑翔器,并对它做了水域实验研究。文章讨论了温差能驱动的滑翔器运动机理及其在垂直剖面的运动分析,得到稳态运动的参数解。结合能够把水域温差能转变为机械能的热机设计以及滑翔器的主要机械结构和控制硬件系统设计,完成了滑翔器的初步设计与开发。滑翔器在千岛湖进行了水域实验,实验结果表明,此水下滑翔器完全能够利用温差能实现预定的滑翔运动。     

一种小型水下自航行器推进系统设计与分析

从系统角度考虑,整体优化,设计了水下自航行器推进系统.通过外形优化减小轴向阻力,根据阻力和综合分析设计螺旋桨,并由敞水池试验验证螺旋桨的性能,在此基础上完成了推进控制系统的分析与优化设计.试验结果证明系统设计方法正确,推进系统性能良好.     

基于表面V形沟槽的圆柱减阻性能研究

为了研究沟槽圆柱在亚临界雷诺数下的阻力特性,采用数值模拟与水槽试验相结合的方法,对沟槽圆柱的减阻性能进行研究.开展三维流场数值模拟,确定最佳仿真模型参数,研究沟槽参数、雷诺数以及迎流角对减阻效果的影响,设计了一种减小端面绕流干扰的水槽试验,验证仿真结果.结果表明:在雷诺数为40000时,沟槽深度为0.0075D(D为圆...     

水下滑翔器浮力驱动机构布局分析

水下滑翔器是一种新型海洋测量平台,它采用浮力驱动方式,并依靠调整重心实现姿态控制.文中从研究水下滑翔器纵垂面内滑翔运动的平衡状态入手,通过对将浮力驱动机构布置在滑翔器的艏部和艉部时的平衡状态受力进行对比分析,指出将浮力驱动机构布置在艏部可以有效缩短重心调节重物的移动距离.并分析了两种布局方式的优缺点,为水下滑翔器的结构设计和控制系统设计提供了参考.     

Research on Bulbous Bow Optimization Based on the Improved PSO Algorithm

In order to reduce the total resistance of a hull, an optimization framework for the bulbous bow optimization was presented. The total resistance in calm water was selected as the objective function, and the overset mesh technique was used for mesh generation. RANS method was used to calculate the total resistance of the hull. In order to improve the efficiency and smoothness of the geometric reconstruction, the arbitrary shape deformation (ASD) technique was introduced to change the shape of the bulbous bow. To improve the global search ability of the particle swarm optimization (PSO) algorithm, an improved particle swarm optimization (IPSO) algorithm was proposed to set up the optimization model. After a series of optimization analyses, the optimal hull form was found. It can be concluded that the simulation based design framework built in this paper is a promising method for bulbous bow optimization.     

Optimization of fishing vessels using a Multi-Objective Genetic Algorithm

A fishing boat hull is used as an example of how hull form optimization can be accomplished using a Multi-Objective Genetic Algorithm (MOGA). The particular MOGA developed during this study allows automatic selection of a few Pareto Optimal results for examination by the designers while searching the complete Pareto Front. The optimization uses three performance indices for resistance, seakeeping and stability to modify the hull shape to obtain optimal hull offsets as well as optimal values for the principal parameters of length, beam and draft. The modification of the 148/1-B fishing boat hull, the parent hull form of the ?stanbul Technical University (?TÜ) series of fishing boats, is presented by first fixing the principal parameters and allowing the hull offsets to change, and secondly by simultaneously allowing variation of both the principal parameters and the hull offsets. Improvements in all three objectives were found. For further research the methodology can be modified to allow for the addition of other performance objectives, such as cost or specific mission objectives, as well as the use of enhanced performance prediction solvers. In addition, one or more hulls could be evaluated by experiment to validate the results of using this particular optimization approach.     

Numerical investigation on the hydrodynamic performance of fast SWATHs with optimum canted struts arrangements

Small Waterplane Area Twin Hulls (SWATHs) are known to have superior seakeeping performance but higher resistance compared to equivalent catamarans or mono-hulls. A way to improve their resistance characteristics is to use unconventional hull forms parametrically defined and optimized by CFD methods. This study builds on previous SWATH optimization studies proposing a comprehensive, systematic investigation on the effect of different shapes and canting angles of the struts. For the first time we demonstrate the importance of considering the shape of the strut that is fully parametrized in our study. The effect of the design speed on the best shape is addressed through a multi-objective optimization targeting the minimum total resistance at two very different speeds, namely the cruise and slow transfer speeds. Optimum hull shapes are discussed in terms of maximum resistance reduction, together with the predicted free waves patterns.     

Hull hydrodynamic optimization of autonomous underwater vehicles operating at snorkeling depth

Traditionally autonomous underwater vehicles (AUVs) have been built with a torpedo-like shape. This common shaping is hydrodynamically suboptimal for those AUVs required to operate at snorkeling condition near the free surface. In this case, the wave resistance associated to the wavy deformation of the sea surface induced by the motion of the platform is an important component of the drag. This work has investigated the optimum hull shape of an underwater vehicle moving near the free surface. Specifically a first-order Rankine panel method has been implemented to compute the wave resistance on a body of revolution moving close to the free surface. A simulated annealing algorithm was then employed to search those set of parameters defining the hull shape that minimize the wave resistance. The optimization was constrained to keep constant the total volume of the vehicle. The total drag of scaled models of the torpedo-like and resulting optimum shapes was measured in the naval tank of the University of Trieste. Measurements showed a smaller resistance of the optimized shape in the range of the considered Froude numbers.     

设计相关动载荷作用下的水下耐压结构拓扑优化

常规耐压结构拓扑优化设计研究主要集中于静水压条件下的设计相关载荷拓扑优化理论及方法。但是,在深海环境下,耐压结构可能面临内爆所产生的冲击载荷,其载荷呈现高频率的周期性变化。为研究载荷变化对耐压结构优化设计的影响,在BILE模型的基础上,结合修正的SIMP插值模型,开展不同频率、设计相关动载荷作用下的水下耐压结构拓扑优化理论及方法研究。设计相关动载荷的难点在于不仅载荷的作用位置和方向在优化过程中发生变化,且其大小也随优化过程进行而发生变化,这是与常规设计相关静载荷本质的不同。通过经典的拱形结构优化算例验证BILE模型在动力学拓扑优化中的可行性,进而研究设计相关动载荷作用下的水下耐压结构的最佳拓扑形式。研究表明,在低频时,圆环型耐压结构无明显变化,但多球交接耐压结构在交接处会出现明显材料聚集;高频时,两者均发生明显变化,得到耐压结构新形式。关于设计相关动载荷作用下的水下耐压结构拓扑优化研究,将对新型水下耐压结构的探索具有一定的工程应用价值。     

Hydrodynamic shape optimization by high fidelity CFD solver and Gaussian process based response surface method

A computational framework for hydrodynamic shape optimization of complex ship hull form is proposed and applied to improve the calm water performance of the KRISO Container Ship (KCS). The framework relies on three key features: a novel shape morphing method based on a combination of subdivision surfaces and free form deformations, a robust three dimensional viscous computational fluid dynamic solver based on the openFOAM open-source libraries and a Gaussian process-response surface method (GP-RSM) based on ordinary Kriging model which has been created to speed-up the evaluation of the quantity of interest (QoI) of the design process.The accuracy of the hydrodynamic solver is proven by comparing the obtained results against available experimental measurements. A preliminary sensitivity analysis on the mesh size has been carried out aiming at reducing the computational burden required by the CFD predictions. Three GP-RSMs have been trained relying on increasing number of hull designs. Each surrogate model has been cross-validated by both leave-one-out and k-fold techniques. The behaviours of these multi-dimensional surfaces have been analyzed in details by sampling the investigated design space with 10⁷ points according to a Full-Factorial algorithm, highlighting the regions of maximum deviation with respect to the resistance of the reference hull. The three optimum designs provided by the corresponding GP-RSM models have been verified by using high-fidelity CFD simulations with a refined mesh configuration. Calm water resistance, wave patterns and pressure distributions over the selected hull surfaces have been discussed in the light of the generated shape variations.     

Hydrodynamic optimization of ship hull forms

An extremely simple CFD tool is used to compare the calm-water drags of a series of hull forms and to define ‘optimized’ monohull ships for which the total (friction+wave) calm-water drag is minimized. The friction drag is estimated using the classical ITTC formula. The wave drag is predicted using the zeroth-order slender-ship approximation. Comparisons of theoretical predictions and experimental measurements for a series of eight hull forms show that—despite the extreme simplicity of the method that is used here to estimate the friction drag and the wave drag—the method is able to rank the drags of a series of hull forms roughly in accordance with experimental measurements. Thus, the method may be used, with appropriate caution, as a practical hull form design and optimization tool. For purposes of illustration, optimized hull forms that have the same displacement and waterplane transverse moment of inertia as the classical Wigley hull, taken as initial hull in the optimization process, are determined for three speeds and for a speed range.     

An inverse hull design approach in minimizing the ship wave

The Levenberg–Marquardt Method (LMM) and a panel code for solving the wave-making problem are utilized in an inverse hull design problem for minimizing the wave of ships. A typical catamaran is selected as the example ship for the present study. The hull form of the catamaran is described by the B-spline surface method so that the shape of the hull can be completely specified using only a small number of parameters (i.e. control points). The technique of parameter estimation for the inverse design problem is thus chosen. The LMM of parameter estimation, which is the combination of steepest descent and Newton’s methods, has been proven to be a powerful tool for the inverse shape design problem. For this reason it is adopted in the present study.In the present studies, the inverse hull design method can not only be applied to estimate the hull form based on the known wave data of the target ship but can also be applied to estimate the unknown hull form based on the reduced wave height. The optimal hull forms of minimizing wave for a typical catamaran in deep water at service speed and at the critical speed of shallow water are estimated, respectively. Moreover, a new hull form with the combining feature of the optimal hull forms for deep water and shallow water is performing well under both conditions. The numerical simulation indicates that the hull form designed by inverse hull design method can reduce the ship wave significantly in comparison with the original hull form.     

Hull form reliability-based robust design optimization combining polynomial chaos expansion and maximum entropy method

In the ship design optimization process, the neglect of the unavoidable uncertainty of parameters in the actual navigation and experimental observations, may lead to a bad result with some hidden dangers in practical applications. Considering the influence of the uncertainty, a new and effective hull form reliability-based robust design optimization (RBRDO) framework, including the hull form modification module and RBRDO module, has been developed and tested in the present work. Radial basis function method is utilized as the parametric hull surface modification technique to generate a series of smooth hull forms while combining polynomial chaos expansions (PCE) method with maximum entropy method (MEM) to conduct the uncertainty analysis for the prediction of the mean and the standard deviation of the objective and the failure probability of constraints. To verify the validity of the method, hull form design optimization of the bow of KCS model is implemented under the influence of the uncertainty. Numerical results indicate that the proposed RBRDO framework is effective compared with traditional Monte Carlo method. Meanwhile, compared with traditional DO case, RBRDO case has higher adaptability to the environmental uncertainty with the lower failure probability, which ensure the robustness and reliability of the optimal hull form.     

Multiple criteria optimization applied to high speed catamaran preliminary design

The demand for high-speed craft (mainly catamarans) used as passenger vessel has increased significantly in the recent years. Looking towards the future and trying to respond to the increasing requirement, high-speed crafts international market is passing through deep changes. Different types of high-speed crafts are being used for passenger transport. However, catamarans and monohulls have been the main choice not only for passenger vessel but also as ferryboat.Generally speaking, the efficient hydrodynamic hull shapes, engine improvements, and lighter hull structures using aluminum and composite materials make possible the increase in cruising speed.The high demand for catamarans are due to its proven performance in calm waters, large deck area compared to monohull crafts and higher speed efficiency using less power. Although the advantages aforementioned, the performance of catamaran vessels in wave conditions still needs to be improved.The high-speed crafts (HSC) market is demanding different HSC designs and a wide range of dimensions focusing on lower resistance and power for higher speed. Therefore, the hull resistance optimization is a key element for a high-speed hull success.In addition to that, trade-off high-speed catamaran (HSCat) design has been improved to achieve main characteristics and hull geometry. This paper presents a contribution to HSCat preliminary design phase. The HSCat preliminary design problem is raised and one solution is attained by multiple criteria optimization technique.The mathematical model was developed considering: hull arrangement (area and volume), lightweight material application (aluminum hull), hull resistance evaluation (using a slender body theory), as well as wave interference effect between hulls, calculated with 3D theory application. Goal programming optimization system was applied to solve the HSCat preliminary design.Finally this paper includes an illustrative example showing the mathematical model and the optimization solution. An HSCat passenger inland transport in Amazon area preliminary design was used as case study. The problem is presented, the main constrains analyzed and the optimum solution shown. Trade off graphs was also included to highlight the mathematical model convergence process.