共查询到19条相似文献,搜索用时 203 毫秒
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艇尾共翼型舵水动力和尾流场特征的数值计算研究 总被引:1,自引:0,他引:1
《中国造船》2019,(1)
为了研究共翼和非共翼两种方式的舵翼操纵面在艇体影响下的水动力性能和尾流场品质,对SUBOFF潜艇标准模型的尾部水平操纵面分别进行了共翼型设计和非共翼型设计,并采用数值模拟方法,计算了两种操纵面产生的艇体水动力和尾流特征。对比分析结果表明:舵角小于10°时,采用共翼型舵的艇体俯仰力矩和潜艇总垂向力比非共翼型增大30%以上;舵角大于10°后,随着舵角增大水动力优势减小,25°舵角时水动力性能基本相当。共翼型舵能够明显消减舵翼结合部涡流,可以增大舵后尾流低速区流体的速度,提高潜艇尾流场品质。采用共翼型舵的尾操纵面设计方式,对于提高潜艇操纵性水动力、改善潜艇尾流区流场品质都能起到积极效果。 相似文献
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针对仿鱼型海洋探测机器人低速时的机动性问题,受鹞鲼鱼类依靠胸鳍摆动实现各种水下运动的启发,设计出一种基于共融理论的复合驱动刚-柔多体耦合仿生鱼胸鳍机构。通过构建基于三维非定常湍流控制方程组的柔性鳍摆动系统水动力学模型,研究仿生胸鳍柔性鳍面摆动时周围压力和速度场的变化情况,分析不同摆动幅度和频率下鳍面的水动力学特性,揭示仿生鹞鲼机器鱼的水下运动机理,对摆动胸鳍的水动力进行仿真。结论表明:鳍面摆动时周围的漩涡能够引起胸鳍面上推力、升力及侧向力按类似正弦变化,而推进力和侧向力的大小随摆动幅值和摆动频率增加而增大。 相似文献
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本文所提出的线性化一般理论是应用奇点分布法来处理超空泡水翼剖面计算中的正(已知翼面形状)反(已知翼面负荷分布)问题。先从经典流体力学里的Green公式出发,结合问题的边界条件,导出了线性化的基本积分方程组。证明了空泡厚度的作用可以用势源分布来表达,而翼面负荷可以用压力偶极子分布来表达。为了求解这一积分方程组,应用了著名的Munk反演公式。求出了在正反问题中确定空泡长度,空泡阻力、升力和力短系数,下翼面坐标或翼面负荷分布,空泡边界坐标,空泡体积等的计算公式。对如何选择合理的空泡模型问题作了讨论。在分析比较了现有的空泡模型之后,作者提出了一种新的半闭式模型,其中的尾流厚度可以从理论上确定,而当空泡长度等于翼弦长时,这一模型退化为开式模型。本文所述的一般理论可以作为建立超空泡水翼剖面工程设计方法的理论基础。 相似文献
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[目的]为了研究水翼的水动力性能对波浪滑翔机设计的影响,[方法]针对波浪滑翔机运动时水翼的摆动特点,基于STAR-CCM+软件的流体与固体相互作用(DFBI)模块,采用SST k-ω湍流模型,模拟出滑翔机水翼在一个周期内主动升沉运动下的被动摆动过程,研究限位角、波高、波浪频率等因素对NACA 0012型水翼的推力系数的影响。[结果]仿真结果表明,被动旋转方法可以有效模拟水翼摆动过程,且被动旋转方法所得平均推力系数与主动旋转的相比小30%左右;滑翔机水翼最大限位角在20°附近时,水翼的水动力性能较优;平均推力系数在一定范围内随波高、波浪频率的增加而增大。[结论]这一结果可为研究波浪滑翔机的推进性能以及在不同海况条件下的水动力性能提供参考。 相似文献
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《中外船舶科技》2018,(4)
波浪滑翔器的水动力性能主要取决于其拍动水翼的设计。在推进效率不变的情况下,采用动网格方法,基于RANS方程与标准的湍流模型,应用ICEM CFD软件和FLUENT软件,分别研究了翼型为NACA0008、NACA0012与NACA0016的拍动水翼的水动力性能,筛选出NACA0012翼型的水动力性能最佳。从工况角度入手,研究了NACA0012翼型拍动水翼的最大转动角度、波浪来流速度、波长及波高对拍动水翼平均推力的影响,定量评估了不同工况下的水动力性能。结果表明:当波浪滑翔器推进效率不变时,在非稳态条件下,翼型为NACA0012的拍动水翼的平均推力较大,水翼的水动力性能较好。 相似文献
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《船舶力学》2013,(12)
为了研究船用水翼前缘抽吸设置对其水动力性能及空泡性能的影响,应用数值模拟的方法进行了系统的计算分析。首先,以NACA0012为研究对象,采用两种湍流模型对翼型绕流进行模拟,通过与实验值对比,确定了合理的湍流模型。随后,计算分析了船用水翼添加前缘抽吸作用后,升力系数、阻力系数和升阻比的变化情况,及对失速角的影响,结果表明船用水翼在前缘布置吸口后可以提高失速角,扩大稳定工作攻角范围,提升翼型升阻比,起到增效的作用。最后,计算了NACA0012翼型及在其前缘加吸口水翼的定常与非定常空泡流动的数值模拟,计算结果表明:定常流动时,在翼型前缘加上吸口,可使空泡尺寸减小,改善了水翼的空泡性能;非定常流动时,加上吸口,可使空泡周期变长,空泡变化范围减小,抑制大规模空泡云的脱落,减少对水翼表面的剥蚀作用,降低空泡对水翼性能的影响。 相似文献
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WUFu-bing ZENGNian-dong ZHANGLiang WUDe-ming 《船舶与海洋工程学报》2004,3(2):7-11
Continuous vorticity panels are used to model general unsteady inviscid, incompressible, and two-dimensional flows. The geometry of the airfoil is approximated by series of short straight segments having endpoints that lie on the actual surface. A piecewise linear, continuous distribution of vorticity over the airfoil surface is used to generate disturbance flow. The no-penetration condition is imposed at the midpoint of each segment and at discrete times. The wake is simulated by a system of point vortices, which move at local fluid velocity. At each time step, a new wake panel with uniform vorticity distribution is attached to the trailing edge, and the condition of constant circulation around the airfoil and wake is imposed. A new expression for Kutta condition is developed to study (i) the effect of thickness on the lift build-up of an impulsively started airfoil, (ii) the effects of reduced frequency and heave amplitude on the thrust production of flapping airfoils, and (iii) the vortex-airfoil interaction. This work presents some hydrodynamic results for tidalstream turbine. 相似文献
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减摇水舱设计完成后要安装在摇摆台上,通过摇摆台精确模拟在特定海况下船舶横摇运动从而对水舱性能进行检测,摇摆台动力装置为电液伺服系统,在模拟不同船型时,配重改变及系统本身零漂,零偏等干扰因素变化使得对其执行机构传统的PD控制参数整定难、适应性差从而模拟精度降低.文章对摇摆台进行数学建模及仿真模型搭建,设计了IGA-PID控制器,采用免疫遗传算法的PID控制,通过抗体间的促进与抑制反应,不依赖控制对象实现系统的自适应,从而对PID控制参数进行整定得到全局最优解.仿真结果表明,该控制算法的应用具有更好的控制效果和鲁棒性,满足水舱测试精度要求. 相似文献
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《船舶与海洋工程学报》2017,(1)
In this study, a vertical axis tidal turbine with flexible blades is investigated. The focus is on analyzing the effect of flexible airfoils types and blade flexibility on turbine net output power. To this end, five different flexible airfoils(Symmetric and Non-symmetric) are employed. The results show that the use of a thick flexible symmetric airfoil can effectively increase output power compared to that achievable with a conventional rigid blade. Moreover, the use of highly flexible blades, as opposed to less flexible or rigid blades, is not recommended. 相似文献
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In this study, a vertical axis tidal turbine with flexible blades is investigated. The focus is on analyzing the effect of flexible airfoils types and blade flexibility on turbine net output power. To this end, five different flexible airfoils (Symmetric and Non-symmetric) are employed. The results show that the use of a thick flexible symmetric airfoil can effectively increase output power compared to that achievable with a conventional rigid blade. Moreover, the use of highly flexible blades, as opposed to less flexible or rigid blades, is not recommended. 相似文献
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The present paper addresses the design and optimization of a flexible composite marine propeller. The aim is to tailor the laminate to control the deformed shape of the blade and consequently the developed thrust. The development of a hydro-elastic model is presented, and the laminate lay-up which minimizes the fuel consumption for the cruising and maximum speed conditions is simultaneously determined. Results show a reduction of 1.25% in fuel consumption for the combined case corresponding to a decrease of 4.7% in the cruising speed condition. Finally, the strength of the optimal blade is analyzed using the Tsai-Wu strength index. After local tailoring of the laminate configuration throughout the propeller a maximum value of 0.7 is determined indicating no failure will occur under normal operation conditions. The results suggest that it is possible to design a medium-sized flexible composite marine propeller that will enable a reduction of the fuel consumption while withstanding the imposed loads 相似文献
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船舶液压起重机延迟反馈吊重消摆控制 总被引:1,自引:1,他引:0
由于操纵和工作环境的变化,起重机的吊重在工作过程中会产生摆动,这种摆动降低了起重机的工作效率和安全性能。文章以集美大学轮机工程实验中心船舶液压起重机为研究对象,采用机电液仿真建模技术及拉格朗日方程,在MATLAB Simulink仿真软件平台上,建立起重机操作液压系统及吊重摆动模型,采用与试验数据对比的方法对所建立的模型进行验证。设计基于吊重摆动位置延迟反馈的控制器,通过将延迟反馈信号叠加到操作信号上的方法实现吊重的消摆控制。结果表明,在各种操作情况下,延迟反馈控制器均能很好地抑制吊重的摆动。 相似文献
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Abhra Roy Chowdhury Wang Xue Manasa Ranjan Behera S. K. Panda 《Journal of Marine Science and Technology》2016,21(1):102-114
This paper investigates the hydrodynamic characteristics of the rectilinear motion of a robotic fish underwater vehicle. This 2-joint, 3-link multibody vehicle model is biologically inspired by a body caudal fin carangiform fish propulsion mechanism. Navier–Stokes equations are used to compute the unsteady flow fields generated due to the interaction between the vehicle and the surrounding incompressible and Newtonian fluid (water) environment. The NACA 0014 airfoil aerodynamic profile has been designed to boost the swimming efficiency by reducing drag as the vehicle undergoes an undulatory/oscillatory motion. Using the Lighthill slender body model, a traveling wave mathematical function is defined to undulate the robotic fish posterior (caudal) region while the motion tracking is carried out by dynamic meshing technique. The results obtained show that though the net lift force approaches to zero, the net thrust or negative drag coefficient maintains a finite value dependent on kinematic parameters like tail beat frequency (TBF) and amplitude span (AS) at a given propulsive wavelength and the forward velocity of the vehicle. The results reveal the effects of TBF and AS on the coefficient of drag friction and the thrust force. Drag coefficients obtained from the simulations are compared and validated with the experimental results. The hydrodynamic results are found to be similar to the kinematic study results and suggest that TBF and AS play the most effective roles in the bioinspired propulsion technique. Relation of these parameters with propelling thrust force and forward velocity is also in conjunction over a given range of TBF and AS values. 相似文献
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利用FLUENT软件数值计算了二维柔性鳍作升沉纵摇运动时的推力系数及推进效率,探讨了修正Bose变形方程、均匀载荷和非均匀载荷悬臂梁变形方程等三种柔性模式下纵摇轴位置对摆动鳍推进性能的影响,其中纵摇轴在尾缘处能够获得更大的推力,而最高的推进效率分别对应修正Bose模式下纵摇轴距首缘1/3弦长处和悬臂梁柔性变形模型下纵摇轴距首缘2/3弦长处.同时计算分析了斯特劳哈尔数、最大攻角等参数对柔性鳍水动力性能的影响,建立了最大推力系数和最高推进效率所对应的参数区间,其中低St数的最高推进效率发生在低αmax,高St数的最高推进效率发生在高αmax. 相似文献