对转垂直轴潮流水轮机数值评估（英文）

In this study, the performance of a contra rotating vertical-axis tidal-current turbine was investigated. The incompressible unsteady Reynolds-averaged Navier-Stokes(U-RANS) equations were solved via two-dimensional(2D) numerical simulation using ANSYS Fluent computational fluid dynamics(CFD) code. An algorithm known as SIMPLE from the CFD code was used to calculate the pressure-velocity coupling and second-order finite-volume discretization for all the transport equations. The base turbine model was validated using the available experimental data. Three given scenarios for the contra rotating turbine were modeled. The contra rotating turbine performs better in a low tip speed ratio(TSR) than in a high TSR operation. In a high TSR operation, the contra rotating turbine inefficiently operates, surviving to rotate in the chaotic flow distribution. Thus, it is recommended to use contra rotating turbine as a part of new design to increase the performance of a vertical-axis tidal-current turbine with a lower TSR.     

风机塔架与叶片相互作用的数值模拟(英文)

Numerical simulations of wind turbine blade-tower interaction by using the open source OpenFOAM tools coupled with arbitrary mesh interface(AMI) method were presented.The governing equations were the unsteady Reynolds-averaged Navier-Stokes(RANS) which were solved by the pimpleDyMFoam solver,and the AMI method was employed to handle mesh movements.The National Renewable Energy Laboratory(NREL) phase VI wind turbine in upwind configuration was selected for numerical tests with different incoming wind speeds(5,10,15,and 25 m/s) at a fixed blade pitch and constant rotational speed.Detailed numerical results of vortex structure,time histories of thrust,and pressure distribution on the blade and tower were presented.The findings show that the wind turbine tower has little effect on the whole aerodynamic performance of an upwind wind turbine,while the rotating rotor will induce an obvious cyclic drop in the front pressure of the tower.Also,strong interaction of blade tip vortices with separation from the tower was observed.     

滑行艇高速航行时的数值模拟(英文)

Planing vessels are applied widely in civil and military situations.Due to their high speed,the motion of planning vessels is complex.In order to predict the motion of planning vessels,it is important to analyze the hydrodynamic performance of planning vessels at high speeds.The computational fluid dynamic method(CFD) has been proposed to calculate hydrodynamic performance of planning vessels.However,in most traditional CFD approaches,model tests or empirical formulas are needed to obtain the running attitude of the planing vessels before calculation.This paper presents a new CFD method to calculate hydrodynamic forces of planing vessels.The numerical method was based on Reynolds-Averaged Navier-Stokes(RANS) equations.The volume of fluid(VOF) method and the six-degrees-of-freedom equation were applied.An effective process was introduced to solve the numerical divergence problem in numerical simulation.Compared with experimental results,numerical simulation results indicate that both the running attitude and hydrodynamic performance can be predicted well at high speeds.     

Design,implementation, and power estimation of a lab-scale flapping-type turbine

A lab-scale flapping-type turbine with a semi-passive activation mode has been designed and implemented. A non-linear dynamic model, developed in our previous work, is validated by a series of experiments along with computational fluid dynamics (CFD) simulations. Previously, the dynamic model was used only to estimate the dynamic response of a flapping-type turbine. In this work, the applicability of the dynamic model is extended to estimate the hydrodynamic forces, extracted power, and efficiency. It was demonstrated from a comparison of the CFD results and measured values that the dynamic model based on a quasi-steady approach estimates the aforementioned performance parameters of measurements well in cases particularly with a low effective angle of attack, thus demonstrating the usefulness of the dynamic model for a flapping-type turbine at an early stage.     

竖轴变偏角潮流发电水轮机的叶片控制机构

为了进行竖轴变偏角潮流发电水轮机的水动力性能的模型试验研究,需要设计该水轮机的试验模型,关键是进行水轮机叶片控制机构的设计.在比较现有的变偏角叶片控制机构的设计思路和工作特点基础上,设计了三种适用于竖轴变偏角潮流水轮机的叶片控制机构,并分别给出了工作原理和装配图,介绍了叶片控制机构的实现方法.最后对三种控制机构的性能、造价等因素进行比较,为进一步的模型试验奠定了基础.     

三维竖轴潮流水轮机水动力性能研究

竖轴水轮机作为潮流能转换为电能的核心装置,其水动力性能的优劣将会直接影响到整体发电系统的效率。为了研究大型竖轴水轮机叶片安装角对水轮机水动力性能的影响,基于多参考系模型(MRF),采用Fluent软件对流场中的模型进行3D数值模拟。在转速和来流速度保持不变,改变安装角时,分析同种翼型5个不同安装角叶片对潮流能水轮机的水动力性能的影响。同时分析在同一安装角和旋转速度条件下,不同来流速度对水轮机水动力性能的影响。结果表明,叶片安装角对竖轴潮流水轮机的能量利用率影响较大,来流速度对水轮机叶片表面的静压力和输出功率具有一定的影响。研究结果对今后竖轴水轮机的设计和生产具有借鉴意义。     

船舶喷水推进器推力分布研究

应用计算流体力学方法对一典型内置推力轴承混流式喷水推进器的流场进行了数值模拟,计算和分析了叶轮、导叶体、进水流道等主要水力部件的推力分布.计算结果显示:(1)在推进特性线上的设计工况,内置推力轴承上的推力约为喷水推进器净推力(合力)的1.5倍,泵静止部件上的推力约为净推力的-0.5倍,进水流道上的推力很小,可忽略不计;(2)各部件上的推力占净推力的比例在推进特性线上的其它工况基本维持不变;(3)在非推进特性线上的工况,各部件上的推力分布不同于推进特性线上的工况,来流速度与泵转速的比值越高时泵静止部件上向后的推力越大,进水流道上的推力不再是可忽略的小量了.喷水推进器推力分布规律的研究结果可为喷水推进器和船尾结构的强度设计时加载水动力作用项提供参考.     

水下航行体回转水动力数值计算研究

准确预报水动力对水下航行体的安全操纵设计而言至关重要。基于商用软件FLUENT数值求解RANS方程,采用定常旋转坐标系,运用相对运动理论及运动叠加原理,并对控制方程中向心力源项空间离散误差进行修正,预报水下航行体做单平面回转运动的受力及力矩。在Re=11.7×106条件下,力和力矩预报精度的偏差在12%以内,表明所采用的数值预报方法有效、可行,具有较好的工程实用价值。     

船用三轴燃气轮机气路故障建模与聚类诊断技术

船用燃气轮机运行在高速、高湿和高盐的工作环境中时,其气路部件在运行过程中发生故障的可能性增大,开展典型气路故障诊断技术研究有助于提升船用燃气轮机运行的可靠性和安全性。通过分析船用燃气轮机积垢、压气机叶顶间隙增大、叶片磨损、机械损伤、涡轮热腐蚀和燃烧室故障等典型气路故障的机理,给出9种典型气路故障时性能参数相对变化的经验判据。采用小偏差建模方法,建立船用三轴燃气轮机气路故障仿真模型,基于经验判据对0.8工况下船用三轴燃气轮机典型气路故障进行模拟,仿真得到9种典型故障下测量参数的相对变化。提出基于聚类分析的船用燃气轮机气路故障诊断方法,并以9种典型气路故障仿真结果为例,验证了该诊断方法的可行性。     

计及叶片载荷的双机对转式海流发电机系泊系统动力分析

本文设计了一种新型的双机对转式海流发电机并对其系泊系统与叶片载荷和直径关系进行模拟分析。首先将单机式海流发电机与已有研究进行对比验证其可靠性，然后在不改变系泊方式的前提下，设计出双机式结构，并通过分析机身位移和旋转比较两种系统的稳定性。为考虑叶片载荷对系泊系统影响，在Orcaflex中对不同精细程度的叶片进行建模，分别对比单一翼型/三翼型/九翼型的数值模拟结果。接着使用M-BEMT软件优化后的翼型参数，对比使用原始升阻力系数的三翼型发电机的模拟结果，同时将使用不同直径叶片的发电机系统进行对比，说明双机式发电机的稳定性更优，对海流发电机及其系泊系统的设计提供重要参考价值。     

喷水推进泵空化性能数值模拟与试验验证

为研究喷水推进泵空化性能,采用计算流体力学(CFD)方法对自行设计的喷水推进泵内部空化流场进行了数值计算与分析。用六面体结构化网格对喷水推进泵的进流管道、叶轮、导叶体和出流管道进行网格划分;通过求解由SST湍流模型封闭的RANS方程计算得到喷水推进泵内部流场,计算得到的扬程、功率和效率特性曲线与试验结果吻合较好。文中还对多个流量的空化性能进行了数值预报,计算结果与试验数据在趋势上具有一致性;小流量工况的临界净正吸头与试验值误差较小,而大流量工况的临界净正吸头与试验值误差较大。研究结果表明:采用CFD方法预报喷水推进泵内部空化流场和空化性能是可行的,可作为喷水推进泵优化设计的有效途径。     

泵喷推进器抗空化性能分析

为改善泵喷推进器抗空化性能以提高舰艇推进器空化初始航速,在验证所用方法可信性的基础上,运用三维反问题设计方法及计算流体力学方法对某排水型船进行泵喷推进器大样本优化设计。结果表明:泵喷推进器低压区的存在形式有3种,即大面积存在、局部存在、在叶片导边和导管进口外壁面呈线状分布;从尺寸选型、叶片负载分布、毂径比、入流角4个方面进行优化设计后,泵喷推进器抗空化性能明显提高。所总结的优化设计方法同样适用于泵喷推进器及导管桨等类似结构推进器的抗空化性能改善。     

旋涡影响下的振动翼水动力性能

Fish are able to make good use of vortices. In a complex flow field, many fish continue to maintain both efficient cruising and maneuverability. Traditional man-made propulsion systems perform poorly in complex flow fields. With fish-like propulsion systems, it is important to pay more attention to complex flow fields. In this paper, the influence of vortices on the hydrodynamic performance of 2-D flapping-foils was investigated. The flapping-foil heaved and pitched under the influence of inflow vortices generated by an oscillating D-section cylinder. A numerical simulation was run based the finite volume method, using the computational fluid dynamics (CFD) software FLUENT with Reynolds-averaged Navier-Stokes (RANS) equations applied. In addition, dynamic mesh technology and post processing systems were also fully used. The calculations showed four modes of interaction. The hydrodynamic performance of flapping-foils was analyzed and the results compared with experimental data. This validated the numerical simulation, confirming that flapping-foils can increase efficiency by absorbing energy from inflow vortices.     

吊舱式CRP推进系统发展及应用前景

介绍吊舱式CRP推进系统的组成、特点,分析营运经济性,实例计算说明吊舱式CRP的方案与其它方案相比经济性优势明显,具有广阔的市场前景。     

船舶汽轮机排汽缸改进优化

排汽缸作为船舶汽轮机的重要部件,其性能可以影响机组的有效焓降以及机组的作功能力;运用CFD软件对某型船舶汽轮机低压排汽缸进行了分析,并结合实际船上条件对其结构进行了改进优化;计算结果表明改进后的排汽缸出口速度分布更加均匀,排汽损失明显降低,可有效提高机组整体性能.     

吊舱推进器定常水动力性能计算

采用FLUENT软件进行拖式吊舱推进器水动力性能的计算,将整体计算域划分为三个区域进行从而达到合理减少计算网格的目的。对于吊舱推进器的整体计算由于涉及到转子/定子物体的相互干扰问题,文中在模拟相互干扰平均效果的定常情况计算中,采用混合面模型进行。对计算方法及边界条件的设置进行了详细介绍。讨论了两种壁面函数对计算结果的影响。计算了不同进速系数下吊舱推进器的推力系数、扭矩系数。采用四套网格进行了吊舱推进器水动力性能计算的比较分析,给出了详细的计算网格参数。分析了计算网格数对吊舱推进器理论预报精度的影响。     

Experimental study on seismic vibration control of an offshore wind turbine with TMD considering soil liquefaction effect

Wind energy is clean and sustainable. Taiwan is establishing offshore wind farms using wind turbines in the Taiwan Strait. However, these are located in an earthquake-prone area with sandy seabed conditions. To ensure their safety and reliability, the turbines’ support structure must be protected against wind, waves, and seismic loads. Tuned mass dampers (TMDs) are commonly employed to reduce structural vibrations. A TMD is more simply incorporated into turbine structures than are other energy dissipation devices. In this study, a 1:25-scale test model with a TMD was constructed and subjected to shaking table tests to experimentally simulate the dynamic behavior of a typical 5-MW wind turbine with a jacket-type support structure and pile foundation. The scaled-down wind turbine model has a nacelle without rotating blades; therefore, the aerodynamic and rotational effects due to the rotating blades were ignored in this study. A large laminar shear box filled with saturated sandy ground was used to simulate the typical seabed conditions of Taiwanese offshore wind farms. The TMD system was designed to be tuned the first-mode frequency of the test model. Two ground accelerations, selected by considering wind farm site condition and near-fault characteristics, were used for excitation in the test. The responses of the test model with and without the TMD system were compared, and the influence of soil liquefaction on the effectiveness of TMD vibration control was addressed.     

上风向与下风向风机气动力性能数值计算分析（英文）

Although the upwind configuration is more popular in the field of wind energy, the downwind one is a promising type for the offshore wind energy due to its special advantages. Different configurations have different aerodynamic performance and it is important to predict the performance of both downwind and upwind configurations accurately for designing and developing more reliable wind turbines. In this paper, a numerical investigation on the aerodynamic performance of National Renewable Energy Laboratory(NREL) phase VI wind turbine in downwind and upwind configurations is presented. The open source toolbox Open FOAM coupled with arbitrary mesh interface(AMI) method is applied to tackle rotating problems of wind turbines. Two 3D numerical models of NREL phase VI wind turbine with downwind and upwind configurations under four typical working conditions of incoming wind velocities are set up for the study of different unsteady characteristics of the downwind and upwind configurations, respectively. Numerical results of wake vortex structure, time histories of thrust, pressure distribution on the blade and limiting streamlines which can be used to identify points of separation in a 3D flow are presented. It can be concluded that thrust reduction due to blade-tower interaction is small for upwind wind turbines but relatively large for downwind wind turbines and attention should be paid to the vibration at a certain frequency induced by the cyclic reduction for both configurations. The results and conclusions are helpful to analyze the different aerodynamic performance of wind turbines between downwind and upwind configurations, providing useful references for practical design of wind turbine.     

螺旋桨敞水性能计算及堵塞效应研究

根据螺旋桨的投影原理以及其几何参数,用三维建模软件 CATIA 建立三维螺旋桨数值模型。根据计算流体动力学（CFD）原理,使用流体动力学软件 Fluent 对螺旋桨数值模型进行分析计算。采用 RANS 方法结合RSM 湍流模型求解螺旋桨三维粘性流场,计算域的离散采用非结构网格方法,运用相对旋转坐标方法（MRF）来模拟螺旋桨的运动,以此求出该螺旋桨在常态以及堵塞效应下的流场特性,并将螺旋桨的数值计算结果与试验结果进行对比以确定该方法的适用性。最后研究堵塞效应的相关性质并将螺旋桨普通敞水性能与螺旋桨在堵塞效应下的敞水性能进行对比,得出堵塞效应对螺旋桨敞水性能的影响。     

125SⅡ型喷水推进泵水动力性能的CFD预报研究

以71SII型喷水推进泵为母型,运用相似理论、CFD数值模拟及试验数据校核相结合的方法,预报了某型船拟使用的同系列的125SII型喷水推进泵的水动力性能。通过CFD分析不仅获得了125SII泵的各种性能,如流量、扬程、功率、效率等,而且还能反映泵内流场细节,便于模型的优化。本研究的意义在于,在没有125SII泵的几何图纸的情况下,运用相似理论从71SII泵的几何模型推得125SII泵的几何模型,据此在方案设计阶段可对新设计船进行快速性预报。结果表明,对由71SII泵的几何模型等比例放大得到的125SII泵模型进行CFD计算所得的不同转速下的功率与由71SII泵的试验P-n曲线通过相似换算所得的各转速下的功率,两者之间的相对误差在7%以内,这表明由71SII泵的几何模型等比例放大得到的125SII泵几何模型及相关的数值模拟是可信的。