某型地效翼船翼型选择分析

地效翼船(WIG)是一种融合了航空技术与船舶技术的新型高性能船舶,而机翼是产生地面效应和提供升力的主要部件,翼型的优劣直接影响地效翼船的飞行性能.根据某型地效翼船的气动布局特点建立分析模型,采用面元法对2种翼型的气动特性进行计算.对比2种翼型的特性曲线,结果表明,在同一条件下,2#翼型具有更大的升力,地效翼船的起降性能更优越,因此该型地效翼船的机翼更适合采用2#翼型.     

地效翼船爬升角导数数值分析方法

地效翼船是一种新型高性能船舶。由于地面效应的存在,其气动力随飞高呈强烈非线性变化,同时姿态的变化往往会引起飞高的变化,因此很难通过试验手段获取气动力对爬升角(或迎角)的导数。本文通过构建地效翼船的升沉强迫振动,推导出数值求解地效翼船气动力对爬升角和爬升角速度导数的理论方法,并采用CFD典型算例验证了方法的可行性和合理性,可以作为工程设计和性能估算的重要手段。     

大厚度带端板地效翼的空气动力特性

本文是以修改的Grenn Martin 21型为基本翼型,进行了风洞试验以确定大厚度带端板地效翼的纵向空气动力特性。 试验结果表明:大厚度带端板翼的地面效应是强烈的,当翼接近地面飞行时,升阻比和升力曲线的斜率都显著增加,由于气动力中心后移,随之产生低头力矩,可能造成纵向不稳定,因此气翼艇有必要装置稳定翼。     

三维流场下地效翼船巡航状态非线性κ-ε湍流气动的数值模拟

本文提出了一种可以较精确地计算地效翼船巡航状态下气动力的设计方法,应用流体力学中线性和非线性湍流理论并结合有限元法对地效翼船进行了气动性能计算,并结合实验数据对比,可以发现应用非线性湍流理论计算值较为精确.同时又将单算主翼气动性能与计算整体地效翼船数值进行对比,发现单算的主翼气动力大于整体算法的,这主要是未考虑主浮舟等附体对气动力的贡献.作为设计之初可以考虑单算主翼,但随着工作的深入一定要对地效翼船整体气动力性能进行研究,以确定巡航状态下是否提供足够的升力,这是地效翼船设计的关键.在进行整体和单体计算后又进行了不同高度下的气动力分析,分析表明随高度增大地效翼船升力明显减少,并得出适合地效翼船巡航的高度.     

三维流场下地效翼船巡航状态非线性k—ε湍流气动的数值模拟

本文提出了一种可以较精确地计算地效翼船巡航状态下气动力的设计方法。应用流体力学中线性和非线性湍流理论并结合有限元法对地效翼船进行了气动性能计算。并结合实验数据对比，可以发现应用非线性喘流理论计算值较为精确，同时又将单算主翼气动性能与计算整体地效翼船数值进行对比，发现单算的主翼气动力大于整体算法的，这主要是未考虑主浮舟等附体对气动力的贡献，作为设计之初可以考虑单算主翼，但随着工作的深入一定要对地效翼船整体气动力性能进行研究，以确定巡航状态下是否提供足够的升力，这是地效翼船设计的关键，在进行整体和单体计算后又进行不同高度下的气动力分析。分析表明随高度增大地效翼船升力明显减少，并得出适合地效翼船巡航的高度。     

飞向未来战场的两枚攻击平台——地效飞行器

另辟蹊径 它是“会飞的船” 地效飞行器,也称作飞翼船、地效翼艇,它利用地(水)面效应和动力增升原理,在地效区里飞行,使升阻比增加,气动效率大大提高,是介于飞机、舰船和气垫船之间的一种新型高速飞行器。 地(水)面效应简称“地效”。当飞行器在接近地(水)以及在起飞和着陆(水)过程中,由于地(水)面与机翼下空气相互作用,在机翼下方产生气垫,环绕在机翼四周的气流发生改变,使飞行器升力增加,阻力减小,导致升阻比(升力与阻力之比)增大。 飞行器在贴近地(水)飞行时,在一定的高度范围内,存在着一个地效区。地面效应与机翼的展弦比(机翼长度与机翼的宽度之比)有关。一般认为,地效区存在于从地(水)面至翼展的1/2高度范围内,地面效应存在范围的高度最大不超过     

复合材料地效翼船结构设计计算方法研究

[目的]在复合材料地效翼船的结构设计中,目前尚无相应的对其结构进行强度和稳定性评估的规范方法。选取复合材料地效翼船设计中夹芯复合材料主浮舟及机翼这2个关键部件的结构强度及稳定性计算方法开展研究。[方法]重点探讨主浮舟及机翼结构的设计载荷计算方法,以及对应夹芯板的强度衡准、整体及局部稳定性计算方法与衡准。利用建立的计算方法对复合材料地效翼船主浮舟的总纵弯曲强度、机翼结构强度以及稳定性进行算例分析。[结果]结果表明,建立的计算方法可以用于复合材料地效翼船主浮舟和机翼结构的强度及稳定性计算,算例中的复合材料地效翼船设计方案满足结构强度和稳定性要求,经受住了实船试验的考核验证。[结论]所得方法可供复合材料地效翼船结构设计计算参考。     

二维地效翼气动力的计算和性能研究

本文基于势流边界元理论（ＢＥＭ）和边界层动量积分关系式数值求解二维地铲翼的气动力,研究了升力正负地效问题及粘性对地效翼升力、俯仰力矩及焦点的影响,并给出了不同地面边界条件的计算结果及相应的粘性修正方法。     

地效翼艇三维组合翼气动特性计算分析

地效翼布局和翼型选择在很大程度上决定地效翼艇的性能和效能,对地效翼艇的设计至关重要。文章根据地效翼布局和翼型的特点,采用基于升力面理论的镜像法计算三维组合地效翼和简单地效翼在地效区和超出地效区的纵向气动特性参数,分析布局型式和外形参数对地效翼气动特性的影响。得到的组合翼在地效区内外比简单地效翼具有更好的升阻特性的结果,表明组合翼布局适合于掠海高飞型地效翼艇,研究也为地效翼布局型式、外形参数选择以及吹风模型制作提供了依据。     

地效翼船起降稳定性研究

地效翼船的起降过程是水动力和气动力相互耦合作用的过程.文章对地效翼船起降过程的特点进行分析,提出了适用此种情况的运动方程,将起降过程的空间运动分解为孤立的纵向运动与横侧运动.使用小扰动线性化分析方法分别研究航向稳定性和纵向稳定性,并且考虑了风、浪对它们的影响.     

半潜式钻井平台风载荷CFD预报

在平台设计过程中,海洋平台受到的风载荷是稳性分析与结构设计需要考虑的重要因素。本文采用CFD技术,对某型半潜式钻井平台在作业工况下受到的风载荷进行了预报,分析了湍流模型、风速剖面形式、湍流强度分布等因素对半潜式钻井平台风载荷的影响。结果表明：不同湍流模型对海洋平台风载荷的预报偏差在2%以内,可以忽略湍流模型的影响；风速剖面对风载荷有较大影响,随着风速梯度的增加而增大；湍流强度分布对海洋平台风载荷的影响在6%以内。研究结论可为建立高精度的海洋平台风载荷数值预报方法提供技术支持。     

岸边集装箱起重机风载荷数值模拟研究

岸边集装箱起重机抗风性能设计是不可缺少的控制性环节。本文对65t-65m岸边集装箱起重机风洞试验的模型进行了计算流体动力学（CFD）数值模拟。通过计算几个典型的风向角和风速工况下起重机风洞试验模型，得到了丰富的流场及压力场信息，并绘制了速度分布和压力分布图。与风洞试验的数值对比，所得误差较小，说明使用CFD数值模拟的方法计算岸边集装箱起重机风载荷是可行的。     

Mathematical model for takeoff simulation of a wing in proximity to the ground

Aircraft flying close to the ground benefit from enhanced efficiency owing to decreased induced drag and increased lift. In this study, a mathematical model is developed to simulate the takeoff of a wing near the ground using an Iterative Boundary Element Method (IBEM) and the finite difference scheme. Two stand-alone sub-codes and a mother code, which enables communication between the sub-codes, are developed to solve for the self-excitation of the Wing-In-Ground (WIG) effect. The aerodynamic force exerted on the wing is calculated by the first sub-code using the IBEM, and the vertical displacement of the wing is calculated by the second sub-code using the finite difference scheme. The mother code commands the two sub-codes and can solve for the aerodynamics of the wing and operating height within seconds. The developed code system is used to solve for the force, velocity, and displacement of an NACA6409 wing at a 4° Angle of Attack (AoA) which has various numerical and experimental studies in the literature. The effects of thickness and AoA are then investigated and conclusions were drawn with respect to generated results. The proposed model provides a practical method for understanding the flight dynamics and it is specifically beneficial at the pre-design stages of a WIG effect craft.     

Experimental investigation of wing-in-ground effect with a NACA6409 section

The aerodynamic characteristics of NACA6409 in the vicinity of the ground were experimentally studied in a wind tunnel. Lift and drag forces, the pitching moment, and the center of pressure were measured with respect to various major aerodynamic parameters, such as the ground clearance, the angle of attack, the aspect ratio (AR), and the endplate type, which resulted in a total number of 420 conditions. In addition, a smoke trace test was conducted to visualize the flow pattern around NACA6409 in the vicinity of the ground. As a result of the ground effect and the influence of the endplate, the lift-to-drag ratio increased at low ground clearance and the center of pressure moved forward to the leading edge; that is, the endplate and ground effects were equivalent to the aerodynamic advantage that results from increasing the AR of the wing. Extended experimental results are useful for understanding the aerodynamic characteristics influenced by each aerodynamic parameter during ground effect as well as for verifying numerical simulation.     

防风网作用下矿石堆场抑尘率计算

基于矿石起尘规律风洞实验中的粒径分布、起动风速等参数,利用CFD数值模拟方法分别计算防风网作用下目前较常见的澳矿、巴西矿和印度矿的抑尘率。研究结果表明,应用CFD计算矿石粉尘运动的结果与风洞实验中的变化规律相符,澳矿、巴西矿和印度矿在防风网作用下的抑尘率分别为53.76%、54.18%和56.07%,防风网抑尘效果明显。     

Experimental ivnestigation on flow fields of viscous fluid around two-dimensional wings and comparison with computational results

To examine the flow field of a viscous fluid around the trailing edge of a wing with respect to the Kutta condition or the Joukowski hypothesis, an experimental investigation into the velocity fields around two-dimensional (2D) wings NACA0012 and NACA4412 was carried out using an X-type hot-wire anemometer in a wind tunnel and the method of colored milk injection in a circulating water channel. The results of these investigations revealed that the flow of a viscous fluid at the trailing edge of a 2D wing is tangential to the face on the pressure side, and that the flow is very slow or reversed on the suction side due to separation when the angle of attack is greater than 7.5°. By flow visualization, a Kármán vortex street was found in the wake of both wings (NACA0012 and NACA4412) when the angle of attack was 5°. These results show that the ordinary Kutta condition with respect to the direction of outflow at the trailing edge is not necessarily satisfied in a viscous fluid, but the Kutta condition with respect to the pressure at the trailing edge is satisfied as usual. Numerical results, which have been obtained as the solution of Reynolds-averaged Navier-Stokes equations, show good agreement with above-mentioned experimental results. Therefore, CFD (Computational Fluid Dynamics) simulation has proved to be very effective for studying steady viscous flow around the trailing edge of a 2D wing.     

大跨度船库结构风荷载分布规律研究

采用刚性模型测压试验研究全天候大跨度船库的风荷载分布规律,讨论了高水位、低水位、有船舶停靠、无船 舶停靠4种工况下风压分布特点。结果表明：船库结构内压随风向角变化明显,对结构风荷载影响很大;结构开口造成部分 风向角下结构内表面正压从而增强了结构表面的风吸力;不同干扰状况下结构的风荷载不同,其中低水位无船舶停靠时的 风荷载最大。     

Validation and application of nonlinear hydrodynamics from CFD in an engineering model of a semi-submersible floating wind turbine

Nonlinear hydrodynamics play a significant role in accurate prediction of the dynamic responses of floating wind turbines (FWTs), especially near the resonance frequencies. This study investigates the use of computational fluid dynamics (CFD) simulations to improve an engineering model (based on potential flow theory with Morison-type drag) by modifying the second-order difference-frequency quadratic transfer functions (QTFs) and frequency-dependent added mass and damping for a semi-submersible FWT. The results from the original and modified engineering models are compared to experimental data from decay tests and irregular wave tests. In general, the CFD results based on forced oscillation tests suggest increasing the frequency-depending added mass and damping at low frequencies compared to first order potential flow theory. The modified engineering model predicts natural periods close to the experimental results in decay tests (within 5%), and the underprediction of the damping is reduced compared to the original engineering model. The motions, mooring line tensions and tower-base loads in the low-frequency response to an irregular wave are underestimated using the original engineering model. The additional linear damping increases this underestimation, while the modified QTFs based on CFD simulations of a fixed floater in bichromatic waves result in larger difference-frequency wave loads. The combined modifications give improved agreement with experimental data in terms of damage equivalent loads for the mooring lines and tower base.     

Investigation of turbulent flows in a waterjet intake duct using stereoscopic PIV measurements

Stereoscopic particle image velocimetry measurements were made in a wind tunnel using a prototype waterjet model. The main wind tunnel provided the vehicle velocity and a secondary wind tunnel was set up as the waterjet propulsion model. Pressure distributions along the ramp and lip sides inside the duct were measured for three jet velocity to vehicle velocity ratios. Three-dimensional velocity fields were obtained at the intake entrance and the nozzle exit of the waterjet system. The flow into the duct was faster in the lip region than on the ramp side. Because of the variation in intake geometry from a rectangular to a circular section and because of the sudden curvature change on the lip side, a pair of counter-rotating vortices was observed in the mean velocity field at the nozzle exit. In addition, the turbulent kinetic energy correlated with the vortex pair was stronger on the lip side than in other areas. Dominant large-scale structures were extracted by using a snapshot proper orthogonal decomposition analysis. It was found that most of the turbulent kinetic energy was attributed to at least three vortices near the nozzle exit. This detailed three-dimensional velocity field will be useful for the verification of CFD simulations applied to the waterjet system.     

浮式风机气动-水动耦合特性数值模拟（英文）

The exploration for renewable and clean energies has become crucial due to environmental issues such as global warming and the energy crisis. In recent years,floating offshore wind turbines(FOWTs) have attracted a considerable amount of attention as a means to exploit steady and strong wind sources available in deep-sea areas. In this study, the coupled aero-hydrodynamic characteristics of a spar-type 5-MW wind turbine are analyzed. An unsteady actuator line model(UALM) coupled with a twophase computational fluid dynamics solver naoe-FOAM-SJTU is applied to solve three-dimensional Reynolds-averaged NavierStokes equations. Simulations with different complexities are performed. First, the wind turbine is parked. Second, the impact of the wind turbine is simplified into equivalent forces and moments. Third, fully coupled dynamic analysis with wind and wave excitation is conducted by utilizing the UALM. From the simulation, aerodynamic forces, including the unsteady aerodynamic power and thrust, can be obtained, and hydrodynamic responses such as the six-degrees-of-freedom motions of the floating platform and the mooring tensions are also available. The coupled responses of the FOWT for cases of different complexities are analyzed based on the simulation results. Findings indicate that the coupling effects between the aerodynamics of the wind turbine and the hydrodynamics of the floating platform are obvious. The aerodynamic loads have a significant effect on the dynamic responses of the floating platform, and the aerodynamic performance of the wind turbine has highly unsteady characteristics due to the motions of the floating platform. A spar-type FOWT consisting of NREL-5-MW baseline wind turbine and OC3-Hywind platform system is investigated. The aerodynamic forces can be obtained by the UALM. The 6 DoF motions and mooring tensions are predicted by the naoe-FOAM-SJTU. To research the coupling effects between the aerodynamics of the wind turbine and the hydrodynamics of the floating platform, simulations with different complexities are performed. Fully coupled aero-hydrodynamic characteristics of FOWTs, including aerodynamic loads, wake vortex, motion responses, and mooring tensions, are compared and analyzed.