非均匀流下桨叶侧斜对螺旋桨空化和压力脉动的影响

侧斜对螺旋桨的水动力性能及空化性能均有十分重要的影响,该文基于k-ωSST湍流模型和Zwart-Gerber-Belamri空化模型对非均匀流条件下四个不同侧斜螺旋桨周围的非定常空化流动情况进行了数值模拟研究。首先进行了螺旋桨水动力性能和空化特性计算,通过与试验结果对比,评估了网格数量的影响以及计算方法的可靠性。在此基础上探讨了侧斜对空化形态以及压力脉动的影响,结果表明：适当地增大侧斜可以使螺旋桨的平均推力得到提升。此外,侧斜的增加可以使桨叶徐徐切入船尾伴流,从而使螺旋桨空化体积的变化趋于平缓,进而有效地降低压力脉动,抑制振动和噪声,提高船舶运行的安全性和舒适性。     

AU5-65螺旋桨紧急倒车工况流场与涡流噪声数值模拟研究

该文利用大涡模拟(LES)与FW-H声学类比方法对AU5-65螺旋桨第一象限(前进正车)和第三象限(紧急倒车)下的流场与涡流噪声进行了数值模拟研究。在规范的网格收敛性分析和亚格子涡模型影响性分析的基础上，采用1 063万网格与SL亚格子涡模型，首先对螺旋桨敞水第一和第三象限不同进速下的流场与水动力性能展开了计算分析，并通过相关试验数据校验了计算方法的可靠性，将不同工况与不同进速系数下的瞬态流场、桨叶切面压力和涡旋结构演化等结果进行了对比分析；在此基础上，结合FW-H方程对AU5-65桨敞水正车前进与紧急倒车时涡流噪声频谱进行了计算分析，探讨了紧急倒车工况下的螺旋桨涡流噪声幅值与频率特征。研究结果表明，该文建立的数值计算方法适用于螺旋桨紧急倒车工况下的流动与噪声模拟。     

船舶螺旋桨流场及水动力数值分析

随着数值计算和计算机技术的飞速发展,计算流体力学已经发展成为流体力学的主要研究手段,作为船舶优化设计和航行性能分析的基本工具,在船舶水动力学分析中得到广泛应用。该文针对船舶螺旋桨流动模拟,描述使用的网格模式和数值方法,探讨水动力计算结果对网格尺度、几何精细度表达及边界层网格形式的依赖性和敏感性,同时在数值模拟的基础上分析螺旋桨叶片边界层、梢涡和尾涡的流动特征,以及螺旋桨流场与水动力的联系。     

小水线面双体船后螺旋桨非定常力特性研究

螺旋桨作为船舶主要振源,其非定常性能的研究对于船舶噪声和振动的控制意义重大。该文采用滑移网格技术,基于分离涡模拟方法(DES),对带首尾鳍船桨一体模型开展了螺旋桨非定常力的数值计算,研究了小水线面双体船后螺旋桨的非定常力特性,并通过与试验结果的对比考察了数值计算方法的精度。计算结果表明,螺旋桨受到的三向力和力矩均有明显的叶频特性,其中推力脉动幅值和水平弯矩脉动幅值较大;此外,分析得出了脉动压力和脉动压力幅值在船体表面局部范围内的分布规律,并将多个测点的脉动压力一阶和二阶叶频幅值与试验测量值对比,其中一阶叶频结果与试验值吻合良好。     

船用螺旋桨理论计算中的数值计算方法

本文着重于介绍船用螺旋桨理论计算中常用的几种数值处理方法和尾涡的计算模型。并对这几种方法作分析比较。指出各自的优缺点。     

桨叶剖面空泡形态发展特性研究

船后螺旋桨空泡诱导脉动压力与空泡形态发展特性密切相关。该文基于单一介质输运方程和Singhal全空泡模型,对NACA翼型进行了局部空泡流的数值计算,计算的平均压力分布和空泡长度与试验结果吻合较好。采用该方法针对Eppler方法设计的叶剖面的空泡形态发展进行了数值分析,提出了一种描述空泡形态几何参数(长度、体积)随新组合环境参数(攻角、空泡数、起始攻角及吸力面主压区压力系数)变化关系的统一表达式,并应用于描述平板空泡形态线性化理论结果、圆弧形水翼空泡形态试验结果以及Eppler方法设计的叶剖面空泡形态数值计算结果,并进行了理论说明。这为控制螺旋桨空泡行为,进而降低空泡脉动压力的螺旋桨设计奠定基础。     

拖式吊舱螺旋桨定常性能理论计算

本文提出拖式吊舱螺旋桨(螺旋桨位于吊舱首部)定常水动力性能的势流理论计算方法。螺旋桨采用升力面理论涡格法、吊舱采用面元法分析计算，二者的相互干扰通过叠代计算来处理。考虑吊舱的影响，修改了尾涡模型。应用本方法，计算了拖式吊舱螺旋桨的定常性能，并与空泡水筒试验结果进行了比较，计算与试验吻合良好。     

三维非定常湍流尾水管涡带计算研究

混流式水轮机弯肘型尾水管在部分负荷工况下产生带气泡的尾水涡流, 涡流在离心力的作用下形成与水流共同旋的涡带，由此产生的低频压力脉动是混流式水轮机面临的一个普遍性问题。水轮机中存在的水力压力脉动现象将诱发转轮叶片疲劳破坏。更有甚者对整个机组、厂房构成威胁, 严重影响了机组的安全稳定运行。本文采用全流道三维非定常流动数值模拟方法, 研究三峡混流式水轮机在部分负荷工况运行时，由尾水管涡带以低频的周期在尾水管内旋进引起的压力脉动现象。采用全流道非定常流动粘性湍流计算，计算结果表明在各记录点都捕捉到了涡带低频压力脉动：频率为0.333Hz, 是转频1.25Hz的3.75分之一，相近工况模型试验实测涡带频率为5.31Hz, 是转频18.62Hz的3.51分之一，从涡带频率看计算结果与试验测量结果一致。     

转桨式水轮机转轮叶片操作力的数值计算

本文对现行转桨式水轮机转轮叶片操作力的计算方法进行了评价，针对其计算方法存在的不足，在此基础上提出了一个计算转桨式水轮机转轮叶片操作力的新方法，用有限单元离叶片体系，采用数值与图解法解析，得到了比较合理可靠的操作力以及叶片枢轴非均匀分布的支反力，并结合实例进行具体演算。     

用三维不定常RANS方程求解船尾绕流

本文详细介绍了用雷诺平均的不定常全三维Ｎ－Ｓ方程求解船尾绕流的数值计算方法。在本方法中，不引入任何简化、近似，使用了Ｋ－Ｅ二方程湍流模式进行了控制方程组的封闭。利用壁函数，指数格式、ＳＩＭＰＬＥＣ计算了ＳＳＰＡ－７２０的船尾绕流，详细给出了计算结果，并与其它算法及试验结果作了比较。     

翼型体广谱声的频域预报方法

本文提出了一种广谱声预报的频域方法，并通过与试验数据的比较证明了方法的有效性，尽管文中以平板翼为例，进行了实例计算，但方法本身适用于任意形体在介质中以亚音速作惯性运动时的广谱声预报。相对于时域方法而言，由于省去了将频域数据转化为时域数据的中间过程，因此该方法较时域方法(Casper and Farassat，2002)更为有效。本文的关键在于具有平均流效果的格林函数的成功应用，由此格林函数所表达的积分算式将在后续文中进一步拓展应用于具有非惯性运动的螺旋桨广谱噪声的预报。     

船舶螺旋桨周围粘流场数值预报与流场分析

本文叙述了通过直接求解雷诺平均应力方程（ＲＡＮＳ）来获得船舶螺旋桨粘流场数值解的方法与数值求解步骤，该方法采用非交错网格系统，利用幂函数格式离散动量方程，预报－校正方法求解速度－压力耦合问题，应用Ｂａｌｄｗｉｎ－Ｌｏｍａｘ代数湍流模式求解雷诺应力项使方程组封闭，以此来获得螺旋桨粘流场，为了验证数值方法的稳定性和可靠性，文中以ＤＴＲＣ４１１９桨为算例，对螺旋桨粘流场进行了数值求解，通过对计算结果的分     

The design of propeller and propeller boss cap fins (PBCF) by an integrative method

Generally, after a marine propeller design, the propeller boss cap fins (PBCF) design concerns with an optimal selection of model test results, without a due consideration of the interaction between the PBCF and the propeller. In this paper, the PBCF and the propeller are considered as a whole system with their design as an integrative process, in which the concept of the increased loading in the blade root is incorporated. The load distribution on the blade becomes well-proportioned due to the increased loading in the blade root, and it is advantageous to the reduction of the vibratory force and the blade tip vortex. The blade root area is stronger in withstanding forces, and is not easy to be vibrated, therefore, the increased loading there is beneficial to the noise reduction. The disadvantage of the increased loading in the blade root is the generation of the hub vortex behind the boss cap, but the hub vortex can be broken up by the energy saving hydrodynamic mechanism of the PBCF. The integrative design method introduced in this paper can provide a higher efficiency for propellers under the same design conditions. In this paper, an integrative propeller and PBCF design method including the theoretical design and the numerical optimization design is proposed, based on the potential flow theory, the CFD tools, the improved particle swarm optimization algorithm, and the model tests. A propeller with the PBCF is designed based on the method of integrated increased loading in the blade root for a cargo vessel in this paper. The cavitation tunnel model test results show that the propeller and the PBCF thus designed enjoys a higher efficiency, and the design method is effective, reliable and practical.     

BROADBAND ROTOR NOISE PREDICTION BASED ON A NEW FREQUENCY-DOMAIN FOUMULATION

This article studies the broadband noise of a rotor in upstream turbulence. A numerical approach is proposed, based on frequency domain, for predicting rotor broadband noise which requires the aerodynamic sources to be integrated over the actual blade surface rather than over the mean-chord surface. The prediction of the radiated rotor broadband noise due to turbulence is made. This method is validated through a comparison between numerical predictions and measured data, with a reasonable agreement. Noise level directivity shows that the main lobe is located along the rotor axis, while the minimum noise occurs in the direction vertical to the rotor axis.     

NUMERICAL ANALYSIS FOR CIRCULATION DISTRIBUTION OF PROPELLER BLADE

A process for numerical analysis of radial circulation distribution of propeller blade is proposed and presented. It is based on the results of numerical simulation of the velocity field around propeller blades and in the wake. The well-known traditional method using tangential velocity data in the wake and applying Stockes's theorem was also examined in the investigation. The results from two approaches are compared with each other. It is found that if the traditional way is utilized, in many cases an unexpected “hump” appears in the circulation distribution at certain outer radius. The authors calculated the circulations directly around blade sections, and it is referred as direct method. The unexpected hump of the circulation distribution disappears in the results of direct method. This article also discusses the reasons of the appearance of the unexpected hump in traditional approach. The direct method is proposed to have a potential in analyzing or verifying the radial road distribution for designed propeller and the numerical analysis instead of experimental validation for circulation distribution can be as a tool in the propeller design process.     

An integral calculation approach for numerical simulation of cavitating flow around a marine propeller behind the ship hull

In this paper, the unsteady cavitating turbulent flow around a marine propeller is simulated based on the unsteady Reynolds averaged Navier-Stokes(URANS) with emphasis on the hull-propeller interaction by an integral calculation approach, which means the propeller and hull are treated as a whole when the cavitating flow is calculated. The whole calculational domain is split to an inner rotating domain containing a propeller and an outer domain containing a hull. And the two split sections are connected together in ANSYS CFX by using the GGI interfaces and the transient rotor stator frame change/mixing model. The alternate rotation model is employed for the advection term in the momentum equations in order to reduce the numerical error. Comparison of predictions with measurements shows that the propeller thrust coefficient can be predicted satisfactorily. The unsteady cavitating flow around the propeller behind the ship hull wake shows quasi-periodic features including cavity inception, growth and shrinking. These features are effectively reproduced in the simulations which compare well to available experimental data. In addition, significant pressure fluctuations on the ship hull surface induced by the unsteady propeller cavitation are compared with experimental data at monitoring points on the hull surface. The predicted amplitudes of the first components corresponding to the first blade passing frequencies match well with the experimental data. The maximum error between the predictions and the experimental data for the pressure pulsations is around 8%, which is acceptable in most engineering applications.     

NUMERICAL PREDICTION OF BLADE FREQUENCY NOISE OF CAVITA- TING PROPELLER

The blade frequency noise of a cavitating propeller in a uniform flow is analyzed in the time domain. The unsteady loading (of a dipole source) and the sheet cavity volume (of a monopole source) on the propeller surface are calculated by a potential-based surface panel method. Then the time-dependent pressure and the cavity volume data are used as the input for the Fowcs Williams-Hawkings formulation to predict the acoustics pressure. The integration of the noise source is performed over the true blade surface rather than the ideal blade surface without thickness. The noise characteristics of the cavitating propeller are discussed. With the sheet cavitation, the thickness (cavitation) noise is larger than the loading noise and is the dominant noise source.The noise directivity is not as clear as that of the noise under a non-cavitation condition. The cavitation noise is attenuated mores lowly than the non-cavitation noise.     

基于CFD方法的船/桨/舵干扰数值模拟

船/桨/舵相互干扰研究在传统船型优化设计和新船型的开发中具有重要意义。应用计算流体力学(CFD)方法对带桨的KCS集装箱船及带桨和舵的KVLCC2油船非稳态粘流场进行了数值模拟,其中船桨舵干扰计算分别采用动量源法、MRF法和滑移网格法,分析研究了各方法及其结果的异同。研究表明不同模拟计算方法均能合理预报出船/桨/舵相互干扰相互作用下速度场和压力场分布等详细流场信息,可用于计算船体阻力、表面压力和桨盘面伴流等。通过这种详细的数值模拟研究,可以更好地理解复杂流动干扰现象。     

带自由液面的艇/桨干扰特性数值模拟与验证研究

带自由液面的艇/桨干扰特性研究是水动力学领域的重点与难点.此文采用数值模拟方法研究了潜艇近水面航行时的艇/桨干扰特性.首先介绍了计算方法:流场采用RANS方法结合RNGk -ε湍流模型求解;自由液面捕捉采用VOF方法;螺旋桨运转采用滑移网格方法;带螺旋桨潜艇表面与计算域内全部采用结构化网格进行离散.然后,对于SUBOFF潜艇模型在不同浸深下的阻力特性进行了数值模拟,分析了自由液面对于模型阻力的定量影响.最后,对于带螺旋桨的SUBOFF潜艇模型在深潜与近水面状态下的艇后推力、扭矩进行了数值模拟,分析了自航因子,研究了艇/桨干扰特性.计算结果与试验结果进行了详细的对比分析,验证了计算方法与计算结果的可靠性.本文的工作可为将来构建数值拖曳水池提供技术支撑.