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施智标 《上海海运学院学报》1995,16(3):36-41
就我国海船通信天线的实船测试情况作了综述。重点介绍了海船发信天线的选择、安装布局、测试的项目和方法,以及提高天线效益的实船测试研究;强调了实测试的重要意义。实船的方法和科学结论,对于海船天线的设计、研制和安装布局都具有重要的参考价值。 相似文献
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本文对六七十年代以来国内外螺旋浆脉动压力实船测试的研究作了一个简要的回顾。内容涉及到历年来螺旋浆脉动压力的实船测试和空泡观察,实船测试的要求和方法,并对今后螺旋浆脉动压力实船测试研究的发展方向提出了一些看法。 相似文献
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论文针对自主研发的长江船舶远程电子签证系统,分别通过总体流程、硬件功能模块和软件架构三方面阐述了系统基本设计思想。然后利用软件模拟平台和实船运行测试对系统性能和功能进行了检验。 相似文献
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对小艇主要量度的选择、型线的设计、设备选择、减振降噪的措施以及实船测试情况作了介绍。该艇应用圆舭艇理论 ,结合国内设计圆舭艇的一些成功经验进行设计。 相似文献
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舰艇螺旋桨水下噪声预测 总被引:5,自引:0,他引:5
螺旋桨空化噪声是舰艇最主要的辐射噪声源。文章分析了螺旋桨噪声平坡形谱曲线的特点,给出源声级谱级曲线的衰减指数值,分析了特征频率和峰值谱级的影响因素。由螺旋桨空化状态下两个特征航速对应的部分频段内的噪声谱级计算式拟合得到水面舰船螺旋桨空化后任意可达航速下的噪声谱曲线。结合叶梢周向速度一定时特征频率处谱级与螺旋桨直径的函数关系和频率一定时叶梢周向速度变化引起的特征频率处谱级变化量,得到潜艇螺旋桨无空化状态下特征频率处谱级,在空化状态下,还需要加上螺旋桨进入尖锐谱峰区和转速进一步升高引起的声级增加量,从而得到了潜艇在任意航态下整个频带内螺旋桨噪声谱级的计算式。利用已有数据对计算式进行了检验,计算声级误差小于4dB。计算中用到的叶梢初生空泡数和判定是否出现窄带调噪声要通过空泡筒试验确定。 相似文献
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《船舶与海洋工程学报》2020,(1)
Despite their high manufacturing cost and structural deficiencies especially in tip regions, highly skewed propellers are preferred in the marine industry, where underwater noise is a significant design criterion. However, hydrodynamic performances should also be considered before a decision to use these propellers is made. This study investigates the trade-off between hydrodynamic and hydroacoustic performances by comparing conventional and highly skewed Seiun Maru marine propellers for a noncavitating case.Many papers in the literature focus solely on hydroacoustic calculations for the open-water case. However, propulsive characteristics are significantly different when propeller-hull interactions take place. Changes in propulsion performance also reflect on the hydroacoustic performances of the propeller. In this study, propeller-hull interactions were considered to calculate the noise spectra.Rather than solving the full case, which is computationally demanding, an indirect approach was adopted; axial velocities from the nominal ship wake were introduced as the inlet condition of the numerical approach. A hybrid method based on the acoustic analogy was used in coupling computational fluid dynamics techniques with acoustic propagation methods, implementing the Ffowcs Williams-Hawkings(FW-H) equation. The hydrodynamic performances of both propellers were presented as a preliminary study.Propeller-hull interactions were included in calculations after observing good accordance between our results, experiments, and quasi-continuous method for the open-water case. With the use of the time-dependent flow field data of the propeller behind a nonuniform ship wake as an input, simulation results were used to solve the FW-H equation to extract acoustic pressure and sound pressure levels for several hydrophones located in the near field. Noise spectra results confirm that the highest values of the sound pressure levels are in the low-frequency range and the first harmonics calculated by the present method are in good accordance with the theoretical values. Results also show that a highly skewed propeller generates less noise even in noncavitating cases despite a small reduction in hydrodynamic efficiency. 相似文献
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SU Yu-min HUANG ShengCollege of Shipbuilding Engineering Harbin Engineering University Harbin China 《船舶与海洋工程学报》2002,1(1):9-15
The potential based low order surface panel method is used to predict the hydrodynamic performance of marine propellers. In present method the hyperboloidal quadrilateral panels are employed to avoid the gap between the panels. The influencecoefficients of panels are calculated by Morino's analytical formulations for increasing numerically calculating speed.The pres-sure Kutta condition is satisfied on the trailing edge of propeller blade by Newton-Raphson iterative procedure.Therefore the 相似文献
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Numerical Calculation
of Marine Propeller Hydrodynamic Characteristics in Unsteady Flow by Boundary Element
Method 总被引:2,自引:0,他引:2
In this paper, a low-order potential based on surface panel method is used for the analysis of marine propellers in unsteady flow.A linear propeller wake model is employed and its geometry is assumed to be independent of the time.The calculation in time domain is carried out from a moment when the rotation of the propeller becomes steady instead of from the moment when the rotation strats from stationary condition.At every time step a linear algebraic equation established on a key blade is solved numerically combined with the Kutta pressure conditon.The calculated results by developed code indicate good convergency and effrctiveness of present algotithm for conventional propellers and highly skewed propellers. 相似文献
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论述主柴油机螺旋桨(FPP、CPP)推进特性的同时,结合螺旋桨推力系数(KP)、扭矩系数(Km)、随螺旋桨进程比,(λp)的变化情况,指出λp在大于某一定值后,螺旋桨将出现负推力和负转矩,这称为螺旋桨的水涡轮工况。此现象多发生在船舶机动作业的紧急换向工况中,对于CPP船若控制不慎,可能引发主机飞车或使船舶实际换向时间太长,两者都将延误船舶紧急避碰时机。现推荐一种"能耗法"的控制方法,可以有效地缩短船舶紧急换向实际时间,避免海难事故,保障航行安全。 相似文献
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船用螺旋桨工作在低速重负荷工况、或采用大侧斜几何型式或采用复合材料时,其流固耦合现象较为突出,螺旋桨设计中若无法准确考虑其间的水弹性影响,将会造成船机桨失配及实船推进性能的错误预报。文章基于螺旋桨环流理论设计方法、螺旋桨流固耦合算法以及逐步逼近法,形成了一套可考虑水弹性影响的螺旋桨设计方法,重点讨论了流固耦合中水动力载荷更新方式、逐步逼近法中预变形松弛因子的选择对设计结果的影响。通过大侧斜螺旋桨及复合材料螺旋桨设计实例,进一步阐述了在螺旋桨设计中考虑水弹性的必要性,也验证了所开发设计平台的有效性。该设计平台为后续复合材料螺旋桨的优化设计提供了基础。 相似文献
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Nai-Xian Lu Rickard E. Bensow Göran Bark 《Journal of Marine Science and Technology》2014,19(2):197-214
This paper deals with numerical simulations of the cavitating flow around two highly skewed propellers operating in open water and mounted on an inclined shaft. The aim of the study is to check the ability of our numerical method in distinguishing the variation in flow features resulting from different blade designs. Moreover, a secondary aim is also to improve the knowledge about the physics that control the growth and collapse of cavitation, and hence also the generation of cavitation noise and erosion on this type of propellers. The investigation is based on incompressible large eddy simulation (LES) in combination with a volume-of-fluid implementation to represent the two phases of liquid and vapour, and a transport equation-based method for the mass transfer between the phases. High-speed video recordings from experiments were made available for comparison. The simulations demonstrate that the current method makes it possible to analyse the main difference in flow features caused by modest design alternation. Furthermore, with suitable grid resolution, LES is demonstrated to be capable of capturing the mechanisms that are important in the cavitation development, and that numerical simulation is a reliable supplement to experiments in advanced propeller design. 相似文献
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以造船CAD/CAM为平台,通过对船舶快速设计的需求分析,指出了现有造船CAD/CAM系统的欠缺之处,提出了解决的方法,论述了系统在船舶设计标准化、规范化和处理由设计产生的生产信息方面可实现快速设计,并针对各个可实现快速设计技术的方面,提出用Vitesse语言编制相应的程序以实现这些技术;通过建立标准元件库实现标准化,编制设计规则实现规范化,运用直接的数据抽取方式实现生产信息获取的正确性、实现产品数据管理。 相似文献
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