共查询到18条相似文献,搜索用时 171 毫秒
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提出一种具有后弯管和直通管2种工作模式的新型振荡水柱装置,并通过水槽实验来探讨做功方式、波周期、波高及质量等因素对该装置从波浪能到气动能量转换的影响。水槽实验表明,当模型工作在后弯管模式下,气室中气流双向做功时,规则波中的俘获宽度比(CWR)最高可达138.6%,随机波中的CWR最高可达94%;气流单向做功时,规则波中CWR最高可达113.7%,随机波中CWR最高可达81.9%。当模型工作在直通管模式下,气流双向做功时,规则波中CWR最高可达81.1%,随机波中CWR最高可达66.2%;气流单向做功时,规则波中CWR最高可达53.9%,随机波中CWR最高可达42.1%。模型在随机波实验中后弯管、直通管工作模式的CWR峰值分别能达到“巨鲸号”的3倍、2倍,显然模型的后弯管工作模式具有更高的能量转换特性。 相似文献
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为降低五边形后弯管装置的吃水深度,在保证弯管横截面积不变的条件下对已有的五边形后弯管模型进行改进,使其五边形底部呈扁平状、迎浪面变宽。在造波水槽中对扁平五边形后弯管模型进行规则波和随机波下的初级能量转换效率试验研究,探究不同质量和不同锚泊点下模型的能量转换特性。试验结果表明,在入射波波高0.1 m、周期1.15 s的规则波下,模型最高输出气动功率和俘获宽度比分别为8.551 W和98.59%,JONSWAP谱下模型的俘获宽度比最高达58.45%,优于历史文献值52%。规则波和随机波下扁平后弯管技术均具有较高的初级能量转换特性。 相似文献
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为提高后弯管(BBDB)波浪能的转换效率,对基于新理念和经验研制的前方后三角浮力舱五边形后弯管模型在造波水槽中进行一级能量转换实验研究。共考虑约束方式、喷嘴比、链长、吃水深度、模型浮态等因素,设置23种实验工况进行对比。实验中测量入射波高、波周期、气室液位和气室内外气压差。实验结果得到,该模型俘获宽度比最高值为121.34%,远优于同样实验条件下前方后圆后弯管模型79.1%的历史文献最高值;并且具有较宽的响应周期,为后弯管在随机波条件下实现高效转换创造条件;在BBDB模型正向波作用自由漂荡运动中,测得最大俘获宽度比为94.73%。模型实验结果与高效空气透平机组的结合,为波浪能的高效、低成本利用提供可能。 相似文献
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提出基于Wells透平平面叶栅CFD数据的设计方法,使用CFD方法得到不同NACA翼型在不同叶栅稠度下的压力系数曲线、效率曲线,并使用这些CFD数据设计一个新的叶轮。实验结果表明:在稳定流动下,当前用于微型导航,用波浪能发电装置叶轮的最高转换效率约为46.61%,而该文设计叶轮的最高转换效率为50.50%;在规则波流动下,当前使用的叶轮的最高转换效率约为41.14%,而该文设计叶轮的最高转换效率为44.66%;当流量系数大于0.067时,该文设计叶轮的转换效率基本上高出当前使用叶轮转换效率10%;此外,该文设计叶轮的高效区的流量系数范围更大,使得新型Wells透平在随机波下有望实现更高的转换效率。 相似文献
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采用特征函数展开和二维格林函数相结合的方法求解底铰等厚度摆式波能转换装置水动力系数及斜向规则波作用下的波浪扰动力矩。二维积分方程中奇异积分项采用复变函数解析法求解,因此同时适用于有限厚度及薄壁底铰摆板的水动力计算。通过与文献及与AQWA软件水动力计算结果的比较,验证程序的正确性。类似于船舶横摇运动,在固有周期附近粘性阻尼对摆式波能转换装置的性能有很大影响。通过在运动方程中添加粘性阻尼项考虑粘性阻尼的作用,并在此基础上给出最佳负载阻尼系数的估算公式,分析波向角和波高对装置最佳转换效率的影响。 相似文献
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90°弯管内二次流(迪恩涡)的数值模拟 总被引:5,自引:0,他引:5
弯管广泛地存在于工业应用的多个领域中,为研究弯管内速度场和压力场的分布,采用CFD技术对不同流态下圆形截面90°弯管内的二次流(迪恩涡)进行了数值模拟。模拟过程采用有限体积法进行空间离散,并利用带旋流修正的k-ε模型进行计算。模拟结果表明:层流状态下沿流动方向截面上的峰值速度和峰值全压变化较小,涡核位于半截面中心;当流体处于过渡区时,流动方向截面上的峰值全压呈递减趋势,峰值速度在0~60°截面上递减,在90°截面上突增,并且涡核开始出现"外扩";完全湍流区时,流动方向截面上的峰值全压显著递减,涡核位置明显"外扩"。 相似文献
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讨论一种结合防波堤的振荡摇摆式波浪能装置的结构和工作原理,并在河海大学河口航道综合试验厅进行物理模型试验。试验以重块和不锈钢板间的摩擦力作为波浪能转换装置的负载阻尼,通过测量不锈钢板两端的拉力及其位移计算波浪能转换输出功率。结果表明,当入射波的周期和浮体的固有周期接近时,浮体的运动接近共振状态,此时波浪能转换平均输出功率和转换效率最高,分别可达0.05 W和17.9%。入射波周期较大时,装置的波浪能转换输出功率较高,但此时其波浪能转换效率低于入射波周期较小时。水深对于浮体的姿态和运动特性起到关键作用,结果表明水深为60 cm时波浪能转换输出功率和转换效率最高。 相似文献
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Performance of OWC wave energy converters: influence of turbine damping and tidal variability
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The performance of oscillating water column (OWC) systems depends on a number of factors in a complex manner. The objective of this work is to analyse the influence of the wave conditions, the damping caused by the turbine and the tidal level on the efficiency of the conversion from wave to pneumatic energy that occurs in the OWC chamber. To achieve this, a comprehensive experimental campaign is carried out, involving in total 387 tests of a model OWC under varying wave conditions (both with regular and irregular waves), damping coefficients and tidal levels. It is found that the damping exerted by the turbine is the factor that most affects the chamber efficiency—even more than the wave conditions. It follows that a proper selection of the turbine is crucial not only to the performance of the turbine itself but also to that of the chamber, which reflects the importance of the turbine–chamber coupling in OWC systems. The next factor in order of importance is the wave period. Finally, we find that the influence of the tidal level, which is examined in this work for the first time, is significant under certain conditions. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
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A floating type pendulum wave energy converter(FPWEC) with a rotary vane pump as the power take-off system was proposed by Watabe et al.in 1998.They showed that this device had high energy conversion efficiency.In the previous research,the authors conducted 2D wave tank tests in regular waves to evaluate the generating efficiency of FPWEC with a power take-off system composed of pulleys,belts and a generator.As a result,the influence of the electrical load on the generating efficiency was shown.Continuously,the load characteristics of FPWEC are pursued experimentally by using the servo motors to change the damping coefficient in this paper.In a later part of this paper,the motions of the model with the servo motors are compared with that of the case with the same power take-off system as the previous research.From the above experiment,it may be concluded that the maximum primary conversion efficiency is achieved as high as 98%at the optimal load. 相似文献
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为研究地震动强度对钢管桩码头结构耗能特性的影响,分析了江苏省某钢管桩码头排架在不同地震峰值加速度下的能量耗散特性,选取与抗震规范加速度反应谱符合程度较好的两条实际地震波和一条人工波作为设计地震动,采用循环荷载作用下的p-y土弹簧模拟桩土相互作用。计算结果表明,在地震动峰值加速度确定的条件下,根据所提方法选择的三条地震波输入结构的总能量大小比较接近;地震作用下,钢管桩码头结构主要耗能形式是阻尼耗能,占比高于80%,滞回耗能占比较小,说明结构损伤程度较低,抗震性能较好;大震情况下损伤主要发生在陆侧第一根桩基,入土深度对桩基滞回耗能分配有较大影响。 相似文献
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Extracting wave energy from seas has been proven to be very difficult although various technologies have been developed since 1970s. Among the proposed technologies, only few of them have been actually progressed to the advanced stages such as sea trials or pre-commercial sea trial and engineering. One critical question may be how we can design an efficient wave energy converter or how the efficiency of a wave energy converter can be improved using optimal and control technologies, because higher energy conversion efficiency for a wave energy converter is always pursued and it mainly decides the cost of the wave energy production.In the first part of the investigation, some conventional optimal and control technologies for improving wave energy conversion are examined in a form of more physical meanings, rather than the purely complex mathematical expressions, in which it is hoped to clarify some confusions in the development and the terminologies of the technologies and to help to understand the physics behind the optimal and control technologies. And as a result of the understanding of the physics and the principles of the optima, a new latching technology is proposed, in which the latching duration is simply calculated from the wave period, rather than that based on future information/prediction, hence the technology could remove one of the technical barriers in implementing latching control technology. From the examples given in the context, this new latching control technology can achieve a phase optimum in regular waves, and hence significantly improve wave energy conversion. Further development on these latching control technologies in irregular waves can be found in the second part of the investigation. 相似文献