The Vertical Distribution and Evolution of Slam Pressure on an Oscillating Wave Surge Converter
The Vertical Distribution and Evolution of Slam Pressure on an Oscillating Wave Surge Converter
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振荡波调压变流器冲击压力的垂直分布及演化
DOI：
10.1115/omae2015-41290
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发表时间：
2015
期刊：
影响因子：
--
通讯作者：
Henry A
中科院分区：
文献类型：
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作者：
Henry A
作用于海上结构物的极端波浪载荷的准确定义对设计工程师来说是一个重大挑战，即使有几十年的经验数据来设计，仍然存在归因于波浪载荷的故障。导致这些负载的环境条件并不常见且高度非线性，这意味着它们尚未得到很好的理解或描述。如果结构大到足以显著影响入射波，则进一步的非线性效应可影响载荷。此外，如果结构是浮动的，并受到波场的激励，那么其响应也可能是高度非线性的，必须包括在分析中。这使得这种结构上的载荷的描述难以确定，并且设计规范通常建议采用各种工具，包括小尺度实验、数值和分析方法，以及经验数据（如果可用）。波浪能转换器（WECs）是一类新的海洋结构物，其提出了新的设计挑战，缺乏在其他行业中发现的设计规范和经验数据。这些机器位于高度暴露和充满活力的场所，旨在受到波浪的激发，预计将在25年的设计寿命内承受极端条件。一个这样的WEC正在由海蓝宝石电力有限公司开发，被称为牡蛎。牡蛎是一种浮力襟翼，靠近海床铰接，水深10至15米，刺穿水面。在波浪的作用下，襟翼被来回驱动，机械能被转化为电能。在以前的实验中，Oyster不仅会受到波浪的冲击，而且偶尔会以很高的角速度撞击水面。这种砰击效应已被确定为一个极端的负载情况下，正在进行的工作来描述它在施加在外蒙皮上的压力，并通过结构的各个部分的这种短时间的脉冲载荷的转移。本文介绍了一系列的第40次规模的实验进行调查的压力在面对的皮瓣在砰击事件。压力传感器的垂直阵列用于测量施加在襟翼上的压力。揭示了冲击压力的上升时间、大小、空间分布和时间演变等特征。这种砰击现象与经典的入水问题，如船舶船体砰击之间的相似之处。利用这种相似性，利用常用的分析工具预测了冲击压力，并与实验测得的冲击压力进行了比较。
The accurate definition of the extreme wave loads which act on offshore structures represents a significant challenge for design engineers and even with decades of empirical data to base designs upon there are still failures attributed to wave loading. The environmental conditions which cause these loads are infrequent and highly non-linear which means that they are not well understood or simple to describe. If the structure is large enough to affect the incident wave significantly further non-linear effects can influence the loading. Moreover if the structure is floating and excited by the wave field then its responses, which are also likely to be highly non-linear, must be included in the analysis. This makes the description of the loading on such a structure difficult to determine and the design codes will often suggest employing various tools including small scale experiments, numerical and analytical methods, as well as empirical data if available.Wave Energy Converters (WECs) are a new class of offshore structure which pose new design challenges, lacking the design codes and empirical data found in other industries. These machines are located in highly exposed and energetic sites, designed to be excited by the waves and will be expected to withstand extreme conditions over their 25 year design life. One such WEC is being developed by Aquamarine Power Ltd and is called Oyster. Oyster is a buoyant flap which is hinged close to the seabed, in water depths of 10 to 15m, piercing the water surface. The flap is driven back and forth by the action of the waves and this mechanical energy is then converted to electricity.It has been identified in previous experiments that Oyster is not only subject to wave impacts but it occasionally slams into the water surface with high angular velocity. This slamming effect has been identified as an extreme load case and work is ongoing to describe it in terms of the pressure exerted on the outer skin and the transfer of this short duration impulsive load through various parts of the structure.This paper describes a series of 40th scale experiments undertaken to investigate the pressure on the face of the flap during the slamming event. A vertical array of pressure sensors is used to measure the pressure exerted on the flap. Characteristics of the slam pressure such as the rise time, magnitude, spatial distribution and temporal evolution are revealed. Similarities are drawn between this slamming phenomenon and the classical water entry problems, such as ship hull slamming. With this similitude identified, common analytical tools are used to predict the slam pressure which is compared to that measured in the experiment.