Design of Wave and Current Generators for Stable Wave Generation in Multidirectional Combined Wave Current tanks

在实验室储罐中产生波浪已经成为支持海上系统设计的模型测试的一个重要方面，包括与本提案直接相关的海洋能源装置。世界上大多数重要的造波设备都是基于力反馈控制的能量吸收造波器。这些原理是在爱丁堡大学的Stephen Salter的领导下，在20世纪70年代首创的，随后在1977年用于多向和多频率的爱丁堡宽波槽的建设，以及它的继任者，弯曲波槽。现在人们认识到，波浪能系统的设计需要了解潮流的影响，潮流系统的运行必须考虑到波浪作用的影响。自然波场是多向的，自20世纪70年代末以来已经有了大规模复制自然波场的设施。然而，现有的波/流组合设备只有非常有限的定向电流能力，通常是以波场再现为代价的。为了进行严格的测试，需要同时控制多向波场和变方向电流，包括控制它们的深度剖面。此外，大多数现有的波/流系统，其流动可以平行于主波发生轴产生，依靠上升流来实现其电流的形成。人们认为，这种方法不能准确地复制浅水速度曲线，适用于波浪和潮汐能量应用，特别是因为上涌水流和造波器之间的力的性质可能导致不可靠的性能，因为大多数现代波浪产生系统中使用的力反馈会受到干扰。精确再现随机多向海洋和独立可指定的洋流特征将需要新一代波浪/洋流组合生成系统。这些仪器应该能够在有洋流的情况下精确地再现具有预先定义的光谱形式的海洋。该团队将建立可靠的原则来指导波浪和电流组合发生器的设计，这些发生器可以整合到实验室设施中，能够产生与精确重现的电流模式一致的预定义多向波场。这将通过制定严格的研究计划来实现，为开发下一代波浪/电流发生器提供必要的科学和工程原理。这些必须能够包含在阵列中，以允许生成具有预定义三维光谱的海洋。该方案将涉及发展多向造波器的数值模型，其中可以包括电流。预计数值分析将基于切割单元方法，该方法适用于具有可变几何形状和动态自由表面的问题。这些模型将在现有的二维水槽的实验测试方案中进行评估，目前的发电能力将在该水槽中得到扩展，随后在爱丁堡弯曲波浪槽中进行评估。比较过程将涉及一个重要的测试程序，涉及最先进的基于PIV的流量测量技术。这些模型一旦建立和评估，将用于指导优化的波浪电流发生器和相关控制系统的开发、设计和建造。这将随后在试验水槽和弯曲水槽中进行实验评估。此外，该团队还将提出方案，指导其他研究人员确定最合适的方法，用于他们自己的波/电流模拟应用，以及随后设计和建造他们的波/电流实验室系统。

The generation of waves in laboratory tanks has become a vital aspect of model testing in support of the design of offshore systems including, and of direct relevance to this proposal, marine energy devices. Most serious wave-making equipment world-wide is based upon force feedback control energy absorption wavemakers. The principles of these were pioneered at the University of Edinburgh, under the leadership of Stephen Salter, in the 1970s and subsequently used in the construction of the multidirectional and multifrequency capable Edinburgh Wide Wave Tank in 1977 and its successor, the Curved Wave Tank. It is now appreciated that the design of wave energy systems requires an understanding of the influence of currents and that the operation of tidal current systems must take account of the influence of wave action. Natural wave fields are multidirectional and facilities for their scale replication have existed since the late 1970s. Existing combined wave/current facilities, however, have only very limited directional current capabilities, generally at the expense of wave field reproduction. For rigorous testing, it is necessary to simultaneously control multidirectional wave fields and variable direction currents, including control of their depth profiles. In addition, most existing wave/current systems, in which flow can be generated parallel to the principal wave generation axis, rely on upwelling to achieve their current formation. It is not believed that this approach can accurately replicate shallow water speed profiles, appropriate for wave and tidal current energy applications, especially since the nature of the forces between upwelled water currents and wavemakers can result in unreliable performance, due to interference with the force feedback used in most modern wave generation systems. Accurate reproduction of stochastic multidirectional seas and independently specifiable current characteristics will require a new generation of combined wave/current generation systems. These should have the capability of accurately reproducing seas with pre-defined spectral forms in the presence of currents. The team will establish robust principles to guide the design of combined wave and current generators, which can be incorporated into laboratory facilities capable of generating predefined multidirectional wave fields coincident with accurately reproduced current patterns. This will be achieved by developing, through a rigorous research programme, the scientific and engineering principles necessary for the development of next generation wave/current generators. These must be capable of inclusion within arrays to allow the generation of seas with predefined three dimensional spectra. The programme will involve the development of numerical models of multidirectional wavemakers, into which current can be included. It is anticipated that the numerical analysis will be based on the cut-cell approach, which lends itself well to problems with variable geometries and a dynamic free surface. These models will be evaluated in a programme of experimental tests in an existing two dimensional flume, in which the current generation capability will be extended, and subsequently in the Edinburgh curved wave tank. The comparison procedure will involve a significant test programme involving state of the art PIV based flow measurement techniques. The models, once established and evaluated will be used to guide the development, design and construction of an optimised wave-current generator and associated control systems. This will be subsequently evaluated experimentally in the test flume and curved tank.The team will, in addition, present protocols to guide other researchers in the identification of the most appropriate methods for their own wave/current simulation applications and in the subsequent design and construction of their wave/current laboratory systems.