Increasing the Life of Marine Turbines by Design and Innovation

潮汐涡轮机上的不稳定负载比风力涡轮机大得多，因为在近海海洋环境中水的密度高且不稳定程度高。此外，通常用于支撑船用涡轮机的焊接低碳钢结构在盐水中的疲劳寿命较低。这可能导致30个月或更短的寿命，而不是30年的设计要求。此外，疲劳寿命限制了潮汐涡轮机可以部署的位置的数量，从而限制了英国的整体实际潮汐资源。本项目旨在开发创新技术，以减少因流动不稳定而产生的不稳定载荷，从而将船用涡轮机的寿命提高一个数量级。第一种采用英国开发的创新液压传动系统，以减少大长度不稳定“阵风”（尺寸大于机器直径）产生的不稳定载荷。液压传动系统使涡轮机的速度能够快速响应“阵风”，确保机器上的负载保持恒定。第二项创新技术旨在减少短长度不稳定“阵风”产生的不稳定载荷，这些阵风小于机器直径。该技术类似于飞机上使用的技术，用于阻止机翼受到空气“阵风”的冲击时飞机升力的突然变化。该技术在机翼上使用“扰流器”、“流体喷射”或“襟翼”，以在“阵风”经过时自动保持叶片升力恒定。该技术将用于潮汐涡轮机叶片，以减少由于短尺度非定常“阵风”而产生的非定常载荷。第二种技术一旦开发出来，也可用作变桨距机构的替代方案，以避免超过峰值载荷。该项目的方法将是使用喷气发动机行业开发的实验测试和计算模型，以了解海洋环境中的不稳定性如何导致不稳定的涡轮机载荷。描述涡轮机对非定常流响应的简化模型将在英国多家潮汐涡轮机公司的潮汐涡轮机设计规范中实施。这将提高英国潮汐涡轮机工业预测气流非定常效应的能力。试验和计算将用于开发新的自动“扰流片”和“襟翼”控制系统，用于控制阵风载荷。该控制系统与创新液压传动系模型一起将在潮汐涡轮机设计规范中实施。这将使成功的非定常负荷减少系统被modeled.Current公布的测量海洋湍流的空间和时间分辨率都是有限的。重要的是，这项研究，改善测量获得。项目成员将与参与该项目的潮汐涡轮机公司以及Supergen合作伙伴合作，以提高可用测量的分辨率。已开发出一种使用传统声学多普勒设备的新方法，如有必要，将在项目中使用该方法，以提高测量分辨率。最后，非定常减载系统和液压传动系统将被纳入潮汐涡轮机的比例模型中，并将在水槽中进行测试。试验将在具有海洋环境流动不稳定特性的情况下进行。这些测试将决定该项目是否成功地实现了非定常减载。减载系统在全尺寸潮汐涡轮机上的成功应用将在延长维护周期和增加使用寿命方面提供好处。此外，随着涡轮机对环境运行条件的敏感性降低，大量潮汐发电站将成为可行的发电站，从而增加英国的潮汐资源。

Unsteady loads on tidal turbines are much larger than in wind turbines because of the high density of water and the high levels of unsteadiness in offshore marine environments. In addition the welded mild steel structures normally used to support marine turbines have a low fatigue life in salt water. This can lead to life of 30 months or less instead of the design requirement of 30 years. In addition fatigue life limits the number of locations where tidal turbine can be deployed, limiting the overall practical UK tidal resource. This project aims to develop innovative technologies which will reduce the unsteady loads which result from flow unsteadiness and thus increase the longevity of a marine turbine by an order of magnitude.Two technologies will be developed. The first uses innovative hydraulic drive trains, developed in the UK, to reduce the unsteady loads created by large length unsteady 'gusts', those larger in size than the machine diameter. The hydraulic drive train allows the speed of the turbine to respond quickly to the 'gust' ensuring that the load on the machine remains constant. The second innovative technology is designed to reduce the unsteady loads created by short length unsteady 'gusts', those smaller than the machine diameter. The technology is similar to that used in aircraft to stop sudden changes in aircraft lift as the wing is hit by an air 'gust'. The technology uses 'spoilers', 'fluid ejection' or 'flaps' on the wing to automatically hold the blade lift constant as the 'gust' moves over it. This technology will be employed on tidal turbine blades to reduce unsteady loading due to short length scale unsteady 'gusts'. Once developed this second technology could also be used as an alternative to variable pitch mechanisms to avoid peak loads being exceeded.The project approach will be to use experimental testing and computational modelling developed in the jet engine industry to understand how the unsteadiness in marine environment resulted in unsteady turbine loading. A simplified model describing the turbine response to unsteady flow will then be implemented in the tidal turbine design code of a number of UK tidal turbine companies. This will improve the UK tidal turbine industries capability to predict the effect of flow unsteadiness.Experiments and computation will be used to develop the new automated 'spoiler' and 'flap' control system for gust loading control. This control system in conjunction with a model for the innovative hydraulic drive train will be implemented in the tidal turbine design codes. This will allow the success of the unsteady load reduction systems to be modelled.Current published measurements of sea turbulence are limited in both their spatial and temporal resolution. It is important to this study that improved measurements are obtained. The project members will work in collaboration with the tidal turbines companies partnered in this project, and with the Supergen partners, to improve the resolution of the available measurements. A new method of using conventional acoustic doppler equipment has been developed and if necessary this will be used in the project to achieve improved measurement resolution.Finally the unsteady load reduction systems and the hydraulic drive train will be incorporated into a scale model of the tidal turbine and this will be tested in a water flume. The tests will be undertaken with flow unsteadiness characteristic of the marine environment. These tests will determine the project's success in achieving an unsteady load reduction.Successful application of the load reduction systems to full scale tidal turbines will provide benefits in terms of extended maintenance periods and increased service life. Furthermore as turbines become less sensitive to their environmental operating conditions a larger number of tidal sites will become available as viable for producing power thereby increasing the UK tidal resource.