Experimental Investigation of the Scalability of WindTurbine Aerodynamics

在过去的十年里，用于将风能转化为电能的风力涡轮机叶片的尺寸迅速增长。新设计的风力涡轮机通常使用风洞中的比例模型进行测试，类似于测试新的飞机设计。然而，风洞内风力涡轮机的比例模型的行为通常不能代表实际部署在现场的风力涡轮机的行为，因为与涡轮叶片周围的气流缩放有关的问题对于长涡轮叶片。本研究的目的是开发一种设计风力发电机风洞试验的新方法。这将通过使用一个风洞来完成，风洞使用高度压缩的空气，在超过200倍的大气压力下，按比例缩放相对于叶片旋转的流动惯性的影响，用于缩小模型风力涡轮机。空气动力学模型将用于将其行为还原为在大气压下运行的真实风力涡轮机。这种方法有可能提高风洞数据的可靠性，用于设计新的风力涡轮机，从而改进性能模型和风力涡轮机设计。作为项目活动的一部分，首席研究员将担任德克萨斯科技大学组织的国家风能资源中心暑期研究所计划的导师，并与本科生，高中生和高中教师一起提供风能主题的培训，并从代表性不足的群体中招募学生进行未来的研究生学习。技术描述该项目的总体目标是开发一种新的方法，用于在风洞内缩放风力涡轮机比例模型试验，以代表现场运行的全尺寸风力涡轮机的雷诺数。风力机空气动力学主要由两个无量纲参数控制，即雷诺数和斯特罗哈尔数，也称为叶尖速比。在过去的十年中，风力涡轮机的规模迅速增长，并且已经将其运行转移到更高的雷诺数。为了让风洞试验给出空气动力学的精确表示，雷诺数和斯特罗哈尔数必须同时与全尺寸涡轮机所经历的相匹配。然而，传统风洞中缩小模型的研究只能匹配其中一个参数，而不能同时匹配这两个参数。该项目将研究参数不匹配的影响，并通过开发一种新的实验方法，允许同时匹配这两个参数，为旋转对空气动力学的影响提供新的见解。这将通过一种独特的高压流设备来实现，其中雷诺数和叶尖速比将与现代大型风力涡轮机相匹配。由于工作气压可以很容易地从1到220 atm变化，因此可以测试大范围的雷诺数，并可能为风洞研究的可扩展性提供新的见解。一个微型风力涡轮机将被建造并安装在现有的高雷诺数测试设施中。实验将在完全动态相似的情况下进行，这将解决关于雷诺数和旋转效应如何决定风力涡轮机的空气动力学行为和功率输出的基本问题。作为项目活动的一部分，首席研究员将担任德克萨斯科技大学组织的国家风能资源中心暑期研究所计划的导师，并与本科生，高中生和高中教师一起提供风能主题的培训，并从代表性不足的群体中招募学生进行未来的研究生学习。

Principal Investigator: Marcus HultmarkNumber: 1435254 Nontechnical DescriptionOver the past decade, the size of wind turbine blades used for the conversion of wind energy to electricity has grown rapidly. New designs for wind turbines are often tested using scale models in a wind tunnel, similar to testing of new airplane designs. However, the behavior of scale models of wind turbines within a wind tunnel often does not represent the behavior of actual wind turbines deployed in the field because of issues relating to the scaling of the air flow around the turbine blades for long turbine blades. The goal of this research is develop a new approach for designing wind tunnel tests for wind turbines. This will be accomplished by using a wind tunnel which uses highly compressed air at over 200 times atmospheric pressure to proportionally scale the effects of flow inertia relative to blade rotation for a scaled down model wind turbine. Aerodynamic models will be used to scale the behavior back up to a real wind turbine operating at atmospheric pressure. This approach has the potential to improve the reliability of wind tunnel data for the design of new wind turbines, leading to improved performance models and wind turbine designs. As the part of the project activities, the principal investigator will serve as a mentor for National Wind Resource Center Summer Research Institute Program, organized at TexasTech University, and work with undergraduate students, high school students, and high school teachers to provide training in wind energy topics and recruit students from under-represented groups for future graduate study.Technical DescriptionThe overall goal of this project is to develop a new approach for scaling wind turbine scale model tests within wind tunnels to Reynolds numbers that are representative of full scale wind turbines in field operation. Wind turbine aerodynamics is mainly governed by two dimensionless parameters, the Reynolds number and the Strouhal number, also known as the tip-speed-ratio. Over the past decade, the size of wind turbines has grown rapidly, and has moved their operation to higher Reynolds numbers. In order for wind tunnel tests to give an exact representation of the aerodynamics, both the Reynolds and the Strouhal number must simultaneously be matched to what is experienced by the full scale turbine. However, studies on scaled down models in conventional wind tunnels can only match one of these parameters, and not both simultaneously. This project will investigate the effect of the parametric mismatch and give new insight into the effect of rotation on the aerodynamics by developing a new experimental approach that will allow for simultaneous matching of both parameters. This will be accomplished using a unique high-pressure flow facility where both the Reynolds number and tip-speed-ratio will be matched to a modern large scale wind turbine. Since the working air pressure can easily be changed from 1 to 220 atm, a wide range of Reynolds numbers can be tested, and can potentially provide new insight on scalability of wind tunnel studies. A miniature wind turbine will be built and installed in the existing High Reynolds Number Test Facility. Experiments will be conducted at full dynamic similarity, which will address fundamental questions about how Reynolds number and rotational effects determine the aerodynamic behavior and power output of wind turbines. As the part of the project activities, the principal investigator will serve as a mentor for National Wind Resource Center Summer Research Institute Program, organized at TexasTech University, and work with undergraduate students, high school students, and high school teachers to provide training in wind energy topics and recruit students from under-represented groups for future graduate study.