Innovative Dual-Rotor Wind Turbine (DRWT) Designs for Improved Turbine Performance and Wind Farm Efficiency

主要研究者：惠虎编号：1438099标题：创新的双转子风力涡轮机（DRWT）设计，以提高涡轮机性能和风电场效率机构：爱荷华州州立大学虽然风力涡轮机被广泛用于风能转换为电能，但仍有许多机会在其设计和操作方面进行改进，以提高风能收集的效率，并降低这些改进导致的成本。 需要改进的一个关键领域是涡轮机转子叶片的设计。 公用事业规模的风力涡轮机中的结构、制造和运输约束导致叶片设计在空气动力学上不完美，特别是在连接转子叶片的轮毂附近的根部区域中。根损失估计在单个风力涡轮机的风能提取中造成约5%的损失。 这个问题在包含许多风力涡轮机的风力发电场中更加复杂，其中空气的混合产生尾流。 由下游涡轮机吸入上游涡轮机尾流导致的风力发电场中的尾流损失在风能收集效率的8%至40%之间，这取决于陆上与海岸风力发电场位置、涡轮机布局和大气稳定性条件。 本研究的目的是进行全面的理论和实验研究，探索一种新的双转子风力涡轮机（DRWT）的概念，以减少这些损失，提高涡轮机的性能和风电场的效率。 在该双转子概念中，较小的一组涡轮机叶片定位在较大叶片附近，以利用空气动力学原理来减少根部损失并提高风力涡轮机效率。 这种新型的双转子风力涡轮机配置将在风洞中使用比例模型进行实验研究。 实验研究将通过先进的计算机模拟来补充，以确定双转子系统的最佳设计。 在教育和扩大参与方面，从这些研究工作中开发的课程模块将纳入爱荷华州州立大学（ISU）的本科生和研究生机械和航空航天工程课程。 ISU现有的项目将用于招募来自工程领域代表性不足的群体的学生参与研究项目。项目成果还将用于筹备可再生能源和风力涡轮机技术研讨会和演示，在当地K-12学校进行演示，以提高公众对风能最新进展的认识。该项目还将继续与风力涡轮机制造商的现有合作。技术描述公用事业规模风力涡轮机的结构、制造和运输限制导致叶片设计在空气动力学方面存在缺陷，特别是在靠近连接转子叶片的轮毂附近的根部区域。根损失估计在单个风力涡轮机的风能提取中造成约5%的损失。 本研究的目的是进行全面的理论、数值和实验研究，以探索一种新型双转子风力涡轮机（DRWT）概念，以减轻根部损失，提高涡轮机性能和风电场效率。 所提出的DRWT概念将采用较小的二次同轴转子，旨在通过使用空气动力学优化的二次转子来减轻主转子根部区域中产生的损失，并通过涡轮机尾流的快速混合和增加的上层气流夹带来减轻风电场中的尾流损失。实验和数值模拟研究的整合将使第一原则为基础的评估建议DRWT的概念。 数值模拟将首先被用来设计一个气动优化DRWT。 将研究优化后的DRWT在非均匀大气边界层（ABL）气流中运行时的气动性能，包括单个涡轮机和涡轮机阵列。为此，将使用爱荷华州州立大学（ISU）的大尺度空气动力学/大气边界层（AABL）风洞进行实验研究。 除了测量涡轮机功率输出和作用在DRWT模型上的动态风载荷外，高分辨率粒子图像测速（PIV）系统还将测量流场，以表征相对于传统单转子风力涡轮机的涡轮机尾涡系统动态特性。高分辨率的大涡模拟（LES）也将与实验研究协调进行，以阐明基本的流动物理。 关于在教育和宣传方面的广泛影响，项目成果还将用于筹备关于可再生能源和风力涡轮机技术的研讨会和演示，在当地K-12学校进行演示，以提高公众对风能最新进展的认识。该项目还将继续与风力涡轮机制造商的现有合作。

Principal Investigator: Hui HuNumber: 1438099Title: Innovative Dual-Rotor Wind Turbine (DRWT) Designs for Improved Turbine Performance and Wind Farm EfficiencyInstitution: Iowa State University Although wind turbines are widely used for conversion of wind energy to electrical power, there are still many opportunities for improvements in their design and operation to increase the efficiency of wind energy harvesting, and the reduction in cost that results from these improvements. A key area for improvement is the design of the turbine rotor blade. Structural, manufacturing, and transportation constraints in utility-scale wind turbines lead to aerodynamically imperfect blade designs, especially in the root region near the hub joining the rotor blade. Root loss is estimated to cause about 5% loss in wind energy extraction for a single wind turbine. This problem is compounded in wind farms containing many wind turbines, where mixing of air creates a wake. Wake losses in wind farms resulting from the ingestion of upstream turbine wakes by downstream turbines range between 8 to 40% of wind energy harvesting efficiency, depending on onshore vs. off shore wind farm location, turbine layout, and atmospheric stability conditions. The goal of this research is to conduct a comprehensive theoretical and experimental study to explore a novel dual-rotor wind turbine (DRWT) concept to mitigate these losses for improved turbine performance and wind farm efficiency. In this dual-rotor concept, a smaller set of turbine blades is positioned near the larger blades to reduce the root loss and improve wind turbine efficiency using aerodynamic principles. This novel dual-rotor wind turbine configuration will be studied experimentally using scale models in a wind tunnel. Experimental studies will be complimented by advanced computer simulations to identify the best design for the dual rotor system. With respect to education and broadening participation, course modules developed from these research efforts will be incorporated into the undergraduate and graduate mechanical and aerospace engineering courses at Iowa State University (ISU). Existing programs at ISU will be used to recruit students from under-represented groups in engineering for participation in the research project. The project results will also be used to prepare seminars and demonstrations on Renewable Energy and Wind Turbine Technology for presentation at local K-12 schools to increase public awareness about recent advances in wind energy. The project will also continue existing collaborations with wind turbine manufacturers.Technical Description Structural, manufacturing, and transportation constraints in utility-scale wind turbines lead to aerodynamically imperfect blade designs, especially in the root region near the hub joining the rotor blade. Root loss is estimated to cause about 5% loss in wind energy extraction for a single wind turbine. The goal of this research is to conduct a comprehensive theoretical, numerical, and experimental study to explore a novel dual-rotor wind turbine (DRWT) concept to mitigate root losses for improved turbine performance and wind farm efficiency. The proposed DRWT concept will employ a secondary, smaller, co-axial rotor that is intended to mitigate losses incurred in the root region of the main rotor by using an aerodynamically optimized secondary rotor, and also mitigate wake losses in wind farms through rapid mixing of turbine wake and increased upper-layer flow entrainment. The integration of experimental and numerical modeling studies will enable a first-principles based evaluation of the proposed DRWT concept. Numerical simulations will first be used to design an aerodynamically optimum DRWT. Aerodynamic performance of the optimized DRWT will be investigated for operation of a single turbine and then a turbine array sited in non-homogenous atmospheric boundary layer (ABL) flows. Towards this end, the large-scale Aerodynamic/Atmospheric Boundary Layer (AABL) wind tunnel at Iowa State University (ISU) will be used for the experimental study. In addition to measuring turbine power outputs and dynamic wind loads acting on model DRWTs, a high-resolution Particle Image Velocimetry (PIV) system will measure the flow field to characterize turbine wake-vortex system dynamics relative to conventional single-rotor wind turbines. Highly resolved Large Eddy Simulations (LES) will be also performed in coordination with the experimental study to elucidate the underlying flow physics. With respect to broader impacts in education and outreach, the project results will also be used to prepare seminars and demonstrations on Renewable Energy and Wind Turbine Technology for presentation at local K-12 schools to increase public awareness about recent advances in wind energy. The project will also continue existing collaborations with wind turbine manufacturers.