基于极小攻角区域流场重构的升力型立轴风轮气动特性改善机理研究

The aerodynamic parameters of the blade of the lift-type Vertical Axis Wind Turbine (VAWT) vary with the azimuth angles in a big extent. The regions close to the 90 ° and the 270 ° azimuth are the two azimuth zones characterized with the poorest performance, which greatly drop the total performance of VAWT, because their attack angles are minimal, lift forces are minimal, the torques are negative. So far no good way are able to solve this problem. This project put forward a new mind that interference airflows are used to rebuild fluid field across the blade in the two azimuth zones, to promote the aerodynamic characteristics of blade, further to improve the overall performance of turbine; and a new technology that a aerofoil type guidance vane, which are able to guide airflow using two surfaces, is used to create interference airflow. Looked a straight-bladed VAWT as the research object, the Detached Eddy Simulation (DES) and PIV flow test method will be used to reveal the principle of rebuilding of fluid field across the blade in the two zones. The Free Vortex Wake Method (FVWM) modified by B-L dynamic stall model and moment experiment will be used to analysis the mechanism of structure development of aerodynamic loading of the blade. The DES and the modified FVWM will be used to investigate the variation of stall characteristic and its effect on the aerodynamic loading. The research objective is to get information of the improvement mechanism of aerodynamic characteristics in the new method. The research results are also expected to provide a new mind for the improvement performance of vertical axis water turbine, and to develop the lift-type turbine.

升力型立轴风轮的叶片气动特性参数随方位角上下波动。90°和270°方位角区域，攻角极小、升力极小、力矩为负值、叶片气动性能差，影响风轮性能，到目前为止还没有很好的办法来解决此问题。本项目提出采用干扰流体来重构上述两区域叶片周围流场，改善叶片气动特性，谋求提高风轮整体性能的新思路；和采用双面可导流的翼型式导流片来生成干扰气流的技术方案。以直叶片风轮为研究对象，采用脱体涡模拟和PIV流场试验，揭示干扰气流影响下两区域叶片周围流场的重构机理；采用经B-L动态失速模型修正的自由涡尾迹法和力矩试验，剖析叶片新涡系和导流片涡系影响下的叶片气动载荷构造形成机理；采用脱体涡模拟和自由涡尾迹法修正模型，揭示流场重构后叶片的动态失速特性变化及其对气动载荷影响规律。研究旨在深入认知流场重构方法的性能改善机理，成果有望为升力型立轴式水轮机的性能改善提供新思路，推动升力型立轴叶轮的发展。

升力型立轴风轮的叶片气动特性参数随方位角上下波动。0°和180°方位角区域，攻角极小、升力极小、力矩为负值、叶片气动性能差，影响风轮性能。本项目提出采用干扰流体来重构上述两区域叶片周围流场，进而改善叶片气动特性。建立了考虑干扰气流影响的双盘面多流管模型，分析了干扰气流在0°和180°两方位角对风力机叶片气动特性的影响规律。研究得出：在扰流作用下，扰流域内叶素气动攻角明显增大，攻角的增幅在0˚≤θ≤15˚及345˚<θ≤360˚引流范围内，随着方位角的增加而增加；在175˚≤θ≤185˚范围内，随方位角的增加而减小。相同引流范围内，攻角的增幅随着尖速比的增大而减小；叶素的切向力系数和转矩在引流范围内都有提高，但增幅在0˚≤θ≤15˚扰流范围内较大，345˚<θ≤360˚次之，175˚≤θ≤185˚范围内增幅最小；扰流对0˚方位角周围性能的改善效果比180˚方位角的好。利用在一定攻角范围内翼型平面绕流为附着流动的特征，建立了翼型式导流叶片，并利用涡流发生器对流动控制的原理，来加大翼型式导流叶片的失速迎角，然后对该导流叶片的气动特性进行了研究。采用DES模拟方法，对加导流叶片的升力型立轴风力机的湍流场进行了研究，深析了加导流叶片后两极小功角区域叶片周围流场的变化规律，揭示流场重构的机理；在低速风洞，采用PIV对加导流片的直叶片立轴风力机的局部流场进行了可视化测试，从试验角度来验证DES模型模拟效果。采用自由涡尾迹方法，从涡诱导作用原理，来分析了导流片涡系对风力机叶片整体性能的影响规律，揭示风力机叶片气动载荷结构。通过研究，本课题为传统升力型立轴风力机的性能改善提供了一种新的思路，也提供了改善方法。此课题的方法，不但可以应用于直叶片垂直轴风力机，也可以应用于φ型垂直轴风力机，具有广阔的应用前景。

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