复合材料风机叶片气动计算与结构设计分析

发布时间：2019-03-12 13:23

【摘要】：本文所采用的风机叶片材料是玻璃纤维增强环氧树脂基复合材料,以一种额定输出功率为20KW的风力发电机为研究基础,对该叶片进行了气动外形设计与气动性能分析,并通过建立有限元模型和压力耦合对叶片进行了结构设计分析。具体研究内容如下:运用Wilson方法对其叶片进行了气动外形设计,得到了叶片展向上不同翼型面处的外形参数。然后运用SOLIDWORKS对风轮进行几何建模。将叶片的几何模型导入Ansys Workbench中划分流场网格,然后选用CFX求解器对额定工况和10个非设计工况下的叶片模型进行气动计算。求解结束后在CFX-Post中对额定工况下的模型进行了流场分析,通过观察计算结果,分析了压力分布、展向上不同翼型面的流线与速度分布以及产生气动升力的机理。此外,利用计算结果对全部11个工况下的模型进行了气动性能分析,并发现该风机的最佳叶尖速比应该在7附近,而现实中额定工况下仅达到了 3.6,相应的功率系数也仅为0.294,与预期值0.3744仍有较大差距。由此提出了改进方案,为该风机后续的气动设计优化提供了设计依据。本文对叶片进行载荷分析并参考铺层设计规范,初步拟定铺层方案;然后使用Ansys ICEM对叶片进行结构网格的划分,运用Ansys建立了叶片的有限元计算模型。针对两种恶劣工况,利用压力耦合技术分别将风压加载到模型外表面的节点处,通过静强度分析,改进蒙皮、主梁等结构的铺层设计方案,使结构满足静强度要求;此外,对叶片结构进行了稳定性分析,结果表明两种工况下结构都满足稳定性要求。最后,对叶片模型进行了模态分析。结果显示叶片一阶固有频率为2.6609,与额定工况的激振频率3.9比较接近,容易发生共振。由此提出了后续的结构合理化设计建议,改变叶片整体或局部的刚度,使固有频率远离风轮转动频率或其它组件的固有频率,避免发生共振。
[Abstract]:The fan blade material used in this paper is glass fiber reinforced epoxy resin matrix composite material. Based on the research of a wind turbine with rated output power of 20KW, the aerodynamic shape design and aerodynamic performance analysis of the blade are carried out. The structural design of the blade is analyzed by establishing the finite element model and pressure coupling. The detailed research contents are as follows: the aerodynamic shape design of the blade is carried out by using the Wilson method, and the shape parameters of the blades at different airfoil surfaces are obtained. Then SOLIDWORKS is used to model the wind turbine geometry. The geometric model of the blade is imported into the Ansys Workbench to divide the flow field grid, and then the CFX solver is used to calculate the blade model under rated and 10 non-design conditions. After the solution is solved, the flow field of the model under rated condition is analyzed in CFX-Post. The pressure distribution, the streamline and velocity distribution of different airfoil surfaces and the mechanism of aerodynamic lift are analyzed by observing the calculated results. In addition, the aerodynamic performance of the model under all 11 working conditions is analyzed by using the calculated results. It is found that the optimum blade tip velocity ratio of the fan should be around 7, but only 3.6 under the rated condition in reality. The corresponding power coefficient is only 0.294, which is still quite different from the expected value of 0.3744. Therefore, the improvement scheme is put forward, which provides the design basis for the aerodynamic design optimization of the fan. In this paper, the load analysis of the blade is carried out and the lamination scheme is preliminarily drawn up according to the design specification of the laminate, then the structural grid of the blade is divided by using Ansys ICEM, and the finite element calculation model of the blade is established by using Ansys. In order to meet the requirements of static strength, the wind pressure is loaded into the joints on the outer surface of the model by using pressure coupling technology. Through the static strength analysis, the overlay design scheme of the structure such as skin, main beam and so on is improved to meet the static strength requirement. In addition, the stability analysis of the blade structure is carried out, and the results show that the structure meets the stability requirements under both conditions. Finally, the modal analysis of the blade model is carried out. The results show that the first order natural frequency of the blade is 2.6609, which is close to the rated excitation frequency of 3.9 and is prone to resonance. Therefore, the following structural rationalization design proposal is put forward, which changes the whole or local stiffness of the blade so that the natural frequency is far away from the rotating frequency of the wind wheel or the natural frequency of other components, and the resonance is avoided.
【学位授予单位】：哈尔滨工程大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TB33;TM315

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