基于CFD的Savonius风机叶片优化研究

发布时间：2018-05-20 12:36

本文选题：Savonius风机 + 扭曲叶片　；参考：《浙江大学》2014年硕士论文

【摘要】：能源是推动经济发展、促进社会进步的重要基础,当今世界正面临矿产资源耗竭的硬性制约和全球环境污染的巨大压力,因此改进能源产业结构,开发可再生能源,已成为全球关注的焦点。风能是一种清洁无污染的可再生能源,由于其储量丰富,开发成本较低,随着我国能源产业结构的改革,风能的开发利用必将对经济、社会和环境协调发展产生深远影响。风力发电是目前技术较为成熟的一种风能利用方式,垂直轴风机在小型风力发电领域应用比较广泛,其中Savonius风机由于启动风速较低、气动噪声较小不受风向限制等特点受到广泛关注。但是Savonius风机输出的转矩具有周期变化的特点,周期性的转矩会导致风机输出功率的变化,容易引起电力系统电压与频率的变动,也会对风机的旋转轴产生频繁的冲击,影响风机的耐久性；同时由于主要依靠迎风面的动力矩与阻力矩之差来做功,Savonius风机的动转矩系数较低,导致风能利用系数较低。叶片是风机最重要的部件之一,叶片结构的优化设计将最大程度的改善风机性能。针对传统Savonius风机的上述缺点,本文提出一种叶片扭曲变形的策略,结合叶片重叠比、叶片高径比、叶片扭角、叶片弧度等叶片结构参数,对叶片结构进行变异设计,并利用计算流体力学(CFD)数值模拟方法研究不同结构参数对于风机动转矩输出性能的影响。首先利用Matlab结合Pro/E对风机叶片三维模型进行参数化建模；然后利用ANSYS Workbench作为协同仿真环境平台建立仿真体系,依据Meshing中制定的网格划分策略和Fluent中设置的求解方案,对不同结构参数Savonius风机叶片的旋转运动进行动态仿真。利用多项式回归、正交试验、交互作用试验等数据分析方法,对不同结构参数进行合理的试验安排。以降低风机叶片动转矩震荡幅度、提高整体动转矩输出能力为优化目标,以动转矩系数曲线、动转矩系数极差、平均动转矩系数等为评价指标,对不同结构参数风机叶片的动转矩输出性能进行分析对比,确定合理的叶片结构参数分布范围,并根据叶片附近压强分布、速度矢量分布等流场特征分析叶片各结构参数变化对于风机叶片动转矩输出性能的影响机理。利用流固耦合仿真分析方法,根据叶片表面应力分布及形变分布对优化前后Savonius风机叶片的力学性能进行分析对比,对比发现优化后叶片结构强度有所下降,故设计隔板作为扭曲叶片的辅助结构以改善其力学性能。以叶片动转矩输出性能为优化目标,对隔板参数进行优化分析,确定合理的隔板分布方式,利用流固耦合仿真分析方法验证其力学性能,并根据流场特征分析隔板作用机理。本文以叶片动转矩输出性能为优化目标,采用叶片扭曲策略和添加辅助结构等方式对Savonius风机叶片进行了结构优化设计,优化过程中所得到的数据及结论可以为工程应用中风机叶片的设计提供数据支持,以降低工程设计的工作量和盲目性；文中叶片各结构参数变化以及辅助结构对于动转矩输出性能的影响机理,可以为进一步的研究提供理论支持。
[Abstract]:Energy is an important basis for promoting economic development and promoting social progress. Today, the world is facing the hard constraints of the depletion of mineral resources and the enormous pressure of the global environmental pollution. Therefore, the improvement of the energy industry structure and the development of renewable energy has become the focus of the global concern. The development and utilization of wind energy will have a profound influence on the coordinated development of economy, society and environment with the reform of the energy industry structure in China.
Wind power generation is a more mature method of wind energy utilization at present. Vertical shaft fan is widely used in the field of small wind power generation. The Savonius fan is widely concerned because of low starting wind speed, small aerodynamic noise and no wind direction restriction. But the torque of Savonius fan output has the characteristic of periodic variation. The periodic torque will lead to the change of the output power of the fan, which can easily cause the change of the voltage and frequency of the power system. It will also have frequent impact on the rotating shaft of the fan, and affect the durability of the fan. At the same time, the dynamic torque coefficient of the Savonius fan is low because it mainly depends on the difference of the dynamic moment of the upwind surface and the resistance moment. The utilization coefficient of wind energy is low.
Blade is one of the most important parts of the fan, and the optimum design of the blade structure will improve the performance of the fan to the greatest extent. In view of the shortcomings of the traditional Savonius fan, a strategy of blade distortion is proposed, which combines blade overlap ratio, blade height to diameter ratio, blade twist angle, blade arc and so on, and the blade structure is carried out. Variation design, and using computational fluid dynamics (CFD) numerical simulation method to study the influence of different structural parameters on the performance of wind motor torque output. First, Matlab combined with Pro/E is used to model the 3D model of fan blade, and then ANSYS Workbench is used as a simulation environment platform to build simulation system, based on Meshing The meshing strategy and the solution scheme set up in Fluent are used to dynamically simulate the rotational motion of Savonius blades with different structural parameters.
By using data analysis methods such as polynomial regression, orthogonal test and interaction test, the reasonable experimental arrangement for different structural parameters is carried out to reduce the dynamic torque vibration amplitude of the fan blade and improve the overall dynamic torque output capacity as the optimization target. The dynamic torque coefficient curve, the dynamic torque coefficient extreme difference, the average dynamic torque coefficient and so on are the evaluation points. The dynamic torque output performance of the fan blade with different structural parameters is analyzed and compared, and the reasonable distribution range of the blade structure parameters is determined. According to the pressure distribution near the blade and the velocity vector distribution, the influence mechanism of the change of the structural parameters of the blade on the dynamic torque output performance of the fan blade is analyzed.
Based on the flow and solid coupling simulation analysis method, the mechanical properties of Savonius fan blades were analyzed and compared according to the stress distribution and deformation distribution of the blade surface. It was found that the structural strength of the blade was decreased after the optimization, so the design partition was used as the auxiliary structure of the twisted blade to improve its mechanical performance. The dynamic torque transmission of the blade was carried out. The performance is the optimization target, the partition parameter is optimized and the reasonable partition mode is determined. The mechanics performance of the partition is verified by the fluid solid coupling simulation analysis method, and the function mechanism of the baffle is analyzed according to the characteristics of the flow field.
In this paper, the blade dynamic torque output performance is optimized, the blade twisting strategy and auxiliary structure are used to optimize the structure of the blade of the Savonius fan. The data and conclusions obtained in the optimization process can provide data support for the design of the apoplexy blade in the engineering application, in order to reduce the workload of the engineering design. The influence mechanism of the changes of the structure parameters and the auxiliary structure on the dynamic torque output performance in this paper can provide theoretical support for further research.
【学位授予单位】：浙江大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM315

【参考文献】