双垂直轴风力发电机组气动性能优化及其尾流特性研究

哈尔滨工业大学工程硕士学位论文

Abstract

With the large-scale exploitation of traditional fossil fuels, problems such as energy crisis have seriously affected the human society. Therefore, shifting towards clean and renewable energy such as wind energy is imperative. Wind turbines are commonly used to harness wind energy, given that vertical axis wind turbines (VAWTs) have the advantages of small size, low noise, suitable for working under turbulent flow, etc. The numerical simulation was used to study the aerodynamic performance and wake characteristics of VAWTs.

An optimal computational fluid dynamics (CFD) mode of a standalone VAWT was selected via independence studies of parameters. At the same time, the results were compared with the previous experimental data, and a good agreement was found. Through the research on the aerodynamic performance of a standalone VAWT, it was found that with the increase of blade speed ratios (BSRs), the airflow flow phenomenon was significant. According to comparisons before and after the correction, the two-dimensional CFD simulations tended to overpredict the power coefficients at high BSRs. Through the analysis of the wake characteristics, it was observed that with the increase of BSRs, the wake velocity recovery became improved. In the cross-stream direction, the influence of wake flows was within one turbine diameter (1D).

Taguchi robust design method was introduced to optimize the aerodynamic performance of the twin VAWTs arranged side by side. The orthogonal table of five parameters and four levels was designed for the optimization analysis. The order of influence of five parameters on the rated BSR was obtained: solidity > pitch angle > airfoil > rotational direction > turbine spacing. Correspondingly, the order of influence of five parameters on the power coefficient was determined: pitch angle > turbine spacing > solidity > airfoil > rotational direction. Through the orthogonal analysis, the parameters of the twin VAWTs under the optimal and worst configurations were determined. It was found that the power coefficients of the optimal and worst configurations of twin VAWTs were raised by 13% and 8%, respectively, from that of their standalone counterparts.

哈尔滨工业大学工程硕士学位论文

With the optimal and worst configurations, the wake characteristics were analyzed. It was found that the twin VAWTs had small wake velocity deficits, and enhanced wake recovery. Based on the analysis results of the aerodynamic performance and wake characteristics, the twin VAWTs with the optimal configuration were taken as the basic unit. Different lateral and longitudinal spacings were used to perform full-factor optimization analysis of turbine layout design. The optimal lateral spacing was 3D, and the longitudinal spacing was 1.2D. It was also observed that the lateral spacing exerted a larger influence on the average power coefficient, whereas the longitudinal spacing had a greater influence on the power density. Through calculations, the average power coefficient with the optimal layout design was 20.3% larger than that of a standalone VAWT.

Keywords:vertical axis wind turbine, CFD simulation, aerodynamic performance, wake characteristics, Taguchi method, optimization analysis

哈尔滨工业大学工程硕士学位论文

摘要 .......................................................................................................................... I ABSTRACT ................................................................................................................ II 第 1 章绪论 (1)

1.1课题背景及研究的目的和意义 (1)

1.2国内外研究现状及分析 (2)

1.2.1 垂直轴风机气动性能研究现状 (2)

1.2.2 垂直轴风机尾流特性研究现状 (4)

1.2.3 垂直轴风机阵列布置研究现状 (6)

1.2.4 国内外文献综述及简析 (7)

1.3本文的主要研究内容 (9)

第 2 章单风机气动性能及尾流特性 (10)

2.1引言 (10)

2.2单风机数值模拟建立及独立性验证 (10)

2.2.1 单风机数值模型简化 (10)

2.2.2 单风机数值模型建立 (11)

2.2.3 计算参数独立性验证 (13)

2.3数值模拟和风洞数据对比分析 (17)

2.3.1 叶片气动力系数修正方法 (18)

2.3.2 切向力系数和径向力系数对比 (19)

2.3.3 数值与试验功率系数对比 (22)

2.4单风机气动性能 (23)

2.4.1 风机内部流场变化情况 (23)

2.4.2 风机叶片气动系数变化情况 (24)

2.5单风机尾流特性 (25)

2.5.1 计算时长选定 (26)

2.5.2 尾流平均速度对比 (27)

2.5.3 不同位置尾流速度对比 (28)

2.5.4 额定尖速比的尾流区域 (31)

2.5.5 不同位置尾流湍流强度对比 (31)

哈尔滨工业大学工程硕士学位论文

2.6本章小结 (32)

第 3 章双风机组气动性能优化 (34)

3.1引言 (34)

3.2田口稳健设计方法 (34)

3.2.1 分析方法及步骤 (34)

3.2.2 品质指标S/N比 (35)

3.3参数设计和正交表建立 (36)

3.3.1 参数的设计和选择 (36)

3.3.2 五因素四水平的正交表 (37)

3.4双风机组优化模拟和分析 (38)

3.4.1 模型的建立以及独立性验证 (38)

3.4.2 额定尖速比变化分析 (43)

3.4.3 正交表中功率性能变化分析 (46)

3.4.4 参数的影响程度 (48)

3.5双风机组的气动性能对比研究 (51)

3.5.1 单双风机功率系数对比 (51)

3.5.2 切向力系数和径向力系数对比 (54)

3.5.3 不同工况风机内部流场对比 (56)

3.6本章小结 (57)

第 4 章双风机组尾流特性及阵列布置优化 (59)

4.1引言 (59)

4.2双风机组尾流特性 (59)

4.2.1 计算时长选定 (59)

4.2.2 尾流平均速度对比 (60)

4.2.3 不同位置尾流速度对比 (61)

4.2.4 不同工况下尾流区域对比 (63)

4.2.5 不同工况下湍流强度对比 (64)

4.3阵列布置模型 (65)

4.3.1 间距选择和模型建立 (66)

4.3.2 计算参数独立性验证 (67)

4.3.3 阵列优化判别指标 (68)

4.4阵列优化分析 (69)

哈尔滨工业大学工程硕士学位论文

4.4.1 不同间距下的分析结果 (69)

4.4.2 横向间距的影响 (72)

4.4.3 纵向间距的影响 (74)

4.5最优阵列分析 (75)

4.5.1 最优阵列的功率系数 (75)

4.5.2 最优阵列的内部流场 (76)

4.5.3 风场阵列布置建议 (79)

4.6本章小结 (79)

结论 (81)

参考文献 (83)

攻读硕士学位期间发表的论文及其它成果 (89)

哈尔滨工业大学学位论文原创性声明和使用权限 (90)

致谢 (91)