升力型與阻力型風力發電效能比較

Abstract

本研究將利用流體力學套裝軟體 Fluent 來對垂直軸式的升力型與阻力型風車的性能與扭矩進行探討，主要改變參數為周速比。對於阻力型Savonius風車的結構進行探討以得到其最佳效能，而探討的參數為重疊比。本研究所使用的升力型風車為H型風車，阻力型風車則使用Savonius 風車。此外也將對阻力型 Savonius 風車進行四顆系統排列來探討效能差異。對於升力型與阻力型的風車分別有與文獻佐證。 由模擬結果可得，阻力型Savonius風車在重疊比0.15得到最佳效能。而在升力與阻力型風車比較上，在較高周速比時升力型風車的效能會優於阻力型，而阻力型風車適合運作在較低周速比處。升力型風車其優勢在於其最佳效能值較阻力型風車多1.52倍，但是其扭矩值太低造成升力型風車的啟動性較差。相對來說阻力型的最佳效能值雖然較差，不過其較佳的扭矩值讓這種風車的啟動性較佳。而四顆系統排列的阻力型Savonius風車由於在運作時彼此之間能產生正向干涉效應，故其整體效能較單顆風車提升1.47倍。

This research employs the computational fluid dynamics (CFD) software, Fluent, to analyze the performance and torque of vertical-axis wind turbines of lift-typed and drag-typed wind turbines. The parameter for simulations is TSR (tip speed ratio). The structure of Savonius wind turbine is tested to identify the optimum performance. The discussion parameter is overlap ratio. The lift-typed wind turbine in this study is H-type one, and the drag-typed wind turbine is Savonius. On the other hand, four Savonius wind turbines in system will be considered, and the comparison to literatures will be given subsequently. Through a series of simulation, the maximum performance of Savonius occurs at the overlap ratio of 0.15. With the comparison between drag-typed and lift-typed turbine, the results show that the lift-typed wind turbine operates at higher TSR, and the Savonius wind turbine works at lower one. The torque value of drag-typed wind turbine is apparently higher than that of lift-typed, especially at lower tip speed ratio. The advantage of lift-typed wind turbine is its maximum power coefficient, and is 1.52 times better than drag-typed. However, its low torque value makes it difficult to operate. On the contrary, the power coefficient of drag-typed wind turbine is a little bit worse than that of the lift-typed one; however, its starting torque is so large that it can generate electric power in low wind speed. On the other hand, the Savonius in system can enhance the performance due to the flow interference occurs between Savonius turbines that produce positive interaction between them.