CFDによるキャンバー翼の空力特性計算と小型垂直軸風車特性予測への応用

概要

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This study carried out CFD (Computational Fluid Dynamics) analyses to build up a database of aerodynamic characteristics of cambered blades like NACA 2518, NACA 4518, and NACA 6518 in order to use it for performance prediction of vertical axis wind turbines (VAWTs). The results showed that, at the neighboring range of zero-angle of attack, the lift coefficients uniformly increase and the moment coefficients uniformly decrease with increasing the Reynolds number. The approximate equations for these dependences on Reynolds number are proposed in the present study. Using the obtained aerodynamic database, performances of virtual small scale VAWTs with cambered blades were predicted by Blade Element Momentum (BEM) method with Double-Multiple Streamtube (DMS) model. Increase in camber of concave-in configuration (usual camber) extends the power curve toward high tip-speed-ratio region although the maximum power decreases. On the contrary, increase in camber of concave-out configuration (inverse camber) diminishes the width of the power-curve peak.