曲板ブレードを有する水平軸小形風車の開発

～第１報：ロータ性能特性およびPIV によるロータ周りの流れの計測～

抄録

The authors have developed a simplified curved-plate blade of high power coefficient for small wind turbine depending on the design concept of the “Appropriate Technology”. In this study, the shapes of the blade are the tapered type, the straight type and the inversely tapered type and the diameter of all experimental model is 600[mm], number of blades is 5, thickness of the aluminum plate is 2[mm]. The bent angles of these three types of the blades are 10, 20 and 30[deg] respectively. Blades pitch angle can be changed manually at 0, 5, 10 15, 20 and 25[deg]. In the experiment of all rotors, the wind speed in the wind tunnel is set at 10[m/s] and the torque and the corresponding to rotational speed were measured by increasing the load gradually. From the results of the experiment, the power coefficient Cp and the tip speed ratio λ were calculated to obtain the power characteristics for different blade types. From these results, the maximum power coefficient for the tapered type is Cpmax=0.278 when bent angle is 30[deg] and blade pitch angle is 10[deg]. Then, the straight type is Cpmax=0.303 when bent angle is 30[deg] and blade pitch angle is 15[deg]. And the inversely tapered type is Cpmax=0.338 when bent angle is 30[deg] and blade pitch angle is 15[deg]. Thus the most efficient model was the inversely tapered type. In addition to clarify the behavior of air flow around the each rotor at the maximum power coefficient, the visualization test was conducted using the smoke oil, high-speed camera and vector analysis with the PIV system. From the visualization test and PIV analysis, it was clarified that the wind speed of inflow around tip of tapered type is about 7.5[m/s], on the other hand, inversely tapered type is about 8.0[m/s]. From these results, it could presume that the latter type is more effectively converting the air flow into the shaft power than that of the former type.