| 摘要 |
A rotor blade (1) comprises a main blade (2) having a substantially fixed chord length (C), a front tip blade (3) having a chord length (C1) smaller than that of the main blade and connected to the main blade so that a front edge (3a) thereof is continuous with a front leading edge (2a) of the main blade, and a rear tip blade (4) having a chord length (C2) greater than that of the front tip blade and connected to the main blade so that a trailing edge thereof is continuous with a trailing edge of the main blade. The blade incidence angle (theta1, theta2), the washout angle (delta1, delta2) and so on of at least either the front tip blade or the rear tip blade, the respective lengths (R1, R2) of the front tip blade (3) and the rear tip blade (4), and the anhedral angle (eta) of the rear tip blade (4) are determined so that tip vortices generated by the front tip blade (3) and the rear tip blade (4) cancel each other to suppress BVI noise.
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