翼背面にV形溝をつけることによる翼性能改善の効果

概要

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Following the study of drag reduction by machining a V-groove along the surface of a cylinder, the drag reduction of an airfoil was experimentally investigated. The airfoil used in this research was NACA 6508 (10) with a 200 mm chord length. First, experiments were done using the airfoil without grooves. The airfoil was placed in the test section of a cryogenic wind tunnel. The Reynolds number was varied from 3×10^5 to 4×10^7,and the angle of attack from -6°to 12°. Pressure distributions along the surface were measured, and velocity and pressure distributions were also calculated. The effects of the V-grooves on the pressure distributions and form drag and lift were obtained. The form drag coefficient of the suction surface was reduced by 0.025 in an angle of attack range from 1°to 4°. The reduction occures because of the decrease in pressure on the front part of the airfoil suction surface. The lift coefficient is also increased by this reduction in pressure. In the case of a cylinder, there were two reasons for reduction : one is that the laminar boundary layers remain on the surface longer, so the pressure drops in the front part, and the other is that the retardation in flow separation and pressure rise occurs on the back part. In our experiments the reduction of drag of an airfoil was achieved as a result of the front reason.
一般社団法人日本機械学会の論文
1997-09-25