A high-performance Ishii airfoil was analyzed using both a wind-tunnel and large-eddy simulations at a low- Reynolds-number condition (Re = 23,000). The design guidelines for an airfoil shape with a high lift-to-drag ratio under the aforementioned condition are described by analyses of flowfields and aerodynamic characteristics of the Ishii airfoil. Compared with conventional airfoils, such as the NACA 0012 and NACA 0002, the shape characteristic effects of the Ishii airfoil on its flowfield and aerodynamic characteristics are discussed. The shape on the suction side of the Ishii airfoil can cause delays in the flow separation at low angle of attacks. The separated flow reattaches, and a separation bubble forms even when trailing-edge separation changes to leading-edge separation. The separation bubble contributes to an increase in lift coefficient. In addition, the Ishii airfoil can gain a high positive pressure on the pressure side as compared with the other two symmetric airfoils due to the camber near the trailing edge.Onthe other hand, the pressure drag of the Ishii airfoil, which is a dominant factor of total drag, is considerably smaller than those of the other two airfoils. It was found that the shape on the suction side as well as that on the pressure side (such as the leading-edge roundness and the camber) are very significant in the low-Reynolds-number airfoil with a high lift-todrag ratio.
ASJC Scopus subject areas
- Aerospace Engineering